HK1226978B - Fluid control system and disposable assembly - Google Patents

Description

Fluid Control Systems and Disposable Components

Technical Field

The present disclosure relates to intravenous infusion therapy. More specifically, the present disclosure relates to a system, components of the system, and methods associated with the system for organizing fluid flow for applications requiring accommodation of a wide range of flow rates, a wide range of input and output pressures, and a wide range of delivered fluid viscosities, such as those seen with intravenous (IV) infusion therapy.

Background Art

Conventionally, healthcare providers have had three technical options for intravenous infusions. Many intravenous infusions are controlled by manually adjusting the resistance in the flow path between the fluid source and the patient based on the operator's observation of the drip rate formed in a chamber consistent with the fluid flow. The range of flow rates that can be controlled by this method is limited by the relatively large and fixed-size droplets and the low reliability of accurately calculating the flow rate by a human operator. This method has serious drawbacks due to the fact that it requires a human observer to maintain an accurate and consistent flow rate. In many cases, there is a lack of trained human observers. This manual method also lacks the important ability to electronically record and communicate infusion results.

Smaller infusions are controlled by using a fixed volume of liquid at a fixed amount of pressure and a fixed resistance to provide a fixed flow rate. Unfortunately, a fixed flow rate and a fixed fluid volume do not provide the flexibility required for most infusions. Similar to manual infusions, this method does not provide the opportunity to electronically record the results of the infusion.

Because of the strong need for more precise flow rate control, flexibility of fluid volume, and the desire to keep track of flow information, many infusions are controlled using positive displacement fluid pumps. These larger positive displacement devices are typically of the peristaltic or reciprocating piston type. Both types of positive displacement devices come at the cost of complexity, size, weight, limited battery life, and significant financial costs. Early versions of positive displacement pumps created a new hazard for patients known as "uncontrolled infusion," in which the highly controlled flow of fluid suddenly becomes uncontrolled when a door or other check mechanism on the pump is released. In response to this undesirable feature, pumps were subsequently required to include a "flow stop" mechanism so that the flow rate would completely stop if the fluid tubing was removed from the flow control device. Unfortunately, the suspension of flow is sometimes dangerous for the patient due to the sudden increase in flow. Another unexpected consequence of active pumping systems is the possibility of infusing a lethal amount of air into the patient. This possibility does not exist under low-pressure gravity infusion. As a result, positive displacement pumps have incorporated air detection systems to prevent this hazard, but these alarm systems are a very significant source of false alarms, leading to operator inefficiency and patient anxiety.

The present disclosure recognizes the inherent safety advantages in low-pressure infusion, the need to accurately control flow, and the necessity of the modern healthcare environment to have electronically available infusion data.

Summary of the Invention

The present disclosure relates to a medical fluid administration device and methods for using the same, the device comprising a fluid path assembly and a flow control device, wherein fluid flow through a fluid flow system is controlled via closed-loop, quasi-static adjustment of line pressure-based resistance in combination with a low-pressure pneumatic pump element. The sensor-based infusion platform (SIP) utilizes wireless communication to a network to maintain device software and data set integrity, broadcast alarms, and record infusion status information.

These and other features of the present disclosure, including various novel construction details and combinations of parts, will now be described in more detail with reference to the accompanying drawings and pointed out in the claims. It will be understood that the specific devices employing the present invention are shown only in an illustrative manner and are not intended to be limiting of the present invention. The principles and features of the present disclosure may be employed in a variety of numerous embodiments without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus and method of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, in which:

FIG. 1a is a rear view of a preferred embodiment of a flow control device (controller) having a fluid pathway (disposable article) mounted to deliver an infusion;

Figure 1b shows the two main components of an embodiment herein, a flow control device or controller with a fluid path (disposable infusion set) mounted in a bag in the rear portion of the device;

FIG2 is a rear perspective view of the flow control device showing the interface to the cassette;

FIG3 shows an exploded view of the controller;

FIG4 shows an assembled disposable article including the cartridge and tubing;

Figure 5a shows a cross-sectional view of the intermediate pumping chamber;

Figure 5b shows the check valve and fluid path to the intermediate pumping chamber;

FIG6 shows a cross-sectional view of the variable resistance device;

FIG7 shows a preferred embodiment of a flow sensing element;

FIG8 a shows a graph of sensor output peaks formed when the flow sensing element is in focus and transmitting light to the detector;

FIG8 b shows a graph of sensor output peaks obtained with a flowing object;

FIG8 c shows a graph of peak sensor output obtained by illuminating one LED;

FIG9 shows an IV stand bracket for a controller;

10 is an exemplary diagram illustrating the insertion of a cartridge (disposable article) into a corresponding cavity of a pump control unit according to an embodiment herein;

11 is an exemplary diagram illustrating alignment of a fluid path with a detector disposed in a cavity of a pump control unit according to an embodiment herein;

12 is an exemplary diagram illustrating inserting a bubble detector element through an opening of a corresponding cartridge into a cavity of a pump control unit according to embodiments herein;

13 is an exemplary diagram illustrating the use of a pump control unit and a corresponding disposable tubing set to deliver fluid to a corresponding recipient according to an embodiment herein;

FIG. 14 is an exemplary diagram illustrating details of a disposable tubing set and a corresponding pump control unit 120 according to embodiments herein.

DETAILED DESCRIPTION

Referring to the accompanying drawings, in which like reference numerals are used throughout the several figures to designate like or similar components, Figures 1a and 1b illustrate an exemplary volume and flow measurement system according to an exemplary embodiment of the present invention. The fully sensor-based infusion platform system includes a disposable, a controller, an IV pole mounting pole, and a network computer.

Reference is now made to Figures 1a and 1b, which illustrate exemplary embodiments of the present invention, with Figure 1a being a rear view of the controller with a disposable article installed, and Figure 1b being a front view of the controller with a disposable article installed. Controller 1 includes a display 2, which is preferably an LCD display, and more preferably a color LCD display with a touch-sensitive input device, such as a capacitive or resistive touch screen overlay 107 (see Figure 3). Alternative user input devices are also contemplated, such as keys or a keyboard, a mouse, a trackball, a touch pad, a joystick, or combinations thereof, as will be understood by those skilled in the art.

The display 2 is housed in a housing or shell 3 formed, for example, from a rigid plastic. The controller includes an interface 4 to a stand cradle arrangement 60 (see FIG9 ), which also serves to mechanically secure the controller 1 to an IV stand 62 (see FIG9 ). The stand cradle 60 may also include a charger for charging an internal battery or battery pack in the controller when the controller is placed in the cradle, for example via charging contacts that align with and electrically couple to charging contacts on the controller, or alternatively via induction. Preferably, the charger can charge the internal battery on either side of the device. The housing 3 may include ergonomically designed finger grips or recesses around the circumference to aid in gripping the device, and may also include a flexible insert that is removably or permanently attached to the housing 3, for example, by overmolding, thermoforming, or otherwise attaching a flexible or resilient material to the rigid shell 3, to further enhance the gripping ability of the device.

Also visible in FIG1 b are the inlet 5 and inlet 6 and outlet 8 tubing of the disposable article. The main inlet 5 connects the primary fluid source (not shown) containing the volume of fluid to be delivered to the device via standard luer fittings as are known in the art. The fluid travels through a cassette housed in the rear portion of the device and then flows through outlet 8 to the patient connection piece.

