Device for measuring vascular endothelium parameters and method for processing the measurement signal

Abstract

The invention relates to a device for measuring the vascular endothelium parameters and a method for processing the measurement signal, in order to determine the index of reactive hyperaemia as a result of vascular endothelial function. The device is characterised in that the air pump (PM) is connected by a pneumatic distributor (MP) to a exhaust valve (ZS) and by the first valve (Z1) to the first pressure cuff (M1), by the second valve (Z2) to the second pressure cuff (M2), by the third valve (Z3) to the third occlusion cuff (M3), and by the tank valve (ZZ) to an air tank (ZP), wherein the pneumatic distributor (MP) is provided with the third pressure sensor (CZ3), and the first differential pressure sensor (CZ1) is located between the air tank (ZP) and the first pressure cuff (M1 ), and the second differential pressure sensor (CZ2) is located between the air tank (ZP) and the second pressure cuff (M2), additionally the air pump (PM), the first differential pressure sensor (CZ1 ), the second differential pressure sensor (CZ2), and the third pressure sensor (CZ3), as well as the first, second, and third, exhaust valve, and tank valve (Z1, Z2, Z3, ZS, ZZ) are connected to the controller (K). The application relates also to a method for processing the measurement signal.

Description

[0001] Device for measuring vascular endothelium parameters and method for processing the measurement signal

[0002] The invention relates to a device for measuring the vascular endothelium parameters and a method for processing the measurement signal, in order to determine the index of reactive hyperaemia as a result of vascular endothelial function.

[0003] A method for assessing the biochemical state of vascular endothelium in mammals, specifically in humans and mice, known from Polish Patent Application No. P.410634, includes taking a sample constituting a fragment of endothelial tissue and subsequently measuring the tyrosine and phenylalanine content, and determining the ratio of tyrosine to phenylalanine content, being an index of the biochemical and functional state of the endothelium, wherein the measurement of the content ratio of these two substances is determined by signal analysis of spectra obtained using a confocal Raman imaging system.

[0004] A method and an apparatus for non-invasively evaluating endothelial activity in a patient, known from European Patent Description No. EP1585424, are used particularly for indicating the presence of an endothelial dysfunction condition by applying an occluding pressure to a predetermined part of an upper or lower limb of the patient to occlude arterial blood flow therein; maintaining the occluding pressure for a predetermined time period; removing the occluding pressure after the elapse of the predetermined time period to restore arterial blood flow; monitoring a digit of an upper or lower limb using a digit-probe for changes in the peripheral arterial tone therein before and after the application of occluding pressure to the upper or lower limb of the patient; and utilizing any detected changes in the peripheral arterial tone for evaluating endothelial activity in the patient. The apparatus comprises an occluding cuff for applying the occluding pressure to a predetermined part of an upper or lower limb of the patient to occlude blood flow therein for a predetermined time period; a monitoring digit-probe for monitoring a digit of said upper or lower limb for changes in the peripheral arterial tone therein before and after the application of said occluding pressure to the upper or lower limb of the patient; and a processor designed for utilizing any detected changes in said peripheral arterial tone, including changes in the dynamic signal time-course following removal of the occluding pressure, for evaluating endothelial activity in the patient, and particularly for indicating the presence of an endothelial dysfunction condition.

[0005] An apparatus for evaluating vascular endothelial function known from European Patent Description No. EP2896358 comprises a first cuff wrapped around one of the upper or lower limbs of a patient, a second cuff wrapped around the same upper or lower limb, a third cuff which is to be wrapped around an upper or lower limb on the opposite side of the patient's body, a cuff pressure controller which controls the pressure applied to the first cuff, the second cuff, and to the third cuff, cuff pressure sensors which detect the air pressure in the second cuff and in the third cuff, a pulse wave detector which detects respective pulse waves in the second cuff and in the third cuff from the outputs of the pressure sensors.

[0006] A vascular endothelial function evaluation apparatus known from the European Patent Description No. EP2918224 comprises a cuff that is mounted to a first part of a patient's body, a cuff pressure control unit that controls pressure applied to the cuff, a pressure sensor that is connected to the first cuff, a cuff pressure detection unit that detects the cuff pressure from an output of the pressure sensor, a pulse wave detection unit that detects pulse waves from the output of the pressure sensor, a blood pressure measuring unit that measures the blood pressure value based on the cuff pressure and the pulse waves, a storage unit that stores therein an elasticity index value Indicating the elasticity of the blood vessel of the patient, and an analysis unit that performs data processing for evaluating the endothelial function of the blood vessel.

