SI24778A - Momentary noninvasive blood pressure monitor and vascular and blood parameters - Google Patents

Abstract

The subject of the present invention is a device and procedures that enable a new method of rapid and ineffective blood pressure and vascular and blood parameters measurement. The invention is based on an electronic device comprising an embedded computer and a photopletizmograph composed of light sources of at least two different wavelengths of light and linear optical sensors with a higher number of photodiodes and a multi-axis accelerator. The optical sensors are positioned in such a way that the observer grips them during the day-to-day tasks, while the lamps illuminate his fingers. The device according to the invention can be mounted on elements of the living environment that need to be opened by pulling out the arm and only suddenly releasing themselves to a certain pulling force, such as a refrigerator door. Alternatively, the device according to the invention can be installed in a dedicated, self-supporting housing, which provides the same effect of instantaneous release of the force applied to the fingers. The procedures according to the invention are calculated from a very short section of recorded photopletizmographic signals and accelerations of saturation of the blood with oxygen, a compressibility coefficient for the observer vessels, a maximum vessel volume, and a volume at equalized external and internal pressure on the walls of the vessels and the current blood pressure.

Description

INSTANT NON-INVASIVE METER OF BLOOD PRESSURE AND VASCULAR AND

BLOOD PARAMETERS

The invention relates to a new construction of a photoplethysmographic (PPG) meter, which together with an accelerometer is used for non-invasive and undisturbed measurement of blood pressure and vascular and blood parameters. The parameter estimates from the measured signals are tied to the use, which ensures that the observer increases the pressure on the meter with his fingers, and then, at a predetermined lock force, instantly releases and removes the pressure on the fingers. From the transient in the PPG signals, it is then possible to estimate the mentioned parameters and blood pressure in a very short time.

The invention is therefore based on an electronic device comprising a built-in computer and a photoplethysmograph consisting of light sources of at least two different wavelengths of light and line optical sensors with a plurality of photodiodes, and a multi-axis accelerometer. Optical sensors are placed in such a way that the observer grabs them by hand during daily tasks, while the lights illuminate his fingers. The device according to the invention can be mounted on elements of the living environment, which must be opened by a hand stroke and only suddenly released at a certain traction force, such as a refrigerator door. However, the device according to the invention can be installed in a dedicated, independent embodiment of the housing, which provides the same effect of instantaneous relaxation of the pressure force on the fingers. The methods according to the invention calculate from a very short section of recorded PPG signals and accelerations the oxygen saturation of the blood, the coefficient of compression for the observed vessels, the maximum vessel volume and volume at equal external and internal pressure on the vessel walls and current blood pressure.

The core of the embedded computer consists of a microcontroller containing an analog-to-digital converter, and as a peripheral, a communication unit for wired or wireless connection to the parent computer server and a display for displaying the measured results are added. The device according to the invention is powered by an internal battery, but when it is connected to the parent computer via a communication wire, it is also powered by this connection.

DESCRIPTION OF THE INVENTION

Problem description

Cardiovascular diseases are often associated with blood pressure. Hypertension is the so-called silent killer. The patient is not directly aware of high blood pressure, and it has a destructive effect on his blood vessels, heart, brain and all internal organs.

Frequent measurement of blood pressure is therefore necessary, especially for patients with hyperthermia infiltrates; ·· · when the neurovegetative system raises blood pressure due to exertion, disease or age. Sphygmomanometers have been used to measure blood pressure for over a hundred years. If the artery in the left arm is squeezed with a cuff with such external pressure as to stop blood flow, there are generally two noninvasive ways to determine the pressure at which the heart pushes blood into the aorta and arteries. The measurement can be auscultatory or oscillometric. In the first case, we listen with a stethoscope when blood flow is heard as we lower the pressure in the cuff. The audible range of turbulent blood flow is defined by the extremes of systolic bloodstream above and diastolic blood talc below. The oscillometric method assumes that the cuff presses on the artery with pressure between diastolic and systolic. In such a case, the manometer detects oscillations during the heartbeat and the detected oscillations can be converted into a blood pressure value.

Measurement methods involving plethysmography are also known. If we have data on the time interval between two heart rate sensations on separate parts of the human body, we can estimate blood pressure from this interval. Normally, the first sensing is an electrical heart pulse measured at systole and an R wave called in the electrocardiogram, and the second sensing is the heart rate detected in the PPG signal on the extremities.

Two other approaches are known regarding PPG signals. The first detects the heart rate in the signal and calculates the area enclosed by the time axis and the pulse amplitude. The area is directly proportional to blood pressure. The second PPG approach takes advantage of the fact that a larger amount of blood in the blood vessels absorbs more red light. Thus, if we squeeze smaller parts of the body with external pressure, usually the fingers of the hands, so long as we squeeze out all the blood, the time of squeezing the blood is directly proportional to the blood pressure.

