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WO2011117861A1 - Evaluation différentielle de la fonction respiratoire - Google Patents

Evaluation différentielle de la fonction respiratoire Download PDF

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Publication number
WO2011117861A1
WO2011117861A1 PCT/IL2011/000247 IL2011000247W WO2011117861A1 WO 2011117861 A1 WO2011117861 A1 WO 2011117861A1 IL 2011000247 W IL2011000247 W IL 2011000247W WO 2011117861 A1 WO2011117861 A1 WO 2011117861A1
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WIPO (PCT)
Prior art keywords
breathing
acoustic signals
analog
phase
average
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PCT/IL2011/000247
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English (en)
Inventor
Merav Gat
Adi Eldar
Konstantin Goulitski
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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00—Instruments for auscultation
    • A61B7/02—Stethoscopes
    • A61B7/026—Stethoscopes comprising more than one sound collector
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Measuring devices for evaluating the respiratory organs
    • A61B5/091—Measuring volume of inspired or expired gases, e.g. to determine lung capacity
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00—Instruments for auscultation
    • A61B7/003—Detecting lung or respiration noise
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0204—Acoustic sensors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/04—Arrangements of multiple sensors of the same type
    • A61B2562/046—Arrangements of multiple sensors of the same type in a matrix array
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Measuring devices for evaluating the respiratory organs
    • A61B5/087—Measuring breath flow

