WO2025154049A1

WO2025154049A1 - Clip configurations for non-invasive peripheral arterial tonometry

Info

Publication number: WO2025154049A1
Application number: PCT/IL2025/050034
Authority: WO
Inventors: Efrat Litman; Eilon Livne; Nimrod KADIM
Original assignee: Itamar Medical Ltd
Current assignee: Itamar Medical Ltd
Priority date: 2024-01-19
Filing date: 2025-01-12
Publication date: 2025-07-24
Anticipated expiration: 2026-07-19

Abstract

A clip apparatus for non-invasive peripheral arterial tonometry measurements includes a first clip member having a first surface configured to receive a first portion of a digit of a patient and a second clip member coupled to the first clip member and having a second surface configured to receive a second portion of the digit. The first clip member and the second clip member are configured to receive the digit in a digit space defined by the first and second surfaces. One of the first clip member or the second clip member is movable toward the other of the first clip member or the second clip member to generate pressure within the digit space. The clip apparatus also includes a uniform pressure applicator configured to uniformly distribute the pressure generated within the digit space to a dorsal portion of the digit and a volar portion of the digit.

Description

CLIP CONFIGURATIONS FOR NON-INVASIVE PERIPHERAL ARTERIAL TONOMETRY

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to United States Provisional Patent Application No. 63/622,928 filed on January 19, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to clip configurations for noninvasive measurement of one or more physiological parameters of a wearer or patient.

BACKGROUND

[0003] Medical devices can be used for monitoring a variety of physiological signals or parameters of a patient, including, for example, signals relating to breathing or respiratory parameters (e.g., blood oxygen levels, oxygen saturation, or oxygen uptake), as well as parameters for blood flow (e.g., heart rate or blood pressure) and blood composition (e.g., glucose concentration). Such devices can be used in connection with monitoring patients for certain sleep disordered breathing (SDB) conditions. For example, certain clinical applications use such devices for monitoring the patient’s physiological signals or parameters.

[0004] It is desirable therefore to improve the construction, design, and implementation of such devices, including optical digital probes used in or with such devices, to enhance their comfort and reliability over the duration of wear by the patient.

SUMMARY

[0005] According to an example of the disclosure, a clip apparatus for non-invasive peripheral arterial tonometry measurements includes a first clip member with a first surface configured to receive a first portion of a digit of a patient and a second clip member coupled to the first clip member and including a second surface configured to receive a second portion of the digit. The first clip member and the second clip member are configured to receive the digit in a digit space defined by the first and second surfaces. One of the first clip member or the second clip member is movable toward the other of the first clip member or the second clip member to generate pressure within the digit space. The clip apparatus also includes a uniform pressure applicator configured to uniformly distribute the pressure generated within the digit space to a dorsal portion of the digit and a volar portion of the digit and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space. The peripheral arterial tone sensor is configured to be positioned at or proximate to the digit and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0006] According to another example of the disclosure, a clip for non-invasive peripheral arterial tonometry measurements includes a first clip member having a first surface configured to receive a first portion of a digit of a patient and a second clip member movably coupled to the first clip member and having a second surface configured to receive a second portion of the digit. The first clip member and the second clip member are configured to receive the digit of a patient in a digit space defined by the first and second surfaces. The first clip member and the second clip member are movable to generate an axial pressure within a range of about 40 mmHg to about 80 mmHg against a distal tip of the digit when the digit is received within the digit space. The clip also includes at least one optical-based peripheral arterial tonometry sensor disposed within the digit space configured to be positioned at or proximate the digit, and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0007] According to another aspect of the disclosure, a clip apparatus for non-invasive peripheral arterial tonometry measurements includes a pair of clip members movable relative to one another to an open configuration for receiving a digit of a patient between the pair of clip members and a closed configuration for clipping the clip apparatus to the digit of the patient. In the closed configuration, the pair of clip members are configured to pressurize at least one fluid-filled chamber around the digit such that pressure applied to each of a dorsal portion of the digit and a volar portion of the digit is (i) a uniform pressure and (ii) within a predetermined range. The clip apparatus also includes at least one optical-based peripheral arterial tonometry sensor coupled to at least one of the pair of clip members and configured for, in the closed configuration, operative placement at or proximate the digit and generation of signals representative of a peripheral arterial tonometry waveform of the patient.

[0008] Preferred and non-limiting examples of the present disclosure will now be described in the following numbered clauses: [0009] Clause 1: A clip apparatus for non-invasive peripheral arterial tonometry measurements, the clip apparatus comprising: a first clip member comprising a first surface configured to receive a first portion of a digit of a patient; a second clip member coupled to the first clip member and comprising a second surface configured to receive a second portion of the digit, wherein the first clip member and the second clip member are configured to receive the digit in a digit space defined by the first and second surfaces, and wherein one of the first clip member or the second clip member is movable toward the other of the first clip member or the second clip member to generate pressure within the digit space; a uniform pressure applicator configured to uniformly distribute the pressure generated within the digit space to a dorsal portion of the digit and a volar portion of the digit; and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space, and configured to be positioned at or proximate to the digit and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0010] Clause 2: The clip apparatus of clause 1, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip apparatus comprises a clip apparatus of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

[0011] Clause 3: The clip apparatus of clause 1 or clause 2, wherein the clip apparatus is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one optical-based peripheral arterial tonometry sensor, the indices comprising at least one of a respiratory disturbance index, an apnea- hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

[0012] Clause 4: The clip apparatus of any of clauses 1-3, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

[0013] Clause 5 : The clip apparatus of any of clauses 1 -4, further comprising a biasing member connected between the first clip member and the second clip member that biases at least one of the first clip member or the second clip member toward the other of the first clip member or the second clip member, thereby generating the pressure.

[0014] Clause 6: The clip apparatus of clause 5, wherein the biasing member comprises a spring comprising a first end connected to the first clip member and a second end connected to the second clip member.

[0015] Clause 7 : The clip apparatus of any of clauses 1 -6, wherein the uniform pressure applicator comprises at least one membrane configured to apply pressure to the digit due to elastic deformation of the at least one membrane by the digit.

[0016] Clause 8: The clip apparatus of clause 7, wherein the uniform pressure applicator is configured to apply substantially uniform pressure to digits of different sizes received within the digit space resulting from the elastic deformation of the at least one membrane.

[0017] Clause 9: The clip apparatus of any of clauses 1-8, wherein the first surface of the first clip member is configured to receive the dorsal portion of the digit and the second surface of the second clip member is configured to receive the volar portion of the digit.

[0018] Clause 10: The clip apparatus of any of clauses 1-9, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

[0019] Clause 11 : The clip apparatus of any of clauses 1-10, wherein the at least one optical -based peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the first clip member or the second clip member and at least one detector mounted to the other of the first clip member or the second clip member.

[0020] Clause 12: The clip apparatus of any of clauses 1-11, wherein the at least one optical -based peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to the second clip member.

[0021] Clause 13: The clip apparatus of any of clauses 1-12, wherein the uniform pressure applicator comprises a first membrane configured to be displaced by the digit as the digit is received within the digit space and which defines a first chamber containing a fluid and a second membrane defining a second chamber communicating with the first chamber, wherein combined volumes of the two chambers maintain a substantially constant uniform pressure about the digit, and wherein the value of the maintained substantially constant uniform pressure varies within a predetermined range for digits of different sizes received in the digit space defined by the first and second surfaces.

[0022] Clause 14: The clip apparatus of clause 13, wherein the first chamber communicates with the second chamber through openings in at least one of the first clip member or the second clip member, and wherein the fluid comprises at least one of a liquid, gel, hydrogel, gas, or foam.

[0023] Clause 15: The clip apparatus of any of clauses 1-14, wherein the uniform pressure applicator is configured to uniformly distribute the pressure generated within the digit space to the dorsal portion of the digit, the a volar portion of the digit, and a distal tip of the digit when the digit is received within the digit space.

[0024] Clause 16: The clip apparatus of any of clauses 1-15, wherein the uniform pressure applicator is configured to apply a uniform pressure of from about 40 mmHg to about 80 mmHg to surfaces of the volar portion, the dorsal portion, and the distal tip of the digit.

[0025] Clause 17: The clip apparatus of any of clauses 1-16, wherein the applied uniform pressure results from a combination of the pressure generated from (i) the movement of at least one of the first clip member or the second clip member toward the other of the first clip member or the second clip member and (ii) elastic deformation of at least one membrane of the uniform pressure applicator applied to the surfaces of the digit.

[0026] 18: The clip apparatus of clause 17, wherein the uniform pressure applicator is configured to apply the uniform pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

[0027] Clause 19: The clip apparatus of any of clauses 1-18, wherein the uniform pressure applicator is configured to maintain a shape for the digit received in the digit space, thereby allowing the clip apparatus to be removed from and reattached to the digit, and wherein the uniform pressure applicator is configured to continue to uniformly distribute the generated pressure to the dorsal portion, the volar portion, and the distal tip of the digit when the apparatus is reattached to the digit.

[0028] Clause 20: The clip apparatus of any of clauses 1-19, further comprising at least one adhesive configured to adhere the apparatus to the digit.

[0029] Clause 21: The clip apparatus of any of clauses 1-20, further comprising an attachment device comprising a fastening portion connected to an external surface of at least one of the first clip member or the second clip member and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

[0030] Clause 22: The clip apparatus of any of clauses 1-21, wherein the first clip member is hingedly connected to the second clip member exerting a biasing force sufficient to retain the digit within the digit space.

[0031] Clause 23: The clip apparatus of any of clauses 1-22, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the first clip member and the second clip member than to the distal end of the first clip member and the second clip member.

[0032] Clause 24: The clip apparatus of any of clauses 1-23, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the first clip member and the second clip member than to either the proximal end or the distal end of the first clip member and the second clip member.

[0033] Clause 25: The clip apparatus of any of clauses 1-24, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the first clip member and the second clip member than to the proximal end of the first clip member and the second clip member.

[0034] Clause 26: The clip apparatus of clause 25, wherein the first clip member and the second clip member are configured such that the distal tip of the digit is received proximate to the distal end of the first and second clip members.

[0035] Clause 27: The clip apparatus of any of clauses 1-26, wherein the uniform pressure applicator comprises a first membrane attached to the first clip member and a second membrane attached to the second member.

[0036] Clause 28: The clip apparatus of clause 27, wherein the first membrane at least partially encloses a first portion of the digit space configured to receive the dorsal portion of the digit and the second membrane at least partially encloses a second portion of the digit space configured to receive the volar portion of the digit.

[0037] Clause 29: The clip apparatus of any of clauses 1-28, wherein the uniform pressure applicator comprises a first membrane forming a plurality of fluidly coupled bladders defining a first portion of the digit space and a second membrane forming a plurality of fluidly coupled bladders defining a second portion of the digit space.

[0038] Clause 30: The clip apparatus of clause 29, wherein the plurality of fluidly coupled bladders formed by the first membrane and/or the plurality of fluidly coupled bladders formed by the second membrane are configured to permit fluid to pass between adjacent bladders as the digit is received within the digit space, thereby providing the uniform pressure.

[0039] Clause 31 : The clip apparatus of any of clauses 1 -30, wherein the first clip member is non- symmetrical to the second clip member.

[0040] Clause 32: A clip for non-invasive peripheral arterial tonometry measurements, the clip comprising: a first clip member comprising a first surface configured to receive a first portion of a digit of a patient; a second clip member movably coupled to the first clip member and comprising a second surface configured to receive a second portion of the digit, wherein the first clip member and the second clip member are configured to receive the digit of a patient in a digit space defined by the first and second surfaces, and wherein the first clip member and the second clip member are movable to generate an axial pressure within a range of about 40 mmHg to about 80 mmHg against a distal tip of the digit when the digit is received within the digit space; and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space configured to be positioned at or proximate the digit, and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0041] Clause 33: The clip of clause 32, comprising a distal applicator configured to distribute the generated axial pressure to the distal tip of the digit.

[0042] Clause 34: The clip of clause 33, further comprising a hinge between the first clip member and the second clip member, wherein the distal applicator covers the hinge.

[0043] Clause 35: The clip of clause 33 or clause 34, wherein the distal applicator comprises a portion of a fluid filled membrane comprising an inwardly facing surface configured to contact the distal tip of the digit.

[0044] Clause 36: The clip of any of clauses 32-35, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip comprises a clip of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

[0045] Clause 37: The clip of any of clauses 32-36, wherein the clip is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one optical-based peripheral arterial tonometry sensor, the indices comprising at least one of a respiratory disturbance index, an apnea-hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

[0046] Clause 38: The clip of any of clauses 32-37, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

[0047] Clause 39: The clip of clause 33, further comprising a radial pressure applicator disposed within the digit space for applying radial pressure to volar and dorsal surfaces of the digit.

[0048] Clause 40: The clip of clause 39, wherein the radial pressure applicator and the distal applicator are configured to uniformly distribute pressure generated within the digit space to the dorsal portion of the digit, the volar portion of the digit, and the distal tip of the digit when the digit is received within the digit space.

[0049] Clause 41: The clip of clause 39 or clause 40, wherein the radial pressure applicator comprises at least one membrane configured to apply pressure to the digit due to elastic deformation of the at least one membrane by the digit.

[0050] Clause 42: The clip of any of clauses 41, wherein the radial pressure applicator and the distal applicator are configured to apply substantially uniform pressure to the digit received within the digit space resulting from the elastic deformation of the at least one membrane.

[0051] Clause 43: The clip of clause 42, wherein the radial pressure applicator and the distal applicator are configured to apply substantially uniform pressure to digits of different sizes received within the digit space resulting from the elastic deformation of the at least one membrane. [0052] Clause 44: The clip of any of clauses 32-43, wherein the first surface of the first clip member is configured to receive a dorsal portion of the digit and the second surface of the second clip member is configured to receive a volar portion of the digit.

[0053] Clause 45: The clip of any of clauses 32-44, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

[0054] Clause 46: The clip of any of clauses 32-45, wherein the at least one optical-based peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the first clip member or the second clip member and at least one detector mounted to the other of the first clip member or the second clip member.

[0055] Clause 47: The clip of any of clauses 32-46, wherein the at least one optical -based peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to the second clip member.

[0056] Clause 48: The clip of any of clauses 32-47, wherein the first clip member and the second clip member are configured to apply the axial pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

[0057] Clause 49: The clip of any of clauses 32-48, wherein the first clip member or the second clip member are configured to maintain a shape for a digit received in the digit space, thereby allowing the clip to be removed from and reattached to the digit, and wherein the first clip member and the second clip member are configured to continue to apply axial pressure to the distal tip of the digit when the clip is reattached to the digit.

[0058] Clause 50: The clip of any of clauses 32-49, further comprising at least one adhesive configured to adhere the clip to the digit.

[0059] Clause 51: The clip of any of clauses 32-50, further comprising an attachment device comprising a fastening portion connected to an external surface of at least one of the first clip member or the second clip member and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

[0060] Clause 52: The clip of any of clauses 32-51, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the first clip member and the second clip member than to the distal end of the first clip member and the second clip member.

[0061] Clause 54: The clip of any of clauses 32-52, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the first clip member and the second clip number than to either the proximal end or the distal end of the first clip member and the second clip member.

[0062] Clause 55: The clip of any of clauses 32-54, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the first clip member and the second clip member than to the proximal end of the first clip member and the second clip member.

[0063] 56: The clip of any of clauses 32-55, wherein the first clip member is non-symmetrical to the second clip member.

[0064] Clause 57: A clip apparatus for non-invasive peripheral arterial tonometry measurements, the clip apparatus comprising: a pair of clip members movable relative to one another to an open configuration for receiving a digit of a patient between the pair of clip members and a closed configuration for clipping the clip apparatus to the digit of the patient, wherein, in the closed configuration, the pair of clip members are configured to pressurize at least one fluid-filled chamber around the digit such that pressure applied to each of a dorsal portion of the digit and a volar portion of the digit is (i) a uniform pressure and (ii) within a predetermined range; and at least one optical-based peripheral arterial tonometry sensor coupled to at least one of the pair of clip members and configured for, in the closed configuration, operative placement at or proximate the digit and generation of signals representative of a peripheral arterial tonometry waveform of the patient.

[0065] Clause 58: The clip apparatus of clause 57, wherein the at least one fluid-filled chamber is enclosed within at least one membrane comprising an inwardly facing surface configured to contact at least one of the dorsal portion, the volar portion, or a distal tip of the digit.

[0066] Clause 59: The clip apparatus of clause 57 or clause 58, further comprising at least one of a liquid, gas, gel, hydrogel, or foam within the at least one fluid-filled chamber.

[0067] Clause 60: The clip apparatus of any of clauses 57-59, wherein the pair of clip members are configured to pressurize the at least one fluid-filled chamber around the digit such that pressure applied to each of the dorsal portion of the digit, the volar portion of the digit, and a distal tip of the digit.

[0068] Clause 61: The clip apparatus of clause 60, wherein the uniform pressure comprises a radial component configured to be applied to the volar portion and/or the dorsal portion of the digit and an axial component configured to be applied to the distal tip of the digit.

[0069] Clause 62: The clip apparatus of any of clauses 57-61, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip apparatus comprises a clip apparatus of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

[0070] Clause 63: The clip apparatus of any of clauses 57-62, wherein the clip apparatus is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one sensor optical-based peripheral arterial tonometry, the indices comprising at least one of a respiratory disturbance index, an apnea- hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

[0071] Clause 64: The clip apparatus of any of clauses 57-63, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

[0072] Clause 65: The clip apparatus of any of clauses 57-64, further comprising a biasing member connected between the pair of clip members that biases at least one of the pair of clip members toward the other of the pair of clip members, thereby generating the pressure.

[0073] Clause 66: The clip apparatus of clause 65, wherein the biasing member comprises a spring comprising a first end connected to the first clip member and a second end connected to the second clip member.

[0074] Clause 67: The clip apparatus of any of clauses 57-66, wherein the uniform pressure applicator is configured to apply substantially uniform pressure to digits of different sizes received within the digit space.

[0075] Clause 68: The clip apparatus of any of clauses 57-67, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

[0076] Clause 69: The clip apparatus of any of clauses 57-68, wherein the at least one opticalbased peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the pair of clip members and at least one detector mounted to the other of the pair of clip members.

[0077] Clause 70: The clip apparatus of any of clauses 57-69, wherein the at least one opticalbased peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to one of the pair of clip members.

[0078] Clause 71: The clip apparatus of any of clauses 57-70, wherein the uniform pressure applicator is configured to apply a uniform pressure of from about 40 mmHg to about 80 mmHg to surfaces of the volar portion and the dorsal portion of the digit.

[0079] Clause 72: The clip apparatus of any of clauses 57-71, wherein the uniform pressure applicator is configured to apply the uniform pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

[0080] Clause 73: The clip apparatus of any of clauses 57-72, wherein the uniform pressure applicator is configured to maintain a shape for a digit received in the digit space, thereby allowing the clip apparatus to be removed from and reattached to the digit, and wherein the uniform pressure applicator is configured to continue to uniformly distribute the generated pressure to the dorsal portion and the volar portion of the digit when the apparatus is reattached to the digit.

[0081] Clause 74: The clip apparatus of any of clauses 57-73, further comprising at least one adhesive configured to adhere the clip apparatus to the digit.

[0082] Clause 75: The clip apparatus of any of clauses 57-74, further comprising an attachment device comprising a fastening portion connected to an external surface of the pair of clip members and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

[0083] Clause 76: The clip apparatus of any of clauses 57-75, wherein one of the pair of clip members is hingedly connected to the other of the pair of clip members exerting a biasing force sufficient to retain the digit within the digit space.

