SU1367937A1 - Apparatus for measuring blood pressure with artificial heart working - Google Patents

Abstract

The device relates to indirect methods for measuring the pressure of the medium in the arteries of the artificial blood circulation systems and can be used in artificial heart machines, as well as in artificial and auxiliary blood circulation devices. The device contains a pressure pulse generator 1, including an electric motor and a piston mechano-pneumatic converter, an artificial ventricle 2, a pneumohistral 3, two seconds with a sl and a

Description

air pressure sensor 4 and 5, air flow sensor 6, piston displacement sensor 6, piston end position sensors 7 and 8, measurement pulse generator 9, average flow meter 10, pressure drop meter 11 on the inverter 12 valves, switch 13, pressure drop meter 14 pneumohighways, two adders 15 and 18, electronic key 16, gauge 17 of the mean value of pressure in the pneumatic chamber of the ventricle, two memory blocks 19 and 20, shaper 21 of the reset pulse. W meter average

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the flow rate contains a piston displacement gauge 22, a multiplier 23, a gauge, 24 ratio and a time interval gauge 25. The pressure drop meter 11 on the valves is implemented as a functional converter. The pressure drop meter 14 in the pneumatic line is designed as a differential amplifier. The device makes it possible to measure, during one cycle of the operation of the ventricle, the values of arterial and venous pressure of the blood with increased accuracy. 1 hp f-ly, 1 ill.

one

The invention relates to medical technology concerns indirect. methods for measuring the pressure of the medium in the arteries of the artificial blood circulation systems, and can be used in artificial j-heart apparatus, as well as in artificial and auxiliary blood circulation apparatus.

The purpose of the invention is to provide measurement of mean arterial blood pressure and an increase in measurement accuracy.

The drawing shows the functional diagram of the device.

The device comprises a pressure impulse generator 1, connected to the artificial ventricle 2 of membrane type by pneumatic line 3, which includes sensors 4 and 5 of pressure in the pneumatic line, while sensor 4 is located at the output of generator 1.

Generator 1 is associated with a piston displacement sensor 6 and sensors 7 and 8 of the final diastolic and end systolic piston positions (not shown).

In addition, the device contains a series-connected measurement pulse shaper 9, a mean flow rate meter 10 and a pressure drop meter 11 at the valves, the output of which is directly and via an inverter 12

with two inputs of the switch 13, the pressure drop meter 14 in the pneumatic line, the adder 15, the electronic key 16, the meter 17 the average value of the pressure in the ventricular chamber, the adder 18, the memory blocks 19 and 20, and the reset pulse pulse generator 21.

. In this case, the meter 10 average

the flow values comprise a piston displacement meter 22 connected in series, a multiplier 23 and a ratio meter 24, the second input of which is connected to the time interval meter 25. The pressure drop meter 11 on the valves is designed as a functional converter that implements the function

0;

KQ (one)

The pressure drop meter 14 in the pneumatic line is designed as a differential amplifier with a gain equal to the ratio of the length of the pneumatic line from the pressure sensor 4 to the ventricle 2 to the distance between the pressure sensors 4 and 5.

R

The pressure drop is determined on the valves and in the air line.

The inclusion in the pneumatic line of two pressure sensors at a distance of 35 from each other allows for the difference

five

of the pressure values P and P measured by them to determine the average during the pulse of measuring the pressure drop

lR on the entire pneumatic line, which is as many (n) times the measured difference, as the length L of the entire pneumatic line from the first pressure sensor to the ventricle is greater than the distance f between the pressure sensors. Consequently, with a constant cross section of the pneumatic line, the average value of the pressure drop on it can be defined as

 (2)

4P.

(P, - Pj). lr-n

As can be seen from (2) in systole a value of 4 is negative, in diastole it is positive.

Since when the volume of the chambers of the ventricle changes, the gas flow 0 in the pneumatic line is equal to the flow of blood through the ventricular valve, the average pressure drop dP on it can be determined in accordance with the dependence

4Р ,, KQ

The scale factor K depends on the properties of the medium and the geometrical, dimensions of the constricting device (not shown). In this device for each of the valves (not labeled), it is set once during calibration.

Thus, the average blood pressure during the measurement pulse is determined in accordance with the dependence

RRC WG 1 (MRm1 + LR ,,), (4)

where P is the average pressure of air in the pneumatic line at the output of the pressure pulse generator during the measurement pulse

The device works as follows.