Definitions

  • This invention relates to medical devices and methods, and more particularly to such devices and methods for analyzing lung functionality.
  • Respiratory problems ail infants and adults alike.
  • Some common lung diseases or conditions include asthma, Chronic Obstructive Pulmonary Disease (COPD), regional collapse (atelectasis), consolidation (e.g. pneumonia), interstitial edema, focal lung disease (e.g. tumor) and global lung disease (e.g. emphysema).
  • COPD Chronic Obstructive Pulmonary Disease
  • regional collapse e.g. pneumonia
  • interstitial edema e.g. pneumonia
  • focal lung disease e.g. tumor
  • global lung disease e.g. emphysema
  • Regional assessment of lung physiology has been carried out using radionucleotide perfusion also known as the "VQ scan".
  • radioactive particles are either injected into the subject's blood system or the subject is allowed to inhale suspended radioactive particles.
  • SPECT images of the lungs are obtained and one or both of the lungs in the image is divided into two or more regions. A separate analysis of each lung region is then performed.
  • each of the two lung images is divided into three parts (top, middle and bottom), and an assessment of lung function or physiology in each region is obtained.
  • regional assessment involves determining the fraction of the radioactivity detected in each region out of the total radioactivity from both lungs. The amount of radioactivity detected in each part may be con-elated with the lung condition in each part.
  • Body sounds are routinely used by physicians in the diagnosis of various disorders.
  • a physician may place a stethoscope on a person's chest or back and monitor the patient's breathing in order to detect adventitious (i.e. abnormal or unexpected) lung sounds.
  • adventitious lung sounds often provides important information about pulmonary abnormalities.
  • U.S. Patent No. 6,139,505 discloses a system in which multiple microphones are placed on a patient's chest. The recordings of the microphones during inhalation and expiration are displayed on a screen, or printed on paper. The recordings are then visually examined by a physician in order to detect a pulmonary disorder in the patient.
  • Kompis et al. disclose a system in which M microphones are placed on a patient's chest, and lung sounds are recorded. The recordings generate M linear equations that are solved using a least-squares fit. The solution of the system is used to determine the location in the lungs of the source of a sound detected in the recordings.
  • US Patent No. 6,887,208 to Kushnir et al provides a system and method for recording and analyzing sounds produced by the respiratory tract. Respiratory tract sounds are recorded at a plurality of locations over an individual's thorax and the recorded sounds are processed to produce an image of the respiratory tract. The processing involves determining from the recorded signals an average acoustic energy at a plurality of locations over the thorax over a time interval from t to t2.
  • acoustic energy at a location is used herein to refer to a parameter indicative of or approximating the product of the pressure and the mass propagation velocity at that location.
  • the image may be used to analyze respiratory tract physiology and to detect pathological conditions. Additionally, a time interval can be divided into a plurality of sub- intervals, and an average acoustic energy determined over the thorax for two or more of the sub-intervals. An image of each of these sub intervals may then be determined and displayed sequentially on a display monitor. This generates a movie showing dynamic changes occurring in the acoustic energy in the respiratory tract over the time interval.
  • WO2007060663 to Kushnir et al provides a system and method for regional assessment of lung functioning.
  • microphones are affixed to the body surface at a plurality of locations over the thorax, and signals indicative of lung sounds are recorded.
  • the signals are analyzed in order to produce a value of a predetermined parameter at each of two or more locations on the body surface over the lungs.
  • the two or more locations at which the parameter was determined are clustered into groups, where each group consists of locations on the body surface overlying a particular region of the lungs.
  • the regions may correspond to anatomical regions of the lungs, or may be determined independently of the lung anatomy.
  • For each group of locations a regional assessment of the underlying lung region is obtained based upon the values of the parameter in the group.
  • the regional assessment may be, for example, the sum of the values of the parameter at the locations in the group, the maximum value, the minimum value or an average value.
  • the regional assessment may be the sum of the values of the parameter at the locations in the group divided by the sum of the values of the parameter in all of the groups.
  • each lung is divided into three regions (top, middle and bottom), and a regional assessment is obtained as explained above for each of the six regions.
  • the lungs are divided into regions so that each region has the same number of overlying microphones.
  • the regional assessment may be presented in the form of a table.
  • US20080221467 to Papyan et al provides a method and system for regional assessment in two or more regions of an individual's lungs.
  • the system includes a plurality of transducers configured to be fixed over the thorax. Each transducer generates a signal P(xi,t) indicative of pressure waves at the location of the transducer.
  • the transducers are divided into subsets, where each subset overlies a specific region of the two or more regions.
  • An energy assessment signal is calculated from each of the signals P(xi,t). For each region, an assessment of the region is calculated from the energy assessment signals of the region.
  • a spirometer is a device used to monitor a person's ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways.
  • a spirometer i.e. Spirometer. United States Patent 4462410 and Portable spirometer. United States Patent 5277195
  • Spirometer is a device that measures how much (volume) and how fast (flow) air is moved into and out of the lungs.
  • a computerized sensor (which is part of the spirometer) calculates and graphs the results. The results demonstrate a person's air flow rates or the volume forced out within the first second. This is the Forced Expiratory Volume in the first second (FEV1). This indicates whether or not there is airway obstruction.
  • Spirometry also records the total volume of air forced out of the lungs. This is the Forced Vital Capacity (FVC).
  • FVC Forced Vital Capacity
  • Air-trapping in COPD differential spirometry could demonstrate and quantify regional air trapping in asthma or COPD that will not be shown in a full forced vital capacity maneuver.
