FR2609622A1 - Apparatus and method for continuous measurement of blood pressure - Google Patents

Apparatus and method for continuous measurement of blood pressure Download PDF

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Publication number
FR2609622A1
FR2609622A1 FR8700462A FR8700462A FR2609622A1 FR 2609622 A1 FR2609622 A1 FR 2609622A1 FR 8700462 A FR8700462 A FR 8700462A FR 8700462 A FR8700462 A FR 8700462A FR 2609622 A1 FR2609622 A1 FR 2609622A1
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France
Prior art keywords
pressure
blood pressure
characterized
method
means
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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.)
Granted
Application number
FR8700462A
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French (fr)
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FR2609622B1 (en
Inventor
Paul Zwirn
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.)
Aix Marseille Universite
Commissariat a lEnergie Atomique et aux Energies Alternatives
Original Assignee
Aix Marseille Universite
Commissariat a lEnergie Atomique et aux Energies Alternatives
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Publication date
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Priority to FR8700462A priority Critical patent/FR2609622B1/en
Publication of FR2609622A1 publication Critical patent/FR2609622A1/en
Application granted granted Critical
Publication of FR2609622B1 publication Critical patent/FR2609622B1/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/02Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/021Measuring pressure in heart or blood vessels
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02Details of sensors specially adapted for in-vivo measurements

Abstract

<P> APPARATUS AND METHOD FOR MEASURING CONTINUOUS AND NON-BLOODY BLOOD PRESSURE. </P> <P> A DISPLACEMENT SENSOR 1 MEASURES THE PULSE. AN APPARATUS 14 RECORDS THESE MEASUREMENTS AND INSERTED INTO BOX 2 BY A PUMP 13 A VARIABLE BACK PRESSURE EQUAL TO THE AVERAGE PRESSURE. THE PULSE CURVE SO FAITHFULLY REFLECTS THE BLOOD PRESSURE CURVE. </P>

Description

APPARATUS AND METHOD FOR CONTINUOUSLY MEASURING PRESSURE
BLOOD
DESCRIPTION
The present invention relates to a continuous blood pressure measuring device as well as a bloodless method using this device.

 There are various methods of measuring blood pressure. We can first note the # ethooes using a catheter that is inserted into the vessel and which give precise results, but which have the disadvantage of being traumatic.

 According to other methods, the pulse, and in particular the radial pulse, is recorded.

 Some of them exploit the modification of the shape of the blood vessel under the effect of the beat; they pose problems for correct implementation, especially if the vessel is not very superficial.

 Among them, let us quote in the State of the art, a pulse sensor fixed on the wrist and provided with a feeler which is placed above the artery. The beats are then measured and recorded. (AYLESBURY and MARIE, "A System for Kcnitoring the Radial Pulse", journal Psychophysiology, published in the United States, vol. 21, n05, pp. 558).

 However, this method cannot provide sufficient precision because the pulse curve can only be linked to the blood pressure curve if there is a back pressure on the artery.

We know that blood pressure oscillates between maximum systolic pressure and minimum diastolic pressure. If you apply a back pressure higher than the systolic pressure, for example at the center of an inflatable cuff, there is no pulse beat: the blood vessel is flattened and the blood circulation temporarily
interrupted.

The gradual deflation of the cuff allows
to note the appearance of beats whose intensity passes by a maximum, which can be according to the case well marked or presenting a common stage to a range of back pressures.

 Studies have shown that The lowest back pressure corresponds to the Maximum intensity of the beats is equal to The Average blood pressure; The shape of the pulse curve can then be superimposed on the pressure curve.

 This is why it is essential to apply this medium pressure. Unfortunately this is variable over time and evolves almost periodically, with a low amplitude and a low frequency.

 This difficulty in reaching the medium pressure explains why the apparatus described above is not provided with a means of applying a back pressure. As a result, it is imprecise.

The invention makes it possible to remedy this drawback and offers a significant improvement in the devices used up to now insofar as it combines a sensor making it possible to record the pulse with a means of application on
artery with a back pressure equal to the average pressure in the artery.

 The signals emitted by the sensor pass through a calculator which periodically calculates the average pressure and adjusts it while recording the variations in the pulse curve as a function of time.

More specifically, the invention firstly relates to a blood pressure measuring device comprising a sealed case applied to the patient's skin and above a blood vessel by a face pierced with an orifice through which a probe protrudes. linked to the bootmaker by return means and the displacement of which is linked to variations in blood pressure in the vessel above which it is disposed, the means of measuring this delacement, a means of connecting this displacement to
blood pressure, as well as a means of varying the
pressure inside the housing under the impulse of a
calculator based on measurements.

The invention also relates to a method for measuring
blood pressure with this device which consists, after a
calibration to link the movement of the probe to the
blood pressure, continuously measuring said pressure and
periodically adjust the pressure introduced by the pump in
The case to make it equal to the average blood pressure that has just been read.