When a pressure is created, the piston of the mechanic-pneumatic converter that is part of generator 1 reciprocates between two end positions. The modes of operation of the artificial ventricle 2 connected to generator 1 of the pneumatic main 3 and, consequently, the pressure of blood created by it are determined by distance between the final positions of motion of the piston and the speeds of its movement in the forward and reverse directions. At the same time, the movement of the piston in the direction accompanied by the expulsion of blood from the fluid chamber of ventricle 2 (from left to right) determines the duration of systole, and the reverse movement accompanied by blood sampling from the input line 3 into the chamber of ventricle 2 determines the duration of diastole.

The impulse of the start of systole from the end-diastolic position sensor and the start of diastole from the sensor 8 of the final systolic position associated with the piston of the generator 1 are fed to the imaging unit 9.

Measurement pulses at the first output of the imaging unit 9 with alternating durations T „s. with systole

25

35

i 30 - and 40

e 45 50 her and T

nam h

in diastole offset from the beginning of the phases, respectively, the first to T j. with (50-60) ms, the second at T 1. (70-80) ms. These values are determined by the time required for the termination of the transient processes in the pneumatic line 3 when moving from one phase of the ventricle 2 to the other.

The signal corresponding to the value of the piston from the output of the sensor 6 is fed to the input of the meter 22, and the measurement pulse from the first output of the driver 9 is fed to another input of the meter 22 and the input of the meter 25. The output of the meter 22 produces a signal corresponding to the movement of the piston - sa measurement, and at the output measuring 25 - a signal corresponding to the duration of the measurement pulse.

The signal from the meter 22 is fed to the input of the dividend meter 24 ratio of the values through the multiplier 23, and from the meter 25 to the input of the divider meter 24 directly. Thus, the meter 10 provides the average value for the duration of the pulse measurement time of the flow rate Q in accordance with the dependence

Q -N: § F

 MSM

(five)

where N is the piston movement during the duration of the measurement pulse;

t ujm

S is the cross-sectional area of the piston;

measurement pulse duration.

In multiplier 23, the signal from meter 22 is multiplied by an amount, numerically equal to S, and becomes equal to the value of the volume described by the piston

during the measurement pulse. Since the 10th key is 16, open for a while

The measurement pulse coincides in time with the phase of measuring the filling volume of the fluid chamber of ventricle 2, Q characterizes both the air flow in the pneumatic line 3 and the blood flow through the ventricular valve 2. The signal from the meter 24 is fed to the input of the meter 11, in which it is erected square and multiplied by a scale factor depending on the properties of the medium and the geometric dimensions of the valve. The signal in code i of meter 11 corresponds to the magnitude of the pressure drop across the valve. Since the design parameters of the arterial and venous valves are different, the scale factor, respectively, has two values, which are set according to the control signal from the second output of the generator 9. When the value of the control signal corresponding to the level of logic O in the systole, the scale factor is K. corresponding to the level of logical 1 in diastole, K.

The signal from the output of the meter 11 is fed to one input of the two-input switch 13 directly, and to the other through the inverter 12. The switch 13 also controls the signal from the second output of the driver 9. At the output of the switch 13, the diastole passes the direct signal from the meter

Nor LR,

 Kjqs

the inverted signal passes through the systole and -K.Q

4Pk

The signals from sensors 4 and 5 of pressure to the inputs of the gauge 14 are the pressure drops in the mono-mains of Eumasia 3, in which the signals are subtracted to determine the pressure drops in the section between the sensors 4 and 5 (LR P. - P7.) And multiplied by n equal to the ratio of the length the entire pneumatic line from sensor 4 to ventricle 2 to the distance between pressure sensors 4 and 5. The signal at the output of the meter 14 LR „

m

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 dP-n, In diastole, the dP value is positive, in systole - negative

In the adder 15, the signals from the sensor 5 4 (PI) and the meter 14 are zmgmiruyutsya. The result of the summation is the signal P corresponding to the value of pressure in the pneumatic chamber of ventricle 2. This signal, through an electron measurement pulse, arrives at a measurer 17 of the average value, at the output of which a signal P is generated, + 4P.

5 The result of measuring blood pressure is obtained at the end of each measurement pulse at the output of the adder 18, the inputs of which receive signals from the meters 14 and 17.