The secondary inlet 6 allows a second fluid to be connected to the device independently of and without affecting the current infusion, and the user can then program the device with the second fluid delivery parameters including a start time. At the secondary infusion programmed start time, the controller 1 will temporarily pause the delivery of the primary infusion, deliver the secondary infusion per the programmed parameters, and then resume the primary infusion. Other infusion devices on the market require the user to suspend the secondary fluid source on the body higher than the first fluid source so that the static pressure of the higher source determines which fluid is delivered. When the static head height of the second fluid source is not sufficiently higher than the static head height of the primary source, the pump will deliver a mixture of both the primary and secondary fluids based on the relative static pressures of the sources, thereby not delivering the secondary fluid at this rate, and therefore not delivering the secondary fluid at the required effective prescribed dose. This problem, namely, the reliance on the user to manipulate both the primary bag height and the secondary bag height, is overcome by means of the present disclosure, as the preferred embodiment will deliver the secondary infusion as programmed independent of the static pressure of the fluid source.

Can see the feature of disposable infusion set (" disposable article ") 16 in Figure 1a, and see the box portion of disposable article in particular, it comprises variable flow resistor 22, flow sensor 23, flow sensor 23 and intermediate pumping chamber 19.Variable flow resistor 22 can be automatically adjusted by controller to match sensed flow rate with program flow rate.Flow sensor 23 comprises flow element in fluid path, and described flow element moves in response to flow rate, and flow sensor 23 not only provides signal representative of flow rate for system, and has unique signal when air is just passing through this sensor.Intermediate pumping chamber 19 is pneumatically coupled to controller, and acts as both pneumatic pump and additional flow sensor.

FIG1 b shows a touchscreen display 2 displaying a graphical user interface divided into several segments. These segments include an information and status display, a status display including virtual navigation buttons, and navigation buttons 7. The colors and shading of the user interface intuitively indicate to the user where more information is available. The user can touch an on-screen object, such as an icon or button, to navigate to a page with more information (which may be arranged in a layered manner, for example), and change or update program parameters as needed.

Referring now to FIG. 2 , the controller 1 is typically shown from the back and side, with the interface for the disposable product visible at the back and side. The rear shell 9 is configured to guide the user to properly place the disposable product into the controller. The asymmetric recess in the rear shell 9, together with recesses 10 and 11, are three of the several features that key the disposable product into the controller. The recesses 10 and 11 are arranged to allow passage of the main inlet 5, the secondary inlet 6, and the outlet pipe 8, respectively, thereby preventing the disposable product 16 from being incorrectly installed. The ribs or splines 12 interlock with the variable flow resistor, manipulate the variable flow resistor, and are positioned to only allow the disposable product to be inserted (thereby preventing uncontrolled flow) only when the flow resistor is in a fully closed position. Once engaged, the splines 12 do not allow the disposable product to be removed from the controller without fully closing the variable flow resistor again.

The light source array 13 and the optical detector 14 are positioned to allow a movable flow element in the disposable article to be located between the light source array 13 and the optical detector 14. When in use, the light source array 13 can preferentially illuminate specific segments of the array, for example based on the expected position of the flow element, thereby enhancing the ability of the optical detector 14 to accurately sense the position of the flow element and conserve power to maximize battery run time. The pneumatic interface 15 to the intermediate pumping chamber (IPC) of the disposable article includes an O-ring seal that helps both guide the nipple on the disposable article and help seal the connection.

Referring now to FIG3 , in which more details of the construction style of the controller 1 can be seen, the pneumatic interface 15 is connected to a manifold 104, which houses valves and sensors and connects the pump chamber assembly 102. The pressure sensor in the manifold 104 allows the system to accurately measure the pressure in each of the intermediate pumping chambers in the disposable product and in the graduated chamber of known volume. Using the valves in the manifold 104 to isolate the graduated chamber of known volume from the intermediate pumping chamber, measuring the pressure present in each chamber, then combining the graduated chamber to the intermediate pumping chamber by opening the valve, and measuring the resulting pressure allows the system to calculate the volume of the fluid in the intermediate pumping chamber using the ideal gas law. As used herein, the term "ideal gas law" is intended to include not only the equation PV=nRT, but also specific cases of this law, such as Boyle's law and Charles' law. The fluid flow rate is calculated by periodically calculating the volume of fluid entering and leaving the intermediate pumping chamber over time.

Pump chamber assembly 102 comprises pump and chamber, and described pump and chamber produce positive pressure source and negative pressure source.These pressure sources are connected to the intermediate pumping chamber of disposable product by manifold 104.Along with negative pressure being connected to intermediate pumping chamber, extract fluid from fluid source.Along with positive pressure being connected to intermediate pumping chamber, expel fluid from chamber.Control to the pressure in each in described source allows system to compensate for the variation of source height and the variation of outlet back pressure.Control to the timing of pressure variation allows system to change the fluid flow rate by system.

A second control measure for fluid flow through the system is achieved by including a variable fluid flow resistor within the fluid flow path, which can be manipulated by a variable fluid flow resistor drive mechanism 103. The drive mechanism 103 includes a motor and gear mechanism that outputs torque to a spline 12 (see FIG2 ) that couples to the variable flow resistor on the disposable article. The spline moves the variable flow resistor from fully closed to fully open as the spline rotates across its 300-degree range of motion. The flow resistor is designed to provide a logarithmic response throughout its range of motion, yielding effective control of the system over a four-order-of-magnitude range (e.g., 0.1 ml/h - 1000 ml/h).

The control board assembly 105, including a processor, microprocessor, or the like and associated electronics, executes the fluid delivery program sent to it by the user interface (UI) board assembly 106. The control board assembly 105 also manages inputs from temperature sensors, external pressure sensors, intermediate pump chamber pressure sensors, and flow sensors; determines and executes changes in pneumatic pressure and resistance settings to match the measured flow rate to the programmed flow rate; and sends infusion status updates to the UI board assembly 106. The UI board assembly 106 includes a three-axis accelerometer for motion sensing and a sensor for monitoring ambient noise levels. The data, including the temperature and pressure signals collected and managed on the control board assembly 105, allows the pump to be context-aware.

The UI board assembly 106 drives the display 2 and manages a user interface that allows the user to program a new infusion, change the parameters of an existing infusion, and view the history and status of infusions running on the device. The UI board assembly 106 also manages communications with the control board assembly 105 and communications to a network computer. The UI board assembly 106 may include one or more wireless, such as radio frequency (RF) or infrared (IR) transceivers, and in a preferred embodiment, includes both an 802.11 (WIFI) radio 108 and an 802.15 (ZIGBEE) radio 109 to enable wireless network communications. Network communications enable the device to send infusion status information to populate, for example, electronic medical records and alarm notifications stored in a network database or remote database for review by a caregiver. Network communications also allow the device to receive updated infusion data sets and software updates.

If the ZIGBEE 109 network is installed in a hospital or other usage environment, the device becomes location-aware, and the device's location can be included in all messages. Since the device's location is often associated with the patient, the device can assist the user in identifying the patient to whom the device is attached. Additionally, because the ZIGBEE network is a mesh network, it allows the software to alert caregivers if the same medication has already been administered to the same patient in the same location. In severe cases, some patients may have up to 12 infusion devices connected. Currently available devices alert caregivers if the same medication is already being administered only if it is on the same device as it is being programmed, which can lead to adverse consequences for the patient.