[0084] Clause 77: The clip apparatus of any of clauses 57-76, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the pair of clip members than to the distal end of the pair of clip members.

[0085] Clause 78: The clip apparatus of any of clauses 57-77, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the pair of clip members than to either the proximal end or the distal end of the pair of clip members or to the distal end of the pair of clip members.

[0086] Clause 79: The clip apparatus of any of clauses 57-78, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the pair of clip members than to the proximal end of the pair of clip members. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Various aspects of the disclosure are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of various examples, and are incorporated in and constitute a part of this specification, but are not intended to limit the scope of the disclosure. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and examples. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. A quantity of each component in a particular figure is an example only and other quantities of each, or any, component could be used. [0088] FIG. 1 is a schematic drawing of a wearable medical device including a digit clip and a wearable monitor, according to an aspect of the present disclosure;

[0089] FIG. 2 is a graph showing a relationship between pressure and volume for digit clip, according to an aspect of the present disclosure;

[0090] FIG. 3A is a side view of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0091] FIG. 3B is a side view of the digit clip of FIG. 3A in an open position;

[0092] FIG. 3C is an exploded view of the digit clip of FIG. 3A;

[0093] FIG. 3D is a cross-sectional view of the digit clip of FIG. 3 A;

[0094] FIG. 3E is a cross-sectional view of the digit clip of FIG. 3 A including a digit inserted into the digit clip;

[0095] FIG. 3F is a top view of the digit clip of FIG. 4A connected to a finger of a patient;

[0096] FIG. 4A is a side view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0097] FIG. 4B is a side view of the digit clip of FIG. 4A in an open position;

[0098] FIG. 4C is an exploded view of the digit clip of FIG. 4A;

[0099] FIG. 4D is a side view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0100] FIG. 4E is a side view of the digit clip of FIG. 4D in an open position;

[0101] FIG. 5A is a side view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0102] FIG. 5B is a side view of the digit clip of FIG. 5A in an open position;

[0103] FIG. 5C is an exploded view of the digit clip of FIG. 5A;

[0104] FIG. 6A is a cross-sectional view of another example of a wearable medical device comprising a digit clip according to another example of the present disclosure;

[0105] FIG. 6B is a cross-sectional view of the digit clip of FIG. 3 A including a digit inserted into the digit clip;

[0106] FIG. 7 is a cross-sectional view of another example of a wearable medical device comprising a digit clip and showing a digit inserted into the digit clip, according to an aspect of the present disclosure;

[0107] FIG. 8A is a cross-sectional view of another example of a wearable medical device comprising a digit clip and an optical-based physiological sensors, according to an aspect of the present disclosure;

[0108] FIG. 8B is a cross-sectional view of another example of a wearable medical device comprising a digit clip and optical-based physiological sensors, according to an aspect of the present disclosure;

[0109] FIG. 9A is a side view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0110] FIG. 9B is a side view of the digit clip of FIG. 9A in an open position;

[0111] FIG. 10A is a side view of another example of wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0112] FIG. 10B is a side view of the digit clip of FIG. 10A in an open position;

[0113] FIG. 11A is a schematic drawing showing another example of a wearable medical device comprising a digit clip including a reusable clip portion and a disposable sleeve, according to an aspect of the present disclosure;

[0114] FIG. 1 IB is a side view of the digit clip of FIG. 11 A;

[0115] FIG. 12A is a side view of another example of a wearable medical device comprising a digit clip, according to an aspect of the present disclosure;

[0116] FIG. 12B is a cross sectional view of the digit clip of FIG. 12A;

[0117] FIG. 12C is another cross-sectional view of the digit clip of FIG. 12A;

[0118] FIG. 13 A is a perspective view of another example of a wearable medical device comprising a digit clip, according to another aspect of the present disclosure;

[0119] FIG. 13B is a side view of the digit clip of FIG. 13 A;

[0120] FIG. 13C is a perspective view of another example of a wearable medical device comprising a digit clip, according to another aspect of the present disclosure;

[0121] FIG. 13D is a side view of the digit clip of FIG. 13C;

[0122] FIG. 14A is a perspective view of a wearable medical device comprising a digit clip and an attachment device, according to another aspect of the present disclosure;

[0123] FIG. 14B is a perspective view of a wearable medical device comprising another example of an attachment device, according to another aspect of the present disclosure;

[0124] FIG. 15A is a perspective view of a wearable medical device comprising another example of an attachment device, according to another aspect of the present disclosure;

[0125] FIG. 15B is a perspective view of a wearable medical device comprising another example of an attachment device, according to another aspect of the present disclosure;

[0126] FIG. 16A is a cross sectional view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0127] FIG. 16B is a cross-sectional view of the digit clip of FIG. 16A;

[0128] FIG. 17A is a cross sectional view of another example of a wearable medical device comprising a digit clip in a closed position, according to an aspect of the present disclosure;

[0129] FIG. 17B is a cross-sectional view of the digit clip of FIG. 17A;

[0130] FIG. 18A is a schematic drawing of components of the wearable medical device of FIG. 1 ; [0131] FIG. 18B is a schematic drawing showing the wearable medical device worn by a patient; [0132] FIGS. 19A-19C are schematic drawings of a physiological monitoring system including a wearable medical device comprising a digit clip, according to aspects of the present disclosure; and

[0133] FIGS. 20A-20F are user interface screens that can be displayed on a mobile or computer device guiding a patient in performing at at-home medical test, according to aspects of the present disclosure.

DETAILED DESCRIPTION

[0134] This disclosure relates to optical digit clip and clip apparatus configurations for attachment to a patient’s digit to non-invasively obtain optical measurements. The clip configurations described herein detect physiological signals including photoplethysmogram (PPG) signals while applying pressure to the patient’s digit. In implementations, the optical digit clips and clip apparatus disclosed herein can be used for non-invasively measuring an arterial tone of the patient, including a peripheral arterial tone of the patient taken at, for taken, a peripheral location on a patient.

[0135] As described in further detail herein, an example optical digit clip comprises optical-based physiological sensors comprising one or more optical light emitting diodes (LEDs) configured to emit light-based radiation at a preconfigured wavelength or range of wavelengths while pressure is applied to the digit. Briefly, PPG can be measured using light sources of various wavelengths. The clip configurations disclosed herein can also measure peripheral arterial tone reflecting pulsatile volume changes of the patient’s arteries. For example, the changes can be measured at the peripheral vascular beds at the distal end of the patient’s fingers over sustained periods of time. In some examples, the clip can be configured to apply a uniform pressure field to the patient’s finger, e.g., by completely encapsulating the measured portion of the patient’s digit (e.g., dorsal portions, volar portions, and/or side portions), including a distal tip of the digit. The clip configuration can advantageously apply near diastolic blood pressure levels of pressure within the clip and thus optimize a dynamic range of the peripheral arterial tone signal. The clip configurations can advantageously prevent confounding veno-arteriolar reflex vasoconstriction at the measurement site. In some examples, the clip configuration can advantageously reduce respiratory and movement artifacts and thus facilitate accurate long term measurement.

[0136] In some examples, a vascular bed of a distal portion of the digit (e.g., a phalanx of the finger) can be a useful location for sympathetic nervous system mediated vasoconstrictor activity. The peripheral arterial tone response to sympathetic changes provides an ability for accurate and robust measurement in a number of sleep and sleep related clinical areas, including for home sleep testing devices.

[0137] As described in further detail below, the level of applied pressure to the patient’s digit is configured to be at a slightly sub-diastolic blood pressure value or range of values. For example, such value or range of values can optimally counterbalance arterial wall tension, which otherwise reduces a dynamic range of the recorded peripheral arterial tone signal by restricting arterial wall motion, while avoiding arterial collapse at any stage of the pulse cycle. In examples, enclosing all of the measured digit within the sub-diastolic uniform pressure field prevents venous distention, and thus avoids potential induction of veno-arteriolar reflex local vasoconstriction, while ensuring tissue perfusion.

[0138] When the wavelength of light increases, the depth of penetration through a patient’s tissue also increases. For example, clip configurations described herein can use LED wavelengths in a range of 200 nm to 1000 nm. Light at such wavelengths can reach the epidermis with capillaries, dermis with arterioles, and arteries of subcutaneous tissues, respectively. Major blood vessels and arteries with strong pulsation are generally located in the skin dermis or subcutaneous tissue. Moreover, certain wavelengths and/or wavelength ranges (e.g., wavelengths in range of 600 nm to 950 nm, particularly red 660 nm and infrared 910 nm and 940 nm) are affected by the oxygenation of blood and as such are better suited for oxygen saturation measurements. For peripheral arterial tone measurements, LED lights are configured to be at wavelengths or ranges of wavelengths that are not affected by the oxygenation of the blood. For example, the wavelengths can be in a range of 200 nm to 600 nm. In this regard, all changes in the peripheral arterial tone signal is a reflection of an amount of blood pulsating through the patient’s finger. The clip systems and devices described herein can be used for measurement at the extremities of the human body, such as the patient’s digits, e.g., fingers, toes, and earlobes. Such locations are advantageous for measuring changes in blood volume, because the vascular bed is shallow and widely spread.

[0139] Clip configurations described herein include a light-emitting diode (LED) that emits light, and a photodetector (e.g., a photodiode) that detects the emitted light. In examples, the clip configurations can include transmissive-type and reflective -type clip configurations. For transmissive-type clip configurations, a photodetector is located on the opposite side of the LED, with skin tissues in between. Transmissive-type clip configurations can measure attenuated light intensity after the light passes through skin tissues. For the reflective-type clip configurations, the photodetector is located next to the LED and the photodetector measures attenuated light intensity after the light is reflected from the skin tissues. In some examples, the clip configuration includes LED to irradiate light, and a photodetector to measure the amount of transmitted and/or reflected light. In some examples, the clip configuration includes an emitter driver to drive the LED, a filter to remove noise (e.g., motion and/or interference) artifacts and enhance the quality of the obtained signal, an analog-to-digital converter, and a microprocessor.

[0140] In implementations herein, the uniform pressure is applied throughout the portion of the digit within the clip (e.g., to a dorsal portion of the digit, a volar portion of the digit, and/or to sides of the digit), including the distal tip. For example, applying pressure sufficient to unload arterial wall tension within the portion of the digit within the clip can cause blood to be trapped in and distend the veins distal to the site of pressure application. In such scenarios, clip configurations as disclosed herein advantageously apply counter-pressure to the distal tip of the digit to avoid venous distention distal to the clip, which can induce local veno- arteriolar reflex vasoconstriction. [0141] Implementations are described herein to provide improved medical systems 100 comprising optical digit clips 112 for use with wearable medical devices 110. An example medical system 100 including features of the optical digit clip 112 and wearable medical devices 110 is shown in FIG. 1. The optical digit clip 112 can be configured to apply uniform pressure to various portions of the digit, including a distal end portion or distal tip of the digit, received within the optical digit clip 112, thereby enhancing and improving signal quality of physiological signals detected by sensors of the optical digit clip 112. The wearable medical devices 110 and optical digit clip 112 disclosed herein can be used to monitor a variety of patient physiological signals or parameters during a study period. Optical digit clips 112 can be used in healthcare settings to measure, e.g., a level of oxygen saturation in a patient’s blood, a patient’s arterial pulse, and/or respiratory parameters of the patient. In some examples, the optical digit clip 112 can be attached to a patient’s finger, toe, or earlobe (or other extremity of the patient’s body). In some implementations, an optical digit clip 112 can use light (e.g., visible light, infrared light, or ultraviolet light) to measure the absorption of oxygen in the blood.

[0142] As previously described, in implementations, the optical digit clip 112 can comprise a PPG or oximetry sensor comprising both a light-emitting diode (LED) and a photodetector, which work together to measure the level of oxygen saturation in the patient’s blood by shining a beam of light through the tissue and detecting the amount of light that is absorbed. In implementations, the optical digit clip 112 further comprises a peripheral arterial tone sensor comprising a peripheral arterial tone light-emitting diode (LED) and a photodetector (e.g., either the same photodetector as the PPG sensor or a different photodetector), which work together to measure the pulsating movement of blood within one or more arteries. The wearable medical device 110 can calculate the oxygen saturation level by comparing the ratio of absorbed to unabsorbed light. The wearable medical device 110 can also calculate physiological measurements related to pulsating movement of blood based on signals detected by the peripheral arterial tone sensor. In certain scenarios, such digit optical clips 112 can be used during surgeries or in critical care settings, where it is important to monitor a patient’s oxygen levels to ensure that the patient is receiving adequate oxygenation. In some example scenarios, the optical digit clip 112 can be used in monitoring sleep-disordered breathing (SDB) conditions in a patient, e.g., sleep apnea and/or related conditions.

[0143] Some optical digit clips 112 include first and second clip members that are movable towards one another. In some examples, when the first and second clip members are closed to enclose a patient’s digit, the clip members can adopt a tubular, cylindrical, or similarly shaped elongated shape and be sized in accordance to the patient’s digit. Optical digit clips 112 can be configured with a clip or clamp portion that presses or clamps against the digit being monitored as will be described in greater detail below.

[0144] Clip configurations disclosed herein advantageously apply substantially uniform pressure to external surfaces of a digit to which they are applied. Optical digit clips 112 herein distribute forces over both top and bottom (e.g., dorsal and volar) surfaces of the digit, including the sides of the digit, and in implementations, the distal tip. Optical digit clip 112 configurations advantageously avoid forces applied to small areas of the digit, which may result in venous distention and/or blood pooling due to uneven force distribution.

[0145] In some examples, the optical digit clip 112 configurations disclosed herein can include a tether or strap for securing the optical digit clip 112 to the digit for preventing movement of the optical digit clip 112 relative to the digit. For example, such tether or strap can prevent distal movement of the optical digit clip 112 relative to the digit. In some examples, the optical digit clip 112 can include tether/straps which, when placed in tension, supply proximally directed forces to the optical digit clip 112 to assist with preventing distal movement of the optical digit clip 112 relative to the user’s finger. For example, such tethers or straps can help to prevent the optical digit clip 112 from detaching from the digit due to the application of internal pressure to the distal tip of the user’s digit.

[0146] Optical digit clips 112 as described herein can be used for a variety of medical applications. For example, optical digit clips 112 can be used by a medical caregiver to obtain an instantaneous reading for peripheral arterial tonometry, oxygen saturation, blood pressure, and other patient physiological parameters. After an acceptable reading is obtained, the caregiver can remove the optical digit clip 112 from the patient’s digit. In home sleep apnea applications, the optical digit clip 112 can be worn substantially continuously for the duration of the night while the patient is in bed and/or asleep. Optical digit clips 112 can also be used for continuous long-term patient monitoring for a period of hours, or for an entire day, or an entire night. An optical digit clip 112 can also be used outside or remote from a medical facility, such as for home and/or remote sleep apnea tests (e.g., HSATs) and/or home and/or remote sleep disordered breathing tests for diagnosing sleep apnea.

[0147] These and other features and characteristics of the present disclosure, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limit of the disclosure.

[0148] As used herein, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0149] As used herein, the terms “right”, “left”, “top”, and derivatives thereof shall relate to aspects of the present disclosure as it is oriented in the drawing figures. However, it is to be understood that embodiments of the present disclosure can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Also, it is to be understood that embodiments of the present disclosure can assume various alternative variations and stage sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are provided as examples. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.

[0150] As used herein, including in the claims, unless otherwise stated, a statement that a function or operation is “based on” an item or condition means that the function or operation is based on the stated item or condition and may be based on one or more items and/or conditions in addition to the stated item or condition.

[0151] As used herein, the terms “communication” and “communicate” refer to the receipt or transfer of one or more signals, messages, commands, or other type of data. For one unit or component to be in communication with another unit or component means that the one unit or component is able to directly or indirectly receive data from and/or transmit data to the other unit or component. This includes a direct or indirect connection that can be wired and/or wireless in nature. Additionally, two units or components can be in communication with each other even though the data transmitted can be modified, processed, routed, and the like, between the first and second unit or component. For example, a first unit can be in communication with a second unit even though the first unit passively receives data, and does not actively transmit data to the second unit. As another example, a first unit can be in communication with a second unit if an intermediary unit processes data from one unit and transmits processed data to the second unit. It will be appreciated that numerous other arrangements are possible.

[0152] The present disclosure is directed to medical systems 100 and devices 110 (shown in FIGS. 1, 18A, and 18B), which can be used for patient monitoring to detect, record, and process data for one or more patient physiological parameters. In some examples, the medical systems 100 and wearable medical devices 110 can be configured for short-term use (e.g., for a few minutes to about an hour, such as during a brief visit to a caregiver facility) and/or long-term and/or continuous use (e.g., in the context of both inpatient and outpatient monitoring). For example, the medical systems 100 and wearable medical devices 110 can be used by patients at home and/or remote from a medical facility. The medical systems 100 and wearable medical devices 110 disclosed herein are configured to be used and/or worn by a patient or wearer. The patient can be inpatient, e.g., a patient admitted to a medical facility, such as a hospital, rehabilitation center, a long term care center, a nursing facility, an assisted living facility, a long term memory care center, or other inpatient clinical facility. Additionally or alternatively, the patient can be outpatient, e.g., a patient that is visiting a healthcare facility, a caregiver, or other medical professional for a short duration, or remotely visiting via telemedicine facilities with the facility.

[0153] The medical systems 100 and wearable medical devices 110 disclosed herein can comprise the optical digit clip 112 (shown in FIGS. 1, 18A, and 18B) for noninvasive measurement of a physiological parameter of a wearer or patient. In some examples, the optical digit clip 112 can be a component of an oximeter for obtaining oxygen saturation measurements for the patient. The optical digit clip 112 can also be used for obtaining peripheral arterial tone measurements. Physiological parameters that can be determined from data collected by the optical digit clip 112 can also include other parameters representative of respiratory function, such as parameter values for oxygen blood levels or oxygen update (e.g., V02max). Physiological parameters that can be determined from data collected by the optical digit clip 112 can also include cardiac or blood flow parameters, such as arterial pulse parameters, blood pressure parameters, or heart rate parameters. Physiological parameters can also include blood metrics, such as blood glucose level, glycemic index, insulin index, fat body composition, protein body composition, blood nutrient level (e.g., iron), blood sodium levels, and/or naturally-produced chemical compound level (e.g., lactic acid). [0154] In some use scenarios, patients using wearable medical devices 110 comprising the optical digit clips 112 may move around during a testing or monitoring activity. For example, the testing or monitoring activity may be a sleep study (e.g., in a sleep lab or a remote home -based sleep study) that can last for an overnight or a long study duration (e.g., between about 3-4 hours, about 6-8 hours, or about 9-12 hours). While examples described herein are in the context of long, continuous duration studies, it is understood that the systems, apparatuses, and methods can be used for shorter duration applications as well. For example, the testing or monitoring activity may be an oxygen saturation measurement during a clinical visit, e.g., lasting for a short duration such as about 10 seconds to about 5 minutes, more particularly about 10 seconds to about 1 minute. The testing or monitoring activity may also be a longer clinical study for e.g., arterial pressure pulse changes, blood pressure monitoring, oxygen saturation changes, etc., during a clinical visit lasting, e.g., for 5 minutes to about an hour. For example, patients may change position, sit-up, stand, walk around, or perform other exercises and activities during monitoring or testing. While sleeping, patients may voluntarily or involuntarily change position or attempt to move, adjust, or reposition sheets, pillows, and other bedding materials. In certain use scenarios, voluntary or involuntary movements can apply forces tending to modify a position or orientation of the optical digit clip 112 relative to the digit being monitored. Implementations herein include features that can resist such forces. In certain use scenarios, such movements can apply forces tending to cause the optical digit clip 112 to fall off or detach from the patient. Implementations herein include features that can resist such forces. As a result, implementations herein can promote signal preservation and/or enhance signal fidelity for optical signals being detected by the optical digit clip 112. Advantageously, implementation herein include features that secure the optical digit clip 112 to the patient in an improved manner so that the optical digit clip 112 does not change orientation or fall off and continues to apply uniform pressure to the digit even if, for example, the optical digit clip 112 catches on or attaches to sheets, bedding, the patient’s clothes, or any other objects in proximity to the patient. [0155] The optical digit clips 112 described herein may include attachment devices to further secure the optical digit clip 112 to the digit of the patient while suitable uniform pressure is applied to the digit for the duration of the study. For example, the optical digit clips 112 disclosed herein can include various arrangements of housings, trays, supports, hinges, biasing members, springs, latches, locking devices, and similar features for securing the optical digit clips 112 to a particular digit of the patient. In some examples, the optical digit clip 112 can be configured to remain in place on the digit of the patient during continuous, long-term use. In such examples, the securing features of the optical digit clip 112 can be suitable for preventing the optical digit clip 112 from becoming dislodged, disconnected, or from falling off of the digit of the patient at an inappropriate or unexpected time. The different optical digit clips 112 described herein are also configured to optimize the quality of the physiological data retrieved during the underlying clinical study. By ensuring proper fit and attachment to the relevant patient extremity, implementations described herein allow for greater reliance on clinical diagnosis that can be drawn from the resulting physiological data. Therefore, the optical digit clips 112 can prevent loss or interruption of signal fidelity and/or medical data. Thus, the optical digit clips 112 of the present disclosure can ensure that data collected by sensors of the optical digit clip 112 is accurate, complete, and is not corrupted or modified by movement noise or changes in position of the optical digit clip 112 relative to the digit.

