EP0235137A1 - Apparatus and method for monitoring organs of the body - Google Patents

Apparatus and method for monitoring organs of the body

Info

Publication number
EP0235137A1
EP0235137A1 EP85905646A EP85905646A EP0235137A1 EP 0235137 A1 EP0235137 A1 EP 0235137A1 EP 85905646 A EP85905646 A EP 85905646A EP 85905646 A EP85905646 A EP 85905646A EP 0235137 A1 EP0235137 A1 EP 0235137A1
Authority
EP
European Patent Office
Prior art keywords
impedance
signals
electrodes
organ
recorder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85905646A
Other languages
German (de)
French (fr)
Inventor
John Andrew Sutton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0235137A1 publication Critical patent/EP0235137A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/05Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/053Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0535Impedance plethysmography

Definitions

  • This invention relates to apparatus for monitoring hollow visceral organs of the body.
  • This invention is based on the observation that it is possible to monitor body function, for example, the function of hollow visceral organs such as the stomach including measuring the volume of the heart, lungs, bladder and uterus dand the volume of fluid within any of these organs, electronically, by measuring differences in impedance across the body through the organ in question using a plurality of electrodes.
  • apparatus for monitoring body functions comprises oscillator means for generating a high frequency oscillation, an oscillator driven constant current generating source, at least one pair of current driven electrodes for attachment to the body of a patient, at least two pairs of voltage sensing electrodes for attachment to the body of the patient, tuner/voltage amplifier means tuned to the frequency of the generator means, converter means for measuring impedance changes registering between pairs of voltage sensing electrodes, impedance indicator means isolating circuit means for receiving signals from the impedance converter, filter means for excluding electronic or biological fluctuations from the equipment or the subject and an impedance offset control, and recorder means for recording the subject signals, the subject signals being received by the recorder means as separate signals.
  • the recorder means may, for example, comprise a chart recorder or oscilloscope, a tape recorder or a microcomputer and preferably in addition to having the capability for receiving the signals from the different electrode pairs separately also has the capability of correcting phase displacement between the signals and recording a combination of the signals.
  • the apparatus can be used to monitor, for example, size, rate of filling or emptying and wall contraction in hollow visceral organs of the body, for example, the stomach, heart, lungs, bladder and uterus.
  • the recording produced by the recorder gives a continuous reading of impedance changes. It shows a base line with fluctuations indicating contractions in the wall of the organ causing changes in impedance.
  • the organ fills the trace rises to a maximum and then decreases towards a base level value, the subsiding trace similarly being superimposed by fluctuations indicating contractions in the wall of the organ.
  • Filling and emptying times of the organ are shown by the speed of ascent to a peak and subsequent decline.
  • Volume can be determined as a function of the magnitude of change of impedance.
  • the magnitude of contractions of the wall are shown as a function of the area of the minor peaks superimposed on the main trace.
  • Processing for example, by Fourier analysis of the signals indicates contractions of the organ in different regions covered by the electrode and by dividing the trace into, for example, time intervals, differences in contractions at different times can be determined giving an indication of, for example, response to a meal or drugs or other stimulus.
  • the trace produced by combining the signals from a large number of electrodes gives an indication of the full impedance displacement of the organ and therefore gives a more sensitive indication of the volume that can be derived from the separate signals.
  • the generator means is a 100 kHz oscillator and the current control means produces a 4 milliamp peak-to-peak constant current drive.
  • a non-invasive method for monitoring stomach volume and rate of filling and/or emptying has long been sought by gastroenterological physicians.
  • a non-invasive method has the advantages of repeatability unlike X-ray or isotopic methods so that the progress of illness or the effects of treatment can be measured.
  • the new device proposed has this capability and has proved so sensitive in practice that it may also be used to quantify the contractions of the stomach. Because pairs of electrodes can be used separately to monitor stomach contractions the progress of contractions through the stomach can be assessed. At the same time because a plurality of electrodes is used the accuracy of the volume measurement is enhanced by surveying an increased region of the body thus including the entire region of the stomach even though the exact position of the stomach cannot be identified from without.
  • the use of at least two pairs of voltage sensing electrodes increases the possibility of recording signals from the region of interest, within the body, which cannot be identified from without.
  • 2 is a 4 milliamp peak-to-peak constant current drive
  • 3 is the stomach
  • 4 is a pair of current driving electrodes
  • 5 is a pair of voltage sensing electrodes
  • 6 is a 100 kHz tuner/voltage amplifier
  • 7 is a detector to recover impedance changes
  • 8 is an impedance meter
  • 9 is a subject signal isolation amplifier
  • 10 is a low pass filter and impedance offset control
  • 11 is a chart recorder
  • 12 is a tape recorder or microcomputer.
  • the current driving and voltage sensing electrodes 4 and 5 are placed on the body of the patient around the organ to be monitored.
  • the signal recorded by the voltage sensing electrodes 5 is passed to the amplifier 6 and converted to impedance by detector/converter 7.
  • the signal from the detector/converter 7 is passed both to impedance meter 8 which gives a direct read out of impedance and to trhe signal isolation amplifier 9 and thence to the low pass filter and recorder.
  • the signals from the separate pairs of voltage sensing electrodes are maintained separate and are individually passed to the recorder so that impedance changes detected by each pair of voltage sensing electrodes can be recorded individually.
  • the recorder preferably also includes means for correcting phase displacement of the individual signals and combining the signals so that the total of the impedance changes recorded by a number of electrodes can also be indicated by the recorder.
  • Figs. 2 and 3 are more detailed self-explanatory circuit diagrams in which like reference numerals have been used to indicate the various components of the apparatus. It will be appreciated that only one set of electrodes 5 is shown in these figures and the circuitry will be duplicated as appropriate to accommodate from the sets of electrodes 5.
  • circuitry shown is merely exemplary of one especially preferred embodiment of the invention - 5 - and the invention is not to be regarded in any way as limited to the arrangement shown.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Physics & Mathematics (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Hematology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Measuring And Recording Apparatus For Diagnosis (AREA)