The advantages of the ZIGBEE network of the preferred embodiment herein are improved safety by enabling communication between all devices within a specific location, coordinating infusions, and communicating to caregivers. Another benefit of the ZIGBEE network is the ability to use ZIGBEE frequency RFID devices on caregivers. When a caregiver moves near a ZIGBEE device equipped with an RFID device, the system recognizes and records the caregiver's association with the device. Associating caregivers, patients, and infusions helps provide complete electronic documentation. When a caregiver chooses to program a new infusion, they select the medication to be infused, for example, by viewing the medication to be infused on the display 2 and selecting it from the device's data set using the touch screen 107, or by using the barcode imager 111 of the controller mounted on the UI board assembly 106 to image a barcode, for example, located on the source of the fluid to be infused, through a window in the bottom of the housing 3. The barcode imager 111 is preferably of a type that decodes one-dimensional and two-dimensional barcodes and can be used for patient identification, medication identification, medication infusion programming, and caregiver identification. The controller 1 is depicted with dual battery packs 112 to provide redundancy and extended runtime for the system.

Referring now to Figures 4, 5a, and 5b, the disposable article 16 includes an inlet tube attached to the inlet. The disposable article 16 may also include a drip chamber and spikes (not shown) that can be used to deliver gravity infusion or can be used in combination with the controller 1 to deliver sensor-based infusion. The disposable article 16 has a primary inlet 5 and a secondary inlet 6, both of which are shown with vent caps 18. Fluid from the primary or secondary fluid source flows through the corresponding inlet 5 or inlet 6 and enters the intermediate pumping chamber 19 through a corresponding valve in a one-way valve or check valve 29. The intermediate pumping chamber 19 is divided into two separate volumes 26 and 27 by a flexible membrane 25.

The fluid entering the chamber flows into volume 26, and gas (air) occupies volume 27. The gas-filled volume 27 is separated from the fluid in the fluid volume 26 by a flexible membrane 25 and has a port 20 shaped like a nipple that is coupled to the pneumatic interface 15 of the controller 1.

When controller 1 applies negative pressure to gas-filled volume 27 through port 20, the flexible membrane moves toward port 20, drawing fluid from the fluid source to fill the chamber. When controller 1 applies positive pressure to gas-filled volume 27 through port 20, the flexible membrane is driven from port 20, displacing fluid from the chamber. When all fluid is driven from volume 26, flexible membrane 25 forms a seal against the fluid outlet of chamber 19. If positive pressure remains in volume 27, the outlet sealed by membrane 25 will prevent fluid flow when fluid flow is undesirable.

Check valves 29 and 30 for each of the primary and secondary flow channels ensure that fluid flows only from the fluid source to the outlet of the disposable article 16. For example, when positive pressure is applied to the gas volume 27 during operation, valve 29 prevents fluid in volume 26 from leaving volume 26 via the respective inlets 5, 6. Likewise, when negative pressure is applied to the gas volume 27 during operation, valve 30 prevents fluid downstream of the intermediate pumping chamber from being drawn back into the pumping chamber.

A pressure sensor in the controller can determine the pressure in the gas-filled volume 27 of the intermediate pumping chamber 19. By sensing the pressure in the gas-filled volume and the pressure in a known calibration volume in the manifold 104, and then by combining the two volumes and measuring the resultant pressure of the combined volume, the volume of gas in the intermediate pumping chamber can be calculated using the ideal gas law.

If the volume of the rigid IPC is precisely known, the volume of liquid in the IPC can be inferred. However, in certain instances, for example, due to variations in manufacturing tolerances, it is preferable not to assume that the IPC volume is precisely known, and it is preferable to monitor the flow rate of liquid out of the system using volumetric calculations that do not require knowledge of the IPC volume and/or the liquid volume. In a preferred embodiment, the flow rate is determined by measuring the initial volume of compressible gas in volume 27 and then by monitoring the pressure drop in chamber 27 over time. In a practice reduction of the system of this embodiment, the combined volumes 26 and 27 of the intermediate pumping chamber 19 of 500 microliters are selected to favor both higher and lower flow rates because the combined volumes 26 and 27 accommodate the need for flow continuity in the lower flow range (e.g., less than 1 ml/hr) and the need to be able to deliver rapid infusions (e.g., greater than 1000 ml/hr), but other volumes are contemplated.

This design allows for the system described herein to pause the delivery of primary fluid entering the primary port 5 and being delivered at the primary flow rate, deliver the secondary fluid at a secondary flow rate from the secondary input port 6, and then resume primary fluid delivery without relying on the user to change the bag height or without relying on additional connections to remember, move the primary infusion mechanism, or otherwise manipulate the primary infusion mechanism. This arrangement prevents the secondary fluid from flowing into the primary infusion source or from drawing the secondary fluid from both the secondary and primary fluid sources at an unknown mixed rate, both of which can occur with other systems if the caregiver is not careful in configuring the system.

The fluid exiting the intermediate pumping chamber 19 flows through a degassing filter 21. In use, many systems combine a peristaltic mechanism with a silicone pumping member. Silicone is semi-permeable to air, and when silicone is combined with the high pressures typically associated with peristaltic devices, air becomes entrained in the fluid being infused. In those devices, an ultrasonic sensor positioned downstream of the pumping mechanism is employed to transmit ultrasonic waves through the tubing of the disposable product, looking for evidence of air. Those devices have been a source of nuisance (false) alarms, and as caregivers have tried to remedy the constant alarms by changing settings, time has been wasted on the disposable product and the medication fluid.

The present disclosure overcomes those problems by eliminating the high-pressure pumping components that are the root cause of those alarms and by instead using a low-pressure barrier membrane and incorporating a degassing filter. It will be seen that the fluid flow sensor output has a characteristic signature for air and can therefore provide an additional layer of safety without inherent false positive (nuisance) alarms. Fluid passing through the degassing filter 21 enters the inlet 30 of the variable flow resistor 22.

With reference now to Fig. 6, when disposable product was used for gravity infusion (that is, when not using controller), cap 39 can be manually rotated to increase or reduce flow, and described flow can be monitored by checking the dripping speed of the fluid of motion through the drip chamber.In the accompanying drawings, piston 34 is shown as being in the position of complete closure.Along with cap 39 rotation, screw thread 41 makes the position of the piston 34 in the cavity of flow resistor body 31 selectively advance or retract according to the direction of rotation, and spiral passage or screw thread 37 are exposed to the fluid of inflow, and the fluid of described inflow enters flow resistor body at inlet 33.

The groove 37 is formed with a pitch, width and/or depth that increases along its length to selectively increase or decrease the flow area aligned with the inlet of the flow resistor. The taper of the pitch, width and/or depth is preferably selected to create a logarithmic increasing flow path for the fluid as the flow resistor moves from the closed position to the fully open position. Since the threads 37 are exposed to the fluid, the fluid travels in the gap created by the threads 37 and the cap 39 to flow into the space between the cap 39 and the piston 34. The fluid in this space exits the flow resistor through the central passage 38 in the piston 34 and flows to the outlet 32.

The piston 34 is sealed by an orifice ring or protrusion 35, which slides within the cavity of the resistor body 31. The cap 39 is sealed by an O-ring 40. Note that when the cap 39 is rotated, it does not translate relative to the body 31. Rotation of the cap 39 causes the piston 34 to translate, exposing or concealing different portions of the threads 37 to selectively increase or decrease fluid flow through the device. In contrast to mechanisms used in other systems, such as sliding clamps and roller clamps, which deliver a bolus of medication to the patient when actuated, the movement of the piston 34 itself does not drive the fluid. Therefore, a bolus of fluid delivered to the patient cannot be generated by opening the resistor. This unique feature adds another layer of safety to the patient and distinguishes the device in this preferred embodiment. An exemplary fluid flow resistor may be as described in commonly owned PCT Application No. PCT/US2009/068349, filed December 17, 2009, the entire contents of which are hereby incorporated by reference. Fluid exiting the variable flow resistor 22 via the outlet 32 enters the flow sensor body 23 (see FIG. 7 ). As the piston 34 translates, the protrusions 36 rest in corresponding grooves 42 to prevent the piston 34 from rotating relative to the flow axis.