[0007] A non-invasive vascular endothelial function assessment device known from the Chinese Patent Application No. CN105232013 (A) comprises three blood pressure cuffs, a cuff pressure control unit, an air pump, two pressure sensors, a signal conditioning and A / D (analogue to digital) acquisition circuit, a data processing unit, and a display module. Each blood pressure cuff is provided with an independent intake passage with an intake valve and an exhaust passage with an exhaust valve, the intake passage of each blood pressure cuff is connected to the air pump, each intake valve and each exhaust valve are controlled by the cuff pressure control unit; two pressure sensors are arranged in the exhaust passages of two of the blood pressure cuffs respectively, the two pressure sensors are connected to the signal conditioning and A / D acquisition circuit which is connected to the data processing unit, and the data processing unit is connected to the display module.

[0008] The main aspect of the invention is such that the air pump is connected by a pneumatic distributor to a exhaust valve, and by the first valve to the first pressure cuff, by the second valve to the second pressure cuff, by the third valve to the third occlusion cuff, and by the tank valve to an air tank, wherein the pneumatic distributor is provided with the third pressure sensor, and the first differential pressure sensor is located between the air tank and the first pressure cuff, and the second differential pressure sensor is located between the air tank and the second pressure cuff, additionally the first differential pressure sensor, the second differential pressure sensor, and the third pressure sensor, as well as the first, second, and third valves, the exhaust valve, and the tank valve are connected to the controller.

[0009] Preferably, the controller is connected to a communication interface.

[0010] Preferably, the controller is connected to a user interface.

[0011] The main aspect of the method according to the invention is such that the first pressure cuff is placed on a patient's limb and the third occlusion cuff is placed proximally to the first pressure cuff, and the second pressure cuff is placed on the second corresponding limb of the patient, and afterwards, the state of vascular endothelium is measured, wherein the measurement is carried out in three measurement phases. During the first measurement phase, the first and second valves, and the tank valve are opened, and the air pump connected to the pneumatic distributor is activated, thereby pumping the air into the first and second pressure cuffs through the opened first and second valves and to the air tank through the tank valve, wherein the pressure level in the pneumatic distributor is monitored by means of the third pressure sensor until a predetermined inflation level is reached, after which the air pump is turned off and all valves are closed, next the pressure difference between the first and second pressure cuffs and the air tank is measured by means of the first and second differential pressure sensors. During the second measurement phase, the third valve is opened, the air pump is activated, and the air is pumped into the third occlusion cuff by means of the pneumatic distributor to a higher pressure than the systolic blood pressure of the patient, wherein the third pressure sensor monitors the pressure level, and then the air pump is turned off and the third valve is closed. During the third measurement phase, the third valve and the exhaust valve are opened, thereby evacuating the air from the third occlusion cuff, after the third measurement phase elapses, the first and second valves, the tank valve, and the exhaust valve are opened, thereby evacuating the air from the first and second pressure cuffs, and the air tank, and after evacuating the air, the valves are closed, wherein during the three measurement phases, the first and second differential pressure sensors measure the value of air pressure difference between the pressures in the pressure cuffs and the pressure value in the air tank, which are recorded, afterwards the measured signals from the first and second differential pressure sensors are processed and analysed.

[0012] Preferably, the signals from the first and second differential pressure sensors are processed, wherein the signal measured by the first differential pressure sensor constituting the pressure difference between the first pressure cuff and the air tank is subsequently filtered using the first high-pass filter, the absolute value is determined in the first absolute value module and is filtered by the first low-pass filter, after which the filtered signal is integrated using the first integration module and the second integration module simultaneously, wherein the first and second integration modules are synchronised by means of a phase controller, after which the value of the signal integrated by the first integration module is divided in the first division module by the value of the signal integrated by the second integration module, and is sent to the third division module, similarly, the signal measured by the second differential pressure sensor constituting the pressure difference between the second pressure cuff and the air tank is subsequently filtered using the second high- pass filter, the absolute value is determined in the second absolute value module and is filtered by the second low-pass filter, after which the filtered signal is integrated using the third integration module and the fourth integration module simultaneously, wherein the third and fourth integration modules are synchronised by means of a phase controller, after which the value of the signal integrated by the third integration module is divided in the second division module by the value of the signal integrated by the fourth integration module, and is sent to the third division module, wherein the value of the output signal from the first division module is divided by the value of the output signal from the second division module, and the obtained value is the reactive hyperaemia index as a result of vascular endothelial function, then it is classified into a specific group, determined on the basis of statistical analysis.