Among all the mentioned methods, only measuring the area under the detected pulses in PPG signals is very fast and the least disturbing, as other methods require blockage of blood flow, with an inflatable cuff or similar device that blisters blood vessels. The process can be uncomfortable and take a long time. Calculating the area under heart rate responses in PPG signals does not have this disadvantage, but it does not provide a reliable and constant assessment of blood pressure, so the measurement must be repeated through a higher heart rate, which again means that the final result is available only after a certain time.

The photoplethysmographic approach also allows a more detailed analysis of the parameters that are characteristic of the blood and blood vessels. If the PPG signal is monitored when performing auscultatory blood pressure measurement, we can record how the signal amplitude changes (range between the point of highest, ie systolic, and the point of lowest, ie diastolic pressure) depending on the increasing external pressure on the vessel or. organ in the pressure cuff. From this connection it is possible to calculate Jftožnošt Oz: stiffness · · · of vessel walls, volume of veins at maximum flexibility and maximum volume of veins and curve of pulsating pressure or systolic, diastolic, and mean blood pressure. Solutions are also known which calculate the blood viscosity from the time required to squeeze blood out of the arteries by external pressure and changes in the PPG level.

Known solutions

The solution and device according to the invention makes it possible to measure the current blood pressure and at the same time the parameters of blood vessels and blood, for example oxygenation, vascular flexibility or vascular volume, in a very short time and without interruption. The device returns the results of measurements and analysis significantly earlier than the known solutions, and at the same time the observed person does not have to participate in the measurement, as it is performed automatically and for a person undisturbed or. unconsciously.

Patents are granted to protect devices for assessing blood pressure or vascular and blood parameters by means of photoplethysmography and external pressure on parts of the human body, such as fingers. Studies on this topic have also been published as follows. In their description, we also state in what way the solution according to the invention differs from them.

In the article Some Effects on the Blood Vessels of the Human Forearm of Local Exposure to Pressures below Atmospheric (J. Physiol., 203, pp. 31-43, 1969), the authors BL Ardill, PH Fentem, RD Finlay, and P. Isaac showed that there is a linear connection between the inflow of blood into the carotid arteries and the external vacuum, at least until the external pressure is 85 mmHg lower than the internal pressure in the vessels. In Theoretical Study on the Sffect of Sensor Contact Force on Pulse Transit Time (IEEE Trans, on BME, vol. 54, no. 8, p. 14901498, 2007), XF Teng and Υ-Τ Zhang examined the change in pulse transition times. , measured between cardiac activation (R wave) and a detected pulse wave with a PPG signal in the fingers. In doing so, they changed and measured the external pressure on the fingers. They found that regardless of the magnitude of external pressure, the rate of blood flow always increases if the internal mean blood pressure is higher. At the same time, the velocity decreases exponentially if the external pressure increases linearly. These findings were exploited in the device according to the invention, but the need for a controlled change in external pressure was avoided. The implementation of the device and the procedures that enable this is the essence of the invention.

European patent application EP 1 623 668 Al, filed under the title Evaluation of blood fluidity by the Japanese inventor Yoshiki Yamakoshi on 2 August 2004, proposes a finger cuff and a photoplethysmograph. The cuff is compressed by interrupting the flow of blood into the finger capillaries. He uses a photoplethysmograph to measure the increase in transparency for red light, which is followed by a smaller absoTfitijt Varadf · · reduced blood volume in the finger. When all the blood is squeezed out, the passage of light is strongest. It measures the time of blood extrusion and shows that it is directly proportional to the viscosity of the blood, which it calculates accurately. The patented device contains a controlled change of external pressure with a finger cuff. It assesses the viscosity of the blood, and the procedure depends on controlling and knowing each external pressure. Blood pressure or other blood parameters or. vascular device does not determine. Although the device according to the invention uses a similar effect, ie a change in vascular volume and thus the amount of blood in a vessel, in contrast to EP 1 623 668 A1 it does not need an element for controlled change of external pressure, but uses external pressure on the observer's body during his daily tasks that are not related to the measurement of blood pressure or blood parameters or. scars.

The upgrade of the application from the previous paragraph was submitted on 15 July 2010 under the title Method and device for evaluation of blood fluidity by the inventors Shinji Koshino, Hiroki Shimizu and Hiroo Sato. The European application is numbered as EP 2 292 142 Al. Instead of a finger cuff, a key is used here, which must be pressed with a finger in a controlled manner until the device takes a measurement. Even in this case, it calculates the viscosity of the blood. According to this application, the device according to the invention also has the essential difference already mentioned: no element is required for the controlled change of the external pressure on the part of the body where the measurement is performed.