7 , fluid entering the flow sensor body 51 is obstructed by the sensor element 52, which is held against the flow opening by a spring 57. The sensor element 52 is generally opaque and houses a transparent transmission element 53, which is transparent (as used herein, the terms "transparent" and "opaque" are used with reference to the wavelength of light emitted by the light array 13) and is designed to transmit light onto the sensor array 14. The transmission element is preferably cylindrical and will be described primarily by reference herein, however, it will be appreciated that the focusing element 53 can be spherical, cylindrical, or other geometric configurations. Alternative embodiments are contemplated having a transmission region that is substantially spherical and thereby focuses the transmitted light onto the sensor. In alternative embodiments, the transmission element 53 can act as a refractive lens or can be a diffractive and/or holographic optical element for focusing the light emitted by the array 13 onto the sensor array 14.

When disposable article 16 is in controller 1, flow sensor 23 is nested between light source array 13 and optical detector array 14 (see FIG2 ). Light emitted from array 13 is collected by cylindrical element 53 and focused on detector array 14. As flow increases, sensor element 52 displaces, and compression spring 57 seats at one end on spring seat 56. Internal flow channel 55 tapers toward outlet 58 to allow for higher flow as more tapered area is exposed by the displaced sensor element 52. Ribs 54 maintain alignment of sensor element 52 with the central flow axis of the flow path.

Various alternative embodiments will be apparent to those skilled in the art, such as using a generally cylindrical transparent element in place of cylindrical element 53, allowing light to propagate through the sensor to the detector without the light being out of focus. As will be appreciated by those skilled in the art, when this type of sensor is coupled with light source array 13 and optical detector 14, it will produce a unique output signal when measuring a passing fluid against passing air. Additionally, because air is compressible, air bubbles produce a distinct output signal, and thus the flow sensor can also function as a bubble detector.

Referring now to Figures 8a to 8c, it can be seen how the signal voltage is significantly enhanced by propagating light through a transparent cylindrical element. Referring now to Figure 8b, a graph is shown that has a clear peak in the optical signal of a flowing object. Figure 8c shows a graph that shows a clear peak in the optical signal of a highly scattering fluid passing through a TPN.

Referring again to FIG. 4 , the fluid passing through the flow sensor 23 flows through the tube 8 to the patient.

Referring now to FIG9 , the controller 1 is mounted to a rack bracket 60 via a sliding interface 4. A corresponding slide 61 receives the controller 1. Low voltage DC power, provided by a cable 63, comes from a transformer connected to a standard AC outlet (not shown) and is delivered through interfaces 4 and 61 to charge the device's battery 112. The rack bracket 60 can be clamped onto any standard IV rack 62 and supports up to four controllers in the embodiment shown.

A review of adverse infusion events in the FDA's reporting database (MAUDE) shows that an alarming number of adverse events occur each year due to caregivers forgetting to replug the infusion pump or after patient movement. Other devices use only a tiny light or icon to indicate when the device is plugged in, which can be easily missed. Subsequent battery alarms and battery failures can prevent patients from receiving their prescribed medication in a timely manner.

The preferred embodiment of the system addresses this unmet need in two ways: first, the power required to pump air to drive the infusion is significantly less than the power required to compress the pumping segment with a peristaltic device, allowing for substantially longer battery life; and if the device is not plugged in, the device display will automatically dim after a period of time away from user input or from sensed motion. The infusion will continue, and the display will periodically become active, but this new behavior will alert the caregiver that the device is not plugged in, whereas a small indicator light or icon, such as is common on conventional devices, is significantly more prominent and therefore more useful.

Another source of adverse events, present in other devices but not in the preferred embodiment of this device, involves occlusions upstream or downstream that prevent the infusion from continuing as programmed. Other devices on the market present two associated risks with respect to occlusion detection: Other devices rely on sensing pressure in the disposable to detect a no-flow condition. If a downstream occlusion occurs as the pump continues, filling the available compliance in the disposable, the pressure in the disposable will increase over time until the pressure sensor is able to read a sufficient pressure in the line to trigger an alarm. When the occlusion is cleared (e.g., when the tightened line is straightened during patient movement), the pressurized fluid in the line is delivered to the patient as a bolus. This presents a significant risk due to the high pressures (above 15 psi) that peristaltic pumps can generate, depending on the set and associated compliance of the delivery catheter and tubing, store and subsequently deliver significant volumes of medication at once.

A second danger associated with pressure sensing as a secondary measure to sensing fluid flow is that, depending on the flow rate, pressure alarm setting, and tubing compliance, the device can operate for over two hours without delivering any medication before sufficient pressure builds in the tubing to activate the alarm. Certain therapeutic processes depend on continuous infusion, and a two-hour interruption can be a significant source of concern. Preferred embodiments of the disclosed system sense flow directly via both a flow sensor and a pressure sensor in the intermediate pumping chamber (redundant flow sensing) and thus immediately sense no-flow conditions regardless of flow rate or tubing compliance. Second, in one non-limiting example embodiment, the system's pneumatic drive typically operates at one psi, with a maximum of 5 psi available for driving the infusion, which is a significant improvement in safety compared to pumps that can deliver fluid at over 15 psi. However, these pressures may vary depending on the embodiment.

Ultimately, the method of the preferred embodiment allows for a significantly smaller, more portable, and more cost-effective method for accurately delivering infusions because the method of the preferred embodiment does not require a delicate mechanism. In instances where infusion delivery and cost have previously been traded off, where infusion data, accuracy, and safety were weighed against the cost of delivering the infusion, the preferred embodiment shifts this economic paradigm. In care settings where cost may have previously driven the use of gravity infusion or simpler infusion devices, the economics and simplicity of use of this method allow infusions to be given at a similar cost, with the improved safety and the advantages of traceable electronic data records further reducing documentation costs.

Additional Examples

Other embodiments herein include a system and method for reducing and/or eliminating the delivery of large amounts of air during the infusion of a fluid into a recipient. In one non-limiting example embodiment, a fluid delivery system as described herein has the ability to sense and purge large amounts of air introduced from a source container during intravenous infusion.

The fluid delivery system includes an infusion pump (mechanical infusion pump). The infusion pump can include any suitable resources, such as sensors, actuators, control logic, etc., to operate a pump mechanism contained within a disposable tubing set. As will be discussed below, the disposable tubing set can include a cassette disposed between a plurality of tubes. The disposable tubing set provides a sterile path from a source fluid container through the pump system to a recipient, such as a patient.

Certain portions of this disclosure are based on the observation that the presence of air in infused fluids presents a patient safety risk. Specifically, it is undesirable for air to be delivered to a patient along with the infused fluid because air emboli can cause several injuries or even death. Air can become introduced into the fluid delivery path between the fluid source and the recipient from a variety of sources. For example, a caregiver may fail to properly decontaminate the disposable tubing set during initial preparation for treatment; air or other gases dissolved in the fluid to be delivered can come out of solution during infusion; air can penetrate the walls of the disposable tubing set and become entrained in the fluid path; movement of the patient and the pump or source container can introduce air pockets into the pump inlet port; and so on.

Another common source of air is a source container containing a fluid to be delivered to a corresponding patient. Typically, the source container is not completely filled with liquid (i.e., the container contains a certain amount of air). In this instance, if the pump continues to pump fluid from the source container while the source container is emptied of liquid, air can be accidentally delivered to the recipient.