Abstract

Appareil de surveillance des fonctions corporelles comprenant un dispositif oscillateur (1) pour générer une oscillation à très haute fréquence, une source constante de courant (2) commandée par l'oscillateur, au moins deux électrodes (4) conductrices de courant pour fixation sur le corps d'un patient, au moins deux paires électrodes (5) détectrices de tension pour fixation sur le corps d'un patient, un dispositif amplificateur de tension/syntomisateur (6) accordé sur la fréquence du générateur (1), un convertisseur (7) pour mesurer les variations d'impédance entre les paires d'électrodes détectrices de tension (5), un indicateur d'impédance, un ciruit d'isolation pour recevoir les signaux en provenance du convertisseur d'impédance (7), un filtre (10) pour exclure les fluctuations électroniques ou biologiques provenant du matériel ou du sujet, et une commande de correction d'impédance, ainsi que des moyens (11 ou 12) pour enregistrer le processus et analyser les signaux provenant du sujet, ces derniers étant reçus par les moyens d'enregistrement (11 ou 12) sous forme de signaux distincts. Sont également décrits des procédés de réalisation d'un enregistrement de la fonction et du volume d'un viscère creux.Apparatus for monitoring body functions comprising an oscillator device (1) for generating a very high frequency oscillation, a constant current source (2) controlled by the oscillator, at least two current-conducting electrodes (4) for attachment to the body of a patient, at least two pairs of voltage detector electrodes (5) for attachment to the body of a patient, a voltage amplifier/syntomizer device (6) tuned to the frequency of the generator (1), a converter ( 7) for measuring the impedance variations between the pairs of voltage detecting electrodes (5), an impedance indicator, an isolation circuit for receiving the signals coming from the impedance converter (7), a filter (10) for excluding electronic or biological fluctuations originating from the material or subject, and an impedance correction control, as well as means (11 or 12) for recording the process and analyzing the signals originating from the subject, the latter being received by the recording means (11 or 12) in the form of distinct signals. Also described are methods of performing a recording of the function and volume of a hollow viscus.