[0013] Preferably, the signal measured by the first differential pressure sensor is filtered by the third low-pass filter and the signal measured by the second differential pressure sensor is filtered by the fourth low-pass filter, after which the filtered signals are compared in a comparator, and the second logic gate and the first logic gate control opening and closing of the first and second valves and the tank valve, wherein the phase controller controls the first logic gate, the second logic gate, the third valve, the exhaust valve, and the air pump.

[0014] Preferably, the measured signals are integrated by the second integration module and the fourth integration module during the first measurement phase for at least 10 seconds, most preferably 20 to 90 seconds, and the measured signals are integrated by the first integration module and the third integration module during the third measurement phase lasting at for 10 seconds, most preferably 20 to 90 seconds.

[0015] Preferably, the air is pumped through the first and second valves into the first and second pressure cuffs to equal values, and possible pressure differences between the first and second pressure cuffs are compensated, wherein the pressure measured by the first differential pressure sensor and the pressure measured by the second pressure sensor are filtered by the third low-pass filter and the fourth low-pass filter, respectively, and the values of the filtered signals are compared, if the difference between the filtered pressure values in the first and second pressure cuffs is higher than the acceptable pressure difference, then, while the exhaust valve is closed, the first and second valves are opened simultaneously, and after the average pressure level is equalised in the first and second pressure cuffs, the first and second valves are closed.

[0016] The device for measuring vascular endothelium parameters and the method for signal processing according to the invention provide a measurement procedure that is completely independent of the operator's skills or experience. In case of some existing methods for determining the vascular endothelium dependent parameters, the operator is obligated to manually handle the occlusion cuff in a specified time window, whereas the method named flow-mediated dilation (FMD), based on analysing the arterial dilation caused by vascular reperfusion of a limb subjected to occlusion, is especially susceptible to errors related to interpretation of the position of the vessel walls in the ultrasound image. The device automatically handles pumping and evacuating the air from the pressure cuffs and the occlusion cuff, using electronically controlled valves and air pump. The advantage of the method is the ability to equalise pressure in the measuring cuffs in a pneumatic (passive) way, by means of opening the valves in both measuring channels. Using a comparator comparing the differential pressure in both measuring cuffs allows automatic equalisation (compensation) of pressure change differences caused e.g., by air losses through minor leaks from the cuffs or changing the position of the limb during examination. Empirical observations clearly indicate a strong dependence of the pulse wave amplitude, recorded by means of a limb cuff, on the level of constant air pressure in the cuff. A possibility to accurately balance the pressures by means of a common pneumatic distributor significantly increases the measurement accuracy and stabilises the conditions of pulse wave recording. Using an assembly of five valves and one common pneumatic distributor with an air pump and a pressure sensor leads to a significant reduction of the level of complexity of the device. Using a pressurised air tank, which constitutes a pressure reference for both differential sensors, allows using sensors with a measurement range that is significantly narrower than the required operating range of the third sensor monitoring the pressure level in the pneumatic distributor. Such configuration increases the resolution of the measurement and significantly widens the dynamic range compared to devices based on sensors measuring the pressure in the cuffs relative to the atmospheric pressure.

[0017] The object of the invention shown in the embodiment is illustrated in drawings, in which Fig. 1 shows a block diagram of the device for measuring vascular endothelium parameters, Fig. 2 - time-courses of the signals controlling the air pump and the valves, Fig. 3 - time-courses of the signals controlling the air pump and the valves using an automatic pressure compensation function in the pressure cuffs, and Fig. 4 - functional diagram of the controller.