In the past, when gravity infusion was the norm, these conditions required careful monitoring by caregivers to avoid endangering patients. In modern hospitals utilizing automated infusion pumps, entrained air is easily detected by an inline air detection and alarm system in the pump. Typically, this detection and alarm system effectively protects the patient. However, whenever an air bubble is detected by the delivery system, the infusion is stopped to prevent air from being injected into the patient. To foreshadow the detection of an air bubble, an alarm notifies the caregiver that the infusion has been paused and that the delivery system requires immediate attention. Concerns about air alarms have become one of the single greatest disruptions to caregiver workflow and patient comfort.

Compared to conventional technology, embodiments herein include a fluid delivery system and a corresponding pump mechanism that is capable of detecting and making appropriate adjustments when a large amount of air is introduced into the pump inlet port. Embodiments herein include a first resource, such as a degassing filter, to remove air from the fluid being delivered to the corresponding patient. Additionally, downstream of the first resource for eliminating air from the fluid, embodiments herein may include a bubble detector. If the degassing filter fails, the bubble detector detects the presence of bubbles and turns off the corresponding pump so that no air is delivered to the corresponding patient. Thus, compared to conventional technology, the bubble detector becomes a backup safety mechanism. In other words, the degassing filter removes unwanted gas, such as air. In the event that the degassing filter fails, the bubble detector provides a backup system.

The disposable tubing set described herein includes an integrated vent and an integrated measurement and control system in the pump, which greatly simplifies the use of primary and secondary infusion workflows. In addition to being able to clear the fluid of smaller bubbles introduced by gases escaping from the solution or diffusing through the tubing wall, the embodiments herein analyze engines that can handle large amounts of air and take appropriate action.

Now, more specifically, Figure 10 is an exemplary diagram illustrating the insertion of a corresponding cassette (also known as a disposable article as previously discussed) into a cavity of a pump control unit according to embodiments herein. Generally, as will be discussed below, cassette 185 facilitates the delivery of fluid received from tube 165-1 to a corresponding patient via tube 165-2.

In one embodiment, the fluid pump 110 in the disposable cassette 185 in FIG10 (a variation of the fluid pump shown in FIG5 a) has a fluid side and an actuation side separated by a flexible membrane or movable piston. The actuator for controlling the movable pump chamber 110 in the cassette 185 is housed in the pump controller unit 120. Similarly, the actuators and sensors for the flow resistor driver, pressure sensor, bubble detector, etc. are housed in the pump controller unit 120. Additional details are discussed in the following figures, such as FIG14.

10 , note that all actuators and all sensors in the pump controller unit 120 can be configured to automatically engage with corresponding components in the cassette 185 as the user loads the disposable cassette 185 into the cavity 125 of the pump controller unit 120. For example, the action of pressing the cassette 185 into the pump controller unit 120 ensures that all mechanisms are properly seated.

In one embodiment, when the pump controller unit 120 is activated, the pump controller unit 120 can determine whether the cassette 185 is properly loaded into the cavity 125. If the pump control unit 120 detects that the cassette 185 is not properly loaded into the cavity 125, the pump control unit 120 generates a warning to the caregiver. The warning indicates that corrective action is required. Alternatively, if the pump control unit 120 detects that the cassette 185 is properly inserted into the cavity 125, the pump control unit 120 enables the pump operator to initiate fluid delivery to the corresponding patient.

As shown in this non-limiting example embodiment, cassette 185 includes tube 165-1 and tube 165-2. The combination of cassette 185, tube 165-1, and tube 165-2 represents a disposable tube set.

Tube 165-1 provides a fluid path from a corresponding fluid source (eg, medication) to an input port of the cassette. Tube 165-2 provides a fluid path from the cassette 185 from an output port of the cassette 185 to a corresponding patient.

As discussed further herein, the fluid pump 110 is interposed between the input port of the cassette 185 and the output port of the cassette 185. The pump control unit 120 controls the fluid pump 110 in the cassette 185 to draw fluid from a fluid source through tube 165-1. The pump control unit 120 further controls the fluid pump 110 to pump fluid to a corresponding recipient through tube 165-2.

In this example embodiment, the sequence of frames in FIG. 10 illustrates the insertion of respective cassettes into respective cavities 185 of the pump controller unit 120 .

At time T1 , an operator (eg, a caregiver) moves the cartridge 185 toward the cavity 125 .

At time T2 , the operator aligns and inserts the upper portion of the cassette 185 into the corresponding position of the cavity 125 of the pump control unit 120 .

At time T3 , the operator fully inserts the cassette 185 into the cavity 125 of the pump control unit 120 .

The cassette 185 may be swung or rotated into the appropriate position after the upper pivot point of the cassette 185 engages the cavity 125 .

Note that, alternatively, the pivot point could be at the bottom of the cavity 125. In this instance, the operator rotates or swings the top of the cassette 185 for full insertion.

According to yet other embodiments, the cassette 185 and/or the cavity 125 in the pump control unit 120 may include a hinge. In such instances, the cassette 185 may swing (e.g., from right to left, or from left to right) into the cavity 125 on the hinge.

According to yet other embodiments, loading of the cartridge 185 may include merely pushing the cartridge 185 into the cavity 125 without rotation.

Thus, the direction or motion associated with loading the cartridge 185 into the cavity 125 may vary depending on the embodiment.

FIG. 11 is an exemplary diagram showing additional details of a cartridge 185 and corresponding cavity 125 according to embodiments herein.

As shown in this example embodiment, the cassette 185 includes openings 135-1 and 135-2 that are disposed adjacent to a segment of the tube 165-2. That is, a portion of the tube 165-2 (representing a portion of the fluid path 115) is disposed between openings 135-1 and 135-2 of the cassette 185.

According to one embodiment, the box 185 is inserted into the cavity 125 by: i) aligning and forcing the first element of the bubble detector element 130 to pass through and rest in the opening 135-1 in the box 185, and ii) aligning and forcing the second element of the bubble detector element 130-2 to pass through and rest in the second opening 135-2 of the box 185.

After the cartridge 185 is inserted into the cavity 125 of the pump control unit 120, the fluid path 115 is positioned between the corresponding bubble detector elements of the detector 130. In other words, in one embodiment, the cartridge 185 is inserted into the cavity 125 such that the portion of the fluid path 115 in the cartridge 185 is aligned between the first bubble detector element and the second bubble detector element. Generally, the bubble detector element 130 detects the presence of bubbles in the fluid passing between the openings 135-1 and 135-2.

This is shown in more detail in FIG. 12 .

12 , the cavity 125 of the pump controller unit 120 includes a bubble detector element 130 - 1 and a bubble detector element 130 - 2 . By way of non-limiting example, each of the bubble detector elements 130 - 1 and 130 - 2 may protrude from a surface of the cavity 125 in the pump control unit 120 .

As previously discussed, inserting the cartridge 185 into the cavity 125 causes the bubble detector element 130-1 to slide in and ultimately rest in the opening 135-1. Additionally, inserting the cartridge 185 into the cavity 125 causes the bubble detector element 130-2 to slide in and rest in the opening 135-2.

Thus, in one embodiment, inserting the cartridge 185 into the cavity 125 aligns the portion of the fluid pathway 115 in the cartridge 185 to be adjacent to the one or more bubble detector elements.

In one embodiment, a space is disposed between bubble detector element 130-1 and bubble detector element 130-2, within which lies a portion of fluid path 115. During operation, bubble detector element 130 monitors fluid passing through the portion of fluid path 115 between or adjacent to the detector elements.