[0156] In some examples, the medical systems 100 and wearable medical devices 110 of the present disclosure can be used for diagnosis and monitoring of respiratory conditions of a patient. For example, an optical digit clip 112 can be attached to a digit of a patient to obtain an instantaneous pulse oximetry measurement and/or peripheral arterial tone for the patient. After the instantaneous measurement is obtained, the optical digit clip 112 can be removed or can remain in place on the digit of the patient for an expected duration providing continuous or periodic patient monitoring. In examples, the optical digit clip 112 is worn by a patient for an extended duration, such as a duration of at least several hours, overnight during a sleep study, or for a multi-night sleep study. In such long term use cases, the attachment device can be used to ensure that the optical digit clip 112 remains in place for the entirety of the study or monitoring duration.

[0157] In some examples, the optical digit clips 112 are configured to obtain physiological data for detection and measurement of respiratory and/or physiological parameters related to sleep apnea and/or disordered breathing. Sleep apnea is a common sleep disorder, which affects millions of people. With this condition, a person may have an interruption in his or her breathing while sleeping that occurs through repetitive pauses or apneic events. There are several types of sleep apnea, of which two prominent types include obstructive sleep apnea (OSA) and central sleep apnea (CSA). CSA can be characterized by pauses in breathing due to a lack of respiratory effort during sleep.

[0158] In CSA, the pauses in breathing throughout the night may be due to the lack of respiratory muscles activating or the brain failing to cause the respiratory muscles to activate. CSA can often be characterized as Cheyne - Stokes Respiration (CSR) in heart failure (HF) patients, and is a common comorbidity, affecting 30-50% of patients with reduced left ventricular ejection fraction (LVEF) and up to 18-30% of patients with preserved LVEF. Untreated CSA has shown to be independently associated with increased mortality and hospitalizations, especially in patients with heart failure. The symptoms of sleep apnea — fatigue, daytime somnolence, shortness of breath, and nocturnal dyspnea — often overlap with those of heart failure, making it difficult to evaluate the effect of cardiovascular therapies on patient symptoms while the sleep apnea remains untreated. Clinicians can be presented with complaints of fatigue and problems sleeping, which could be due to OSA or CSA. Understanding which patients to systematically screen and test for OSA and/or CSA can be challenging. In addition, heart failure clinicians need to be aware of treatment options for their patients as they may differ from the best options for other sleep apnea patients.

[0159] In some examples, the optical digit clip 112 can be used for at home or remote sleep studies, increasing availability of such at-home options. Home or remote sleep studies allow for systematic screening of more patients than could be tested at specialized centers or facilities. More specifically, the medical systems 100 and devices 110 disclosed herein can be used for home and/or remote sleep apnea tests (e.g., HSATs) and/or home and/or remote sleep disordered breathing (SDB) tests for diagnosing sleep apnea and/or for sleep stage (e.g., Rapid Eye Movement (REM), Light Sleep, Deep Sleep and Wake) identification for a patient or subject. Beneficially, such tests do not need to be performed at a sleep study center or facility. Instead, the tests can be performed at a patient’s home allowing the patient to sleep in his or her own bed, meaning that falling asleep can be easier and more convenient than for sleep studies performed at specialized centers or facilities. Further, the attachment devices of the present disclosure can be used to prevent the optical digit clip 112 from becoming dislodged or from falling off of the digit of the patient, ensuring that data collected by the optical digit clip 112 during the home or remote sleep test is accurate, complete, and free from artefacts resulting from movement of the optical digit clip 112 relative to the digit being monitored.

[0160] Information collected by the optical digit clips 112 and other sensors of the medical device 110 can be used for providing various types of medical feedback and information for clinicians and for the patient. For example, the medical device 110 can be configured to generate indices representative of respiratory function and/or breathing quality of the wearer or patient based on signals detected by sensors of the optical digit clip 112. For example, the generated indices can include one or more of: a respiratory disturbance index; an apnea-hypopnea index; a central apnea-hypopnea index; and/or a percentage of total sleep time with Cheyne - Stokes Respiration pattern (%CSR). Information detected by the sensors of the optical digit clip 112 can also be analyzed to provide information representative of sleep staging identification. The respiratory indices and sleep staging information can be estimates determined from conventional values produced by polysomnography. The medical device 110 can also generate data representative of detected acoustic signals (e.g., acoustic decibel detection) used for monitoring snoring level and body position information representative of discrete states from motion signals from an accelerometer of a chest sensor of the medical device 110.

[0161] With continued reference to FIG. 1, in some examples, the medical systems 100 and wearable medical devices 110 of the present disclosure can also include monitoring or sensing devices separate from the optical digit clip 112, which can be coupled to other portions of a patient’s body than the optical digit clip 112. For example, the medical systems 100 and devices 110 disclosed herein can further comprise a wrist-worn monitor 118 (shown in FIGS. 1, 18A, and 18B) or device in wired or wireless communication with the optical digit clip 112. The wrist-worn monitor 118 can include processing circuitry for receiving and processing data from the optical digit clip 112. In addition, the wrist-worn monitor 118 can include wireless communications circuitry and a processor coupled to the memory for storing recorded data and for wirelessly transmitting data from the optical digit clip 112 and/or wrist-worn monitor 118 to remote servers or computer devices. The medical system 100 and wearable medical device 110 can also include a chest motion sensor device 120 (shown in FIGS. 1, 18 A, and 18B) configured to be disposed on an upper chest area of the wearer or patient. The chest motion sensor device 120 can include a snoring microphone and an accelerometer. In some examples, the wrist- worn monitor 118 and/or the chest motion sensor device 120 can also include ECG electrodes and a body impedance sensor. [0162] As previously described, the optical digit clip 112 can be configured to receive or cover the distal part of the digit of the patient and to apply uniform pressure to portions of the digit while sensors detect or obtain signals representative of, for example, light transmittance through tissue of the digit received within the optical digit clip 112. In some examples, the pressure applied to the digit by the optical digit clip 112 is provided as a uniform pressure field within a predetermined range extending from a proximal portion (e.g., a middle or proximal phalanges portion) of the digit to a distal tip of the digit. The optical digit clip 112 is configured to apply the substantially uniform pressure (e.g., a sub-diastolic and/or peripheral arterial pressure) to a portion of the digit, while sensing physiological signals representative of, for example, pulsatile volume changes of the patient’s arteries.

[0163] In some examples, the applied uniform sub-diastolic pressure is sufficient to facilitate unloading of arterial wall tension and/or to facilitate an increase in a dynamic range of a peripheral arterial signal of the patient relative to signals (e.g., PPG or arterial volume signals) obtained without the uniform sub-diastolic pressure. The optical digit clip 112 can also be configured to avoid venous blood pooling or engorgement and stasis, which inhibits retrograde venous shock wave propagation. In some examples, the pressure applied by the uniform pressure field may be sufficient to prevent free venous flow due to, for example, hydrostatic pressure and shock waves, while allowing the veins to carry blood delivered by the arteries out of the finger.

[0164] The optical digit clip 112 can also avoid induction of veno-arterial-mediated vasoconstriction. In this way, the optical digit clip 112 can be configured to allow for the partial unloading of arterial wall tension, which significantly improves a dynamic range of the measured signal. In some examples, the optical digit clip 112 can be configured so that peripheral arterial constrictions, when present, are shown by attenuation in a peripheral arterial signal. The peripheral arterial constrictions can be a marker of sympathetic activation.

[0165] In some examples, the optical digit clip 112 can also be configured to measure optical density related changes of arterial blood volume in the digital arteries, such as changes associated with each heartbeat. Peripheral arterial constrictions, when present, can be shown by attenuation in signal amplitude of a detected signal. The peripheral arterial constrictions can be a marker of sympathetic activation. [0166] In some examples, certain signal(s) measured by the optical digital clip 112 are representative of pulsatile volume changes in arteries of a digit (e.g., in a distal tip or fingertip of the patient). The pulsatile volume changes can reflect a relative state of the arterial vasomotor activity, which relate indirectly to a level of sympathetic activation. Peripheral arterial vasoconstriction, which mirrors sympathetic activation, can be shown as attenuation of signal amplitude for signals detected by an optical sensor of the optical digit clip 112.

[0167] In some examples, an inner portion of an optical digit clip 112 can include one or more structures, fluids, or combinations thereof (referred to herein as a uniform pressure applicator, distal applicator, and/or radial pressure applicator), which create or distribute the uniform pressure field to the digit. For example, the uniform pressure applicator may include an elastic member operatively disposed in the optical digit clip 112 and attached to an open end of the optical digit clip 112, such that an enclosed seal is formed between an inner portion of the optical digit clip 112 and the elastic member to define a pocket sized to receive a digit of the patient. A fluid (such as air, an inert gas, or an inert liquid) may be inserted (e.g., injected or released) into the pocket, causing the elastic member to elastically deform. For example, an inert gas includes a gas that does not chemically react with material of the elastic member or with other material(s) that form the chamber containing the gas. In certain contexts described herein, examples of inert gases include neon gas and/or argon gas. An inert liquid can include a liquid that does not chemically react with the material of the elastic member or with other material(s) that form the chamber containing the liquid. In certain contexts described herein, an example of an inert liquid can be water or other aqueous solution. In some examples, the elastic member can be configured to apply the uniform sub-diastolic pressure to a portion of the patient’s body (e.g., to a distal two-thirds of the patient’s digit). In some examples, the uniform pressure field may be static and, when utilized in conjunction with the peripheral arterial tone LED and a photodetector of a peripheral arterial tone sensor, produces a peripheral arterial signal or measurement. As previously described, the peripheral arterial tone signal or measurement can be more sensitive than conventional PPG measurements obtained without applying the uniform pressure field to the digit.

[0168] In some examples, noise reduction (e.g., improved signal to noise ratio) in the peripheral arterial tone signal or measurement may be achieved by applying sufficient pressure to partially unload, but not occlude, the wall tension of the arteries in the finger, when the finger is near heart level. This may allow the arterial wall to move freely to accommodate the pulsatile blood delivery of the heart. The applied pressure may be slightly above the maximum pressure in the veins when the hand is fully lowered (e.g., 5% higher and/or the like).

[0169] In some examples, a peripheral arterial tone signal may rise and fall with changes in the patient’s sympathetic nervous system and may be linked to an oxygen saturation signal, actigraphy, and a snore microphone via a breathing disturbance index. Attenuation of the peripheral arterial tone signal may reflect digital vasoconstriction and increased sympathetic nerve activity and can serve as a marker for arousal from sleep. The peripheral arterial signal may also detect the peripheral vasoconstriction associated with REM sleep.

[0170] In some examples, the pressure applicator structures of the optical digit clip 112 can be configured to provide a uniform pressure to the digit within a target range of about 40 mmHg to about 70 mmHg. In examples, the pressure applicator structures can be preconfigured to implement a predetermined range of pressures so as to not adversely affect tissue perfusion. For example, such range can be determined based on clinical analysis indicating that while arterial pressure exceeds a counter-pressure permitting inflow of arterial blood, for blood to return via the veins, venous pressure overcomes the applied external pressure. The induced elevation of venous pressure can cause the upstream microcirculation to be pressurized to a pressure level intermediately between the outgoing venous blood and the incoming arterial blood. As such, the transmural pressure of the microcirculation within the applied pressure field is greater than zero and collapse of the microcirculation is prevented.

[0171] As previously described, the pressure applied to particular portions of the digit is intended to be a static and uniform or substantially uniform (e.g., within 10%, 5%, or 1 % of uniform) across surfaces of the digit, including the volar surface, dorsal surface, and distal tip. The target range for uniform pressure can be selected in order to provide a relatively large operating zone in which pressure remains substantially constant with changes in digit volume. As previously described, changes in digit volume can be due to changes in instantaneous blood volume related to arterial blood volume of the digit. The relationship between pressure and digit volume is shown in the graph of FIG. 2, which shows an operating zone of about 60 mmHg to about 64 mmHg where the pressure remains substantially constant with the changes in volume. However, an actual pressure value for a particular digit is a function of the thickness and mechanical characteristics of the distensible material. For example, the pressure range or operating zone for the optical digit clip 112 can be about 40 mmHg to about 70 mmHg. [0172] In some examples, an intensity of force or pressure can vary based on a size of the digit received within the digit space. For example, an intensity of the applied uniform pressure can be greater for larger digits and less for smaller digits. However, the optical digit clip 112 can be configured such that the applied pressure remains both uniform and within the range of about 40 mmHg to about 70 mmHg for all anticipated digit sizes. For example, for the smallest patients, the applied pressure may be very close to 40 mmHg, while for the largest anticipated patients, the applied pressure can be equal to or slightly below 70 mmHg. It can also be important to control temperature of the digit during monitoring. For examples, the optical digit clip 112 can be configured to maintain temperature at a fingertip surface within a narrow range around 36° C. [0173] The optical digit clips 112 of the present disclosure can be configured to be positioned on and/or used with digits of a patient, such as on fingers or toes. Furthermore, the optical digit clip 112 can be adjustable, so that it can be used with many or all possible digit dimensions. When used with a hand and fingers, the optical digit clip 112 can be configured to allow for fixation to any or all of the index finger (pointer finger or forefinger), middle finger, ring finger, little finger (pinky), or thumb. Accordingly, the dimensions of the optical digit clip 112 may be different corresponding to the average person’s dimensions for these patient digits. When used with a foot and toes, the optical digit clip 112 can be configured to allow for fixation to any or all of a hallux (big toe or great toe), second toe (long toe), third toe (middle toe), fourth toe (ring toe), and/or fifth toe (little, pinky, or baby toe). Furthermore, when correctly positioned on and/or fixed to the digit, the optical digit clip 112 can receive, surround, and/or enclose both a volar (also referred to a front or palmar) portion of the digit and a dorsal (also referred to as a rear) portion of the digit.

[0174] Portions or sections of the patient’s hand, foot, or digit include phalanges of the patient’s hand or foot. For example, a first or distal portion of the digit can include a portion of the digit that surrounds, encloses, or covers the distal phalanges bone of the patient’s hand or foot. The second or middle portion of the digit can include a portion of the digit that surrounds, encloses, or covers the intermediate or middle phalanges of the patient’ s hand or foot. The third or proximal portion of the digit can include a portion of the digit that encloses, surrounds, or covers the proximal phalanges bone of the digit, which is connected to a metacarpal bone of the patient’s hand or a metatarsal bone of the patient’s foot. In some examples, the optical digit clip 112 is configured to extend over or receive the distal phalanges, distal knuckle, and at least a portion of the middle phalanges of the patient’s digit. In other examples, the optical digit clip 112 can be longer extending over and/or receiving the distal phalanges, distal knuckle, and middle phalanges, as well as portions of the proximal knuckle and/or proximal phalanges of the digit.

[0175] For convenience, this disclosure presents clip apparatus that are broadly presented as follows.

[0176] Example features that relate to peripheral arterial tone sensors that are configured to be positioned at or proximate to a patient’s digit and to provide signals representative of a peripheral arterial tonometry waveform of the patient for providing non-invasive peripheral arterial tonometry measurements.

[0177] Example features that relate to uniform pressure applicators configured to uniformly distribute pressure generated within a digit space defined by a clip apparatus to both a dorsal portion and a volar portion of a patient’s digit. For example, the uniform pressure applicator may be configured so that an equal pressure is applied to the dorsal portion and to the volar portion of the patient’s digit. Alternatively, or in addition, the uniform pressure applicator can be configured such that pressure applied to the digit by the uniform pressure applicator is uniformly distributed over surfaces of the dorsal portion and the volar portion of the digit, which are received within the clip apparatus. For example, pressure applied by the uniform pressure applicator to the dorsal portion of the digit can be uniformly distributed over the surface of the dorsal portion, which is contacted by a first clip member of a clip apparatus. In a similar manner, pressure applied by the uniform pressure applicator to the volar portion can be uniformly distributed over a surface of volar portion, which is contacted by a second clip member of the clip apparatus.

[0178] Example features that relate to clip members of a clip apparatus that are movable towards one another to generate an axial pressure within a predetermined range against a distal tip of a patient’s digit.

[0179] Example features that relate to clip members of a clip apparatus that are configured to pressurize at least one fluid-filled chamber around a patient’s digit such that pressure applied to each of a dorsal portion and a volar portion of the digit is (i) a uniform pressure and (ii) within a predetermined range.

[0180] A clip apparatus can include some or all of the example features described herein. For instance, in one implementation, a clip apparatus can include a first clip member with a first surface configured to receive a first portion of a digit of a patient and a second clip member coupled to the first clip member and including a second surface configured to receive a second portion of the digit. The first clip member and the second clip member can be configured to receive the digit in a digit space defined by the first and second surfaces. One of the first clip member or the second clip member can be movable toward the other of the first clip member or the second clip member to generate pressure within the digit space. The clip apparatus can also include a uniform pressure applicator configured to uniformly distribute the pressure generated within the digit space to a dorsal portion of the digit and a volar portion of the digit and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space. The peripheral arterial tone sensor can be configured to be positioned at or proximate to the digit and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0181] In another implementation, a clip for non-invasive peripheral arterial tonometry measurements can include a first clip member having a first surface configured to receive a first portion of a digit of a patient and a second clip member movably coupled to the first clip member and having a second surface configured to receive a second portion of the digit. The first clip member and the second clip member can be configured to receive the digit of a patient in a digit space defined by the first and second surfaces. The first clip member and the second clip member can be movable to generate an axial pressure within a range of about 40 mmHg to about 80 mmHg against a distal tip of the digit when the digit is received within the digit space. The clip can also include at least one optical-based peripheral arterial tonometry sensor disposed within the digit space configured to be positioned at or proximate the digit, and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0182] In another implantation, a clip apparatus for non-invasive peripheral arterial tonometry measurements can include a pair of clip members, which are movable relative to one another, to an open configuration for receiving a digit of a patient between the pair of clip members and a closed configuration for clipping the clip apparatus to the digit of the patient. In the closed configuration, the pair of clip members can be configured to pressurize at least one fluid-filled chamber around the digit such that pressure applied to each of a dorsal portion of the digit and a volar portion of the digit is (i) a uniform pressure and (ii) within a predetermined range. The clip apparatus can also include at least one optical-based peripheral arterial tonometry sensor coupled to at least one of the pair of clip members and configured for, in the closed configuration, operative placement at or proximate the digit and generation of signals representative of a peripheral arterial tonometry waveform of the patient. [0183] FIGS. 3A-17B show different examples of optical digit clips and associated clip apparatuses that include different attachment mechanisms, hinges, biasing members, and tethers for providing the uniform pressure field to a digit, which can be securely attached to the digit for long-term (e.g., daily or overnight) use. As noted above, applying force/pressure to the distal tip of the digit, which is within a predetermined range and substantially uniform with force/pressure applied to other portions (e.g., a volar portion and dorsal portion) of the digit, can improve accuracy of peripheral arterial tonometry signals by reducing or eliminating venous pooling at the distal tip of the digit, and by reducing arterial wall tension without occluding blood vessels. The wearable medical device and digit clips shown in FIGS. 3 A to 17B are configured to provide the uniform pressure in order to improve accuracy for sensed physiological signals.