  • Response to bronchodilator differential FVC (Forced Expiratory Vital Capacity) can detect reasons for paradoxical response to bronchodilator.
  • Cystic Fibrosis a quantitative measurement of localized airways obstruction and structural damage in the early stages of CF may be obtained.
  • a non-invasive, radiation-free system for providing differential pulmonary functionality comprising: a plurality of sound transducers adapted to be applied to a planar region of the chest or back skin of an individual to produce analog voltage acoustic signals indicative of pressure waves at each transducer location; an analog to digital converter connected with said transducers for converting said analog acoustic signals into digital form; an electronic processor connected with said analog to digital converter; and a spirometry system connected with said processor.
  • a method of providing differential pulmonary functionality comprising: attaching a plurality of sound transducers to a planar region of the chest or back skin of an individual; using a spirometer, measuring the total volume of air inhaled and exhaled by the individual during at least one breathing cycle; acquiring analog voltage acoustic signals indicative of pressure waves produced at each transducer location during the same at least one breathing cycle; converting said analog acoustic signals into digital form; and using said total air volume and said analog acoustic signals to calculate the relative air flow in each area of the lungs.
  • Fig. 1 is a schematic block diagram outlining the main components of the system according to the present invention.
  • Fig. 2 shows the correlation between total flow (x-axis) and acoustic envelope
  • Fig. 3 is a flowchart describing an example algorithm for computing separated airflow of the lungs.
  • Fig. 4 is a flowchart showing an example envelope calculation algorithm, based on recognition of peaks.
  • the present invention discloses a system and method for providing a non-invasive, radiation-free imaging system that provides differential pulmonary function (split-lung) based on quantitative lung sound information in different regions of the lungs, such as disclosed in WO2007060663 combined with lung function assessed by spirometry.
  • differential pulmonary function split-lung
  • Fig. 1 is a schematic block diagram outlining the main components of the system according to the present invention.
  • the system 100 comprises a plurality of N sound transducers 105, of which four are shown, applied to a planar region of the chest or back skin of individual 110 (not shown in the drawing).
  • the transducers 105 may be applied to the subject by any means known in the art, for example using an adhesive, suction, or fastening straps.
  • Each transducer 105 produces an analog voltage signal 115 indicative of pressure waves arriving to the transducer.
  • the analog signals 115 are digitized by a multichannel analog to digital converter 120.
  • the data signals 125 are input to a memory 130.
  • Data input to the memory 130 are accessed by a processor 135 configured to process the data signals 125.
  • the signals 125 may be de-noised by filtering components. For example frequencies above or below the known range of lung sounds can be filtered out, as well as vibrations originating from external noise (due to speaking etc.).
  • Each signal 125 may also be subject to band pass filtering so that analysis is done only on frequency components within a range of interest.
  • An input device such as a computer keyboard 140 or mouse 145, is used to input relevant information relating to the examination such as personal details of the individual 110.
  • the input device 140 may also be used to input values of one or more times t1 and t2 that specify times at which the signals P(Xj,t) are to be analyzed or that specify one or more time intervals over which no signals are to be analyzed.
  • the processor 135 calculates the value of a parameter at a plurality of locations over the lungs at the specified times or over the specified time intervals.
  • the locations at which the parameter is calculated are divided into groups, where each group overlies a region of the lungs.
  • the processor 135 is further configured to perform a regional assessment of the lungs.
  • the regional assessment comprises for each of the groups determining the value of one or more regional parameters where each regional parameter is obtained in a calculation involving the parameter values calculated at the various locations in the region.
  • a regional parameter may be the sum of the parameters in the region, the maximum of the parameter value, the minimum or the average.
  • the regional parameter values may be normalized by dividing the regional parameter by the sum of the regional parameter values.
  • System 100 additionally comprises a spirometer 160 connected to a mouthpiece 170.
  • the spirometer 160 calculated parameters (flow, volume, time) are input to memory 130.
  • the spirometer may comprise a spirometer.
  • System 100 may additionally comprise display means 150 for graphical or alpha-numerical display of the test results.
  • the main goal of system is to measure non-invasively the general air-flow of breathing, separated at least into two parts: left and right, i.e. the part that flows into the left lung and the part that flows into the right lung.
  • Air-flow in the air-ways of a lung produces vibrations which may be explained by turbulent flow.
  • the source of these vibrations can be classified by its frequency response, which corresponds to the air-way's size: big air-ways excite vibrations at low frequency range while small air-ways excite vibrations at high frequency range.
  • the vibration is caused by a kind of dissipation process having two main mechanisms operating when air flows into a lung's air-way.
  • the first one is the characteristics of the response of the elastic walls of a lung's air-way to air flow which occurs due to the fact that the walls have non regular structure. In this case the non regular wall structure leads to local changes of the flow velocity and hence to local differences of pressure which apply force on the elastic walls of the air-ways at neighboring points with different cross section area.
  • vibrations are also caused (or changed) due to local changes of the flow (that change the local static pressure on the airway walls). Therefore, in general, when the flow is increased the vibration is increased too.
  • the standard method to measure air flow is by a spirometer which is widely used in Spirometry.
  • Intensity of vibration may be presented by an amplitude modulation envelope of a signal recorded by microphones which are placed on the chest or back of a subject during breathing.