Note that the inclusion of multiple bubble detector elements 130 is shown by way of non-limiting example only. In certain embodiments, only a single bubble detector element disposed adjacent to a portion of fluid path 115 is required to detect the presence of bubbles. In such instances, if desired, cavity 125 may include only a single bubble detector element disposed adjacent to fluid path 115 to detect the presence of bubbles. The single element may transmit a signal to the passing fluid and then monitor for a reflected signal indicative of the presence of bubbles. Where multiple elements are deployed, one of the elements may be a transmitter and another element may be a receiver.

12 , the pump control unit 120 may include a bubble detector resource 172 coupled to one or more bubble detector elements 130. During operation, such as delivering a fluid to a recipient, when a bubble is detected that could otherwise be an undesirable substance in the fluid being delivered to the corresponding recipient, the bubble detector resource 172 notifies the controller in the pump control unit 120 of this condition.

In one embodiment, in response to detecting the presence of bubbles or other substances in the fluid being delivered to the recipient, as indicated by the detector resource 172, the pump control unit 120 terminates the delivery of the fluid and may set off an alarm to notify the appropriate caregiver of the condition. As previously discussed, intravenous delivery of gas to a patient can be harmful or fatal.

FIG. 13 is an exemplary diagram illustrating a fluid delivery system according to embodiments herein.

As shown, the fluid delivery system 1300 includes a fluid source 189 - 1 , a pump control unit 120 , and a disposable tubing assembly (e.g., a combination of a cassette 185 , tubes 165 - 1 , and tubes 165 - 2 ). In this example embodiment, the cassette 185 has been inserted into the corresponding cavity 125 of the pump control unit 120 .

The pump control unit 120 controls a corresponding pump resource (eg, the fluid pump 110 ) in the cassette 185 to deliver fluid from the fluid source 265 to the recipient 182 through a fluid path passing through the tube 165 - 1 , the cassette 185 , and the tube 165 - 2 .

14 is a diagram illustrating an example of a disposable cassette and a corresponding pump control unit according to embodiments herein.

As previously discussed, the present embodiment includes a cassette 185 that fits into the corresponding cavity 125 of the pump control unit 120. In addition to including tubes 165-1 and 165-2, it is noted that the present embodiment may also include tube 165-3. In one embodiment, the combination of resources including tubes 165-1, 165-2, 165-3, and cassette 185 represents an assembly, for example, a disposable tubing set.

As the name suggests, a disposable tubing set can be discarded after being used to deliver the corresponding fluid to a patient. The pump controller unit 120 can be used in conjunction with a new disposable tubing set to deliver the fluid to the next patient. Thus, the pump controller unit 120 is reusable across multiple patients. However, each corresponding disposable tubing set is only used on a single patient.

As shown and as previously discussed, the cassette 185 is inserted into the corresponding cavity 125 of the pump control unit 120 to provide a connection between the resources in the cassette 185 and the resources in the pump control unit 120 .

For example, when the cassette 185 is inserted into the cavity 125 of the pump control unit 120, the valve actuator resource 192 (e.g., a valve controller) becomes coupled to the corresponding valve 160 in the cassette 185. During pump operation, the valve actuator resource 192 in the pump control unit 120 controls valves 160-1 and 160-2. Further in this example embodiment, it is noted that the valve actuator resource 194 in the pump controller unit 120 controls valve 160-3.

Via control of valve 160-1, the pump control unit 120 can control the flow of fluid received from the first fluid source 189-1 through the tube 165-1 and the main inlet 170-1 to the pump chamber 110. For example, an open valve 160-1 can enable fluid from the fluid source 189-1 to flow through the tube 165-1 and the main inlet 170-1 into the pump chamber 110. A closed valve 160-1 prevents fluid from flowing through the tube 165-1 and the main inlet 170-1 into the pump chamber 110.

Via control of valve 160-2, the pump control unit 120 can control the flow of fluid received from the second fluid source 189-2 through the tube 165-2 and the secondary inlet 170-2 to the pump chamber 110. For example, an open valve 160-2 can enable fluid to flow through the tube 165-2 and the secondary inlet 170-2 into the pump chamber 110. A closed valve 160-2 prevents fluid from flowing through the tube 165-2 and the secondary inlet 170-2 into the pump chamber 110.

Depending on the embodiment, each of the valves 160 can default to an open position or a closed position when the cassette 185 is not inserted into the cavity 125 of the pump control unit 120. For example, in one embodiment, each of the valves 160 (e.g., valves 160-1, 160-2, and valve 160-3) is normally open before the cassette 185 is inserted into the cavity 185. After the cassette 185 is inserted into the cavity 125, the pump controller unit 120 can adjust the default state to any desired open or closed setting.

The valve actuator resource pump in the controller unit 120 can control the corresponding valve 160 in any suitable manner depending on the type of valve. For example, depending on the type of valve, the valve 160 can be electromechanically controlled, hydraulically controlled, pneumatically controlled, etc. via input from the pump control unit 120.

When the cartridge 185 is loaded into the cavity 125 of the pump control unit 120, the corresponding actuator resources in the control unit 120 engage to control each corresponding valve to the desired open position or closed position. By way of non-limiting example embodiment, as a safety feature, when the cartridge 185 is first loaded into the cavity 125 of the control unit 120, the actuator resources in the pump control unit 120 can be configured to control each of the valves 160-1, 160-2, and 160-3 to the closed position.

The pump control unit 120 opens and closes the valve 160 when the corresponding fluid is pumped from the one or more fluid sources 189 .

For example, in order to pump fluid from the first fluid source 189-1 through the main inlet 170-1 into the pump chamber 110, the pump control unit 120 opens valve 160-1 and closes valve 160-2 and valve 160-3. When only valve 160-1 is opened, the pump control unit 120 controls the pump chamber actuator 193 so that fluid is pumped into the pump chamber of the fluid pump 110 through pipe 165-1. After a sufficient amount of fluid is pumped into the pump chamber of the fluid pump 110, the pump control unit 120 closes valve 160-1 and valve 160-2 and opens valve 160-3. When only valve 160-3 is opened, the pump control unit 120 controls the pump chamber actuator 193 so that the fluid in the pump chamber 110 is pressurized to the degassing filter 140 in the fluid path 115 downstream through valve 160-3.

In order to draw fluid from the second fluid source 189-2 through the secondary inlet 170-2 into the pump chamber 110, the pump control unit 120 opens valve 160-2 and closes valve 160-1 and valve 160-3. When only valve 160-2 is opened, the pump control unit 120 controls the pump chamber actuator 193 to draw fluid into the pump chamber of the fluid pump 110 through pipe 165-2. After a sufficient amount of fluid is drawn into the pump chamber of the fluid pump 110, the pump control unit 120 closes valve 160-1 and valve 160-2 and opens valve 160-3. When only valve 160-3 is opened, the pump control unit 120 controls the pump chamber actuator 193 to pressurize the fluid in the pump chamber of the fluid pump 110 along the fluid path 115 downstream through valve 160-3 to the degassing filter 140.

Embodiments herein may include switching between drawing fluid from different fluid sources 189 and delivering such fluid to a recipient 182. For example, in a first pumping cycle, the pump controller unit 120 may be configured to control valves to deliver fluid from fluid source 189-1 to the recipient 182 in a manner as previously discussed; in a second pumping cycle, the pump controller unit 120 may be configured to control valves to deliver fluid from fluid source 189-2 to the recipient in a manner as previously discussed; in a third pumping cycle, the pump controller unit 120 may be configured to control valves to deliver fluid from fluid source 189-1 to the recipient 182 in a manner as previously discussed; in a fourth pumping cycle, the pump controller unit 120 may be configured to control valves to deliver fluid from fluid source 189-2 to the recipient in a manner as previously discussed; and so on. Thus, a single pump chamber 110 (e.g., a diaphragm pump) in the cassette 185 may be used to deliver fluid from different sources to the recipient 182.