[0018] Example 1

[0019] The device for measuring the vascular endothelium parameters comprises an air pump PM which is connected by a pneumatic distributor MP to a exhaust valve ZS and by the first valve Z1 to the first pressure cuff M1 , by the second valve Z2 to the second pressure cuff M2, by the third valve Z3 to the third occlusion cuff M3, and by the tank valve ZZ to an air tank ZP. The pneumatic distributor MP is provided with the third pressure sensor CZ3, and the first differential pressure sensor CZ1 is located between the air tank ZP and the first pressure cuff M1, and the second differential pressure sensor CZ2 is located between the air tank ZP and the second pressure cuff M2. The air pump PM, the first differential pressure sensor CZ1 , the second differential pressure sensor CZ2, and the third pressure sensor CZ3, as well as the first, second, third, drain, and tank valves Z1 , Z2, Z3, ZS, ZZ are connected to the controller K, which is connected to a communication interface IK.

[0020] Example 2

[0021] A device for measuring the vascular endothelium parameters realised as in Example 1 except that the controller K is connected to a user interface IU.

[0022] Example 3

[0023] A method for processing the measured signal such that the first pressure cuff M1 is placed on a patient's limb and the third occlusion cuff M3 is placed proximally to the first pressure cuff M1, and the second pressure cuff M2 is placed on the second corresponding limb of the patient, and next the state of vascular endothelium is measured, wherein the measurement is carried out in three measurement phases A, B, C. During the first measurement phase A, the first and second valves Z1, Z2, as well as the tank valve ZZ are opened, and the air pump PM connected to the pneumatic distributor MP is activated, by which the air is pumped into the first and second pressure cuffs M1 , M2 through the opened first and second valves Z1, Z2 and to the air tank ZP through the tank valve ZZ, wherein the pressure level in the pneumatic distributor MP is monitored by means of the third pressure sensor CZ3 until a predetermined inflation level is reached, after which the air pump PM is turned off and all valves Z1 , Z2, Z3, ZZ are closed. Next, the pressure difference between the first and second pressure cuffs M1 , M2 and the air tank ZP is measured by means of the first and second differential pressure sensors CZ1, CZ2. During the second measurement phase B, the third valve Z3 is opened, the air pump PM is activated, and the air is pumped into the third occlusion cuff M3 by means of the pneumatic distributor MP to a higher pressure than the systolic blood pressure of the patient, wherein the third pressure sensor CZ3 monitors the pressure level, and then the air pump PM is turned off and the third valve Z3 is closed. During the third measurement phase C, the third valve Z3 and the exhaust valve ZS are opened, thereby evacuating the air from the third occlusion cuff M3, after the third measurement phase C elapses, the first and second valves Z1 , Z2, the exhaust valve ZS, and the tank valve ZZ are opened, thereby evacuating the air from the first and second pressure cuffs M1 , M2, and the air tank ZP. After evacuating the air, the valves are closed, wherein during the three measurement phases A, B, C, the first and second differential pressure sensors CZ1 , CZ2 measure the value of air pressure difference between the pressures in the pressure cuffs M1 , M2 and the pressure value in the air tank ZP, which are recorded, afterwards the measured signals from the first and second differential pressure sensors CZ1 , CZ2 are processed and analysed. The signals from the first and second differential pressure sensors CZ1, CZ2 are processed, wherein the signal measured by the first differential pressure sensor CZ1 constituting the pressure difference between the first pressure cuff M1 and the air tank ZP is subsequently filtered using the first high-pass filter FG1 , the absolute value is determined in the first absolute value module MW1 and is filtered by the first low-pass filter FD1 , after which the filtered signal is integrated using the first integration module MC1 and the second integration module MC2 simultaneously, wherein the first and second integration modules MC1 , MC2 are synchronised by means of a phase controller KF. Next, the value of the signal integrated by the first integration module MC1 is divided in the first division module MD1 by the value of the signal integrated by the second integration module MC2, and is sent to the third division module MD3, similarly, the signal measured by the second differential pressure sensor CZ2 constituting the pressure difference between the second pressure cuff M2 and the air tank ZP is subsequently filtered using the second high-pass filter FG2, the absolute value is determined in the second absolute value module MW2 and is filtered by the second low-pass filter FD2, after which the filtered signal is integrated using the third integration module MC3 and the fourth integration module MC4 simultaneously, wherein the third and fourth integration modules MC3, MC4 are synchronised by means of a phase controller KF, after which the value of the signal integrated by the third integration module MC3 is divided in the second division module MD2 by the value of the signal integrated by the fourth integration module MC4, and is sent to the third division module MD3, wherein the value of the output signal from the first division module MD1 is divided by the value of the output signal from the second division module MD2, and the obtained value is the reactive hyperaemia index as a result of vascular endothelial function ks, then it is classified into a specific group, determined on the basis of statistical analysis. Additionally, the signal measured by the first differential pressure sensor CZ1 is filtered by the third low-pass filter FD3 and the signal measured by the second differential pressure sensor CZ2 is filtered by the fourth low-pass filter FD4, after which the filtered signals are compared in a comparator KM, and the second logic gate OR and the first logic gate AND control opening and closing of the first, second, and tank valves Z1 , Z2, ZZ, wherein the phase controller KF controls the first and second logic gates AND, OR, the third valve Z3, the exhaust valve ZS, and the air pump PM. In the method, the measured signal is integrated by the second integration module MC2 and the fourth integration module MC4 during the first measurement phase A for 10 seconds, and the measured signal is integrated by the first integration module MC1 and the third integration module MC3 during the third measurement phase C for 10 seconds.