[0184] FIGS. 3A-3F show an example wearable medical device 310 comprising a clip apparatus, optical digit clip device, or clip 312, also referred to herein as a finger clip, clip assembly, optical assembly, or optical sensing device. As described in further detail herein, the clip 312 can comprise sensor(s) for non-invasively obtaining PPG signals and signals for peripheral arterial tone. The optical digit clip 312 comprises two or more members 314, 316 (referred to herein as “clip members”), which can be elongated trays, shells, plates, or other supports, configured to move relative to one another (e.g., in a parallel configuration, in a pivotally coupled configuration, or in some other configuration), to facilitate an increase/decrease in distance between the clip members 314, 316 during relative movement thereof. For example, the clip members 314, 316 can be pivotally coupled at a hinge point, can be connected through a pivot rod, biasing member, and/or spring. The clip members 314, 316 can also be connected by a ratchet mechanism, which secures the clip members 314, 316 together and is size-adjustable so that the clip 312 can be used with digit of different sizes. In examples in which the clip 312 comprises two members 314, 316 pivotally coupled to one another via a hinge 318, the hinge 318 may be operatively disposed at a proximal end 320 or a distal end 322 of the clip 312, or at any position between the proximal end 320 and the distal end 322 of the clip members 314, 316. In other examples, the clip members 314, 316 may function as a clip while remaining parallel to one another and defining a space therebetween sufficient to generate pressure on a digit inserted within the space.

[0185] In some examples, the proximal ends 320 of the clip members 314, 316 can form or define an opening 324 (shown in FIG. 3A) or gap sized to receive the digit being monitored by the clip 312. Furthermore, the clip members 314, 316 can comprise inwardly facing or inner surfaces 326a, 326b (shown in FIGS. 3D and 3E) configured to receive and support portions of the patient’s digit. For example, the first clip member 314 can comprise an inner surface 326a (shown in FIGS. 3D and 3E) configured to receive a dorsal portion of the patient’s digit. The second clip member 316 can comprise inner surface 326b configured to receive portions of the volar surface of the digit.

[0186] In some examples, the clip members 314, 316 can be molded structures formed, for example, from a rigid plastic (e.g., acrylonitrile butadiene styrene (ABS), polyester, polycarbonate, polypropylene, polyethylene, or polyethylene terephthalate). The clip 312 can also include sealing structures, such as an internal O-ring or cushion, positioned to provide a tight seal around the wearer’s digit.

[0187] As previously described, the wearer’s digit can be, for example, a finger or toe. For example, the optical digit clip 312 can be configured for insertion onto a middle finger of the patient, as shown in FIG. 3F. The optical digit clip 312 can also be inserted onto a little finger, a ring finger, or a pointer or index finger of the patient. In other examples, the optical digit clip 312 can be configured to be worn on a big toe (hallux), second toe, third toe, fourth toe, fifth toe, or on any other convenient extremity. In some examples, the clip members 314, 316 can be sized to receive a distal phalanges and a portion of a middle phalanges of the digit. In other examples, the clips members 314, 316 can be extended in length and configured to receive the distal phalanges, middle phalanges, and a portion of the proximal phalanges of the digit.

[0188] Dimensions of the clip members 314, 316 of the optical digit clip 312 can depend upon the type of digit being monitored by the wearable medical device 310. For an optical digit clip 312 configured to be worn on a wearer’s middle finger, the clip members 314, 316 can have an axial length LI (shown in FIG. 3A) of about 4 cm to about 8 cm. The open proximal end 324 of the clip 312 (e.g., gap between proximal ends 320 of the first clip member 314 and the second clip member 316) can have an outer diameter GDI (shown in FIG. 3 A) of about 3 cm to about 4 cm and an inner diameter ID1 (shown in FIG. 3A) of about 2 cm to about 3 cm. In some implementations, the dimensions of the clip members 314, 316 can be adjusted to accommodate varying digit sizes of the patient. For example, an inner diameter of a digit space 328 (FIG. 3D) defined by inner surfaces 326a, 326b of the clip members 314, 316 can vary within a range of about 2 cm to about 3 cm when the patient inserts his or her middle through the open proximal end [0189] In some examples, two clip members 314, 316 of the clip 312 are pivotally connected at the hinge 318, meaning that the clip 312 can be moved between a closed position (shown in FIG. 3A) an open position (shown in FIG. 3B) by, for example, rotating the first clip member 314 and/or the second clip member 316 about the hinge 318, as shown by arrow Al in FIG. 3 A and arrow A2 in FIG. 3B. The hinge 318 can be structured to provide sufficient clearance between the clip members 314, 316 so that the clip members 314, 316 can be easily opened and closed without blocking each other. For example, clip members 314, 316 can include cut-out portions or other structural features to provide sufficient clearance between members 314, 316. In other examples, the hinge 318 can include a slot (e.g., a vertical slot in ring or tab portion 325) which receives protrusion 330 and allows for upward movement thereof, whereby the clip members 314, 316 can move vertically relative to one another and pivot relative to one another. Similar structural features and cut-out portions can be used with respect to hinges and clip members of the optical digit clip devices illustrated and described with respect to FIGS. 1, 14A, 14B, and 15B, and may also be used with respect to other examples of optical digit clip devices described herein. As described in further detail herein, the clip 312 can also include various pressure applying materials such as cushions, pads, membranes, or supports comprising, for example, air, foam, gel, or hydrogel attached to inner surfaces 326a, 326b of the clip members 314, 316 and/or disposed within the digit space 328 enclosed by the clip members 314, 316. Additional pressure applying material (e.g., air, gel, hydrogel, etc.) can be disposed proximate to the distal ends 322 of the clip members 314, 316 for contacting and applying pressure to distal tip of the digit. The additional pressure applying material near the distal ends 322 can be configured to optimize or smooth out force/pressure applied to the distal tip of the digit at or adjacent hinge 318 by the clip members 314, 316 as the clip 312 closes. Otherwise, pressure may be applied to the distal tip of the digit and/or to other surface of the digit less uniformly.

[0190] With continued reference to FIGS. 3A-3F, as previously described, the first clip member 314 and the second clip member 316 can be elongated trays, sheets, shells, or similar supports for receiving portions of the digit. The clip members 314, 316 can be molded or formed with a concave curvature (e.g., a concave inner surface 326a, 326b) that matches, aligns with, accurately aligns with, or substantially matches curvature of portions of the digit. In some examples, the first clip member 314 can be a dorsal clip member configured to receive a dorsal portion (e.g., back portion) of the digit. The second clip member 316 can be a volar clip member configured to receive a volar (e.g., palmar or front) portion of the digit 2. In other examples, the first clip member 314 can be configured to receive a left side portion of the digit 2 and the second clip member 316 can be sized to receive the right side of the digit 2. In some examples, the first clip member 314 and the second clip member 316 can be symmetrical or substantially symmetrical, with a clam shell design, configured so that each clip member 314, 316 receives or supports a substantially equal size portion of the digit 2. In other examples, one of the clip members 314, 316 can be larger and/or can be configured to support a larger portion of the digit 2 than the other clip member 314, 316.

[0191] The first clip member 314 and the second clip member 316 can be configured to receive the digit in the digit space 328 (shown in FIGS. 3D and 3E) defined by the inner surfaces 326a, 326b of the clip members 314, 316. In order to retain the digit within the digit space 328, one of the first clip member 314 or the second clip member 316 is movable toward the other of the first clip member 314 or the second clip member 316, which pressurizes one or more fluids between the first and second clip members 314, 316. For example, the first clip member 314 can be pivotally or hingedly connected to the second clip member 316 at the hinge 318 or hinge point. As shown in FIGS. 3A-3C, the hinge 318 can be formed by a protrusion 330, such as a detent, or pin, extending from sides of one of the clip members 314, 316. For example, the protrusion 330 can extend from sides of the first clip member 314, as shown in FIG. 3C, defining a pivot point that is substantially transverse to a longitudinal axis of the elongated clip members 314, 316. As shown in FIGS. 3A and 3B, the protrusions 330 are received in corresponding rings 325, hooks, or depressions in the second clip member 316, thereby forming the hinge 318 allowing the second clip member 316 to pivot toward or away from the first clip member 314 about the hinge 318 formed by the protrusions 330 and rings 325. As discussed above, in other examples, the rings 325 can comprise a slot for allowing the clip members 314, 316 to both rotate and move vertically relative to one another.

[0192] In other examples, a hinge 418 (shown in FIGS. 4A-4C) can be formed from a post, rod, bar, or similar member provided for connecting a first clip member 414 to a second clip member 416. For example, as shown in FIGS. 4A-4C, an optical digit clip device or clip 412 can comprise the first clip member 414, the second clip member 416, and rods or pins 434a, 434b, which forms a pivot points or a hinge 418 about which clip members 414, 416 are pivotally connected. The first clip member 414 and the second clip member 416 each comprise rings or u-shaped hooks, brackets, or connectors 432 configured to receive the rod 434, as shown in FIGS. 4A and 4B. The first and second clip members 414, 416 are configured to rotate about the rod 434, thereby allowing the clip 412 to move between the closed position (shown in FIG. 4 A) and the open position (shown in FIG. 4B). In examples, first and second clip members 414 can be separately attached (e.g., using a first and second hinges on opposing sides) to provide clearance space for the digit of a patient.

[0193] In other examples, the hinge 418 can be a living hinge (shown in FIGS. 4D and 4E) formed between a first clip member portion 414 and a second clip member portion 416. More specifically, the first clip member portion 414 and the second clip member portion 416 can form an integral structure, such as an elongated plate or shell formed, for example, by injection molding. The integral structure can include a living hinge portion 436. The living hinge portion 436 can be a molded area that is thinner than other portions of the integral structure allowing the molded structure to bend or flex about the living hinge portion 436 (e.g. about the molded thinner area of the structure). This configuration allows a first clip member portion 414 of the integral structure to easily move towards or away from a second clip member portion 416 about the living hinge portion 436.

[0194] In some examples, the integrated clip members 414, 416 or integral structure can be shaped, molded, or configured, such that it is biased toward a closed position (shown in FIG. D). In such instances, a biasing force (e.g., due to a spring bias of the hinge and/or an externally applied biasing member) biases the clip members or clip member portions 414, 416 to a closed position and exerts force/pressure to the digit received within the digit space, thereby contributing to the uniform pressure field provided to the digit by the clip 412.

[0195] In some examples, an optical digit clip device or clip 512 can further comprise a separate or separable biasing member 538, such as a metal spring, for exerting pressure on the clip members 514, 516 and for maintaining the clip 512 in a closed configuration. An example of the clip 512 including the separate biasing member 538 is shown in FIGS. 5A-5C.

[0196] As shown in FIGS. 5A-5C, the optical digit clip 512 comprises the dorsal or first clip member 514, the volar or second clip member 516, and the biasing member 538. The clip 512 is shown in a closed position in FIG. 5A and in an open position in FIG. 5B. As in previous examples, the first clip member 514 and the second clip member 516 can be elongated plates or trays comprising a rigid plastic material. The biasing member 538 or spring can comprise an elongated ductile member, such as a metal wire, that is bent or coiled to form the spring. The biasing member 538 can include a central coiled portion 540, which provides the biasing force, a first leg 542 fixed or engaged to the first clip member 514, and a second leg 544 fixed or engaged to the second clip member 516. For example, as shown in FIGS. 5A-5B, the clip members 514, 516 can comprise a groove 546 on an inner surface or outer surface of the clip member 514, 516 sized to receive the corresponding leg 542, 544 of the biasing member 538 or spring. The legs 542, 544 of the biasing member 538 can be retained in the respective grooves 546 by an adhesive, a snap or friction fit, or a mechanical connector or fastener.

[0197] The biasing member 538 or spring is configured to exert the biasing force on the clip members 514, 516, which moves the clip members 514, 516 toward the closed position. Therefore, in order to insert a digit into a digit space between the first clip member 514 and the second clip member 516, the patient or practitioner can grasp proximal ends 520 of the first and/or second clip members 514, 516 and move the proximal ends 520 of the clip members 514, 516 away from each other with sufficient force to overcome the biasing force of the biasing member 538 or spring. Once the biasing force is overcome and the clip members 514, 516 are moved to the open position (shown in FIG. 5B), the patient can inert his or her digit into the digit space between the first clip member 514 and the second clip member 516. The patient or practitioner can then release the proximal ends 520 of the clip members 514, 516, allowing the biasing force of the biasing member 538 or spring to return the clip members 514, 516 to the closed position (shown in FIG. 5A) cinched about the digit thereby applying a pressure field to the digit within the digit space. In other examples, the patient or practitioner can open the clip members 514, 516 by, for example, pinching or pressing against grip portions on distal ends 522 of the clip members 514, 516, moving the distal ends 522 of the clip members 514, 516 towards one another and causing the proximal ends 520 of the clip members 514, 516 to move apart from one another.

[0198] Having described external features of the digit clips 312, 412, 512, internal structures disposed within the digit space 328 and/or attached to inner surfaces of the clip members 314, 316, 414, 416, 514, 516 will now be described. The internal structures can include cushioning and/or pressure applicators for applying pressure to surface(s) of the digit received within the digit space 328. In some examples, such cushioning and/or pressure applicators are configured to provide uniform pressure to the surface(s) of the digit received within the digit space 328. Exemplary pressure applicators of the clip 312 are shown in FIGS. 3D and 3E. These features can also be integrated with the clips 412, 512 shown in FIGS. 4A-4D and 5A-5C. The clip 312 also comprises electric circuitry and sensors, such as a PPG sensor and/or peripheral arterial tone sensor, for obtaining physiological measurements determined from light transmittance or reflectance of the digit. Exemplary electronic components of the optical digit clip 312 are shown in FIGS. 8 A and 8B.

[0199] With reference to FIGS. 3D and 3E, the clip 312 comprises a uniform pressure applicator 348 disposed in the digit space 328. FIG. 3D is a cross-sectional view of the clip 312 including the uniform pressure applicator 348. FIG. 3E is a cross-sectional view of the clip 312 and uniform pressure applicator 348 with the digit 2 inserted into the digit space 328 between the first clip member 314 and the second clip member 316.

[0200] The uniform pressure applicator 348 is configured to uniformly distribute pressure generated within the digit space 328 to portions of the digit 2 (shown in FIG. 3E). In particular, the uniform pressure applicator 348 can be configured to apply radially inwardly directed pressure (shown by arrows A3 in FIG. 3E) to the volar surface 6 and the dorsal surface 4 of the digit 2. The uniform pressure applicator 348 can also apply radially inwardly directed pressure to side surfaces of the digit 2 between the dorsal surface 4 and the volar surface 6. The uniform pressure applicator 348 can also be configured to apply a substantially uniform axially directed pressure (shown by arrows A4 in FIG. 3E) to the distal tip 8 of the digit 2. For example, a magnitude of the radial pressure against the dorsal and volar surfaces 4, 6 can be equal to or substantially equal (e.g., within about 10%, 5%, or 1%) to the axial pressure against the distal tip 8. As previously described, the uniform distribution of pressure to surfaces 4, 6, 8 of the digit 2 received within the digit space 328 can facilitate unloading of arterial wall tension. The unloading of the arterial wall tension can facilitate an increase in a dynamic range of a peripheral arterial tone signal measured by optical sensors of the clip 312 compared to signals (e.g., PPG signals) detected by sensors without applying uniform subdiastolic pressure to the digit 2. Uniform pressure distribution can also mitigate distal venous pooling or distention to avoid induction of venoarterial-mediated vasoconstriction. As such, the uniform pressure applicator 348 contributes to the improved signal quality for peripheral arterial tonometry signals provided by sensors of the optical digit clip 312. [0201] The uniform pressure applicator 348 is configured to apply and/or distribute at least two types of pressure or external forces to surfaces 4, 6, 8 of the digit 2. First, the uniform pressure applicator 348 can be configured to apply pressure produced by the clip 312 and/or biasing member 538 or spring (shown in FIGS. 5A-5C), which bias the clip members 314, 316 toward the closed position. In order to apply such external force/pressure to the digit, the uniform pressure applicator 348 can be configured to contact sides and/or peripheral portions of the digit 2 received within the digit space 328. The uniform pressure applicator 348 can be configured to receive and apply uniform pressure to digits of different sizes. Specifically, while a magnitude of pressure uniformly applied to surfaces 4, 6, 8 of the digit 2 may be different for digits of different sizes, the uniform pressure applicator 348 is configured to ensure that the applied pressure is uniform or substantially uniform.

[0202] In addition to uniformly distributing external force/pressure generated by relative movement of the first clip member 314 toward the second clip member 316 and/or pressure due to the biasing force of the biasing member 538 or spring, the uniform pressure applicator 348 is also configured to uniformly distribute and apply forces resulting from elastic deformation or wall tension produced by the uniform pressure applicator 348 itself. In some examples, the uniform pressure applicator 348 can comprise membrane(s) or sheet(s) disposed within the digit space 328. The membrane(s) or sheet(s) can initially be loose or flaccid and can be contacted and displaced by the digit 2 as the digit 2 is inserted into or received within the digit space 328. Displaced portions of a sheet(s) or membrane(s) are configured to exert the additional force against surfaces 4, 6, 8 of the digit 2 due to wall tension or elastic deformation of the sheet(s) or membrane(s). These additional elastic deformation or wall tension forces are governed by Laplace’s law relating differences in pressure between pressurized fluid in fluid-containing chambers (e.g., containing air, an inert gas, or inert liquid) enclosed by the sheet(s) or membrane(s) and the unpressurized digit space 328. In this regard, a distending pressure within a distensible space is substantially proportional at equilibrium to a wall tension measure in a wall of the space divided by a principal radii of curvature of the space. In this regard, a static pressure applied by the fluid within the fluidcontaining chamber remains substantially constant irrespective of changes in volume of the digit space 328, e.g., changes in volume caused by arterial blood flow within the patient’s digit received within the digit space 328. In examples, if the patient’s digit 2 were to be partially removed from within the digit space 328, the remaining portion of the patient’s digit 2 will still be subject to substantially same external pressure. As with forces related to movement of the clip members 314, 316, the elastic deformation or wall tension force or pressure is applied uniformly to surfaces 4, 6, 8 of the digit 2 received within the digit space 328. Specifically, the uniform pressure applicator 348 is configured to uniformly distribute the wall tension or elastic deformation forces in both a radial direction (shown by arrows A3 in FIG. 3E) to the volar and dorsal surfaces 4, 6 of the digit 2 and in axial (e.g., longitudinal) direction of digit 2 (shown by arrows A4 in FIG. 3E) at, for example, the distal tip 8 of the digit 2.