The cartridge 185 may also include a degassing filter 140 disposed in the fluid path 115 downstream from the valve 160 - 3 .

In one embodiment, the degassing filter 140 is positioned upstream relative to the fluid flow resistor 145. Positioning the degassing filter 140 upstream relative to the fluid flow resistor 145 ensures that the degassing filter 145 remains at a positive pressure (e.g., a pressure higher than the pressure at the location monitored by the pressure sensor 150, as will be discussed below) during fluid delivery.

As the name suggests, and as previously discussed, the degassing filter 140 disposed in the cartridge 185 removes any air or gas from the fluid traveling downstream along the fluid path 115 toward the fluid resistor assembly 145. In one embodiment, air is exhausted from the fluid path 115 to the open air.

The fluid resistor driver 195 controls the degree to which the flow of a corresponding fluid along the fluid path 115 toward the recipient 182 is resisted by the fluid resistor 145. In a manner similar to that previously discussed, the fluid resistor 145 may be controlled in any suitable manner, e.g., electromechanically, hydraulically, pneumatically, etc.

The cassette 185 also includes a pressure sensor 150 disposed downstream relative to the fluid flow resistor 145. In one non-limiting example embodiment, the pressure sensor 150 monitors the pressure of the fluid disposed and passing through the fluid path 115, as shown. Via a pressure sensor circuit 196 in communication with the pressure sensor 150, the pump control unit 120 is able to determine the pressure of the fluid being delivered to the recipient 182 at a downstream location in the fluid path 115 relative to the fluid flow resistor 145.

In one embodiment, the pressure sensor circuit 196 detects when there is a downstream obstruction that prevents the corresponding fluid from being delivered to the recipient 182. For example, in one embodiment, when the pressure sensor circuit 196 detects that the pressure at the location monitored by the pressure sensor 150 is above a threshold, the pressure sensor circuit 196 generates a corresponding signal indicating an obstruction condition and/or indicating that the fluid cannot be delivered to the recipient 182. A detected pressure below the threshold generally indicates that there is no downstream obstruction and that fluid is being delivered to the recipient 182.

In addition, as previously discussed, it is noted that the cartridge 185 may include an opening 135-1 and an opening 135-2. The bubble detector element 130-1 protrudes through or into the opening 135-1; the bubble detector element 130-2 protrudes through or into the opening 135-2. The bubble detector circuit 172 monitors signals received from one or more elements 130-1 and 130-2.

During pumping of the fluid to the recipient 182, the degassing filter 140 removes gas from the infusion line (fluid path 115) before the gas reaches the element 130. If the degassing filter 140 fails and an air bubble is detected by one or more of the detector elements 130-1 and 130-2, the bubble detector circuit 172 generates a corresponding signal to the pump control unit 120 to interrupt the delivery of the corresponding fluid to the recipient 182. This prevents any gas in the fluid from being delivered to the recipient 182 in the event that the degassing filter 140 happens to be unable to remove the gas.

By way of non-limiting example, in one embodiment, in response to receiving an indication that bubbles are detected in the fluid being delivered to the corresponding recipient 182, the pump control unit 120 can be configured to close the valve 160-3 and/or deactivate the fluid pump 110 to interrupt the delivery of the fluid to the recipient.

Thus, embodiments herein may include a disposable cartridge 185 that includes a fluid path 115. The fluid path 115 includes a degassing filter 140 and a flow resistor 145. The degassing filter 140 is disposed in the fluid path 115 downstream of the fluid pump 110. The flow resistor 145 is disposed in the fluid path 115 downstream of the degassing filter 140. As previously discussed, still other embodiments herein may include a pressure sensor 150. In the example embodiment shown, the flow path 115 includes the pressure sensor 150. The pressure sensor 150 monitors the pressure of the fluid in the fluid path 115 at a location in the fluid path 115 that is a location in the fluid path between the flow resistor 145 and the portion of the fluid path 115 between the first detector element 130-1 and the second detector element 130-2.

Empty source container:

A common problem with all infusions is that they are difficult to monitor and determine when a fluid container is empty, forcing a container change. When a fluid container becomes empty, the flow rate is typically reduced from the physician-prescribed flow rate to a "keep the vein open" or KVO rate. If an empty or nearly empty container is not replaced or replenished, the infusion pump will completely stop the flow, and the site may clot and otherwise become unusable. If the caregiver is unable to resolve the situation, a new infusion site may need to be found for the subsequent infusion. This increases the risk of infection, potentially resulting in patient harm.

For "secondary" infusions, a fluid container containing a different IV (intravenous) solution is attached to the source-side primary fluid line, and the secondary infused fluid is temporarily infused in place of the primary fluid until the secondary container is empty. During these infusions, care must be taken with the secondary fluid container so that air does not enter the infusion line, set off an alarm, or stop the flow of fluid.

A method for monitoring the status of a fluid container has been used to estimate the fluid volume in the secondary container and program the secondary mode of the pump that delivers this volume. This method is prone to error due to erroneous or inaccurate estimation of the fluid infusion rate or the amount of fluid remaining in the container. In addition, the actual amount of fluid in the IV bag is highly variable. The actual volume can vary by more than 10% from the rated value. The user constantly balances between attempting to deliver the entire contents of the fluid source, not ending delivery due to air in the flow path, or wasting fluid.

The ability to deliver the entire contents of the bag to the patient, detect when the fluid source is empty, and then automatically purge the air before an alarm is sounded greatly reduces caregiver workload and improves patient safety.

Paramedic Infusion Automation:

Another benefit of the integrated vent and air detection scheme in the pump is the simplified preparation of the secondary infusion. Currently, when a caregiver is preparing a secondary infusion, in addition to setting the bag at the correct height, the caregiver must completely purge all air from all source lines before connecting the source lines to the primary flow path. Furthermore, the secondary infusion source container must be suspended substantially above the primary fluid source. This configuration is error-prone, time-consuming, and can delay treatment.

Embodiments herein improve this workflow by not needing to manually purge air. According to embodiments herein, a secondary source container such as fluid source 189-2 and corresponding tube 165-3 can be connected to disposable cassette 185 when there is air in the line. When secondary infusion (e.g., fluid delivery from fluid source 189-2 to recipient 182) begins, fluid pump 110 simply starts pumping. The air (e.g., gas) in fluid path 115 is automatically purged by the vent in the online degassing filter 140. When detecting liquid, the volume counter of the infusion begins.

In many cases where a secondary infusion is being performed, the desired secondary fluid flow rate is different from the desired primary fluid flow rate. In this case, the operator must program the infusion pump (pump controller 120) with the estimated volume in the secondary fluid source 189-2 so that when the fluid pump 110 has infused that volume at the prescribed secondary rate, the pump will automatically transition to the primary flow rate. However, common errors caused by incorrectly estimating the container volume or inaccurately setting the secondary volume to be infused make this method unreliable, requiring frequent monitoring by the caregiver to ensure that the appropriate fluid is being infused at the appropriate rate and to prevent air from entering the infusion line and stopping the flow.