0 The signal from sensor 7 in memory block 19 records the measurement result of the average venous / blood pressure. The signal from sensor 8 j in memory block 20 records

5 result of measurement of mean blood pressure. The signal from the former 21 clears the memory blocks and thus prepares them to record the result.

0, the blood pressure measurement in the next cycle of operation of the ventricle 2. Consequently, in memory blocks 19 and 20, the result of blood pressure measurement is stored from the moment the pulse of measurement 5 ends to the moment the discharge pulse arrives. The reset pulse signal also resets the gauges 17,22 and 25.

Thus, the device allows one way (in accordance with the dependence of P i P + (+

 ) on the same functional elements measure the mean sign. Both arterial and venous pressure with increased accuracy, which opens up the possibility of optimal control of the artificial heart when creating a blood flow that is adequate to the needs of the perfused object.

Increase in pressure measurement accuracy. laziness of the blood is achieved by measuring and accounting for the magnitude of the pressure drop across the pneumohighway, which

55 reduces the methodological error, as well as the reduction of the methodological error, the magnitude of the pressure drop across the valves due to the use of the measurement method, eliminating the need to determine the empirical coefficients characterizing the design features of the artificial ventricle.

Claims (2)

1. A device for measuring blood pressure during operation of an artificial heart, comprising a pressure pulse generator, including an electric motor and a piston mechanopneumatic converter, coupled with an artificial ventricular membrane t-type pneumatic line, a first pressure sensor in the pneumatic line, a measurement pulse shaper, an average value meter expense. and the first memory block, 20 of which the position of the piston and the second The first adder is about the fact that, in order to provide measurement of mean arterial blood pressure and increase measurement accuracy, it is equipped with a piston displacement sensor connected to the information input of the average value gauge of the end diastolic and systolic piston positions associated with it , the second pressure sensor in the pneumatic line, connected in series by a pressure drop meter on the valves, an inverter and a switch, is second. the input of which is connected to the input of the inverter, serially connected by a pressure drop meter in the pneumatic line, a second adder, the second input of which is connected to the first pressure sensor in the pneumatic line and to the first input of the meter, the pressure drop in the pneumatic line, the second input of which is connected to the second pressure sensor in the pneumatic line, With an electronic key and an average pressure gauge in the ventricular pneumatic chamber, a shaper of discharge pulses and a second memory block, the first control input is Wow connected to the output dat25 thirty the input of the measurement pulse generator, the first output of which is connected to the input of the reset pulse generator, with the first information input of the average flow meter and the control input of the electronic switch, and the second output with the control inputs of the switch and the pressure drop meter on the valves, the second input of the first of which and the output of the second one are combined, and the information input measuring the pressure drop at the valves is connected to the output of the average value flow meter. 35 h a40 Editor N.Lazarenko 2. The device according to claim 1, 1 and 2, so that the average flow meter is made in the form of successively connected displacement meter for the piston, multiplier and ratio meter, the second input of which is connected to the time interval meter, and The first input of the piston displacement meter is connected to the piston displacement sensor, and the second input of the piston displacement measuring body and the input of the time interval meter are connected to the first output of the measurement pulse former. Compiled by A. Dmitriev Tehred A. Kravchuk 45 Proofreader V. Girn to 1367937 The tip of the final systolic position of the piston and to the first input of the measurement pulse generator, the second g control input to the output of the reset pulse generator, to the control input of the average flow meter, to the first control the input of the first memory block and to the control input of the average pressure gauge in the ventricular pneumonal chamber, the output of which is connected to the first input of the first adder, the second input of which is connected to the switch output, and the output to the information inputs of the first and second memory blocks, the second the control input of the first memory block is connected to the output of the end diastolic probe 5 0 the input of the measurement pulse generator, the first output of which is connected to the input of the reset pulse generator, with the first information input of the average flow meter and the control input of the electronic switch, and the second output with the control inputs of the switch and the pressure drop meter on the valves, the second input of the first of which and the output of the second one are combined, and the information input measuring the pressure drop at the valves is connected to the output of the average value flow meter. five h a2. A device according to claim 1, 1, and so forth that the average consumption meter is complete in the form of successively connected displacement meters for the piston, multiplier and ratio meter, the second input of which is connected to the time interval meter, the first input The piston displacement meter is connected to the piston displacement sensor, and the second input of the piston displacement meter and the time interval meter input are connected to the first output of the measurement pulse former. Proofreader V. Girn to