Description

- 1 -
APPARATUS AND METHOD FOR MONITORING ORGANS OF THE BODY
This invention relates to apparatus for monitoring hollow visceral organs of the body.
This invention is based on the observation that it is possible to monitor body function, for example, the function of hollow visceral organs such as the stomach including measuring the volume of the heart, lungs, bladder and uterus dand the volume of fluid within any of these organs, electronically, by measuring differences in impedance across the body through the organ in question using a plurality of electrodes.
According to the invention apparatus for monitoring body functions comprises oscillator means for generating a high frequency oscillation, an oscillator driven constant current generating source, at least one pair of current driven electrodes for attachment to the body of a patient, at least two pairs of voltage sensing electrodes for attachment to the body of the patient, tuner/voltage amplifier means tuned to the frequency of the generator means, converter means for measuring impedance changes registering between pairs of voltage sensing electrodes, impedance indicator means isolating circuit means for receiving signals from the impedance converter, filter means for excluding electronic or biological fluctuations from the equipment or the subject and an impedance offset control, and recorder means for recording the subject signals, the subject signals being received by the recorder means as separate signals.
The recorder means may, for example, comprise a chart recorder or oscilloscope, a tape recorder or a microcomputer and preferably in addition to having the capability for receiving the signals from the different electrode pairs separately also has the capability of correcting phase displacement between the signals and recording a combination of the signals. - 2 - The apparatus can be used to monitor, for example, size, rate of filling or emptying and wall contraction in hollow visceral organs of the body, for example, the stomach, heart, lungs, bladder and uterus.
The recording produced by the recorder gives a continuous reading of impedance changes. It shows a base line with fluctuations indicating contractions in the wall of the organ causing changes in impedance. When the organ fills the trace rises to a maximum and then decreases towards a base level value, the subsiding trace similarly being superimposed by fluctuations indicating contractions in the wall of the organ. Filling and emptying times of the organ are shown by the speed of ascent to a peak and subsequent decline. Volume can be determined as a function of the magnitude of change of impedance. The magnitude of contractions of the wall are shown as a function of the area of the minor peaks superimposed on the main trace. Processing, for example, by Fourier analysis of the signals indicates contractions of the organ in different regions covered by the electrode and by dividing the trace into, for example, time intervals, differences in contractions at different times can be determined giving an indication of, for example, response to a meal or drugs or other stimulus.
The trace produced by combining the signals from a large number of electrodes gives an indication of the full impedance displacement of the organ and therefore gives a more sensitive indication of the volume that can be derived from the separate signals.
In one specific form of the apparatus, the generator means is a 100 kHz oscillator and the current control means produces a 4 milliamp peak-to-peak constant current drive.
A non-invasive method for monitoring stomach volume and rate of filling and/or emptying has long been sought by gastroenterological physicians. A non-invasive method has the advantages of repeatability unlike X-ray or isotopic methods so that the progress of illness or the effects of treatment can be measured. The new device proposed has this capability and has proved so sensitive in practice that it may also be used to quantify the contractions of the stomach. Because pairs of electrodes can be used separately to monitor stomach contractions the progress of contractions through the stomach can be assessed. At the same time because a plurality of electrodes is used the accuracy of the volume measurement is enhanced by surveying an increased region of the body thus including the entire region of the stomach even though the exact position of the stomach cannot be identified from without.
