FR2475882A1 - DEVICE FOR MEASURING BLOOD PRESSURE - Google Patents

Abstract

THE MEASURING DEVICE INCLUDES AN INFLATABLE AIR CHAMBER AND MICROPHONE CUFF AS WELL AS AN APPARATUS CONNECTED TO THE CUFF AND SERVED TO MEASURE AND INDICATE SYSTOLIC PRESSURE AND DIASTOLIC PRESSURE. A PRESSURE SENSOR 39, CONNECTED TO THE AIR CHAMBER, INCLUDES A RESISTIVE BRIDGE 91 WHICH IS CONNECTED TO AN AMPLIFIER 101. AN AUTOMATIC ZERO-RESETTING DEVICE 75 INCLUDES A DIFFERENTIAL AMPLIFIER 113 WHICH AN INPUT IS CONNECTED TO THE OUTPUT OF THE L ' AMPLIFIER 101 THROUGH A TRANSISTOR 117 CONTROLLED BY A PULSE GENERATOR 81. THE OUTPUT OF AMPLIFIER 113 IS CONNECTED TO A TERMINAL 91D OF BRIDGE 91. WHEN THE APPLIANCE IS SWITCHED ON, THE GENERATOR 81 MOMENTLY BLOCKS TRANSISTOR 117 AND DEVICE 75 RESETS BRIDGE 91 TO ZERO BEFORE STARTING MEASUREMENTS.

Description

The invention relates to an iasurc device? blood pressure

including a bedroom

  EFC-s; mabtl; inflatable, intended to be fixed on a person

  pressure sensor 31 'exa: iainer, a sensor /, n cormnunication fluid -: c ct chamber, and electronic means Electrically connected to this pressure sensor and capable

  : - ngendr r electric pressure signals reDresen-

  both the value of the pressure in the chamber.

  A blood pressure measuring device known from US Pat. No. 3,450,131 has a

  microphone which is connected to a logic circuit through

  mediated by different electronic components. He com

  In addition, it has an inflatable cuff and a pressure capler.

  which is connected to a recording device of the

  1 pressure through an analog converter

  that can be disconnected and a door circuit.

  During a blood pressure measurement, the cuff is inflated - a pressure higher than the systolic pressure (it is then deflated slowly, so that in a certain pressure zone Korotkoff sounds which are transformed into signals are obtained. electric by

  the microphone. At each sound of Korotkoff, converts

  analog / digital service and the door circuit are pilots

  by the logic circuit so that the measured pressure

  this moment by the pressure sensor is recorded

  in the pressure recording device. The first recorded pressure value corresponds to the systolic pressure and the last pressure value

  recorded at diastolic pressure.

  With such a device for measuring the pressure

  blood pressure, measurement errors, which can reach

  considerable size depending on the kind of pressure sensor

  used, may be caused by drift

zero point of this sensor.

  It would be possible, for example, to provide a multi-pole rheostat or potentiometer for zero point registration, as is known with measuring devices of various types. However, with a device

  measurement of blood pressure, which is intended

  4: Mrent L;, be used by the patient himself, such a

  potentiometer is of little value because no

  Zero point calibration will only be performed before a sufficient

many measures.

  The object of the invention is to create a device

  measurement of blood pressure in which no measurement error can occur as a result of

  Zero point drift in the pressure sensor.

  According to the invention, this object is achieved with a device for measuring blood pressure of the type defined in the preamble, essentially because this

  measuring device comprises on the one hand a device for

  Zero setting connected to the pressure sensor and / or to a cir-

  bake following said pressure sensor and on the other hand electrical means for generating a reset order to zero, so that, when the reset order is transmitted to zero, the zero offset adjusts the

  aforesaid electric pressure signal to the value

respond to zero pressure.

  Other advantageous features of

  the invention will appear on reading the description

next.

  For the purpose of clarification, we must

  take "blood pressure" and "pressure in the air chamber" as the relative pressure

  measured in relation to the ambient atmospheric pressure.

  The invention will now be described in more detail with respect to a particular embodiment shown in the drawing. In this: FIG. 1 represents, in top view, a device for measuring the pressure, FIG. 2 represents a block diagram of a device for measuring the pressure, FIG. 3 represents the diagram of the pressure sensor. 0 is a diagram illustrating the time course of a measurement of the blood pressure, and, Figure 5 shows the schematic of a variant of the invention.

  an amplifier with a reset device to zero.