[0203] Features of the uniform pressure applicator 348 for providing the elastic deformation or wall tension force will now be described in detail. As shown in FIGS. 3D and 3E, the uniform pressure applicator 348 can comprise a first or inner membrane 350, a second or outer membrane 352, and a first chamber 354 and a second chamber 356 between the membranes 350, 352. The chambers 354, 356 can contain a fluid (e.g., a liquid, pressurized gas, or air at atmospheric pressure). Pressurization of the fluid in the chambers 354, 356 resulting from elastic deformation of the second or outer membrane 352 causes the first or inner membrane 350 to exert force against the digit 2. This force is referred to herein as the elastic deformation or wall tension force. In some examples, the inner chamber 354 and the outer chamber 356 can be fluidly coupled with one another via openings, gaps, or slots 358 defined by an inner shell portion 360 of the first clip member 314 or the second clip member 316. In some examples, the first clip member 314 or the second clip member 316 can also include holes, gaps, or openings 362 for expelling a fluid (e.g., air) from the clip 312 as the outer chamber 356 expands, which occurs as the digit 2 is received within the digit space 328.

[0204] In operation, upon insertion of the digit 2 into the digit space 328, the outer membrane 352 elastically deforms to accommodate increased pressure caused by insertion of the digit 2. Due to wall tension or elastic deformation forces, the outer membrane 352 pressurizes the chambers 354, 356 with a pressure or force that is transmitted through the fluid in the chambers 354, 356 and exerted against the inner membrane 350 and digit 2. Due to curvature of the outer membrane 352, the pressure at equilibrium is a function of the wall tension of the outer membrane 352 divided by the two principal radii of curvature of a shape enclosed by the outer membrane 352. By allowing for pressurization of the chambers 354, 356, the uniform pressure applicator 348 effectively maintains a constant or relatively constant pressure within the digit space 328 when the digit is inserted into the digit space 328, regardless of a size of the digit 2. Additionally, because the chambers 354, 356 are filled with fluid, the pressure is generally applied uniformly to the digit 2, via the inner membrane 350. [0205] More specifically, when the two chambers 354, 356 are present, inserting the digit 2 into the digit space 328 expands/stretches the flaccid inner membrane 350, which causes corresponding elastic expansion/stretching of the outer membrane 352 as the fluid (e.g., air) in the inner chamber 354 is pushed through the slots 358 into the outer chamber 356, thereby pressurizing fluid in the fluidly coupled inner and outer chambers 354, 356. The pressurized fluid exerts substantially uniform pressure on the digit 2 via the flaccid inner membrane 350, which is pressed onto and conforms to the exterior surfaces 4, 6, 8 of the digit 2. Thus, the wall tension or elastic deformation force exerted on the digit 2 provides an added or addition force or pressure, which is exerted on the digit 2 in combination with forces/pressures resulting from moving the first clip member 314 toward the second clip member 316 and/or the biasing forces of the biasing member 538 or spring. [0206] In some examples, an additional hole or slot 358 can also be defined in the inner membrane 350, as shown in FIGS. 3D and 3E. The additional hole or slot 358 can be positioned proximate to the portion of the digit space 328, which receives the distal tip 8 of the digit 2. In this configuration, the digit 2 inserted into the digit space 328 may function as a pressurizing component as well as a seal for the inner chamber 354. Specifically, when the digit 2 is inserted, even though the inner membrane 350 contains the opening or slot 358, air can be trapped and pressurized within a sealed space by surfaces of the clip 312, membrane(s) 350, 352, and the digit 2. This pressurization prevents the fluid or air in the chambers 354, 356 from passing into the digit space 328 and depressurizing the chambers 354, 356, meaning that the inner membrane 350 remains collapsed against the digit 2. In this configuration, there can also be a small gap or buffer of air within the digit space 328 proximate to the distal tip 8 of the digit 2. The air gap or buffer can be fluidly coupled with air in the chambers 354, 356. Upon insertion of the digit 2 into the digit space 328, the chambers 354, 356 are pressurized, as previously described. Furthermore, uniform pressure can be applied to the distal tip 8 of the digit 2 because the small gap or air buffer is pressurized along with fluid (e.g., air) in the chambers 354, 356. In other examples, an inner surface of the first or inner membrane 350 can be flush and pressed against the distal tip 8 as well as other surfaces 4, 6 of the digit 2, as described above, and can provide uniform pressure to the distal tip 8 of the digit 2.

[0207] In some examples, as shown in FIGS. 3D and 3E, a peripheral edge of the inner membrane 350 and a peripheral edge of the outer membrane 352 are both connected to or about the proximal ends 320 and/or proximal opening 324 of the first and second clip members 314, 316. In this configuration, as shown in FIGS. 3D and 3E, the clip 312 comprises a single inner membrane 350 and a single outer membrane 352, each of which span or extend between the first clip member 314 and the second clip member 316.

[0208] In another example, as shown in FIGS. 6A and 6B, the clip 312 can include separate membranes for the first clip member 314 and the second clip member 316. For example, as shown in FIGS. 6A and 6B, the dorsal or first clip member 314 can comprise a first inner member 350a extending generally between the proximal end 320 and the distal end 322 of the first clip member 314. The first clip member 314 can also include an outer membrane 352a extending generally between the proximal end 320 and the distal end 322 of the first clip member 314. The first inner membrane 350a and the first outer membrane 352a define or enclose an inner chamber 354a and an outer chamber 356a, which can be filled with a fluid, gas, or air. In a similar manner, the volar or second clip member 316 includes both a second inner membrane 350b and a second outer membrane 352b, each of which extend between the proximal end 320 and the distal end 322 of the second clip member 316. The second inner membrane 350b and the second outer membrane 352b form or define an inner chamber 354b and an outer chamber 356b, which can be filled with the gas, fluid, or air.

[0209] In some examples, the clip 312 can include components for sealing the holes, openings, or slots 358 in order to restrict fluid flow through the chambers 354, 356. Sealing the chambers 354, 356 defined by the membranes 350, 352 prevents the chambers 354, 352 from re-inflating when the digit 2 is removed from the clip 312. For example, the clip 312 can further comprise one or more valves, such as a check-valve, one-way valve, etc., positioned within the slots 358 extending through portion(s) of the first clip member 314 and/or the second clip member 316. As previously described, the slots 358 in the clip members 314, 316 permit the fluid (e.g., air) to pass from between the chambers 354, 356 (e.g., when the digit is inserted into the digit space 328). The valve can be a one-way or check valve that prevents air from flowing back into the inner chamber 354 for re-inflating the inner chamber 354 when, for example, the digit 2 is removed from the digit space 328. As such, the valve allows the clip 312 to be reusable for a particular patient without needing to resize the clip apparatus. An exemplary valve, specifically a duck bill valve 364, which can be inserted in an opening 362 of the first clip member 314 or the second clip member 316 is shown in an open position in FIG. 7. [0210] In use, the patient or practitioner first obtains the optical digit clip 312 and removes any packaging from the clip 312. Once any packaging is removed, the patient inserts his or her digit 2 into the clip 312, as previously described, by moving the clip members 314, 316 to the open position. Once the digit 2 is in place, the patient allows the clip 312 to close around the digit 2. As the clip 312 cinches against the digit 2, the inner membrane 350 is displaced by the digit 2, which causes the fluid (e.g., air) in the chamber 354 to exert a force on the duckbill valve 364 causing the valve 364 to transition from a closed position to the open position (FIG. 7). Once the valve 364 opens, the fluid passes through the valve 364 and into the second or outer chamber 356. When the digit 2 is removed from the clip 312, the valve 364 returns to the closed position and prevents fluid or air from passing back into the inner chamber 354, meaning that the inner chamber 354 does not re-inflate and that the clip 312 remains sized to accommodate the patient’s digit 2 and to apply pressure to the digit 2 within a predetermined range. When ready to use the clip 312 again, the clip members 314, 316 can be positioned about the patient’s digit 2, while allowing the clip 312 to move to the closed position. With the clip 312 in the closed position, the inner membrane 350 presses against the digit 2 applying the uniform pressure to the surfaces 4, 6, 8 of the digit 2, as previously described.

[0211] The wearable medical device 310 comprising the clip 312 further comprises the opticalbased physiological sensors, such as a PPG sensor 388 (shown in FIGS. 8A and 8B) and a peripheral arterial tone sensor 366 (shown in FIGS. 8A and 8B). The peripheral arterial tone sensor 366, the PPG sensor 388, and associated electronic circuitry can be positioned in a housing or enclosure positioned on the first clip member 314 or the second clip member 316. The clip members 314, 316 can also comprise structures for providing mechanical support for the electronic components of the clip 312 and the sensors 366, 388, such as a circuit board and/or computer processor, which can be in electronic communication with the sensors 366, 388. In particular, the electronic components and associated circuitry can comprise electronics circuits for receiving and/or processing signals representative of physiological parameters of the patient and for transmitting the received and processed physiological information to other devices through, for examples, a wireless transmitter or a connection cable 134 (shown in FIG. 1 and 3F).

[0212] As previously described, the PPG sensor 388 can be configured to measure the level of oxygen saturation in the patient’s blood by shining a beam of light through the tissue and detecting the amount of light that is absorbed. In some examples, as previously described, the PPG sensor 388 comprises an LED that emits light (e.g., light with a wavelength from about 200 nm to about 100 nm). In some examples, the emitted light can be either in the red wavelength (about 660 nm) and IR (Infra-Red) wavelength (about 910 nm to about 940 nm). The PPG sensor 388 can be configured to measure changes in absorbance of the digit 2 at both red and infrared light at peak wavelengths of approximately 660 nm and 910 nm, respectively. In some examples, the PPG LED can have a maximum optical output power of about 65 mW. Measurements from the PPG sensor 388 can be used to calculate the oximetry signal according to the pulse oximetry principles.

[0213] The peripheral arterial tone sensor 366 can be configured to be positioned at or proximate to the digit 2. The peripheral arterial tone sensor 366 comprises a peripheral arterial tone lightemitting diode (LED) and is configured to measure the pulsating movement of blood within one or more arteries. As previously described, the peripheral arterial tone sensor 366 measures signals representative of pulsatile volume changes in arteries of the digit 2 (e.g., in a distal tip 8 of the digit 2), which reflect a relative state of the arterial vasomotor activity, and which relate indirectly to a level of sympathetic activation. Peripheral arterial vasoconstriction, which mirrors or is indicative of sympathetic activation, can also be shown as attenuation of signal amplitude for signals detected by the peripheral arterial tone sensor 366.

[0214] In some examples, the wearable medical device 310 includes or is in electronic communication with a controller 138 (shown in FIG. 18A), such as a computer processor. The controller 138 can be configured to control acquisition of the physiological signals from the PPG sensor 388 or peripheral arterial tone sensor 366 and/or to control the transmission of data (e.g., data collected during a sleep study) based on physiological signals detected by the sensors 366, 388. As previously described, signals detected by the sensors 366, 388 can be used for determining PPG and peripheral arterial tone, as well as blood pressure, heart rate, and other physiological parameter values for the patient.

[0215] With continued reference to FIGS. 8A and 8B, the peripheral arterial tone sensor 366 comprises the peripheral arterial tone LED 368 for emitting light in a suitable wavelength for detecting peripheral arterial tone signals. As previously described, the peripheral arterial tone LED 368 can also be configured to emit non-visible radiation, such as infrared light. The peripheral arterial tone sensor 366 further comprises a detector (e.g., a photodetector 370) for detecting reflectance or transmittance of the light from or through portion(s) of the digit 2. For example, the photodetector 370 can be an optical detector configured to detect intensity of visible, ultraviolet, and/or infrared light. The PPG sensor 388 can comprise a PPG LED 390 positioned to project light towards either the same photodetector 370 used for detecting the peripheral arterial tone signals or to a different photodetector.

[0216] In some examples, as shown in FIG. 8A, the peripheral arterial tone LED 368 and/or the PPG LED 390 are mounted to one of the first clip member 312 or the second clip member 314 and the photodetector 370 is mounted to the other of the first clip member 312 or the second clip member 314. This configuration is a transmissive-type clip configuration where skin tissue is positioned between the LED 368, 390 and the photodetector 370, such that emitted light passes through the skin tissue and to the photodetector 370. For example, as shown in FIG. 8 A, the LED 368, 390 are mounted to the dorsal or first member 314 and the photodetector 370 is mounted to the second or volar clip member 316.

[0217] In other examples, as shown in FIG. 8B, the peripheral arterial tone sensor 366 can comprise a peripheral arterial tone LED 368 and photodetector 370 mounted to the same clip member 314, 316, in a reflectance-type clip configuration. For example, as shown in FIG. 8B, the peripheral arterial tone sensor 366 comprises a peripheral arterial tone LED 368 mounted to the second or volar clip member 316 and a photodetector 370, which is also mounted to the second or volar clip member 316. Positioning both the peripheral arterial tone LED 368 and the photodetector 370 on the volar or second clip member 316 and proximate to a volar surface 6 of the digit 2 can be preferable to positioning portions of the peripheral arterial tone sensor 366 proximate to the dorsal surface 4 of the digit 2. In particular, volar portions of the digit 2 are generally soft and fleshy, with areas of subcutaneous fat. As such, portions of arteries are generally more visible in the volar portion of the digit 2, meaning that better light reflectance signals can be obtain from the volar portion of the digit 2 than from the dorsal portion, thereby providing a better peripheral arterial tonometry signal. In some examples, as shown in FIG. 8B, the PPG LED 390 is amounted to the first clip member 314 in a transmissive-type configuration to emit light through skin tissue towards the photodetector 370. In other examples, the PPG LED 390 can be positioned on the second clip member 316 along with the peripheral arterial tone LED 368 and photodetector 370 in a reflectance-type configuration.

[0218] FIGS. 9A and 9B show another example of an optical digit clip device or clip 912. As in previous examples, the clip 912 comprises a dorsal or first clip member 914 comprising a first or inner surface 926a configured to receive a first portion of a digit 2 of a patient and a volar or second clip member 916 coupled to the first clip member 914 and comprising a second or inner surface 926b configured to receive a second portion of the digit 2. As in previous examples, the first clip member 914 and the second clip member 916 are configured to receive the digit 2 in a digit space 928 defined by the inner surfaces 926a, 926b of the first clip member 914 and the second clip member 916. Further, one of the first clip member 914 or the second clip member 916 can be movable toward the other of the first clip member 914 or the second clip member 916 to generate pressure within the digit space 928. As in previous examples, the clip 912 also comprises the uniform pressure applicator and optical-based physiological sensors, such as the PPG sensor and/or the peripheral arterial tone sensor, disposed in the digit space 928. The peripheral arterial tone sensor can be configured to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0219] The optical digit clip 912 shown FIGS. 9 A and 9B differs from previous examples in positioning of the hinge 918, which connects the first clip member 914 to the second clip member 916. Specifically, for the clip 912, the hinge 918 is positioned proximate to a proximal end 920 of the clip members 914, 916, near to the portion of the inner surfaces 926a, 926b of the clip members 914, 916 that receive proximal portions of the digit 2 (e.g., proximal phalanges of a finger). For example, the hinge 918 can be positioned closer to the proximal end 920 of the first clip member 914 and the second clip member 916 than to the distal end 922 of the first clip member 914 and the second clip member 916. In other examples, the hinge 918 can be positioned at a middle of the clip members 914, 916 (e.g., substantially halfway between the proximal end 920 and the distal end 922 of the clip members 914, 916).

[0220] In some cases, positioning the hinge 918 proximate to a proximal end 920 of the clip members 914, 916 can assist in maintaining positioning of the clip member 914, 916 on the patient’s digit 2 and/or preventing the clip 912 from falling off or detaching from the digit 2 during use. For example, having a proximal hinge 918 can mean that the clip members 914, 916 exert forces (e.g., proximally directed forces) on the digit 2, drawing the clip 912 farther onto the digit 2 and preventing the clip 912 from falling off of the digit 2. By contrast, a hinge 318 (shown in FIGS. 3A-3F) positioned proximate to the distal end 322 of the clip members 314, 316 may exert a distally directed force on the digit 2, which could cause the clip 312 to slip off of or detach from the digit 2, especially if the digit clip 312 is not retained on the digit 2 by a tether or adhesive. [0221] Another advantage of a clip 912 with a proximal hinge 918 can relate to size and configuration of the distal end 922 of the clip 912. For example, a clip 912 with distal ends 922 that open when the digit 2 is inserted (e.g., using a more proximally disposed hinge 918) may create additional space at the distal end 922 of the clip 912, meaning that pressure applying material can be applied near distal ends 922 of the clip members 914, 916 for applying increased or additional pressure to the distal tip of the digit 2.

[0222] FIGS. 10A and 10B show another example of a wearable medical device comprising an optical digit clip device or clip 1012. As in previous examples, the clip 1012 comprises a dorsal or first clip member 1014 comprising a first or inner surface 1026a configured to receive a dorsal or first portion of a digit 2 of a patient and a volar or second clip member 1016 coupled to the first clip member 1014 and comprising a second or inner surface 1026b configured to receive a volar or second portion of the digit 2. As in previous examples, the first clip member 1014 and the second clip member 1016 are configured to receive the digit 2 in a digit space 1028 defined by the inner surfaces 1026a, 1026b of the first clip member 1014 and the second clip member 1016. One of the first clip member 1014 or the second clip member 1016 can be movable toward the other of the first clip member 1014 or the second clip member 1016 to generate pressure within the digit space 1028. As in previous examples, the clip 1012 also comprises the uniform pressure applicator 1048 and the optical-based physiological sensors, such as the PPG sensor and/or the peripheral arterial tone sensor, disposed in the digit space 1028. As previously described, the peripheral arterial tone sensor is configured to provide signals representative of a peripheral arterial tonometry waveform of the patient.

[0223] The digit clip 1012 of FIGS. 10A and 10B differs from previous examples in a shape and configuration of proximal ends or proximal portions 1020 of the clip members 1014, 1016. Specifically, as shown in FIGS. 10A and 10B, proximal portions 1020 of the clip members 1014, 1016 are flexible and bent radially outwardly (as shown by arrows A5 in FIGS. 10A), which expands a proximal opening 1024 of the clip 1012. Distal ends or distal portions 1022 of the clip 1012 can be more rigid and resistant to flexing or bending. In this configuration, the patient’s digit 2 can be inserted into the digit space 1028 defined by the first clip member 1014 and the second clip member 1016 without moving or opening more distal portions 1022 of the first and second clip members 1014, 1016. [0224] In some examples, after the digit 2 is inserted into the digit space 1028, the flexible proximal portions 1020 of the clip members 1014, 1016 can be bent radially inwardly to contact proximal portions of the digit 2 (e.g., to contact the proximal or middle phalanges of the digit). In some examples, the proximal ends or proximal portions 1020 of the clip members 1014, 1016 may be held in an inwardly bent position by attaching a clamp 1072 (shown in FIG. 10A) or clip (e.g., a C-ring, bracket, or similar connector) around the proximal portions 1020 of the clip members 1014, 1016, thereby securing the proximal portions 1020 of the clip members 1014, 1016 to the digit 2.