Further, the use of at least two pairs of voltage sensing electrodes increases the possibility of recording signals from the region of interest, within the body, which cannot be identified from without.
Moreover, whereas impedance methods have been proposed for monitoring rates of change of cardiac volume and therefore the power of contraction and heart muscle the results have not been quantifiable. Therefore accurate measurements of the volume of blood ejected by the heart, known as cardiac output, have not been feasible. If electrodes of the new device are placed over the stomach and a measured volume of water or other suitable liquid drunk the impedance change can be measured so that impedance changes can be related to the volume drunk. Thus, when other electrodes are used to record the cardiac volume changes the results obtained can be quantified by reference to the recorded gastric change results. In this way a new, non-invasive device for monitoring cardiac performance is available.
Further, in any measurements of function where reference, comparison, or standardisation between signals from the organ being monitored and any other region of the body is required, additional sets of electrodes are used.
The invention will now be described in greater detail by way of example with reference to the drawing which shows a block diagram of a single channel circuit showing only one pair of voltage sensing electrodes; whereas in practice at least two voltage sensing channels would be used. In the drawing, 1 is a 100 kHz oscillator,
2 is a 4 milliamp peak-to-peak constant current drive, 3 is the stomach, 4 is a pair of current driving electrodes, 5 is a pair of voltage sensing electrodes, 6 is a 100 kHz tuner/voltage amplifier,
7 is a detector to recover impedance changes, 8 is an impedance meter, 9 is a subject signal isolation amplifier, 10 is a low pass filter and impedance offset control, 11 is a chart recorder and 12 is a tape recorder or microcomputer.
In using the apparatus the current driving and voltage sensing electrodes 4 and 5 are placed on the body of the patient around the organ to be monitored. The signal recorded by the voltage sensing electrodes 5 is passed to the amplifier 6 and converted to impedance by detector/converter 7. The signal from the detector/converter 7 is passed both to impedance meter 8 which gives a direct read out of impedance and to trhe signal isolation amplifier 9 and thence to the low pass filter and recorder. When more than one voltage sensing channel is used the signals from the separate pairs of voltage sensing electrodes are maintained separate and are individually passed to the recorder so that impedance changes detected by each pair of voltage sensing electrodes can be recorded individually. The recorder, however, preferably also includes means for correcting phase displacement of the individual signals and combining the signals so that the total of the impedance changes recorded by a number of electrodes can also be indicated by the recorder.
Figs. 2 and 3 are more detailed self-explanatory circuit diagrams in which like reference numerals have been used to indicate the various components of the apparatus. It will be appreciated that only one set of electrodes 5 is shown in these figures and the circuitry will be duplicated as appropriate to accommodate from the sets of electrodes 5.
It will also be appreciated that the circuitry shown is merely exemplary of one especially preferred embodiment of the invention - 5 - and the invention is not to be regarded in any way as limited to the arrangement shown.