[0024] The air pump PM, and the first, second, third, drain, and tank valves Z1 , Z2, Z3, ZS, ZZ are controlled by the signals generated by the phase controller KF with time courses shown in fig. 2, wherein the air pump is activated PP in the beginning of the first and second measurement phases A, B, after which the air pump is turned off PZ. Additionally, after activating PP the air pump, during the first measurement phase A, while the first, second and tank valves Z1 , Z2, ZZ are opened O, the air is pumped into the first pressure cuff M1 , the second pressure cuff M2, and the air tank ZP by the air pump PM, and after they are inflated, the first, second, and tank valves Z1 , Z2, ZZ are closed Z, during the second measurement phase B, while the third valve Z3 is open O, the air is pumped into the third occlusion cuff M3 by the air pump PM, and after it is inflated, the third valve Z3 is closed Z, and during the third measurement phase C, the third and exhaust valves Z3, ZS are opened O, and after evacuating the air from the third occlusion cuff M3, are closed Z. After finishing the measurement, the other first, second, drain, and tank valves Z1 , Z2, ZS, ZZ are opened 0, and after the air is evacuated through them, they are closed Z.

[0025] Example 4

[0026] The method for processing the measurement signal carried out as in Example 3 except that the air is pumped through the first and second valves Z1 , Z2 into the first and second pressure cuffs M1, M2 to equal values, and pressure differences between the first and second pressure cuffs M1, M2 are compensated, wherein the pressure measured by the first differential pressure sensor CZ1 and the pressure measured by the second differential pressure sensor CZ2 are filtered by the third low-pass filter FD3 and the fourth low- pass filter FD4, respectively, and the values of the filtered signal are compared by the comparator KM, if the difference between the filtered pressure values in the first and second pressure cuffs M1 , M2 is higher than the acceptable pressure difference, then, while the exhaust valve ZS is closed, the first and second valves Z1 , Z2 are opened simultaneously, and after the average pressure level is equalised in the first and second pressure cuffs M1, M2, the first and second valves Z1, Z2 are closed. In the method, the measured signal is integrated by the second integration module MC2 and the fourth integration module MC4 du ring the first phase A of the measurement for 90 seconds, and the measured signal is integrated by the first integration module MC1 and the third integration module MC3 during the third phase C of the measurement for 90 seconds.