[0225] FIGS. 11A and 11B show another example of an optical digit clip device or clip 1112, which includes a reusable clip portion 1172 and a disposable sleeve 1174. As shown in FIGS. 11A and 11B, the reusable clip portion 1172, comprises a first clip member 1114 pivotally connected to a second clip member 1116. The first clip member 1114 and the second clip member 116 are movable towards one another to generate pressure on a digit 2 enclosed in the disposable sleeve 1174. The reusable portion 1172 of the clip 1112 can also comprise electrical components of the wearable medical device 1110, such as optical -based physiological sensors including a peripheral arterial tonometry sensor 1166 and/or a PPG sensor 1188 configured to be positioned at or proximate to the digit 2 and to provide signals representative of a peripheral arterial tonometry waveform and/or oximetry waveform of the patient. As in previous examples, the PPG sensor 1188 comprises a PPG LED 1190 and the peripheral arterial tone sensor 1166 comprises a peripheral arterial tone LED 1168. The sensors 1166, 1188 can further comprise the photodetector 1170 for detecting light emitted from the LED 1168, 1190 and reflected from or transmitted through the digit 2 of the patient. The LED 1168, 1190 and photodetector 1170 can be mounted to the first clip member 1114 or the second clip member 1116.

[0226] The clip 1112 also includes the disposable sleeve 1174 configured to be worn on or wrapped around the digit 2. The disposable sleeve 1174 can comprise a compressive material that exerts radial and/or axial pressure on the digit 2. In some examples, the compressive material and other structural features of the disposable sleeve 1174 can be selected to apply pressure to specific portions of the digit 2. For example, the disposable sleeve 1174 can include areas of varying wall thickness for applying different magnitudes of pressure to different portions of the digit 2. Also, portions of the disposable sleeve 1174 can be inwardly stressed or biased to provide additional pressure to portions of the digit 2. Desirably, the areas of varying wall thickness and/or positioning of biased and stressed regions of the disposable sleeve 1174 are selected so that, when the disposable sleeve 1174 is engaged to the reusable portion 1172, the clip 1112 provides the uniform pressure field to the surfaces 4, 6, 8 of the digit 2.

[0227] In use, the disposable sleeve 1174 is positioned over and/or wrapped around the digit 2. Once the disposable sleeve 1174 is in place on the digit 2, the first and second clip members 1114, 1116 can be opened allowing the digit 2 and disposable sleeve 1174 to be inserted into a digit space 1128 defined by the clip members 1114, 1116. Once the digit 2 and disposable sleeve 1172 are in the digit space 1128, the clip members 1114, 1116 are released causing the clip members 1114, 1116 to contact and press against the disposable sleeve 1174. In some examples, the clip members 1114, 116 can comprise hooks, locks, latches, or similar engaging structures configured to engage corresponding portions of the disposable sleeve 1174 for securing the clip members 1114, 1116 to the disposable sleeve 1174. Furthermore, as previously described, the disposable sleeve 1174 can be configured to distribute pressure provided by the clip members 1114, 1116 so that pressure is uniformly provided to surfaces 4, 6, 8 of the digit 2 enclosed within the disposable sleeve 1174.

[0228] After sensing or monitoring is completed, the reusable portion 1172 can be disconnected from the disposable sleeve 1174 by, for example, pulling the reusable portion 1172 away from the disposable sleeve 1174 with sufficient force to overcome the lock or engagement between the reusable portion 1172 and the disposable sleeve 1174. Once the reusable portion 1172 is removed from the disposable sleeve 1174, the patient can remove the disposable sleeve 1174 from his or her digit 2 and discard the disposable sleeve 1174. The reusable portion 1172 can be cleaned or otherwise prepared to be reused by the patient and/or to be used by other patients.

[0229] FIGS. 12A-12C show another example of a wearable medical device 1210 comprising an optical digit clip device or clip 1212 for non-invasive physiological measurements, such as PPG and/or peripheral arterial tonometry measurements. The clip 1212 comprises a clamp 1272 configured to engage and exert pressure against a body 1274, such as a rigid or semi-rigid shell. The clamp 1272 can comprise a first portion or leg 1214 configured to engage a first portion of the body 1274 for exerting a radially inwardly directed pressure against the first portion of the body 1274 and a second portion or leg 1216 configured to engage and exert radially inwardly directed pressure against a second portion of the body 1274. As shown in FIGS. 12A-12C, the clamp 1272 can be a C-clip or similar structure including a central or intermediate portion 1276, which biases the first leg 1214 and the second leg 1216 of the clamp 1272 towards a closed position, which causes the first leg 1214 and the second leg 1216 to exert the radially inwardly directed force against the portions of the body 1274.

[0230] The clip 1212 also includes the body 1274 or shell. In some examples, the body 1274 can comprise a tubular structure enclosing a digit space 1228 defined by the inner surfaces 1226 of the body 1274 and configured to receive a digit of a patient. The body 1274 can comprise a uniform pressure applicator 1248 configured to uniformly distribute the pressure generated within the digit space 1228 to portions or surfaces of the digit and optical-based physiological sensors, such as a PPG sensor and/or peripheral arterial tonometry sensor, disposed within the digit space 1228. The PPG sensor and/or peripheral arterial tone sensor are configured to be positioned at or proximate to the digit and to provide signals representative of an oximetry and/or peripheral arterial tonometry waveform of the patient.

[0231] As shown in FIGS. 12B and 12C, the body 1274 comprises one or more sealed air bladders 1278 nested within the body 1274 or shell. In some examples, portions of the one or more sealed air bladders 1278 can extend through a slot(s) 1280 disposed at a circumferential location of the body 1274 or shell. After the digit 2 is inserted into the digit space 1228 defined by the body 1274 or shell, the clamp 1272 can be applied to the external portions of the one or more sealed air bladders 1278, thereby pressurizing an interior of the one or more sealed air bladders 1278 and causing inner surfaces of the one or more sealed air bladders 1278 to exert pressure against the digit 2. In examples, one or more of the air bladder 1278 can be exposed at a particular circumferential location (radially outward of slot 1280). The clamp 1272 can compress the exposed portion of the air bladder 1278 extending through the slot 1280, thereby reducing inconsistent compression or pressure due to patient movement and orientation (e.g., if the patient presses against other portions of body 1274 where air bladder 1278 is not exposed, the internal pressure will not change).

[0232] In some examples, the clamp 1272 can be a clip, such as a clipping device that clamps down on the exposed portion of the air bladders 1278, where they extend through slots 1280 to pressurize the air bladders 1278. In other examples, the clamp 1272 may have a ratchet mechanism to adjust the pressure to accommodate different finger sizes. For example, a ratchet mechanism can be used to adjust externally applied pressure of the clip 1212, in addition to or in place of a spring biased hinge. In other examples, the clip 1212 can comprise a multi-chamber structure including multiple air bladders 1278 that are fluidly connected, as described in earlier examples.

[0233] FIGS. 13A-13D show additional examples of wearable medical devices 1310 comprising an optical digit clip device or clip 1312 for obtaining non-invasive peripheral arterial tonometry measurements. As in previous examples, the clip 1312 comprises a dorsal or first clip member 1314 comprising a first or inner surface 1326a configured to receive a first or dorsal portion of a digit 2 of a patient. The digit clip 1312 also includes a volar or second clip member 1316 coupled to the first clip member 1314 and comprising a second or inner surface 1326b configured to receive a volar or second portion of the digit 2. As previously described, the first clip member 1314 and the second clip member 1316 are configured to receive the digit 2 in a digit space 1328 defined by the inner surfaces 1326a, 1326b of the clip members 1314, 1316. The clip members 1314, 1316 can be configured to move toward one another to generate pressure within the digit space 1328. The clip 1312 can also include any of the previously described uniform pressure applicators disposed in the digit space 1328 configured to uniformly distribute pressure generated within the digit space 1328 to a dorsal portion and a volar portion of the digit. The clip 1312 can further comprise the optical-based physiological sensor(s), such as the PPG sensor and/or the peripheral arterial tone sensor, disposed within the digit space 1328 that provides signals representative of the peripheral arterial tonometry waveform of the patient.

[0234] Unlike in previous examples, the first clip member 1314 and the second clip member 1316 are not symmetrical. Instead, the clip members 1314, 1316 can be different sizes and/or can be configured to receive different sized portions of the digit 2. For example, the second clip member 1316 may be sized to receive, support, or enclose more than 50%, more than 60%, or more than 75% of a volume of the digit 2. By contrast the first clip member 1314 may be configured to receive, support, or enclose less than 50%, less than 40% or less than 25% of a total volume of the digit 2.

[0235] In one particular example, as shown in FIGS.13A and 13B, the volar or second clip member 1316 can comprise a closed cylinder (e.g., a cylinder having a closed distal end 1322 and an open proximal end 1320) sized to receive the digit 2. The cylindrical second clip member 1316 comprises an open top or volar portion including a space or opening 1382 for improved accessibility. The dorsal or first clip member 1314 is attached to the second clip member 1316 and is configured to move from an open position (shown in FIG. 13 A), where the first clip member 1314 is pivoting away from the opening 1382, to a closed position (shown in FIG. 13B), where the first clip member 1314 covers the opening 1382 in the cylindrical second clip member 1316, thereby forming an enclosed digit space 1328. When the first clip member 1314 is in a closed position, the inner surface 1326a of the second clip member 1316 and the inner surface 1326b of the first clip member 1314 or flap surround the digit 2 exerting pressure on the digit 2. The first clip member 1314 or flap can be convex-shaped on the outside and can be configured to seal the opening 1328 in the second clip member 1316.

[0236] In another example, as shown in FIGS. 13C and 13D, the non-symmetrical first clip member 1314 and second clip member 1316 form the open proximal end 1320 of the clip 1312. More specifically, as shown in FIGS. 13C and 13D, an inner surface 1326 of the second clip member 1316 can be a concave inner surface 1326a sized to receive a volar portion of the digit. The first clip member 1314 can be pivotally coupled to the second clip member 1316. Furthermore, the first clip member 1314 can comprise or form a flap with a concave inner surface 1326b that opens and closes. When in the closed position, the open proximal ends 1320 of the first clip member 1314 and the second clip member 1316 form a proximal opening 1324 for inserting the digit 2 into the digit space 1328 enclosed by the clip members 1314, 1316.

[0237] In order to ensure that the digit clip remains securely attached to a patient for long term or continuous use (e.g., for the duration of a sleep study), the present disclosure is also directed to attachment devices 1502 for securing the digit clip in place on the digit of the patient. FIGS. 14A- 15B show examples of wearable medical devices 1410 comprising an optical digit clip device or clip 1412 and different examples of attachment devices 1502 for securely attaching the clip 1412 to the patient’s digit. The attachment devices 1502 disclosed herein can include various arrangements of straps, tethers, bands, sleeves, collars, and similar connectors for securing the clip 1412 to a particular digit 2 of the patient. The attachment device 1502 can be configured to hold the clip 1412 in place on the digit 2 of the patient during continuous, long-term use, thus preventing the clip 1412 from becoming dislodged, disconnected, or from falling off of the digit 2 of the patient at an inappropriate or unexpected time. Additionally or alternatively, the various attachment mechanisms described herein are configured to optimize the quality of the physiological data retrieved during the underlying clinical study. By ensuring proper fit and attachment to the relevant patient extremity, implementations described herein allow for greater reliance on clinical diagnosis that can be drawn from the resulting physiological data. Therefore, the attachment devices 1502 can prevent loss or interruption of signal fidelity and/or medical data, which occurs when a clip 1412 falls off of the digit 2 of the patient. The attachment devices 1502 can also ensure that data collected by sensors of the wearable medical device 1410 is accurate, complete, and is not corrupted or modified by movement noise or changes in position of the clip 1412 relative to the digit 2.

[0238] In some examples, the attachment device 1502 can be made from soft and flexible materials designed to tightly constrict against surfaces of the clip 1412 and/or against the digit 2 of the patient, thereby forming a secure engagement between the clip 1412 and the digit 2. For example, the attachment devices 1502 secured to the clip 1412 can be partially or entirely formed from a thermoplastic elastomer, such as silicone, polypropylene, low-density polyethylene, synthetic rubber (e.g., polychloroprene), or natural rubber (e.g., isoprene). In other examples, portions of the attachment device 1502 can be formed from more rigid plastic materials, such as acrylonitrile butadiene styrene (ABS), polyester, polycarbonate, polypropylene, high-density polyethylene, or polyethylene terephthalate.

[0239] As shown in FIG. 14A, the clip 1412 is connected to an attachment device 1502 connected to the proximal end 1420 of the first clip member 1414 or the second clip member 1416. The attachment device 1502 includes a clip apparatus fastening portion 1514 connected to the clip 1412 and a skin securement portion 1532 extending from the fastening portion 1514 configured to releasably couple the attachment device 1502 to a skin surface of the patient. For example, an adhesive, such as an acrylic adhesive or a low surface energy (LSE) adhesive, can be used to adhere the fastening portion 1514 to the clip 1412. Adhesives used for this application can include features such as high initial bond for immediate usability, good chemical and humidity resistance, -40°F to 300°F short-term temperature resistance, anti-lifting performance on curved surfaces, and no major surface preparation or primer application needed. As a specific example, the adhesive can include an acrylic adhesive such as 300LSE manufactured by 3M of Saint Paul, Minnesota, USA. For example, the fastening portion 1514 can include an inwardly facing surface and an outwardly facing surface. The inwardly facing surface can be adhered to an external surface of one of the clip members 1414, 1416.

[0240] The attachment device 1502 further comprises the skin securement portion 1532 including an inwardly facing surface configured to contact the skin surface of the patient and an outwardly facing surface. In some examples, the inwardly facing surface includes an adhesive, such a hydrogel and/or removable adhesive, for attaching the skin securement portion 1532 to the skin surface of the patient. The skin securement portion 1532 can be an elongated member having an axis L3. The axis L3 can be transverse or substantially transverse (e.g., about 90 degrees) relative to the axis LI, L2 of the clip 1412 and the fastening portion 1514. In an example, the skin securement portion 1532 can be configured to at least partially wrap about the digit of the patient, e.g. around a proximal phalange of the finger. In an example, the skin securement portion 1532 can be configured to attach to a proximal phalange portion of the front of the hand (when viewed towards the palm).

[0241] FIG. 14B shows another example of a wearable medical device 1410 comprising a clip 1412 and attachment device 1502. As shown in FIG. 14B, the attachment device 1502 includes the fastening portion 1514 for securing the attachment device 1502 to one of the clip members 1414, 1416 of the clip 1412 and the skin securement portion 1532 for securing the attachment device 1502 to, for example, a third portion or proximal phalanges of a digit of the patient. However, unlike in FIG. 14A, the attachment device 1502 of FIG. 14B includes a skin securement portion 1532 that is a longitudinally extending elongated member having a width W 1 that is wider than a width W2 of the fastening portion 1514. As shown in FIG. 14B, the longitudinal axis LI of the fastening portion 1514 and the longitudinal axis L2 of the clip 1412 are parallel or substantially parallel (e.g., within about 10 degrees of parallel) with a longitudinal axis L3 of the skin securement portion 1532. The fastening portion 1514 of the attachment device 1502 can be secured to an external surface of one of the clip members 1414, 1416 as in previous examples. For example, the fastening portion 1514 can be adhered to the external surface of the clip 1412 by a hydrogel, a removable adhesive, or a permanent adhesive. In other examples, the fastening portion 1514 can be connected to the clip 1412 by mechanical fasteners, such as pins, screws, nails, staples, or thread (e.g., stitching).

[0242] The skin securement portion 1532 shown in FIG. 14B is an elongated member configured to be connected to, for example, the third portion or proximal phalanges of the digit. For some patients, the skin securement portion 1532 may also extend proximally beyond the third portion or proximal phalanges of the digit. In such cases, the skin securement portion 1532 can be configured to be adhered to or engage to the palm, top portion of the patient’s hand, or other portions of the hand or wrist. In order to secure the skin securement portion 1532 to the digit, hand, or wrist, the skin securement portion 1532 can include an adhesive or adhesive layer for adhering the skin securement portion 1532 to the digit 2. The adhesive layer can be a hydrogel and/or removable adhesive, for removably coupling the attachment device 1502 and the clip 1412 to the patient.

[0243] FIG. 15A shows another example of the wearable medical device 1410 comprising the clip 1412 and the attachment device 1502 configured to be secured to or worn about a wrist of the patient. The attachment device 1502 of FIG. 15A comprises the fastening portion 1514 connected to an external surface of one of the clip members 1414, 1416 and the skin securement portion 1532 configured to be releasably coupled to a skin surface of the patient. Unlike in previous examples, in which the skin securement portion of the attachment device connected to portion(s) of the digit (e.g., to third or proximal portions of the same digit that is inserted into the digit housing), the skin securement portion 1532 of FIG. 15A is configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device 1502 to the patient. For example, the skin securement portion 1532 can comprise a strap, ribbon, tether, sleeve, band, cuff, collar, bracelet, or similar wearable connector or anchor configured to be worn on the wrist, forearm, or arm of the patient for securing the clip 1412 in place and for preventing the clip 1412 from detaching from the digit of the patient at unexpected or inappropriate times. The attachment device 1502 can also include a middle portion 1540, such as a tether or strap, extending between the housing fastening portion 1514 and the skin securement portion 1532 of an appropriate length to extend from the patient’s finger to the wrist, forearm, or arm of the patient. The middle portion 1540, such as the tether or strap, can be configured to rest against an outwardly facing side of the patient’s hand when the clip 1412 is worn by the patient.

[0244] As shown in FIG. 15 A, the skin securement portion 1532 of the attachment device 1502 is an annular or partially annular bracelet 1564 configured to be worn about the wrist of the patient. The bracelet 1564 can be formed from a stretchable and/or elastomeric material so that the bracelet 1564 can expand, allowing the bracelet 1564 to be used for patients with substantial variability in wrist size. In addition, in some examples, the bracelet 1564 can include a clasp, lock, buckle, or another resizing mechanism for resizing the bracelet 1564 to provide additional size adjustability for the bracelet 1564.

[0245] FIG. 15B shows another example of a wearable medical device 1410 comprising the clip 1412 and the attachment device 1502 connected to an external surface of one of the clip members 1414, 1416. As in previous examples, the attachment device 1502 comprises the fastening portion 1514 that is permanently or removably connected to the external surface of one of the clip members 1414, 1416. For example, the fastening portion 1514 can be an elongated member including one or multiple slots 1560, holes, or openings configured to receive corresponding protrusions 1562 for securing the fastening portion 1514 to the clip 1412. When connected to the clip 1412, the fastening portion 1514 can be oriented with a longitudinal axis LI of the fastening portion 1514 parallel or substantially parallel (e.g., within about 10 degrees of parallel) to a longitudinal axis L2 of the clip members 1414, 1416 and clip 1412.

[0246] Unlike in previous examples, the attachment device 1502 of FIG. 15B also includes an anchor portion 1566 configured to be secured to a digit of the patient that is different from the digit inserted into the digit space of the clip 1412. For example, the clip 1412 can be connected to a middle finger of the patient and the anchor portion 1566 can be connected to an index finger and/or ring finger of the patient. Alternatively, the clip 1412 can be connected to a pointer or index finger of a patient and the anchor portion 1566 can be connected to a middle finger of the patient. In another example, the clip 1412 can be connected to a ring finger of a patient and the anchor portion 1566 can be connected to a middle finger of the patient.

[0247] In some examples, as shown in FIG. 15B, the attachment device 1502 includes a single anchor portion 1566 connected to a single housing fastening portion 1514. The single anchor portion 1566 can be an expandable ring including two size-expanding sections 1568 positioned on opposite sides of the ring configured to unfold so that the ring can expand, meaning that the ring can be worn by patients with wider digits (e.g., fingers). Also, as in previous examples, the ring can be formed from a stretchable and/or elastomeric material which can stretch to accommodate larger digits. In order to apply the clip 1412 of FIG. 15B to a digit of a patient, the patient or practitioner attaches the attachment device 1502 to an external surface of one of the clip members 1414, 1416 by, for example, inserting the protrusions 1562 extending from the clip membersl414, 1416 through the openings or slots 1560 of the housing fastening portion 1514. The patient then inserts the clip 1412 onto the digit being sensed or measured and simultaneously inserts an adjacent or neighboring digit through the anchor portion 1566 for securing the clip 1412 in place on the digit 2. For example, as previously described, the clip 1412 can be inserted onto the middle finger of the patient while the anchor portion 1566 slides onto the patient’s index finger.