  The device for measuring the pressure of

  shown in Figure i has a Dartboard 1 sus-

  hi.ble dG-% r-i: & J to the person's bdras to eagle tc u. apaurel dsign dagn a set by 3. The deformable armband cuntJehU- one ha. u..bz'e air / jonflable-, formed of a pocket: C _u-chuch, sa that a microphone and it is connected de -faço; l OJ2ac: lale _ device 3 to i using a pipe 5 which provides a hose connected to the inner tube as well as a key. re i: '? With the microphon and, on the side of the device, a plug-in connector 7. The apparatus 3 has a housing? with a threaded connection 9a on which is fastened in a chase manner, by means of a nut connecting a poeps 3 with a cylindrical substantially cylindrical pump body. As shown in FIG. 9, there is provided a connector 15, a connector, and an electrical connector 17, which is a

  c ...: - cf: zsif on thequal connector 7 can A-be

  plug. In out-c r, is: - ', Evéu a fitting 19 formed of a

  plug-chl. if you want to get a headphone, you can use it.

  In addition, the app has several push-button interrupters.

  21, 23, 25 without a clasp, a numeric display unit

  27 and other constructive elements, pneumatics

  and electrodes, arranged inside the housing 9.

  FIG. 2 diagrammatically shows the inflatable air chamber 31 and the microphone 33 belonging to the cuff 1, as well as part of the

  constructive, pneumatic and electrical elements,

  placed in the apparatus 3. The air chamber 31 is connected, by the loose pipe co.ntenu in the pipe 5 and by air ducts arranged in the apparatus 3, via a valve of no -retour 35 to the pump 13 and a drain valve 37 electrically controllable and a pressure sensor 39. The pump 13 is still filled

  an air inlet provided with a non-return valve 41.

  The two non-return valves 35 and 41 are mounted from -

  such as by alternative manual compression and release of the pump body, air may be sucked

  in the atmosphere and repressed in the inner tube 31.

  The microphone 33 is connected by conductors

  the input of filtering means 51 whose output is connected both to the earphone connector 19 and to a discriminator 53 which has an adjustment potentiometer 54, for setting a lower value of

  threshold, as well as a pulse shaping circuit.

  member or its output is connected to a / control element 55. The pressure sensor 39 comprises a converter converter assembly, consisting of piezo-resistive elements and connected to the input of an amplifier 57. The output of it is connected to the control element 55 on the one hand by a

  differentiator 59, on the other hand by a parallel link

  lele who bypasses the latter. The pressure sensor

  39 and the amplifier 57 are still connected to a device

  tif 75 automatic reset to zero which is still connected by

  a conductor at an output of the control element 55.

  The output of the differentiator 59 is also connected to the control element 55 and furthermore to an input of a regulator 61. The control element 55 is also connected to an input of the regulator 61 whose output is connected to the electromagnetic actuating member of the exhaust valve 37. The control element 55 presents

  in addition two connections respectively connected to conden-

  63 and 65 forming an analog memory. The element! 55 is moreover connected to a display control member 67 which notably comprises a converter

  analog / digital and which is connected to the display unit

  27. A discriminator 69 has an input still connected to the output of the differentiator 59 and an output connected to an input of a heart rate meter 71 as well as to the control element 55.

  heart rate 71 still has a pilot entry

  connected to the control element 55 and a memory

  analogue also connected to the control element 55.

  The push switch 21 is connected to the control element 55 and the push switch 23 to the display control element 67. In addition, there is provided a supply voltage source 73, comprising

  battery, which is connected to the power supply terminals

  different active elements and the ground connection. The push-button switch 25 and the control element 55 are connected to the voltage source 73 which, in addition to the battery, also has some logic elements and a regulator for the stabilization of the voltage. food. The battery is contained in

  a container that can be closed with a lid.

  The arrangement of the zero resetting device 75 as well as the

  pressure sensor 39 connected to this device and the amplifier

  indicator 57, whose circuits are shown in FIG.

  3. Figure 3 also shows the communication organ

  55, of which only the generator has been shown

  of pulses, designated by 81 as a whole. This genera-

  pulse generator 81 comprises a capacitor 83, one of which is connected to the pole / of the supply voltage source 73. The other electrode of the capacitor 83 is connected to ground via a resistor 85 as well as the input of an inverter 87. The output of this inverter 87 is connected to the base of a transistor 89 whose emitter is connected to the positive pole of the supply voltage source 73 and whose collector is connected to other elements of the control member 55 and to the

zero reset 75.