The invention will now be described more concretely with the aid of the following figures, annexed by way of illustration and in no way limitative:
- Figure 1 shows a possible embodiment of
the apparatus for operating the invention,
FIG. 1 # represents, in section, a pulse sensor according to the invention,
FIG. 2 represents a typical curve of blood pressure,
- Figure 3 shows the organization chart of prc.ece em # LOyé.

 FIGS. 1 and 1A show first of all a pulse sensor 1 fixed at the end of a forearm 20 by a strap 10 and which is made up of a waterproof boot 2 and which is in contact with the skin by a surface pierced with a hole 5. A feeler 3 protrudes from this hole 5 and is connected to the case 2 by an elastic and waterproof membrane 4. This feeler 3 is placed above the artery whose beats it now follows.

 The end of the probe 3 oriented towards the inside of the housing carries a phototransistor 6 opposite which is a light-emitting diode 7. Two wires referenced 8 and 9 respectively connect the photctransistor 6 and the diode 7 to a measuring device 14 comprising a computer and exit from the housing 2 by a nozzle 17 on which is threaded the end of a flexible t ## e 11 by which a pneumatic pump 13, itself connected to the measuring device 14 by an electric line 12, can introduce variable pressure in the case 2.

The measuring device 14 includes analog-digital converters and a processing unit allowing
the execution of the Software, the organizational structure of which is shown below. It includes displays of systolic pressures, diastolic pressures, average pressures and heart rates, as they appear from acquisitions and calculations.

 The operation of the apparatus will now be described with the aid of FIG. 2 also.

 The evolution of blood pressure is a pseudo-periodic curve; that where alternates systolic 26 and diastolic pressures 25. This curve is in fact the superposition of two pseudo-periodic oscillations: one, directly due to heartbeats, to the same frequency and gives the general shape of the curve; The other is a carrier of low amplitude and low frequency. It follows that two neighboring systolic 26 or diastolioues 25 pressures do not have the same value, and that the point measurement methods, by an inflatable cuff for example, are not always precise enough.

The mean blood pressure, which can be defined as the mean value of The pressure in the interval between two neighboring diastolic pressures 25, and for which the area 29 is equal to the sum of these areas 27 and 28, is therefore also variable. It is however necessary to know its evolution, because it must be applied permanently on
The artery so that we can record a pulse curve that has the same function as the blood pressure curve.

 The process which is the subject of the invention summarized in FIG. 3 makes it possible to satisfy these requirements.

It includes a preliminary 5D calibration phase of
The device whose purpose is to connect the blood pressure to the pulse curve by a known conversion factor. In order to obtain an initial average pressure 51, a double inflatable cuff 21 (the method can also be applied to a single-chamber cuff) of known type is used, one inflatable chamber of which is connected to a first inanometer 30 and the other inflatable chamber has a second pressure gauge 31.

 A pressure sensor not shown here makes it possible to route the pressures measured to the measuring device 14 through two lines 40 and 41.

 These chambers are at the same pressure but the manometers give information of a different nature: the first manometer 30 measures the pressure introduced into the cuff, the second manometer 31 measures the amplitude of the blood pressure oscillations.

The double cuff 21 is inflated to a pressure greater than the systolic pressure and then slowly deflated; the second pressure gauge 31 begins to record oscillations when the inflation pressure drops below a systolic pressure peak 26. When the deflation continues
The cuff, The amplitude of the oscillations increases.

 The average pressure, obtained when the oscillations recorded on the second pressure gauge 31 begin to decrease, is recorded on the first pressure gauge 35 and determines the initial value of the back pressure; this initial back pressure is created in the housing 2 by the action of the pump 13 (step 52), which makes it possible to obtain a pulse curve similar to that of the blood pressure. Measurements can then be undertaken.

When the initial average pressure has been set in the housing 2, the measurement device 14 is calibrated. The double cuff 21 is again inflated above the systolic pressure and then deflated
Slowly. A comparison 53 of the information of the sensor 1 and of the cuff 21 is then carried out. It reads on the first pressure gauge 30 The two pressures corresponding on the one hand to the beginning of these oscillations and on the other hand to the end of the decrease in
Their amplitude, as recorded by The second manometer 31.

These are respectively a systolic pressure and a pressure
diastolic (step 54).

Simultaneously, for each of these pressures, the
cuff used has transmitted a signal to the measuring device 14,
which makes it possible to identify on The pulse curve generated by the
pulse sensor and recorded by the computer the places
where these measurements were made. It is therefore now
possible to calibrate the pulse curve in pressure usual at
Using a conversion factor 55.

The computer integrated in the measuring device 14
reads the pulse curve at reduced intervals, of the order of five milliseconds; the software allows to record
The appearance of systolic 26 and diastolic 25 pressures; between two neighboring diastolic pressures, it calculates the average value of the pressures recorded and thus provides the evolution of the average pressure for each pulse beat. The adjustment of
the back pressure supplied by the pump 13 is therefore possible and makes it possible to maintain a pulse curve which faithfully reflects the pressure curve. However, this adjustment is not necessarily made during each beat because the frequency of variation of the average pressure is very low.

 According to one possible embodiment, the adjustment is carried out every other beat 35.