[0248] FIG. 16A is cross-sectional views of another example of a wearable medical device comprising an optical digit clip device or clip 1612 for non-invasive peripheral arterial tonometry measurements in a closed position. FIG. 16B is a cross-sectional view of the clip 1612 in an open position. As in previous examples, the clip 1612 comprises a dorsal or first clip member 1614 comprising a first or inner surface 1626a configured to receive a first or dorsal portion of a digit of a patient and a volar or second clip member 1616 movably coupled to the first clip member 1614 and comprising a second or inner surface 1626b configured to receive a second or volar portion of the digit. The clip 1612 can also include a hinge 1618 between the first clip member 1614 and the second clip member 1616. In other examples, as previously described, the clip 1612 can comprise a ratchet that biases the clip members 1614, 1616 to the closed position and adjusts the pressure to accommodate different finger sizes. For example, the ratchet mechanism may be used to adjust externally applied pressure of the clip 1612, in addition to or in place of a spring biased hinge.

[0249] As in previous examples, the first clip member 1614 and the second clip member 1616 are configured to receive the digit 2 of a patient in a digit space 1628 defined by inner surfaces 1626a, 1626b of the clip members 1614, 1616. Also, the first clip member 1614 and the second clip member 1616 are moveable toward one another from the open position (shown in FIG. 16B) to the closed position (shown in FIG. 16A). As in previous examples, the wearable medical device further comprises optical-based physiological sensors, such as a PPG sensor and/or a peripheral arterial tonometry sensor, disposed within the digit space 1628 configured to be positioned at or proximate the digit 2 and to provide signals representative of oxygen saturation and/or a peripheral arterial tonometry waveform of the patient.

[0250] Unlike in previous examples, as shown in FIGS. 16A and 16B, the clip 1612 further comprises a distal applicator 1684 configured to distribute an axial pressure to the distal tip of the digit 2 received within the digit space 1628. The axial pressure can be generated by the movement of the first clip member 1614 toward the second clip member 1616 as the clip 1612 moves to the closed position. Axial pressure can also be generated by biasing members, such as a spring, living hinge, or ratchet mechanism of the clip 1612, which biases the clip 1612 toward the closed position. In some examples, the first clip member 1614 and the second clip member 1614 can be configured to generate an axial pressure within a range of about 40 mmHg to about 70 mmHg, which is transferred to the distal tip of the digit 2 through the distal applicator 1684.

[0251] The distal applicator 1684 can comprise a sheet, membrane, cushion, pillow, pad, or similar soft support extending over an inner surface of the hinge 1618 positioning to contact the distal tip of the digit 2 when the digit 2 is inserted into the digit space 1628 and the clip 1612 is in the closed positon. For example, as shown in FIGS. 16A and 16B, the distal applicator 1684 can comprise a membrane 1686 extending between a distal end 1622 of the first clip member 1614 and a distal end of the second clip member 1616, thereby covering the hinge 1618. The membrane 1686 can enclose a fluid-filled chamber 1688, which supports the membrane 1686 so that the membrane 1686 is positioned to contact the distal tip 8 of the digit 2. In some examples, the chamber 1688 can be a sealed chamber 1688, which is separate from and not in fluid communication with any other chambers disposed in the digit space 1628. In other examples, the chamber 1688 can be in fluid communication with other chambers of the clip 1612 meaning that fluid displaced from the chamber 1688 can flow to other chambers within the digit space 1628 allowing such other chambers to inflate or expand to improve contact with the digit 2.

[0252] In some examples, the clip 1612 further comprises a radial applicator 1690 disposed within the digit space 1628. The radial applicator 1690 can be configured to apply a radially inwardly directed pressure to surfaces of the digit 2 received within the digit space 1628. For example, the radial applicator 1690 can be configured to apply the radially inwardly directed pressure to the dorsal and volar surfaces of the digit 2. In some examples, the radial applicator 1690 comprises one or multiple membranes 1650 extending over inner surfaces 1626a, 1626b of the clip members 1614, 1616. In some examples, the radial applicator 1690 comprises a single tubular membrane 1650 extending, for example, between the proximal end 1620 and the distal end 1622 of the clip members 1614, 1616. In other examples, as shown in FIGS. 16A and 16B, the radial applicator 1690 comprises a first membrane 1650 extending between the proximal end 1620 and the distal end 1622 of the first clip member 1614 and a second membrane 1650 extending between the proximal end 1620 and the distal end 1622 of the second clip member 1616.

[0253] As in previous examples, the one or multiple membranes 1650 of the radial applicator 1690 can define or enclose one or more fluid filled chambers 1654. The chambers 1654 can be pressurized to support the membranes 1650. In particular, as in previous examples, when the chambers 1654 are pressurized, biasing forces created by moving the clip 1612 to the closed position are applied as radially inwardly directed pressure to the dorsal and volar surfaces of the digit 2 received within the digit space 1628 by the chambers 1654 and membranes 1650. Furthermore, the clip 1612 is configured so that the axial pressure from the distal applicator 1684 is simultaneously applied to the distal tip 8 of the digit 2 along with the radial pressure from the radial applicator 1690. In some examples, the radially inwardly directed pressure and the axial pressure can be substantially uniform or substantially equal (e.g., within a range of 40 mmHg to 70 mmHg), thereby obtaining the previously described benefits of sensors readings obtained when uniform pressure is applied to the digit 2.

[0254] FIG. 17A is cross-sectional views of another example of a wearable medical device 1710 comprising an optical digit clip device or clip 1712 for non-invasive peripheral arterial tonometry measurements in a closed position. FIG. 17B is a cross-sectional view of the clip 1712 in an open position. As in previous examples, the clip 1712 comprises a dorsal or first clip member 1714 comprising a first or inner surface 1726a configured to receive a first or dorsal portion of a digit 2 of a patient and a volar or second clip member 1716 movably coupled to the first clip member 1714 and comprising a second or inner surface 1726b configured to receive a second or volar portion of the digit 2. The clip 1712 can also include a hinge 1718 between the first clip member 1714 and the second clip member 1716.

[0255] As in previous examples, the first clip member 1714 and the second clip member 1716 are configured to receive the digit 2 of a patient in a digit space 1728 defined by the inner surfaces 1726a, 1726b. Also, the first clip member 1716 and the second clip member 1716 are moveable toward one another from the open position (shown in FIG. 17B) to the closed position (shown in FIG. 17A). As in previous examples, the clip 1712 further comprises an optical-based physiological sensor, such as a PPG sensor and/or a peripheral arterial tonometry sensor, disposed within the digit space 1728 configured to be positioned at or proximate the digit 2 and to provide signals representative of oxygen saturation and/or a peripheral arterial tonometry waveform of the patient.

[0256] The clip 1712 further comprises a uniform pressure applicator 1748 configured to uniformly distribute the pressure generated within the digit space 1728 to a dorsal portion 4 of the digit 2 and a volar portion 6 of the digit 2 received within the digit space 1728. However, unlike in previous examples, as shown in FIGS. 17A and 17B, the uniform pressure applicator 1748 comprises a first membrane 1750 forming multiple fluidly coupled bladders 1754 defining a first portion of the digit space 1728. For example, the first membrane 1750 can be connected between the proximal end 1720 and the distal end 1722 of the first clip member 1714 defining the multiple fluidly coupled bladders 1754 extending axially along an inner surface 1726a of the first clip member 1714. [0257] The fluidly coupled bladders 1754 are fluidly connected together so that applying pressure to a particular bladder 1754 causes fluid contained within the particular bladder 1754 to move to another bladder 1754 as shown by arrows A6 in FIGS. 17A and 17B. Allowing fluid to pass between the multiple fluidly coupled bladders 1754 can improve fit of the clip 1712. Including the multiple fluidly coupled bladders 1754 may also resist removal of the digit 2 from the digit space 1728 reducing the possibility that the clip 1712 would be removed prematurely or unexpectedly during, for example, a sleep study.

[0258] In some examples, the uniform pressure applicator 1748 further comprises a second membrane 1752 forming a plurality of fluidly coupled bladders 1756 defining a second portion of the digit space 1728. For example, the second membrane 1752 can be connected to and/or extend between the proximal end 1720 and the distal end 1722 of the second clip member 1716. As previously described, the multiple fluidly coupled bladders 1756 can be arranged in a row extending axially along an inner surface 1726b of the second clip member 1716. The multiple fluidly coupled bladders 1756 can be configured to permit fluid to pass between the fluidly coupled bladders 1754 as a digit 2 is inserted into the digit space 1728 to improve fit and sizing of the clip 1712. As previously described, the membranes 1750, 1752 and the multiple fluidly coupled bladders 1754, 1756 are configured to provide and/or distribute uniform pressure to surfaces of the digit 2 including the dorsal surface 4, volar surface 6, and distal tip 8. In particular, the uniform pressure applicator 1748 is configured to provide the radially inwardly directed pressure against the dorsal and volar surfaces 4, 6 of the digit 2 and to apply a substantially uniform axial pressure to the distal tip 8 of the digit 2.

[0259] Having described the wearable medical devices and digit clips of the present disclosure in detail, features of medical systems for monitoring patient physiological parameters will now be described. The medical systems can include any of the previously described wearable medical devices and digit clips configured to be attached to a digit, such as a finger or toe of the patient. As previously described, the digit clip 112 can include the optical -based physiological sensors for detecting signals representative of physiological parameters of the patient. The medical systems and wearable medical devices 110 can also include other sensors and devices for obtaining physiological information for a patient and for transmitting the obtaining information from the wearable medical device 110 to remote computer devices, servers, and networks. [0260] FIGS. 1, 18A, and 18B show features of an exemplary wearable medical device 110 comprising the digit clip 112 for noninvasive measurement of physiological parameters of a patient. The digit clip 112 can comprise sensors, such as a PPG sensor 130 and/or a peripheral arterial tone sensor 136 (shown in FIG. 18 A). The patient can be, for example, a patient undergoing a medical test, such as an at home medical test. For example, the patient can be undergoing a home or remote sleep apnea test, in which the digit clip 112 is worn on a digit of the wearer overnight while the wearer is sleeping. In other examples, the patient can be undergoing tests for other aspects of patient respiration or other respiratory conditions. The tests can be multiple hours in duration. The wearable medical device 110 and digit clip 112 can also be worn by a patient in a medical facility for continuous and ongoing monitoring of respiratory parameters of the patient over a period of hours or days.

[0261] As previously described, the digit clip 112 can comprise an oximeter or PPG sensor 130 for obtaining an oxygen saturation measurement for the patient and/or a peripheral arterial tone sensor 136 for obtaining a peripheral arterial tone waveform. In some examples, the digit clip 112 is a pneumatic probe configured to be mounted to the digit of a patient for providing continuous measurements, such as peripheral arterial tone measurements representative of a relative state of vasomotor activity in a distal part of the patient’s digit.

[0262] The wearable medical device 110 can also comprise the wearable monitor, such as the wrist-worn monitor 118. The wrist-worn monitor 118 can be a battery-powered monitoring device, which can be worn on a wrist, forearm, arm, or another convenient location of the wearer. The wrist-worn monitor 118 can be electrically connected to the digit clip 112 by the connecting cable 134. The wrist-worn monitor 118 can comprise electronical circuitry of the wearable medical device 110 including the controller 138. The wrist-worn monitor 118 can also include a wireless transceiver 140 or communications module for wireless transmission of captured and/or processed data from the medical device 110 to a remote computer device or computer server.

[0263] In some examples, the wrist-worn monitor 118 also includes one or more physiological sensors 148 (shown in FIG. 18A), which can be the same or different than the physiological sensors of the digit clip 112, for detecting additional physiological information for the patient. For example, the physiological sensor 148 can include a wrist-based PPG sensor comprising, for example, at least one light emitting device (e.g., a photoemitter) and at least one light detecting device (e.g., a photodetector). In some examples, the wrist-worn monitor 118 comprises multiple physiological sensors 148, such as multiple PPG sensors 148. For example, the wrist-worn monitor 118 can comprise a plurality of light emitting devices (e.g., three light emitting devices having different wavelengths) and a light detecting device (e.g., configured to detect light of each wavelength of the light emitting devices). The wrist-worn monitor 118 can also include other sensors 150, such as position or motion sensors (e.g., a body position sensor or an arm position sensor). In other examples, the sensor 150 can be a heart or blood flow sensor for measuring pulse, ECG, blood pressure, and/or cardiac physiological parameters.

[0264] In some examples, the medical device 110 further comprises the chest motion sensor device 120 configured to be positioned on a chest of the patient. As shown in FIGS. 1, 18 A, and 18B, the chest motion sensor device 120 can be connected to the wrist-worn monitor 118 by a second connecting cable 152 and can be configured to provide sensed data to the controller 138 of the wrist-worn monitor 118 for processing and/or to the wireless transceiver 140 of the wrist-worn monitor 118 for transmission to the remote computer device or server. The chest motion sensor device 120 can comprise a housing 142 (shown in FIG. 1), such as a rigid plastic housing, enclosing circuitry for detecting movement and acoustic signals in proximity to the wearer. Signals detected by sensors of the chest motion sensor device 120 can be related to snoring, body position, and/or the wearer’s chest movement. The housing 142 can comprise an adhesive surface or adhesive layer on a bottom portion of the housing 142, which can be configured to be adhered to the chest of the patient to maintaining positioning of the chest motion sensor device 120 on the wearer’s chest for obtaining sensor data from sensors of the chest motion sensor device 120. As shown in FIG. 18A, in some examples, the chest motion sensor device 120 comprises an acoustic snore sensor 144 and a chest movement sensor 146. The snore sensor 144 can be an acoustic decibel detector comprising, for example, a highly sensitive microphone that responds to snoring and other sounds in the audio range. The snore sensor 144 can be configured to convert detected sounds to a signal that provides a reliable indication that such sounds have been detected. The chest movement sensor 146 can be an accelerometer, such as a 3 -axis accelerometer, that provides a signal that reflects the movement of the chest, which can be translated, for example, both to the patient’s sleeping posture (supine, prone, right, left and sit) and to the chest movement signal resulted by the subject’s breathing during the night.

[0265] In some examples, as previously described, the wearable medical device 110 can be configured to transmit, such as via the wireless transceiver 140 of the wrist-worn monitor 118, medical data, such as medical information based on signals detected on sensors 130, 136 of the digit clip 112 and/or signals detected by sensors 144, 146 of the chest motion sensor device 120. In such an example, the wireless connection may include at least one of the following: a cellular connection, a Bluetooth connection, Advanced Message Queuing Protocol (AMQP) connection, Constrained Application Protocol (CoAP) connection, a WiFi connection, a ZigBee connection, a Z-Wave connection, a wireless personal area network (WPAN) connection, an Infrared Data Association (IrDA) connection, or any combination thereof.

[0266] As described in further detail in connection with FIGS. 19A-19C, signals and/or data detected and/or processed by the wearable medical device 110, wrist- worn monitor 118, and/or chest motion sensor device 120 can be transmitted, via the wireless transmitter 140, to remote servers for further processing and for preparing reports summarizing collected data. For example, data can be wirelessly transmitted from the wearable medical device 110 to an intermediate or gateway device, such as a mobile phone running a data collection application. The mobile phone can be configured to store received data in memory and to transmit the received data to the remote server on a continuous or ongoing basis.

[0267] Once data is received by the remote server, the server can execute software to analyze the received data using various automatic algorithms for detecting respiratory and other events that occurred during sleep, as well as periods of REM, deep sleep, light sleep and wakefulness. A pulse rate signal can be derived from the received data and used in the automatic analysis. The received data, such as night data from the sleep study, can be viewed by a technician and, if required, automatically detected events can be revised manually. The received analyzed data can then be used to generate reports, such as comprehensive reports of a patient sleep study including statistics and graphic presentations of recorded data and test results. Once generated, the comprehensive report(s) including the overnight sleep study data can be stored in Web Server storage and delivered to interested parties (e.g., a prescribing physician, a caregiver, or the patient) via the Internet.

[0268] Having described the wearable medical device 110 and digit clip 112, as well as the various exemplary attachment devices used to secure the digit clip 112 to the digit of the patient, physiological monitoring systems 1900 for controlling the wearable medical device 110 and/or for collecting, storing, analyzing, and providing feedback about physiological information detected by the digit clip 112 and/or the wearable medical device 110 will now be described in detail. Exemplary physiological monitoring systems 1900 for collecting and analyzing data collected by the digit clip 112 and associated wearable medical devices 110 are shown in FIGS. 19A-19C. Specifically, FIGS. 19A-19C are schematic drawings and block diagrams of the system 1900 showing communication pathways for transmitting detected information and other data from the digit clip 112 and wearable medical device 110 to remote computer devices or computer servers. Further, FIG. 19B shows a patient lying on a bed wearing the wearable medical device 110 and digit clip 112, as may occur during an overnight sleep study. FIG. 19C shows an awake patient sitting in a chair while wearing the wearable medical device 110 and the digit clip 112, as may occur when the digit clip 112 is used for periodic or continuous monitoring of patient physiological parameters.

[0269] As shown in FIGS. 19A-19C, the system 1900 comprises a remote monitoring device 1902 (shown in FIG. 19A) in communication with the wearable medical device 110. For example, the remote monitoring device 1902 can be in communication with the controller 138 of the wrist- worn monitor 118 and/or with other electronic or monitoring circuitry of the wearable medical device 110 for receiving information detected by sensors 130, 136 of the digit clip 112. The system 1900 can also include a wireless communication network 1906, and/or a wired connection 1908 for transmitting information, such as data detected by sensors of the wearable medical device 110, from the wearable medical device 110 to the remote monitoring device 1902. [0270] Devices of the wireless communications network 1906 can include one or more of the following types of communication circuitry: cellular communications circuitry, Bluetooth® communications circuitry, Advanced Message Queuing Protocol (AMQP) circuitry, Constrained Application Protocol (CoAP) circuitry, WiFi circuitry, ZigBee circuitry, Z-Wave circuitry, wireless personal area network (WPAN) circuitry, Infrared Data Association (IrDA) circuitry, or any combination thereof. For example, wireless communications circuitry of the remote monitoring device 1302 may be configured to establish at least one of the following types of wireless connections with the wearable medical device 110 and/or digit clip 112: a cellular connection, a Bluetooth® connection, an Advanced Message Queuing Protocol (AMQP) connection, a Constrained Application Protocol (CoAP) connection, a WiFi connection, a ZigBee connection, a Z-Wave connection, a wireless personal area network (WPAN) connection, an Infrared Data Association (IrDA) connection, or any combination thereof. [0271] In some examples, the remote monitoring device 1902 can include one or more devices capable of receiving information from and/or communicating information to the wearable medical device 110 and/or to other computer servers (e.g., via the wireless communication network 1906, via wired connection 1908, etc.). In some examples, the remote monitoring device 1902 can include a server or a group of servers. Additionally or alternatively, the remote monitoring device 1902 can include at least one other computing device separate from or including the server and/or group of servers, such as a portable and/or handheld device (e.g., a computer, a laptop, a personal digital assistant (PDA), a smartphone, a tablet, and/or the like), a desktop computer, and/or other like devices, as described herein. In some examples, the remote monitoring device 1902 may include at least one network interface (e.g., a server network interface and/or the like), at least one data storage device (e.g., a server database and/or the like), at least one processor (e.g., a server processor and/or the like), any combination thereof, and/or the like. For example, the remote monitoring device 1902 may include at least one processor operatively connected to a non- transitory computer-readable medium. In some examples, the remote monitoring device 1902 can be in communication with at least one data storage device (e.g., a server database and/or the like), which may be local or remote to the remote monitoring device 1902. In some examples, the remote monitoring device 1902 may be capable of receiving information from, storing information in, communicating information to, or searching information stored in the data storage device (e.g., a server database and/or the like).