  The pressure sensor 39 has a mounting

  piezo-resistive bridge 91, formed of semiconducting materials

  Four-limb, four-limb, four-limb, four-limb, four-terminal, 91a, 91b, 91c, and 91d resistance resistor. The terminal 91a is connected to the input of an amplifier 97 and, via a resistor 95, to the negative pole of the stabilized supply voltage source 73. The non-inverting input of the amplifier 97 is grounded while the output of this amplifier 97 is connected to the terminal 91b of the bridge assembly 91. The resistance

  and amplifier 97 together form a source of cou-

constant rant 93.

  The amplifier 57 comprises a differential operational amplifier 101 which constitutes the amplifier itself and whose output is connected to the inverting input of this amplifier 101, by means of an anti-coupling resistor 103 and a capacitor

  mounted in parallel with it. Through the

  by means of an adjusting potentiometer 99 and a fixed resistor 107, the terminal 91c of the bridge assembly 91

  is connected to the inverting input of the amplifier 101.

  The terminal 91d of the bridge assembly 91 is connected to the non-inverting input of the amplifier 101. Its output is connected to the differentiator 59 as well as to the control member 55. The zero resetting device 75 has an amplifier differential operation 113 whose non-inverting input is grounded and whose inverting input

  is connected to the output of amplifier 101 via

  resistance 115 and the path

  source-drain of a field effect transistor 117. La -

  transistor gate 117 is connected to the collector of the transistor.

  tor 89 of the pulse generator 81. The output of the amplifier

  The indicator 113 is connected to the inverting input thereof via an anticoupling capacitor 119.

  through a resistor 121, the output of the amplifier 1

  Factor 113 is also connected to the non-inverting input

  of the amplifier 101 and at the terminal 91d of the bridge assembly 91.

  The non-inverting input of amplifier 101 is further connected to ground via two

  resistors in series 123, 125. The junction of the two resistors

  Furthermore, the wires 123, 125 are connected to the positive pole of the supply voltage source 73 through a switch 127 and to the display driver 67 via a diode 129. The switch 127 is housed in the battery tray and can not be

  only when this tray is open.

  The operation of the blood pressure measuring device will now be described. To make a measurement, the cuff 1 is connected to the apparatus 3 by the line 5 and this cuff is attached to the person's arm

to examine.

  The apparatus 3 is designed so that it can conveniently be held with one hand, the pump 13

serving as a handle.

  In the diagram of FIG. 4, the curve 151 represents the variation of the pressure p in the air chamber 31 and the curve 153 the variation of the cross-sectional cross section q of the exhaust valve 37, in

function of time t.

  When the cuff 1 is fixed, the device is put into operation at the instant t by means of an o

  short manual pressure on the actuator, that is,

  to say on the button of the push-button switch

  25. This turns on the power supply voltage source.

  73 which thus provides two stabilized voltages, i.e. a positive voltage and a negative voltage

compared to the mass.

  The exhaust valve 37, open as soon as the supply voltage is switched on, remains open until the beginning of the pump, that is to say up to the instant t1. In the time interval between instant to and instant t1, the pressure p in the air chamber 31 has a value of zero. When switching on the supply voltage source 73, that is to say at the appearance

  of the positive supply voltage, the generator of

  pulses 81 emits a pulse whose length is determined by

  born by the characteristics of the capacitor 83 and the

  resistance 85 as well as by the switching characteristic

  transistor 89 and which is for example between

0.3 and 1.5 s.

  - The appearance of the supply voltage or

  the pulse emitted by the pulse generator 81 con-

  for the zero resetting device 75, an order for resetting the zero point of the pressure sensor 39. The transistor 117 serving as an electronic interrupt member, which was previously blocked, is made conductive by said pulse. The amplifier 113 then begins to work as an integral regulator and sends a current to the terminal 91d of the bridge assembly 91. This current is modified

  until the voltage between the inputs of the ampli-

  therefore, the voltage at the output of the amplifier 101 has reached a zero value. The resistor 115 and the capacitor 119 are dimensioned such that the control time constant is, for example, equal to approximately 0.05 s, that is to say clearly

  shorter than the duration of the pulse emitted by the

  The regulator is therefore quickly enough

  to reset the pressure sensor 39 for

  the duration of the pulse emitted by the pulse generator

81.