[0027] List of indications in the drawing:

[0028] AND - first logic gate,

[0029] CZ1 - first differential pressure sensor,

[0030] CZ2 - second differential pressure sensor,

[0031] CZ3 - third pressure sensor,

[0032] FD1 - first low-pass filter,

[0033] FD2 - second low-pass filter,

[0034] FD3 - third low-pass filter,

[0035] FD4 - fourth low-pass filter,

[0036] FF1 - first high-pass filter,

[0037] FG2 - second high-pass filter,

[0038] IK - communication interface,

[0039] III - user interface,

[0040] K - controller, ke - index of reactive hyperaemia as a result of vascular endothelial function,

[0041] KF - phase controller,

[0042] KM - comparator,

[0043] M1 - first pressure cuff,

[0044] M2 - second pressure cuff,

[0045] M3 - third occlusion cuff,

[0046] MP - pneumatic distributor,

[0047] MW1 - first absolute value module,

[0048] MW2 - second absolute value module,

[0049] MC1 - first integration module,

[0050] MC2 - second integration module,

[0051] MC3 - third integration module,

[0052] MC4 - fourth integration module,

[0053] MD1 - first division module, MD2 - second division module,

[0054] MD3 - third division module,

[0055] O - valve open,

[0056] OR - second logic gate,

[0057] PP - pump activated,

[0058] PZ - pump turned off,

[0059] PM - air pump,

[0060] Z - valve closed,

[0061] Z1 - first valve,

[0062] Z2 - second valve,

[0063] Z3 - third valve,

[0064] ZP - air tank,

[0065] ZS - exhaust valve,

[0066] ZZ - tank valve,

[0067] A - first measurement phase,

[0068] B - second measurement phase,

[0069] C - third measurement phase.

Claims

Claims1. A device for measuring the vascular endothelium parameters comprising three cuffs mounted on the patient's limbs, provided with valves and pressure sensors connected to a controller, which is additionally connected to an air pump and an interface, characterised in that the air pump (PM) is connected by a pneumatic distributor (MP) to a exhaust valve (ZS) and by the first valve (Z1) to the first pressu re cuff (M1), by the second valve (Z2) to the second pressure cuff (M2), by the third valve (Z3) to the third occlusion cuff (M3), and by the tank valve (ZZ) to an air tank (ZP), wherein the pneumatic distributor (MP) is provided with the third pressure sensor (CZ3), and the first differential pressure sensor (CZ1) is located between the air tank (ZP) and the first pressure cuff (M1), and the second differential pressure sensor (CZ2) is located between the air tank (ZP) and the second pressure cuff (M2), additionally the air pump (PM), the first differential pressure sensor (CZ1 ), the second differential pressure sensor (CZ2), and the third pressure sensor (CZ3), as well as the first, second, and third, exhaust valve, and tank valve (Z1 , Z2, Z3, ZS, ZZ) are connected to the controller (K).

2. The device according to claim 1 characterised in that the controller (K) is connected to a communication interface (IK).

3. The device according to claim 1 characterised in that the controller (K) is connected to a user interface (IU).

4. A method for processing the measured signal comprising placing a pressure cuff on a patient's limb being examined, characterised in that the first pressure cuff (M1) is placed on a patient's limb and the third occlusion cuff (M3) is placed proximally to the first pressure cuff (M1), and the second pressure cuff (M2) is placed on the second corresponding limb of the patient, and next the state of vascular endothelium is measured, wherein the measurement is carried out in three measurement phases (A, B, C), during the first measurement phase (A), the first and second valves (Z1 , Z2), as well as the tank valve (ZZ) are opened, and the air pump (PM) connected to the pneumatic distributor (MP) is activated, by which the air is pumped into the first and second pressure cuffs (M1 , M2) through the opened first and second valves (Z1 , Z2) and to the air tank (ZP) through the tank valve (ZZ), wherein the pressure level in the pneumatic distributor (MP) is monitored by means of the third pressure sensor (CZ3) until a predetermined inflation level is reached, after which the air pump (PM) is turned off and all valves (Z1 , Z2, Z3, ZZ) are closed, next the pressure difference between the first and second pressure cuffs (M1 , M2) and the air tank (ZP) is measured by means of the first and second differential pressure sensors (CZ1, CZ2); during the second measurement phase (B), the third valve (Z3) is opened, the air pump (PM) is activated, and the air is pumped into the third occlusion cuff (M3) by means of the pneumatic distributor (MP) to a higher pressure than the systolic blood pressure of the patient, wherein the third pressure sensor (CZ3) monitors the pressure level, and then the air pump (PM) is turned off and the third valve (Z3) is closed; during the third measurement phase (C), the third valve (Z3) and the exhaust valve (ZS) are opened, thereby evacuating the air from the third occlusion cuff (M3), after the third measurement phase (C) elapses, the first and second valves (Z1 , Z2), and the exhaust valve (ZS) are opened, thereby evacuating the air from the first and second pressure cuffs (M1 , M2), after evacuating the air, the valves are closed, wherein during the three measurement phases (A, B, C), the first and seconddifferential pressure sensors (CZ1 , CZ2) measure the value of air pressure difference between the pressures in the pressure cuffs (M1, M2) and the pressure in the air tank (ZP), which are recorded, afterwards the measured signals from the first and second differential pressure sensors (CZ1 , CZ2) are processed and analysed.