What is needed is an inexpensive and reliable system and method for detecting when an infusion container is empty, as well as a method for providing a signal to an infusion pump to change the infusion rate, to provide a warning signal to a caregiver that the container needs to be refilled or replaced, or to switch to a different infusion source. What is also needed is a reliable system and method for use with an automatic secondary infusion mechanism that provides detection of the transition from secondary fluid flow to primary fluid flow. Embodiments herein meet these needs.

transportation:

Another common problem for caregivers delivering infusion therapies is interruption of the fluid delivery flow due to errors that occur due to movement of the patient and or the fluid delivery system. For example, during movement of the patient or equipment, a small amount of air can be introduced into the line (fluid path 115). Most infusion pump systems detect air in the line, alarm, and stop the infusion. The patient is protected from air embolism, but this creates extra work for the caregiver and can delay treatment. As previously discussed, the embodiments herein automatically purge air from the inlet tubing during transport, enabling continued fluid delivery without prompting the caregiver to replace the disposable tubing set.

Although the present invention has been specifically shown and described with reference to its preferred embodiments, it will be understood by those skilled in the art that various formal and detailed changes may be made therein without departing from the spirit and scope of the present application as defined in the appended claims. Such changes are intended to be covered by the scope of the present application. Therefore, the above description of the embodiments of the present application is not intended to be restrictive. On the contrary, any limitations of the present invention are set forth in the following claims.

Claims (14)

1. A fluid transport system, comprising: A fluid delivery assembly includes an inlet, an outlet, a pneumatic pump, a fluid flow resistor, and a fluid path, the fluid path extending between the inlet and the outlet, the fluid flow resistor being arranged in the fluid path, and the pneumatic pump being a diaphragm pump. A pressure sensor monitors the pressure of the gas applied to the pumping chamber of the pneumatic pump, the application of which causes the diaphragm pump to pump fluid from the inlet through the fluid path to the outlet; A controller for controlling the flow rate of fluid through the fluid path, operable to control gas pressure and the setting of the fluid flow resistor, operable to adjust the setting of the fluid flow resistor to deliver fluid through the fluid path from the outlet to a receiver, the fluid flow resistor being adjustable by the controller within a range between a fully open setting and a fully closed setting to control the flow rate indicated by the received flow rate setting, the adjustment of the fluid flow resistor setting by the controller being operable to cause a corresponding adjustment of the flow rate; The controller is also operable to determine changes in gas pressure and apply those changes to control the flow rate of the fluid through the fluid path. The flow velocity of the fluid through the fluid path is calculated by: measuring the gas pressure applied to the pumping chamber of the diaphragm pump, measuring the gas pressure in a chamber of known volume, and then calculating the corresponding volume of the pumping chamber of the diaphragm pump over time based on the gas pressure applied to the pumping chamber and the known volume; and The pressure change represents an adjustment applied to the gas pressure setting so that the flow rate of the fluid through the fluid path matches the received flow rate setting. 2. The fluid delivery system of claim 1, wherein the controller monitors the fluid pressure in the fluid path at a location in the fluid path between the bubble detector and the fluid flow resistor in the fluid delivery assembly. 3. The fluid transport system according to claim 1, wherein the controller dynamically controls the setting of the fluid flow resistor to control the flow rate of the fluid through the fluid path. 4. The fluid delivery system according to claim 1, wherein the controller periodically calculates the fluid volume entering and leaving the chamber of the pneumatic pump over time based on the gas pressure detected by the pressure sensor, so as to dynamically control the flow rate of the fluid through the fluid path. 5. The fluid delivery system of claim 1, wherein the controller controls the gas pressure input to the chamber of the pneumatic pump to compensate for height variations of the source supplying the fluid to the inlet. 6. The fluid delivery system of claim 5, wherein the controller controls the gas pressure input to the chamber of the pneumatic pump to compensate for fluid back pressure variations present at the outlet. 7. The fluid transport system according to claim 1, wherein the received flow rate setting is achieved by setting a non-zero flow rate of the continuous fluid flow through the fluid flow resistor; and In addition to being able to adjust the setting of the fluid flow resistor, the controller is also able to control the magnitude of the applied gas pressure used to operate the pneumatic pump, so as to set and control the flow rate according to the received flow rate. The controller is operable to repeatedly adjust the orifice setting of the fluid flow resistor to fall between a fully open setting and a fully closed setting, thereby delivering fluid at the flow rate indicated by the received flow rate setting. 8. The fluid transport system according to claim 1, wherein the received flow rate setting indication falls within the range between a non-zero minimum flow rate setting and a non-zero maximum flow rate setting for the corresponding flow rate. 9. The fluid delivery system of claim 8, wherein the controller is operable to sense the flow rate of the fluid passing through the fluid path; and The controller is operable to adjust the setting of the fluid flow resistor between a fully open setting and a fully closed setting, so that the sensed flow velocity of the fluid through the fluid path matches the received flow velocity setting; and The controller is operable to control the pressure of the pneumatic pump and the setting of the fluid flow resistor to provide continuous flow of fluid through the fluid path to the receiver at the received flow rate setting. 10. The fluid delivery system of claim 1, wherein the controller is operable to modify the setting of the fluid flow resistor to a new setting between a fully open setting and a fully closed setting, so as to control the flow rate of the fluid through the fluid path to a desired flow rate setting input to the fluid delivery system. 11. The fluid transport system of claim 1, wherein the flow rate of the fluid through the fluid path is controlled to the received flow rate setting by applying the change in gas pressure. 12. The fluid transport system according to claim 1, wherein the fluid transport system further comprises: A flow control valve is disposed in the fluid path between the pneumatic pump and the fluid flow resistor, and the controller is operable to control the setting of the flow control valve to selectively control the flow of fluid through the fluid flow resistor to the target receiver. 13. The fluid delivery system of claim 1, wherein the controller is operable to control the time of applying a change in gas pressure to control the flow rate of the fluid flowing through the fluid path as indicated by the received flow rate setting. 14. A fluid transport system comprising: Fluid path; A pneumatic fluid pump, arranged in the fluid path to deliver fluid to a receiver, wherein the pneumatic fluid pump is a diaphragm pump; A degassing filter, arranged in the fluid path, operable to remove gas from the fluid passing through the fluid path; A gas sensor, arranged in the fluid path, is configured to detect air in the fluid passing through the fluid path; A pressure sensor is disposed in the fluid path between the fluid flow resistor and the gas sensor. The pressure sensor monitors the pressure of the gas applied to the pumping chamber of the pneumatic pump, the application of which causes the diaphragm pump to pump fluid through the fluid path. The fluid flows downstream from the inlet port through the fluid path to the outlet port. The degassing filter is arranged downstream of the pneumatic fluid pump in the fluid path. The fluid flow resistor is arranged downstream of the degassing filter in the fluid path. The gas sensor is arranged downstream of the fluid flow resistor in the fluid path. The fluid delivery system further includes a controller for controlling the flow rate of fluid through the fluid path. The controller is operable to control gas pressure and the setting of the fluid flow resistor. The controller is operable to adjust the setting of the fluid flow resistor to deliver fluid through the fluid path from the outlet to the receiver. The fluid flow resistor can be adjusted by the controller within a range between a fully open setting and a fully closed setting to control the flow rate indicated by the received flow rate setting. The adjustment of the fluid flow resistor setting by the controller is operable to cause a corresponding adjustment of the flow rate. The controller is also operable to determine changes in gas pressure and apply those changes to control the flow rate of the fluid through the fluid path. The flow velocity of the fluid through the fluid path is calculated by: measuring the gas pressure applied to the pumping chamber of the diaphragm pump, measuring the gas pressure in a chamber of known volume, and then calculating the corresponding volume of the pumping chamber of the diaphragm pump over time based on the gas pressure applied to the pumping chamber and the known volume; and The pressure change represents an adjustment applied to the gas pressure setting so that the flow rate of the fluid through the fluid path matches the received flow rate setting.