  When the pulse emitted by the pulse generator 81 disappears, the transistor 117 resumes its blocking state. The amplifier 113 constitutes with the capacitor 119 a memory which maintains at the output of the amplifier the previously adjusted voltage. During the blocking of the transistor 117, the pressure sensor 39 remains in its reset state. It can be pointed out in this respect that resistance 121 has a value that is equal

  at least ten times, more precisely around sixty-

  ten times, the impedance of the bridge assembly 91, measured between its power supply terminals 91a and 91b. In addition, the value

is - -

  resistance 123 / at least one hundred times the impedance

  of the bridge 91. With the resistor 121, the amplifier-113

  I therefore practically a source of current which, even when the bridge assembly 91 becomes unbalanced during the measurement,

  provides it with a virtually constant current.

  The display control device 67 is arranged such that, at the time of application of the supply voltages, the three fields of the display unit 27 begin by indicating all three the value 8 during a short period of time. time interval, for example until

  have passed the pulse emitted by the pulse generator

  81. What is indicated next is the pressure evaluated by the pressure sensor 39 now recalibrated,

that is, the value zero.

  This signals to the user that the pressure sensor 39 is properly recalibrated. Between times t1 and t2, the air is pumped back into the air chamber 31 by manual action on the pump 13, so that an air pressure is established in this chamber.

  greater than the systolic pressure. Shortly after completion

  pumping, the exhaust valve 37 is automatically opened at time t3 so that the air leaves

  the chamber 31 by the valve 37 escaping at -atmos-

  and the pressure drops in the inner tube 31.

  The pressure sensor 39 then sends the amplifier that follows a pressure signal, that is to say a voltage, the magnitude of which is proportional to the pressure p. The

  differential quotient dp / dt is calculated in the differential

  59. The regulator 61 acts on the discharge valve

  37 so that the differential quotient dp / dt remains constant until the pressure oscillations which are caused by the cardiac activity and which will be described

  below, during the measurement phase itself.

  This measurement phase itself is

  proceeds as follows, somewhat simplified.

  When the pressure p begins to decrease from a maximum greater than the systolic pressure p, pressure oscillations are observed from the moment t4 which are due to the heartbeats. These pressure oscillations are captured by

  the discriminator 59. The discriminator 69 creates an im-

  pulse at each pressure swing, caused by

  a heartbeat, for which the different quotient

  The differential dp / dt exceeds a predetermined threshold of at least 100 Pa / s and for example 400 Pa / s. These pulses form

  a series of pulses which is designated 155 in Figure 4.

  When the pressure in the air chamber 31, decreasing, is within a certain zone, the blood causes by its flow into the artery surrounded by the cuff 1, for each blood ripple caused by a heartbeat , breaths, that is to say the so-called sounds of Korotkoff. These Korotkoff sounds are transformed by the microphone 33 into electrical sound frequency signals and addressed to the discriminator 53, via the filtering means 51, which preferably also causes amplification. When the voltage of the Korotkoff noise signals exceeds the lower threshold value, established by the discriminator 53, the pulse shaping circuit belonging to this discriminator causes a pulse each time to the control member 55. This series of pulses is designated 157 in FIG. 4 and extends from time t5 to time t6-. In the controller 55, the pulses created by the pressure oscillations and the pulses created by the Korotkoff sounds are addressed to an AND gate. This AND gate constitutes a coincidence circuit and, during each pulse of the pulse sequence, it opens a window for the pulses of the pulse series 157. The signals from the microphone therefore continue to be processed only when they fall into a window opened by a pressure swing, that is to say when there is

  a coincidence between the noise signals and the oscillations

  pressure. The sounds of Korotkoff can thus be distinguished from the spurious noises and these

to be eliminated.

  The control member 55 has a switching

  electronic transmitter that connects the output of the amplifier

  57 to the memory 63, from the start of the application

  the same. The controller 55 also has means for detecting the appearance of the first Korotkoff signal which crosses the above AND gate. When the first Korotkoff signal occurs, the memory 63 is separated from the conductor from the amplifier 57 of the pressure measuring channel. In this memory 63 is stored the value of the present pressure

  when the first noise signal of Korot-

  koff, that is, the systolic pressure.