Claims

- 6 -C L A I M S
1. Apparatus for monitoring body functions comprising oscillator means for generating a high frequency oscillation, an oscillator driven constant current generating source, at least one pair current driven electrodes for attachment to the body of a patient, at least two pairs of voltage sensing electrodes for attachment to the body of the patient, tuner/voltage amplifier means tuned to the frequency of the generator means, converter means for measuring impedance changes registering between pairs of voltage sensing electrodes, impedance indicator means, isolating circuit means for receiving signals from the impedance converter, filter means for excluding electronic or biological fluctuations from the equipment or the subject and a impedance offset control, and recorder means for recording the subject signals, the subject signals being received by the recorder means as separate signals.
2. Apparatus according to claim 1, wherein the recorder means comprises a chart recorder or oscilloscope, a tape recorder or a microcomputer.
3. Apparatus according to claim 1 or claim 2, wherein the recorder, in addition to having the capability for receiving the signals from the different electrode pairs separately also has the capability of correcting phase displacement between the signals and recording a combination of the signals, and in addition means to analyse and process signals as required.
4. A method of producing a record of the function of a hollow visceral organ which comprises :
attaching at least one pair current driven electrodes to the body of a patient around the region of the organ to be monitored; attaching at least two pairs of voltage sensing electrodes to the body of the patient around the region of the organ to be monitored; - - passing an oscillated driven constant current through the current driven electrodes; measuring the voltages received by the voltage sensing electrodes; converting said voltages to determine impedance through the organ; separately passing signals correlated to the impedance values recorded by said electrodes to a recorder and producing a continuous record of changes of impedance through the organ.
5. A method according to claim 4, wherein the separate signals produced from the voltage sensing electrodes are corrected for phase displacement and are combined to produce a record corresponding to the combination of the impedance changes across the organ.
6. A method according to claim 4, wherein the separate signals produced from the voltage sensing electrodes are processed separately In order to quantify the changes in impedance, in various regions of the organ of interest, as, for example, in the determination of volume, magnitude and periodicity of contraction, emptying and filling rates.
7. A method according to claim 4 or claim 5 or claim 6, wherein the impedance changes determined by a plurality of pairs of voltage sensing electrodes attached to the body around the region of the organ of interest are compared, standardised or combined with the signals obtained from an additional set of electrodes attached to a different part of the body.
EP85905646A 1984-11-15 1985-11-15 Apparatus and method for monitoring organs of the body Withdrawn EP0235137A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB848428831A GB8428831D0 (en) 1984-11-15 1984-11-15 Monitoring organs of body
GB8428831 1984-11-15

Publications (1)

Publication Number Publication Date
EP0235137A1 true EP0235137A1 (en) 1987-09-09

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP85905646A Withdrawn EP0235137A1 (en) 1984-11-15 1985-11-15 Apparatus and method for monitoring organs of the body

Country Status (5)

Country Link
EP (1) EP0235137A1 (en)
JP (1) JPS62501267A (en)
AU (1) AU5069685A (en)
GB (2) GB8428831D0 (en)
WO (1) WO1986002819A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE68922452T2 (en) * 1988-08-19 1995-09-07 Hewlett Packard Co Device for measuring uterine contractions.
WO1995035060A1 (en) * 1994-06-20 1995-12-28 Auckland Uniservices Limited Brain damage monitor
US6631292B1 (en) * 2001-03-23 2003-10-07 Rjl Systems, Inc. Bio-electrical impedance analyzer
AU2002952265A0 (en) * 2002-10-25 2002-11-07 Upfal, Jonathan Implantable sensor
US7758522B2 (en) * 2007-01-03 2010-07-20 General Electric Company Combined uterine activity and fetal heart rate monitoring device
US20090204017A1 (en) * 2008-02-12 2009-08-13 Pandit Ashit M Uterine activity monitoring using impedance plethysmography

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US387436A (en) * 1888-08-07 o neil
US3874368A (en) * 1973-04-19 1975-04-01 Manfred Asrican Impedance plethysmograph having blocking system
FR2294677A1 (en) * 1973-11-09 1976-07-16 Thomson Medical Telco Cardio-pulmonary diagnostic appts using HF current - has electrodes mounted in front and rear of thorax
US4059169A (en) * 1976-02-09 1977-11-22 Hagen Winston H Monitor for biological volume changes
FR2354744A1 (en) * 1976-06-16 1978-01-13 Commissariat Energie Atomique OCCLUSION RHEOPLETHYSMOGRAPHY DEVICE
US4506678A (en) * 1982-06-07 1985-03-26 Healthdyne, Inc. Patient monitor for providing respiration and electrocardiogram signals

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8602819A1 *

Also Published As

Publication number Publication date
JPS62501267A (en) 1987-05-21
GB2190751B (en) 1988-07-13
GB8428831D0 (en) 1984-12-27
AU5069685A (en) 1986-06-03
GB2190751A (en) 1987-11-25
WO1986002819A1 (en) 1986-05-22
GB8711445D0 (en) 1987-06-17

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