[0272] In some examples, the system 1900 can be configured for conducting a home and/or remote sleep study using the digit clip 112 and wearable medical device 110 of the present disclosure. In particular, as shown in FIGS. 19B and 19C, the wrist-worn monitor 118 can be strapped to a wrist of a patient and the digit clip 112 can secured to the patient’s digit or finger. For example, as previously described, the attachment devices disclosed herein can be used to secure the digit clip 112 to the digit of the patient ensuring that the digit clip 112 does not become dislodged during the home and/or remote sleep study. As previously described, the wrist-worn monitor 118 can be configured to receive PPG signals, as well as a peripheral arterial signal and/or oxygen saturation data from the digit clip 112. The wrist-worn monitor 118 can also receive actigraphy (movement) data from the chest motion sensor device 120 and transmit the relevant data using an application running on a mobile device, such as the gateway device 1910, via the communication network 1906 to a remote computer system 1930 (e.g., one or more web servers) for further processing.

[0273] The system 1900 depicted in FIGS. 19A-19C is useful for conducting a home and/or remote sleep study, such as an overnight sleep study. For example, as shown in FIG. 19B, the patient may wear the wearable medical device 110 and the digit clip 112 while sleeping in a bed. Data such as physiological data obtained from the sleep study can be stored on the remote computer system 1930 and obtained, preferably after conclusion of the sleep study, for evaluation. The data may include respiratory and other events that occurred during sleep as well as periods of REM, deep sleep, light sleep and wakefulness. The pulse rate signal may be derived from the peripheral arterial signal and used in the automatic analysis. For example, the system 1900 can be configured to generate various parameters, including but not limited to: a respiratory disturbance index, an apnea-hypopnea index, a central apnea-hypopnea index, a percentage of total sleep time with Cheyne-Stokes Respiration pattern and sleep staging identification. A report may be generated, and the relevant data of the sleep study may be viewed on a screen and the automatically detected events can be revised manually by a physician as needed.

[0274] As previously described, the digit clips 112 and wearable medical devices 110 disclosed herein can be used for obtaining physiological measurements for a patient remote from a medical facility, such as at home. For example, as previously described, the digit clips 112 and medical devices 110 disclosed herein can be used for Home and/or Remote Sleep Apnea Tests (e.g., “HSATs”). In order to guide patients in performing such at home tests, the patient can be provided with verbal or written instructions for performing the at home study. For example, the instructions can guide the patient in how to correctly remove the digit clip 112 from packaging and prepare the digit clip 112 for use. The instructions may also include guidance for how to attach the digit clip 112 to the patient’s digit and/or for using the attachment device to secure the digit clip 112 in place on the digit 2. The instructions can also include guidance on how long the digit clip 112 should be worn and/or on how to transmit collected data from the wearable medical device 110 to the remote server after the study has been completed.

[0275] In some examples, instructions can be provided on an electronic device, such as a patient’s smart phone or personal computer. Examples of instruction screens or a user interface for guiding the patient in performing an HSAT at-home study using the digit clip 112 and wearable medical device 110 are shown in FIGS. 20A-20F. Specifically, FIG. 20A is a Welcome Screen explaining to the patient the type of study that will be performed. FIG. 20B is an instruction screen showing the patient how to attach the wrist-worn monitor to his or her wrist. FIG. 20C is an instruction screen showing the patient how to attach the chest motion sensor device to his or her chest. FIG. 20D is an instruction screen showing the patient how to attach the digit clip 112 or finger probe to his or her finger. Specifically, as shown in FIG. 20D, the patient is instructed to attach the digit clip 112 to any finger of his or her non-dominant hand. FIG. 20E is a Start Recording screen providing a virtual button for the patient to press when he or she is ready to begin recording sleep study data. Finally, FIG. 20F is a Good Morning or Study Completed Screen informing the patient that the sleep study has been completed and that recorded data is being transmitted from the wearable medical device 110 to the remote computer server.

[0276] Although various non-limiting examples of the invention have been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred aspects, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed examples, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any example can be combined with one or more features of any other aspect or example.

Claims

WHAT IS CLAIMED IS:

1. A clip apparatus for non-invasive peripheral arterial tonometry measurements, the clip apparatus comprising: a first clip member comprising a first surface configured to receive a first portion of a digit of a patient; a second clip member coupled to the first clip member and comprising a second surface configured to receive a second portion of the digit, wherein the first clip member and the second clip member are configured to receive the digit in a digit space defined by the first and second surfaces, and wherein one of the first clip member or the second clip member is movable toward the other of the first clip member or the second clip member to generate pressure within the digit space; a uniform pressure applicator configured to uniformly distribute the pressure generated within the digit space to a dorsal portion of the digit and a volar portion of the digit; and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space, and configured to be positioned at or proximate to the digit and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

2. The clip apparatus of claim 1, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip apparatus comprises a clip apparatus of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

3. The clip apparatus of claim 1, wherein the clip apparatus is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one optical-based peripheral arterial tonometry sensor, the indices comprising at least one of a respiratory disturbance index, an apnea-hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

4. The clip apparatus of claim 1, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

5. The clip apparatus of claim 1, further comprising a biasing member connected between the first clip member and the second clip member that biases at least one of the first clip member or the second clip member toward the other of the first clip member or the second clip member, thereby generating the pressure.

6. The clip apparatus of claim 5, wherein the biasing member comprises a spring comprising a first end connected to the first clip member and a second end connected to the second clip member.

7. The clip apparatus of claim 1, wherein the uniform pressure applicator comprises at least one membrane configured to apply pressure to the digit due to elastic deformation of the at least one membrane by the digit.

8. The clip apparatus of claim 7, wherein the uniform pressure applicator is configured to apply substantially uniform pressure to digits of different sizes received within the digit space resulting from the elastic deformation of the at least one membrane.

9. The clip apparatus of claim 1, wherein the first surface of the first clip member is configured to receive the dorsal portion of the digit and the second surface of the second clip member is configured to receive the volar portion of the digit.

10. The clip apparatus of claim 1, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

11. The clip apparatus of claim 1, wherein the at least one optical -based peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the first clip member or the second clip member and at least one detector mounted to the other of the first clip member or the second clip member.

12. The clip apparatus of claim 1, wherein the at least one optical -based peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to the second clip member.

13. The clip apparatus of claim 1, wherein the uniform pressure applicator comprises a first membrane configured to be displaced by the digit as the digit is received within the digit space and which defines a first chamber containing a fluid and a second membrane defining a second chamber communicating with the first chamber, wherein combined volumes of the two chambers maintain a substantially constant uniform pressure about the digit, and wherein the value of the maintained substantially constant uniform pressure varies within a predetermined range for digits of different sizes received in the digit space defined by the first and second surfaces.

14. The clip apparatus of claim 13, wherein the first chamber communicates with the second chamber through openings in at least one of the first clip member or the second clip member, and wherein the fluid comprises at least one of a liquid, gel, hydrogel, gas, or foam.

15. The clip apparatus of claim 1, wherein the uniform pressure applicator is configured to uniformly distribute the pressure generated within the digit space to the dorsal portion of the digit, the volar portion of the digit, and a distal tip of the digit when the digit is received within the digit space.

16. The clip apparatus of claim 1, wherein the uniform pressure applicator is configured to apply a uniform pressure of from about 40 mmHg to about 80 mmHg to surfaces of the volar portion, the dorsal portion, and the distal tip of the digit.

17. The clip apparatus of claim 1, wherein the applied uniform pressure results from a combination of the pressure generated from (i) the movement of at least one of the first clip member or the second clip member toward the other of the first clip member or the second clip member and (ii) elastic deformation of at least one membrane of the uniform pressure applicator applied to the surfaces of the digit.

18. The clip apparatus of claim 17, wherein the uniform pressure applicator is configured to apply the uniform pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

19. The clip apparatus of claim 1, wherein the uniform pressure applicator is configured to maintain a shape for the digit received in the digit space, thereby allowing the clip apparatus to be removed from and reattached to the digit, and wherein the uniform pressure applicator is configured to continue to uniformly distribute the generated pressure to the dorsal portion, the volar portion, and the distal tip of the digit when the apparatus is reattached to the digit.

20. The clip apparatus of claim 1, further comprising at least one adhesive configured to adhere the clip apparatus to the digit.

21. The clip apparatus of claim 1, further comprising an attachment device comprising a fastening portion connected to an external surface of at least one of the first clip member or the second clip member and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

22. The clip apparatus of claim 1, wherein the first clip member is hingedly connected to the second clip member exerting a biasing force sufficient to retain the digit within the digit space.

23. The clip apparatus of claim 1, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the first clip member and the second clip member than to the distal end of the first clip member and the second clip member.

24. The clip apparatus of claim 1, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the first clip member and the second clip member than to either the proximal end or the distal end of the first clip member and the second clip member.

25. The clip apparatus of claim 1, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the first clip member and the second clip member than to the proximal end of the first clip member and the second clip member.

26. The clip apparatus of claim 25, wherein the first clip member and the second clip member are configured such that the distal tip of the digit is received proximate to the distal end of the first and second clip members.

27. The clip apparatus of claim 1, wherein the uniform pressure applicator comprises a first membrane attached to the first clip member and a second membrane attached to the second member.

28. The clip apparatus of claim 27, wherein the first membrane at least partially encloses a first portion of the digit space configured to receive the dorsal portion of the digit and the second membrane at least partially encloses a second portion of the digit space configured to receive the volar portion of the digit.

29. The clip apparatus of claim 1, wherein the uniform pressure applicator comprises a first membrane forming a plurality of fluidly coupled bladders defining a first portion of the digit space and a second membrane forming a plurality of fluidly coupled bladders defining a second portion of the digit space.

30. The clip apparatus of claim 29, wherein the plurality of fluidly coupled bladders formed by the first membrane and/or the plurality of fluidly coupled bladders formed by the second membrane are configured to permit fluid to pass between adjacent bladders as the digit is received within the digit space, thereby providing the uniform pressure.

31. The clip apparatus of claim 1, wherein the first clip member is non- symmetrical to the second clip member.

32. A clip for non-invasive peripheral arterial tonometry measurements, the clip comprising: a first clip member comprising a first surface configured to receive a first portion of a digit of a patient; a second clip member movably coupled to the first clip member and comprising a second surface configured to receive a second portion of the digit, wherein the first clip member and the second clip member are configured to receive the digit of a patient in a digit space defined by the first and second surfaces, and wherein the first clip member and the second clip member are movable to generate an axial pressure within a range of about 40 mmHg to about 80 mmHg against a distal tip of the digit when the digit is received within the digit space; and at least one optical-based peripheral arterial tonometry sensor disposed within the digit space configured to be positioned at or proximate the digit, and to provide signals representative of a peripheral arterial tonometry waveform of the patient.

33. The clip of claim 32, comprising a distal applicator configured to distribute the generated axial pressure to the distal tip of the digit.

34. The clip of claim 33, further comprising a hinge between the first clip member and the second clip member, wherein the distal applicator covers the hinge.

35. The clip of claim 33, wherein the distal applicator comprises a portion of a fluid filled membrane comprising an inwardly facing surface configured to contact the distal tip of the digit.

36. The clip of claim 32, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip comprises a clip of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

37. The clip of claim 32, wherein the clip is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one optical-based peripheral arterial tonometry sensor, the indices comprising at least one of a respiratory disturbance index, an apnea-hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

38. The clip of claim 32, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

39. The clip of claim 33, further comprising a radial pressure applicator disposed within the digit space for applying radial pressure to volar and dorsal surfaces of the digit.

40. The clip of claim 39, wherein the radial pressure applicator and the distal applicator are configured to uniformly distribute pressure generated within the digit space to the dorsal portion of the digit, the volar portion of the digit, and the distal tip of the digit when the digit is received within the digit space.

41. The clip of claim 39, wherein the radial pressure applicator comprises at least one membrane configured to apply pressure to the digit due to elastic deformation of the at least one membrane by the digit.

42. The clip of claim 41, wherein the radial pressure applicator and the distal applicator are configured to apply substantially uniform pressure to the digit received within the digit space resulting from the elastic deformation of the at least one membrane.

43. The clip of claim 42, wherein the radial pressure applicator and the distal applicator are configured to apply substantially uniform pressure to digits of different sizes received within the digit space resulting from the elastic deformation of the at least one membrane.

44. The clip of claim 32, wherein the first surface of the first clip member is configured to receive a dorsal portion of the digit and the second surface of the second clip member is configured to receive a volar portion of the digit.

45. The clip of claim 32, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

46. The clip of claim 32, wherein the at least one optical-based peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the first clip member or the second clip member and at least one detector mounted to the other of the first clip member or the second clip member.

47. The clip of claim 32, wherein the at least one optical-based peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to the second clip member.

48. The clip of claim 32, wherein the first clip member and the second clip member are configured to apply the axial pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

49. The clip of claim 32, wherein the first clip member or the second clip member are configured to maintain a shape for a digit received in the digit space, thereby allowing the clip to be removed from and reattached to the digit, and wherein the first clip member and the second clip member are configured to continue to apply axial pressure to the distal tip of the digit when the clip is reattached to the digit.

50. The clip of claim 32, further comprising at least one adhesive configured to adhere the clip to the digit.

51. The clip of claim 32, further comprising an attachment device comprising a fastening portion connected to an external surface of at least one of the first clip member or the second clip member and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

52. The clip of claim 32, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the first clip member and the second clip member than to the distal end of the first clip member and the second clip member.

53. The clip of claim 32, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the first clip member and the second clip member than to either the proximal end or the distal end of the first clip member and the second clip member.

54. The clip of claim 32, further comprising a hinge connecting the first clip member to the second clip member, wherein the first clip member and the second clip member each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the first clip member and the second clip member than to the proximal end of the first clip member and the second clip member.

55. The clip of claim 32, wherein the first clip member is non-symmetrical to the second clip member.

56. A clip apparatus for non-invasive peripheral arterial tonometry measurements, the clip apparatus comprising: a pair of clip members movable relative to one another to an open configuration for receiving a digit of a patient between the pair of clip members and a closed configuration for clipping the clip apparatus to the digit of the patient, wherein, in the closed configuration, the pair of clip members are configured to pressurize at least one fluid-filled chamber around the digit such that pressure applied to each of a dorsal portion of the digit and a volar portion of the digit is (i) a uniform pressure and (ii) within a predetermined range; and at least one optical-based peripheral arterial tonometry sensor coupled to at least one of the pair of clip members and configured for, in the closed configuration, operative placement at or proximate the digit and generation of signals representative of a peripheral arterial tonometry waveform of the patient.

57. The clip apparatus of claim 56, wherein the at least one fluid-filled chamber is enclosed within at least one membrane comprising an inwardly facing surface configured to contact at least one of the dorsal portion, the volar portion, or a distal tip of the digit.

58. The clip apparatus of claim 56, further comprising at least one of a liquid, gas, gel, hydrogel, or foam within the at least one fluid-filled chamber.

59. The clip apparatus of claim 56, wherein the pair of clip members are configured to pressurize the at least one fluid-filled chamber around the digit such that pressure applied to each of the dorsal portion of the digit, the volar portion of the digit, and a distal tip of the digit.

60. The clip apparatus of claim 59, wherein the uniform pressure comprises a radial component configured to be applied to the volar portion and/or the dorsal portion of the digit and an axial component configured to be applied to the distal tip of the digit.

61. The clip apparatus of claim 56, wherein the signals representative of the peripheral arterial tonometry waveform are obtained during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification, and/or wherein the clip apparatus comprises a clip apparatus of a home sleep apnea test for obtaining signals during at least one of a home and/or remote sleep apnea test, a home and/or remote sleep disordered breathing test, and/or for sleep stage identification.

62. The clip apparatus of claim 56, wherein the clip apparatus is configured to generate indices representative of respiratory function and/or breathing quality of the patient based on the signals provided by the at least one optical-based peripheral arterial tonometry sensor, the indices comprising at least one of a respiratory disturbance index, an apnea-hypopnea index, a central apnea-hypopnea index, or a percentage of total sleep time with a Cheyne-Stokes Respiration pattern (%CSR).

63. The clip apparatus of claim 56, further comprising a wrist-worn monitor in wired or wireless communication with the at least one optical-based peripheral arterial tonometry sensor comprising processing circuitry for receiving and processing the signals provided by the at least one optical-based peripheral arterial tonometry sensor.

64. The clip apparatus of claim 56, further comprising a biasing member connected between the pair of clip members that biases at least one of the pair of clip members toward the other of the pair of clip members, thereby generating the pressure.

65. The clip apparatus of claim 64, wherein the biasing member comprises a spring comprising a first end connected to the first clip member and a second end connected to the second clip member.

66. The clip apparatus of claim 56, wherein the uniform pressure applicator is configured to apply substantially uniform pressure to digits of different sizes received within the digit space.

67. The clip apparatus of claim 56, wherein the digit comprises at least one of a little finger, a ring finger, a middle finger, or an index finger of the patient.

68. The clip apparatus of claim 56, wherein the at least one optical-based peripheral arterial tonometry sensor comprises at least one emitter mounted to one of the pair of clip members and at least one detector mounted to the other of the pair of clip members.

69. The clip apparatus of claim 56, wherein the at least one optical-based peripheral arterial tonometry sensor comprises at least one emitter and at least one detector, each of which are mounted to one of the pair of clip members.

70. The clip apparatus of claim 56, wherein the uniform pressure applicator is configured to apply a uniform pressure of from about 40 mmHg to about 80 mmHg to surfaces of the volar portion and the dorsal portion of the digit.

71. The clip apparatus of claim 56, wherein the uniform pressure applicator is configured to apply the uniform pressure for a duration of at least one of 8 hours, 12 hours, 16 hours, or 24 hours.

72. The clip apparatus of claim 56, wherein the uniform pressure applicator is configured to maintain a shape for a digit received in the digit space, thereby allowing the clip apparatus to be removed from and reattached to the digit, and wherein the uniform pressure applicator is configured to continue to uniformly distribute the generated pressure to the dorsal portion and the volar portion of the digit when the apparatus is reattached to the digit.

73. The clip apparatus of claim 56, further comprising at least one adhesive configured to adhere the clip apparatus to the digit.

74. The clip apparatus of claim 56, further comprising an attachment device comprising a fastening portion connected to an external surface of the pair of clip members and a securement portion configured to be worn on a wrist, forearm, and/or arm of the patient for releasably coupling the attachment device to the patient.

75. The clip apparatus of claim 56, wherein one of the pair of clip members is hingedly connected to the other of the pair of clip members exerting a biasing force sufficient to retain the digit within the digit space.

76. The clip apparatus of claim 56, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the proximal end of the pair of clip members than to the distal end of the pair of clip members.

77. The clip apparatus of claim 56, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to a middle of the pair of clip members than to either the proximal end or the distal end of the pair of clip members or to the distal end of the pair of clip members.

78. The clip apparatus of claim 56, further comprising a hinge connecting the pair of clip members, wherein the pair of clip members each comprise a proximal end and a distal end, and wherein the hinge is positioned closer to the distal end of the pair of clip members than to the proximal end of the pair of clip members.