  When now the pressure in the chamber

  The first sound of Korotkoff is followed by other sounds of Korotkoff. The control member comprises means that briefly connect the output of the amplifier 57 to the memory 65 for each Korotkoffi noise, that is to say for each pulse of the series of pulses 157. At each noise of Korotkoff a new value of the pressure is thus stored in the memory 65, the amplitude of these values of the pressure decreasing gradually. As already described, the series of pulses 157 extends to the instant t6. Since no further pulses occur after time t6, the value of pressure p measured at time t6 remains

  stored in memory 65 until the device stops.

  This memory value then represents the dias-

  tolique. The control member 55 furthermore has a circuit which determines when, during a predetermined time interval of 2 to 10 s, for example 5 s, there no longer appears Korotkoff noise. At the end of this interval, that is to say at time t7, the control member 55 sends the regulator 61 a signal that makes it open completely the valve 37. The pressure p therefore decreases very rapidly and reached again at time t8 the zero value, that is to say the ambient atmospheric pressure. The control member 55 is furthermore designed so that it connects the output of the amplifier

  57, to the display driving element 67, until the

  both t7 at regular intervals of for example 0.3 s.

  The display unit 27 therefore displays the momentary pressure each time. The control member 55 could however be constructed in such a way that the pressure is displayed

  each time, during each impulse of the series of impulse

  155 during the time interval extending from

the instant t4 at time t7.

  The control member 55 furthermore has means which momentarily put into action the measurer of

  heart rate 71 so that it measures the frequency

  during the onset of the series of impulses

  155 and calculates the average value over a few

  sions. This average value is stored in the memory of the heart rate meter 71 until it stops.

the device 3.

  The control member 55 is still designed

  in such a way that the memory 63 or 65 or the memory

  storing heart rate can be cyclically interrogated by a short push on the pusher switch 21. The relevant memory value, stored

  in analog form, is then brought to the

  display lot 67 and transformed by it into one

  digital signal. The latter is brought to the advertising unit

  chage 27 so that it indicates to the choice the pressure

  systolic pressure, diastolic pressure or car-

  Diaque. The display control element 67 contains a network interposed between the drivers of the memories 63, 65 and analog / digital converters, this network

  can be switched by the push switch 23.

  When the pressure is displayed, this makes it possible to choose an indication in kilopascals or in Torrs, the switching being effected by a short press on the push-button switch 23. When the memory values have all been read, the apparatus 3 can be turned off, i.e. the supply voltage source 73 can be disconnected,

  by briefly pressing the push-button switch

  stop 25 so that the measurement is completed. The ap-

  This also has a timer switch. This switch stops the device, or when it:. Is not pumped after a predetermined time interval of for example 1 minute or, when a measurement is made, at the latest 1 minute after the end

  measurement operations. It is thus ensured that the

  the wire is disconnected even when the user forgets to press the on / off push-button switch 25 at the end of the measuring operations or in case of interruption

of these operations.

  The pressure sensor 39 is therefore automatically reset to zero by the action of the on / off pushbutton switch 25, this maneuver being necessary.

  at the beginning of each measurement. Since this registration is done each-

  a short time before the actual measurement of the pressure, any drift of the zero point of the bridge assembly 91 is always eliminated impeccably during all measurements. The zero resetting device 75 makes it possible moreover to zero the bridge assembly 91 even when its deviation from the zero point is 1 pre-resin

  equal to more than 100% of the measuring range of the pressure.

  The general operation of the device having -----

  has been exposed, it remains to explain how the pressure measuring channel can be tested. For this purpose, the switch 127 is closed when the air chamber 31. is without pressure or, better, when the apparatus 3 is engaged but separated from the cuff 1. This detunes the bridge assembly 91 in a defined manner. The display unit 27 then indicates a pressure to coincide with a test value which is for example carried on a data sheet. When the switch 127 is closed, the display control unit 67 receives, via the diode 129, a voltage which has the effect of causing the display unit 27 to signal, in particular by means of the when the switch 127 is in the test position, that is to say, is closed, when the switch 127 is reopened, measurements can again be made normally. FIG. 5 represents a constant amplifier

  a variant of the amplifier 57 and designated here with

  by 257, / a reset device to zero 275. The amplification

  Differential Operator 301, counter-resistance

  coupling, constitutes the amplifier itself and pos-

  seds inputs that are connected to a pressure sensor

  (not shown) The zero registration device 275 pos-

  is a 313 amplifier that is completely protected against

  the couplings and which serves as an impedance converter. The in-

  non-inverting amplifier 313 is connected to the

  output of the amplifier 301 via a

  The non-inverting input of the amplifier 313 is further connected to ground via a switch member 317. The output of the amplifier 313 is connected to the differentiator which follows it as well.

than the control organ.