The U.S. patent, entitled Total compliance method and apparatus for noninvasive arterial blood pressure measurement, was obtained by inventors Justin S. Clark and Shuxing Sun under number 5423322 on June 13, 1995. They protected a device that compresses a finger with a cuff with known external pressure and observes PPG-amplitudes of pulsating pressure (between diastolic and systolic) as a function of external pressure. In a longer measurement, the vascular compression model is calculated from the course of the PPG signal and blood pressure is assessed. Although the device according to the invention is also based on the compressibility model of the veins, which can be connected to the PPG signals or. their leads, however, the device is designed differently and also the procedures for estimating the parameters are different. The device according to the invention does not have an element for the controlled creation of external pressure on the observer's fingers, but exploits external forces that occur during the observer's routine tasks. Also, the assessment of parameters and blood pressure is not based on a pulsating vascular volume curve, but on the instantaneous intrusion of blood into partially emptied vessels.

In the past, the Faculty of Electrical Engineering, Computer Science and Informatics has developed a combined sensor that can be installed in the openings of household appliances. The sensor contains a photoplethysmograph, measuring sheets for measuring traction, thermistors for measuring temperature and an accelerometer. We protected it with Slovenian patent no. SI 24037 (A), 70. 10 ** 201Š * under ·· · title Computer device and procedure for undisturbed measurement of functional health parameters. It also contains a patent claim that protects the blood pressure detection procedure. The procedure refers to the PPG signal from the light sensor and the force signal from the force sensor. It compares the changes in external (traction) force and observes the amplitude of the dynamic component in the PPG signal in parallel. From this ratio, he estimates blood pressure. The device according to the invention also uses a photoplethysmograph and an accelerometer, but does not require the measurement of external force. The methods according to the invention do not compare PPG amplitudes with the current magnitude of the external force, but evaluate the parameters of blood and blood vessels and blood pressure from the course of PPG signals when there is a sudden change in external force. In general, the design and operation of the device according to the invention are different from the patented solution, but the use in both cases can be the same, ie by installing the device in the openers of household appliances.

A new solution

Experiments have shown that approximately the same traction force is always required to open the refrigerator door. An average force of 23.98 N was measured for the selected refrigerator, and the standard deviation was ± 2.43 N. The opening is done by the user pulling the opener with his fingers, increasing the force to the peak required for the door to "peel off". . At this point, the pressure on your fingers drops abruptly. When pulled, blood is first expelled from the finger veins, venoles, capillaries, and arterioles, but this process is completed at about 20% of the force required to open the door. As the force escalates, the arteries are partially or completely emptied. When the door sags, an influx of blood rushes into the emptied veins. If the fingers are illuminated with red and infrared light, the withdrawal of blood when pulling the opener is manifested as an increase in light intensity penetrating through the fingers, and at the moment of opening the door, the light flux rapidly deteriorates, as it is increasingly obscured by returning blood. in the fingers.

The rate of blood flow is quadratically dependent on the increase in blood volume as it flows into the vessel. The change in volume depends exponentially on the difference between internal and external pressure on the veins. The external pressure is caused by the door before it opens, and is practically the same with each use. The difference is therefore directly proportional to the internal blood pressure that presses on the vessel walls at the moment the door opens. The rate of blood return, and thus the reduction in the intensity of the light that passes through the fingers, is also directly proportional to the internal blood pressure from the opening of the door.

The procedure for assessing the current blood pressure is related to the perception of the moment when the door opens or. when the external pressure on the fingers of the hand is relieved. Because of the jerky movement of the photoplethysmograph, which is built into the door opener or into a special, independent manual δζ ’natfiizncf * device, significant accelerations occur, which are detected by an accelerometer.

Procedures for determining blood and vascular parameters and estimating current blood pressure are based on the model of compressible, round vessels and on Beer-Lambert's law of light absorption in substances. Absorption depends on the properties of the substance and on the length of the path through the substance. In our case, it is blood, and the length of the translucent path is determined by the diameter of the vessel, which changes over time, so we denote it by d (t) as a function of time. If we illuminate a part of a round vessel in the length L of units of length, the volume of blood in this vascular section is:

_{V (t) =} li ^>, (1)

The volume of a vessel and blood in it depends on the properties (parameters) of the vessel and on the internal and external pressure on the selected vascular section. Deal:

P (t) =

V ₀ e ^ ^P ^ \ ceP _z > P _n

V _m - (Vm - V ₀ ) e “^ ^(Pn “ ^Pz \ č <

(2) where P _n and P are _: internal and external vein pressure, V _{m is the} maximum vein volume, Po is the vein volume at equal internal and external pressure, and C _{m is the} coefficient of maximum vein flexibility.