  • the algorithm of amplitude envelope calculation might differ according to the problem to be solved, but the main concept of this algorithm is to generate a smoothed curve which presents the average variations of the vibration intensity along time, without the effects of transient sounds and other noises which are not related to the air flow.
  • the ratio between the average vibration envelopes of the left and right lungs can give the ratio between the flow of the left and right lungs providing that the total airways cross sections for the left and the right lung are similar.
  • the differential spirometer of the present invention is based on the following observations:
  • the breath sound vibration envelope is correlated to the air flow.
  • the general air-flow can be divided according to the ratio between the sum or average values of the left and the right envelopes.
  • Fig. 3 is a flowchart describing an example algorithm for computing separated airflow of the lungs.
  • the algorithm receives initial raw data from a matrix of N (e.g. 40) microphones placed on a subject's back or chest, which record vibrations during breathing and raw data from a spirometer, which measures total air flow rate of the subject's breathing.
  • N e.g. 40
  • the location of each microphone is determined by a row number r and a column number c.
  • the raw data of each microphone may be presented as Sig(r,c,t), where t denotes the time scale.
  • the raw data from both microphones and spirometer may be provided to memory 130 with time stamps for synchronizing the two devices. Alternatively, the system may attach time stamps to the incoming signals automatically.
  • step 310 the raw data from each microphone is filtered by a band pass filter, for example between 100 and 1000 Hz. Generally this filtering is done to remove energy of signals which correspond to heart sounds (low frequencies) or to noises (high frequencies).
  • step 320 the start and end points of an inspiration phase of each recorded breath cycle are identified on the time scale of a record, by processing the raw data of the spirometer.
  • the algorithm finds points of the flow data where it crosses the zero value. We shall refer to these points as where / is the cycle number and j equals 1 for a starting point of the inspiration phase and 2 for an end point of the inspiration phase.
  • the signal envelopes are calculated. This calculation may have different variants.
  • the envelope may be calculated by computing a standard deviation value in a sliding window, by computing the Hilbert transform of the signal, by implementing a median value in a sliding window or by a number of other ways.
  • the envelope may be calculated for the whole signal or for each cycle or even for each phase of a breathing cycle separately.
  • Fig. 4 is a flowchart showing an exemplary envelope calculation algorithm, based on peaks recognition.
  • the envelope is calculated for each phase of the breathing cycle separately, but may also be calculated for entire breathing cycles or for a series of breathing cycles.
  • the algorithm calculates the absolute value of each signal in the time intervals that corresponds to the predetermined phase of a breathing cycle (i.e. the union of the inspiration and expiration intervals).
  • step 410 all points corresponding to the maximal values (peaks) are found for each phase.
  • step 420 the algorithm calculates a median filter for the vector of these peaks, with a sliding window whose length is equal to 10% (or any other percentage) of the length of the peaks vector.
  • step 430 a running average is calculated for the resultant median peaks vector, with a sliding window whose length is equal to 10% (or any other percentage) of the length of the vector and uniform weighting coefficients equaling 1 over the window length.
  • step 440 the resulting (heavily filtered) peaks vector is interpolated (using cubic interpolation or similar) in order to generate the envelope vector Env(t) in the original time resolution
  • step 340 summary or average envelopes are computed at each phase (inspiration and expiration) of the recorded breathing, corresponding to the left and right lungs.
  • j - is the index of the microphone, which is running over ni microphones for the left side and over n r for the right side.
  • step 350 the flow/volume curves (that were retrieved from the spirometer) which correspond to a specific phase (either inspiration or expiration) for all the breathing cycles are averaged.
  • all curves are normalized for a [0,1] time interval with constant step, using a standard interpolation function (in this context 0 means start time of the phase, 1 means end time of the same phase).
  • 0 means start time of the phase
  • 1 means end time of the same phase.
  • all curves are summarized and divided by the number of cycles in the recorded signal.
  • the averaged curve is interpolated again back to the original time scale: m is the number of breathing cycles; j is the index of each cycle tnorm is the normalized time scale
  • Fj(t mm) ) is the time normalized air flow function in the specific phase in cycle j
  • step 360 the separated flow is calculated.
  • the first method is the most intuitive one: at each time point t we split the average flow F(t) by the ratio of the left and right lungs' vibration envelope.
  • F e nvLeft! nsp (t) is the estimated left lung flow based on the relative acoustic envelope for the inspiration phase and similar formulas for the flow during the expiration phase and for the right lung.
  • An alternative method is to loosen that coupling by forcing a match between the vibration envelope and the flow only at the start and end times (t 0 , tend) of the breathing phase.
  • this technique on the integrals of the flow from to to nd which is actually the Volume.
  • the total volume of inhaled/exhaled air is calculated by time integration of the total flow/volume curve at each phase of the recorded breathing.
  • ⁇ 5 ⁇ is the average duration of the inspiration phase (over all cycles) and T exp is the same average for the expiration phase.
  • V em Rig t lnsp AvgEnvRight Insp (t) V em Right Exp ⁇ AvgEnvRight** (t)
  • F env Lef( ns (t) is the estimated left lung flow based on the relative acoustic envelope for the inspiration phase and similar formulas for flow during the expiration phase and the right lung.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biomedical Technology (AREA)
  • Molecular Biology (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • General Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Pulmonology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Animal Behavior & Ethology (AREA)
  • Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Pathology (AREA)
  • Biophysics (AREA)
  • Physiology (AREA)
  • Acoustics & Sound (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