  To carry out the zero registration, the organ

  switch 317 is momentarily closed when the chamber

  air chamber 31 is without pressure. This has the effect of grounding that of the electrodes of the capacitor 319 which is connected to the amplifier 313. This gives rise, between the two electrodes of this capacitor 319, a voltage difference which is maintained at the reopening of the organ

switch 317.

  The switch member 317, which is shown as a simple switch, could be constituted

  for example by a separate push-button switch, without

* ratcheting, or by a contact of the push-button on / off, without snapping. The switch member 317 could however also be constituted by a controlled transistor, like the transistor 117, by a generator

pulse.

  In this respect, it may further be noted that the transistor 117 could also be replaced by the contact of a manually operated switch, for example a non-latching push switch, or a relay. The zero reset command could also be issued by manually operating a switch, including the on / off switch. It would also be possible to equip the device with a pressure switch device

  sensib e /, such as a membrane switch. This one

  It should be in communication with the inner tube and be electrically connected to the zero resetting device in such a way that it performs zero resetting either continuously when the air chamber is without pressure or during certain phases in which other

conditions are still met.

  The device could also be modified in other ways. For example, instead of a piezo-resistive bridge mounting, the transducer pressure sensor could include another converter or measurement, for example an inductive or capacitive converter. Even in this case, it would be possible to perform a registration

  automatically with a zero-setting device, direc-

  in the converter or in a component

  of the pressure measurement channel following it.

  In addition, instead of being connected by

  the pressure sensor could be brought into

  communication with the inner tube directly

in this one.

  It can still be noted that several of the

  components and electronic blocks which are shown in

  res 2, 3 and 5 could be combined into integrated circuits.

  In summary, it can therefore be said about the reset device that the command can be issued either by manual action on a switch such as a pushbutton without snap or without

  human intervention by a switch organ of the

  operative part. The person using the device must therefore, to cause reset to zero, actuertout at most a switch but not a potentiometer or other organ

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Claims (6)

1. Measuring device   of blood pressure comprising a chamber de-   shaped inflatable (31), intended to be fixed on a person   sounds to be examined, a pressure sensor (39) in communication with   tion of fluid with this chamber (31), and electrical means   tronic devices (101, 301) electrically connected to this sensor   pressure (39) and capable of generating electrical signals   pressure sensor representing the value of the pressure in said chamber (31), characterized in that the measuring device comprises on the one hand a zero resetting device (75, 275) connected to the pressure sensor (39) and or a circuit (101, 301) following said pressure sensor (39) and electrical means (25, 81, 317) for generating a zero reset order, such that, when the zero reset command is issued, the zero resetting device (75, 275) adjusts the aforesaid electrical pressure signal to the corresponding value at zero pressure.   2. Device according to claim 1, characterized   in that the means to generate the order of recapture   Zeroing includes a switch member (25).   3. Device according to claim 2,   characterized in that the switch member (25) has a   actuating element with manual actuation.   4. Device according to claim 3, characterized   characterized in that the switch member (25-) is identical to the switch member for applying the supply voltage. 30.5. Device according to any one of   Claims 1 to 4, characterized in that the means for ___   generating the reset order to zero include a general   pulser (81) and that. the mechanism for   Zeroing (75) is arranged so that it adjusts the pressure signal to the value corresponding to the zero pressure during the duration of the pulse emitted by the generator. pulses (81).   6. Device according to any one of   Claims 1 to 5, characterized in that the device   resetting device (75) comprises a regulator and a   memory in order to regulate a pilot signal.   and store this signal during the retrieval operation. zero.   7. Device according to claim 6, characterized   characterized in that the pressure sensor (39) comprises a bridge arrangement (91) whose electrical resistance of at least one branch depends on the pressure and that the   output of the regulator is connected to a terminal (91d) of the bridge floor (91).   ] C ,: D ;;. "9o:!,!,!,". -,: ".. 'c'.s- in this cue the anise: o'O: e   (Ä-s es. *., C: c_'t, ... ó '._ prisYJ.D :! r Jor' '-   C ,. Sovt n-i - in u.n C = p -, ux fe o: z. ",; prj. ion which is born either in   uin mfard conible (1) is not fixed to the person   born ? exainer be 'a-ns a.pparel. (3 rei _the way   c; e, l -, iiAba y '1 - azsarc' by a 'nduit-e (5).