5. The method according to claim 4, characterised in that the signals from the first and second differential pressure sensors (CZ1, CZ2) are processed, wherein the signal measured by the first differential pressure sensor (CZ1 ) constituting the pressure difference between the first pressure cuff (M1 ) and the air tank (ZP) is subsequently filtered using the first high-pass filter (FG1), the absolute value is determined in the first absolute value module (MW1) and is filtered by the first low-pass filter (FD1), after which the filtered signal is integrated using the first integration module (MC1) and the second integration module (MC2) simultaneously, wherein the first and second integration modules (MC1 , MC2) are synchronised by means of a phase controller (KF), after which the value of the signal integrated by the first integration module (MC1 ) is divided in the first division module (MD1 ) by the value of the signal integrated by the second integration module (MC2), and is sent to the third division module (MD3), similarly, the signal measured by the second differential pressure sensor (CZ2) constituting the pressure difference between the second pressure cuff (M2) and the air tank (ZP) is subsequently filtered using the second high-pass filter (FG2), the absolute value is determined in the second absolute value module (MW2) and is filtered by the second low-pass filter (FD2), after which the filtered signal is integrated using the third integration module (MC3) and the fourth integration module (MC4) simultaneously, wherein the third and fourth integration modules (MC3, MC4) are synchronised by means of a phase controller (KF), after which the value of the signal integrated by the third integration module (MC3) is divided in the second division module (MD2) by the value of the signal integrated by the fourth integration module (MC4), and is sent to the third division module (MD3), wherein the value of the output signal from the first division module (MD1) is divided by the value of the output signal from the second division module (MD2), and the obtained value is the reactive hyperaemia index as a result of vascular endothelial function (ke), then it is . classified into a specific group, determined on the basis of statistical analysis.

6. The method according to claim 5, characterised in that the signal measured by the first differential pressure sensor (CZ1) is filtered by the third low-pass filter (FD3) and the signal measured by the second differential pressure sensor (CZ2) is filtered by the fourth low-pass filter (FD4), after which the filtered signals are compared in a comparator (KM), and the second logic gate (OR) and the first logic gate (AND) control opening and closing of the first, second, and tank valves (Z1 , Z2, ZZ), wherein the first logic gate (AND), the second logic gates (OR), the third valve (Z3), the exhaust valve (ZS), and the air pump (PM) are controlled by the phase controller (KF).

7. The method according to claim 5, characterised in that the measured signal is integrated by the second integration module (MC2) and the fourth integration module (MC4) during the first measurement phase (A) for at least 10 seconds, preferably 20 to 90 seconds, and the measured signal is integrated by the first integration module (MC1) and the third integration module (MC3) during the third measurement phase (C) for at least 10 seconds, preferably 20 to 90 seconds.

8. The method according to claim 4, characterised in that the air is pumped through the first and second valves (Z1, Z2) into the first and second pressure cuffs (M1, M2) to equal values, and pressure differences between the first and second pressure cuffs (M1 , M2) are compensated, wherein the pressure measured bythe first differential pressure sensor (CZ1) and the pressure measured by the second differential pressure sensor (CZ2) are filtered by the third low-pass filter (FD3) and the fourth low-pass filter (FD4), respectively, and the values of the filtered signal are compared by the comparator (KM), if the difference between the filtered pressure values in the first and second pressure cuffs (M1 , M2) is higher than the acceptable pressure difference, then, while the exhaust valve (ZS) is closed, the first and second valves (Z1 , Z2) are opened simultaneously, and after the average pressure level is equalised in the first and second pressure cuffs (M1, M2), the first and second valves (Z1 , Z2) are closed.

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