Cette invention concerne un système non invasif, sans émission de rayons, utilisé pour évaluer la fonction respiratoire différentielle, ledit système comprenant : plusieurs transducteurs de son conçus pour être appliqués sur une zone plane de la poitrine ou du dos d'un sujet pour produire des signaux sonores de tension analogiques indicateurs d'ondes de pression à chaque emplacement des transducteurs, un convertisseur analogique-numérique relié aux transducteurs pour convertir les signaux sonores analogiques en signaux numériques, un processeur électronique relié au convertisseur analogique-numérique et un spiromètre relié au processeur.
PCT/IL2011/000247 2010-03-25 2011-03-15 Evaluation différentielle de la fonction respiratoire Ceased WO2011117861A1 (fr)

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US28274910P 2010-03-25 2010-03-25
US61/282,749 2010-03-25

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112816562A (zh) * 2020-12-29 2021-05-18 全测(厦门)科技有限责任公司 一种超声波回波信号包络的计算方法、装置、系统及存储介质

Citations (9)

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Publication number Priority date Publication date Assignee Title
US4462410A (en) 1981-06-26 1984-07-31 Lse Corp. Spirometer
US5277195A (en) 1992-02-03 1994-01-11 Dura Pharmaceuticals, Inc. Portable spirometer
US6139505A (en) 1998-10-14 2000-10-31 Murphy; Raymond L. H. Method and apparatus for displaying lung sounds and performing diagnosis based on lung sound analysis
US20030018276A1 (en) * 2000-10-06 2003-01-23 Mansy Hansen A. Acoustic detection of endotracheal tube location
US6887208B2 (en) 2002-01-10 2005-05-03 Deepbreeze Ltd. Method and system for analyzing respiratory tract sounds
US20050182337A1 (en) * 2004-02-04 2005-08-18 Meir Botbol Method and system for analysing respiratory tract air flow
WO2007060663A1 (fr) 2005-11-25 2007-05-31 Deepbreeze Ltd. Méthode et système pour évaluer la physiologie pulmonaire régionale
US20080221467A1 (en) 2007-02-06 2008-09-11 Deepbreeze Ltd. Method and systms for regional assessment of pulmonary function
US20080281219A1 (en) * 2007-04-11 2008-11-13 Deepbreeze Ltd. Method and System for Assessing Lung Condition and Managing Mechanical Respiratory Ventilation

Patent Citations (9)

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US4462410A (en) 1981-06-26 1984-07-31 Lse Corp. Spirometer
US5277195A (en) 1992-02-03 1994-01-11 Dura Pharmaceuticals, Inc. Portable spirometer
US6139505A (en) 1998-10-14 2000-10-31 Murphy; Raymond L. H. Method and apparatus for displaying lung sounds and performing diagnosis based on lung sound analysis
US20030018276A1 (en) * 2000-10-06 2003-01-23 Mansy Hansen A. Acoustic detection of endotracheal tube location
US6887208B2 (en) 2002-01-10 2005-05-03 Deepbreeze Ltd. Method and system for analyzing respiratory tract sounds
US20050182337A1 (en) * 2004-02-04 2005-08-18 Meir Botbol Method and system for analysing respiratory tract air flow
WO2007060663A1 (fr) 2005-11-25 2007-05-31 Deepbreeze Ltd. Méthode et système pour évaluer la physiologie pulmonaire régionale
US20080221467A1 (en) 2007-02-06 2008-09-11 Deepbreeze Ltd. Method and systms for regional assessment of pulmonary function
US20080281219A1 (en) * 2007-04-11 2008-11-13 Deepbreeze Ltd. Method and System for Assessing Lung Condition and Managing Mechanical Respiratory Ventilation

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Title
KOMPIS ET AL., CHEST, vol. 120, no. 4, 2001
KOMPIS M ET AL: "Acoustic Imaging of the Human Chest", CHEST, THE COLLEGE, CHICAGO, IL, US, vol. 120, no. 4, 1 October 2001 (2001-10-01), pages 1309 - 1321, XP002237833, ISSN: 0012-3692, DOI: 10.1378/CHEST.120.4.1309 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112816562A (zh) * 2020-12-29 2021-05-18 全测(厦门)科技有限责任公司 一种超声波回波信号包络的计算方法、装置、系统及存储介质

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