 The measurements can then be extended at will by repeating the operations 62 of FIG. 3: the measuring device 14 periodically determines, after a selection 56 of the pulses, for example for all pulses of an even order, the average pressure by a integration 57 of the pulse curve and converts it into pressure units. The introduction 58 of a variable back pressure equal to the average pressure previously calculated is carried out by the pump 13 in Le bottier 2.

 The measurements 59, 60 and 61 of the systolic pressure, the diastolic pressure and the heart rate can then be carried out during the next pulse before adjusting the back pressure again.

 The results can be provided in different forms that the skilled person can implement without difficulty: output of the curves on screen or on paper, digital display of the values of systolic, diastolic and average pressures as well as the heart rate. calculated by the device 14, possibly keeping a temporary record in memory of the results.

Claims (10)

 1. Continuous blood pressure measuring device comprising a waterproof case (2) applied to the skin of a patient and above a blood vessel by a face pierced with an orifice (5) by which exceeds a probe (3) linked to the bitter by elastic means (4) and whose displacement with respect to the housing (2) is linked to variations in blood pressure; means (6, 7, 14) for measuring this displacement, a means (21) for connecting this displacement to the blood pressure, characterized in that it comprises in turn means (13) exerting a variable pressure at L ' inside the case (2) under the impulse of a computer using the measurements.
 2. Continuous blood pressure measuring device as claimed in claim 1, characterized in that the means exerting variable pressure in the housing is a pump.
 3. Process for continuous measurement of pressure sO - ine with the device according to claim 1, characterized in that c # 'it consists, after etz'onnage making it possible to connect the edge of the probe (3) to the pressure in the blood vessel, to continuously measure the blood pressure and to periodically adjust the back pressure introduced by the means (13) in Le bo, te (2) to make it equal to the average pressure which is calculated by the device (14 ).
 4. A method for this continuous measurement of blood pressure according to claim 2, characterized in that the initial salinity of the back pressure is measured by an oscillometric method.
 5. Method for this continuous measurement of blood pressure according to claims 3 and 4, characterized in that the calibration takes place after application in the case (2) using the means (13), this pressure being equal to the pressure exerted by the means (21) corresponding to the average pressure calculated according to claim 4.
 6. Process this continuous measurement of blood pressure
 according to any one of claims 3 to 5, characterized in
 what Calibration includes an operation during which
 the peaks corresponding to the systolic and diastolic pressures recorded are identified by signals emitted by the pressure sensor associated with the cuff (21).
 7. A continuous blood pressure measurement method according to claim 6, characterized in that it consists in applying to the displacements of the sensor (1) a conversion factor calculated from the pressure-pressure correspondences obtained jointly by the oscillometric method and The pulse sensor, so as to calibrate the pulse curve in units of pressure.
 8. A method for continuously measuring blood pressure according to claim 3, characterized in that the reading of the average pressure is made at least every two pulses, and in that the systolic (38) and diastolic pressures (37) which immediately follow these pulses are also noted, as well as the heart rate.
 9. A method of continuous measurement of blood pressure according to claims 3 and 8, characterized and that the reading of the average pressure is done by a r: yerne of the measurements carried out during a pulse.
 10. A method of continuously measuring blood pressure according to claim 9, characterized in that the reading of the dean pressure is obtained by the average of the resures carried out in the interval between two neighboring astolic pressures (25).
FR8700462A 1987-01-16 1987-01-16 Apparatus and method for continuously measuring blood pressure Expired - Fee Related FR2609622B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR8700462A FR2609622B1 (en) 1987-01-16 1987-01-16 Apparatus and method for continuously measuring blood pressure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR8700462A FR2609622B1 (en) 1987-01-16 1987-01-16 Apparatus and method for continuously measuring blood pressure

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FR2609622A1 true FR2609622A1 (en) 1988-07-22
FR2609622B1 FR2609622B1 (en) 1994-06-17

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5247944A (en) * 1990-04-10 1993-09-28 Kabushiki Kaisha Tokai Rika Denki Seisakusho Skin movement detector

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880145A (en) * 1972-10-02 1975-04-29 Stein Paul D Method and apparatus for continuously monitoring blood pressure
FR2352530A1 (en) * 1976-05-26 1977-12-23 Barr & Stroud Ltd Method and apparatus for determining the instantaneous blood pressure
FR2559051A1 (en) * 1984-02-07 1985-08-09 Zwirn Paul Method and devices for detecting the arterial pulse

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880145A (en) * 1972-10-02 1975-04-29 Stein Paul D Method and apparatus for continuously monitoring blood pressure
FR2352530A1 (en) * 1976-05-26 1977-12-23 Barr & Stroud Ltd Method and apparatus for determining the instantaneous blood pressure
FR2559051A1 (en) * 1984-02-07 1985-08-09 Zwirn Paul Method and devices for detecting the arterial pulse

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5247944A (en) * 1990-04-10 1993-09-28 Kabushiki Kaisha Tokai Rika Denki Seisakusho Skin movement detector

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FR2609622B1 (en) 1994-06-17

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