Equation (2) confirms the practical fact that the veins stretch and contract in two different modes, joining at a point that is the same as the internal and external pressure at the vessel and therefore the transverse pressure on the vessel wall is equal to 0. This point is also important for the processes included in the present invention. We choose it as the center of the time axis (t = 0), so that we will describe the times in the interval P _z > P _n as negative, and in the interval P _z <P _n as positive.

When the circulating organ is transilluminated, the luminous flux detected on the exit side of the organ is determined by Beer-Lambert's law:

/ iCt) = I _Oii e- ^£ i ^{[dW + d]} , (3) where tallow is the intensity of the incident light flux with the z- ^th wavelength, ε, the generalized extinction coefficient for that light and the substance through which it passes (in in our case blood), d is the alternate path length that light travels through the surrounding tissues combined with the ratio of the extinction coefficients for the blood and the surrounding tissues. The generalized extinction coefficient is defined as:

~ Q) (To, i £ d, i) T (4) where c ₀ means the concentration of oxygen in the blood (oxygenation in%), _i in'š _di are the extinction · · coefficients at the ž-th wavelength of light for oxyhemoglobin , ie. hemoglobin with oxygen, and deoxyhemoglobin, i. homoglobin without oxygen.

When we combine equations (1) and (3), we come to the connection between the output luminous flux and the diameter of the vessels (in our case the arteries):

I? (T) = (5)

Equation (5) is logarithmic and subtracted over time. The first two terms on the right-hand side of the equation are independent of time, so they are omitted from the derivative, leaving:

₌ „2 2 (6) dt Ii (t) ¹ nL dt '

Since we are in a discrete situation, we must replace the derivatives in equation (6) with differences so that we obtain:

= (7) / i (t)

Finally, we connect equations (2) and (7):

in _ _o2 2 ”- - CI ¹ vL l rri U., 0, P _z > P _n (8) ^ 21 = _ε 2 2_ (μ y) ¹

Cm n ^t j Cm n £ / _1 'Vm-Vo ⁿ t _k2 - _e ^Vm ~ ^V ° ^{n tk} 2; j = i.

k ₂ > Pz -? n>

(9) where the time moments t _kl and t _{k2 are} determined from PPG signals so that t _kl coincides with the moment when the external force pressure disappears, for example when the door is opened, and t _k2 is the later moment at which ΔΕ ( t> ₂ ) ~ 0 ·

The essence of the invention is a solution for non-invasive and unobtrusive measurement of blood and vascular parameters and current blood pressure. The sensor components of the device are connected to the built-in computer, which takes care of the measurements. Measurement procedures and their further processing and extraction of information about the observer's functional health are guided by computer algorithms that determine the functionality and purpose of the device according to the invention.

The device contains the following elements:

1. field of optical sensors,

2. light sources with at least two wavelengths of light,

3. perpetual accelerometer,

4. microcontroller unit,

5. display unit,

6. communication unit and

7. power supply unit with power switch.

Optical sensors are used to capture photoplethysmographic signal (PPG), ie. the luminous flux transmitted by the observer's fingers. Light is emitted by LEDs of at least two types, such as red (R) and infrared (IR). The field of light-emitting diodes is also in the composition of the device according to the invention. The accelerometer detects sudden movements of the device according to the invention. Measurement analysis procedures are performed in the microcontroller unit, and the results are displayed on the display unit. They are also sent to the parent device - a computer server, via a communication unit that can operate wirelessly or with a wired connection. In the latter embodiment, the wired communication connection is also used to power the device according to the invention (for example according to the USB standard). Otherwise, a special power supply unit containing an electric battery is also installed in the device according to the invention.

The design and operation of the method and device according to the invention are explained by 5 figures, 2 of which show the design of the device according to the invention, and the remaining 3 show the course of processes determining the properties of the device according to the invention.

Figure 1 shows a block structure of a device according to the invention. The microcontroller 100 controls the light sources 110 and receives signals from the light sensors 120 and the accelerometer 130. The light sensor transmits analog signals amplified by the unit with operational amplifiers 125. The microcontroller unit has a built-in analog-to-digital (A / D) converter with which digitizes captured analog signals. It analyzes them by the methods according to the invention and displays the results on the display unit 140. It also communicates them to the parent computer with the communication unit 150. The connection can be wired 155 and in this case it is also used to power the device according to the invention. The battery 160 provides a permanent supply of power to the device when the switch 165 is turned on;

Figure 2 shows the puzzle of the meter, i. devices according to the invention. The bracket 200 is a printed circuit board that connects all the electronic elements of the device. At the top are light sensors 121, 122, 123 and 124, which are designed as linear fields with a plurality of photodiodes. At the bottom are connected the battery 160 for powering the device, the microcontroller 100, the unit with operational amplifiers 125, the accelerometer 130 and the communication unit 150, which has a connector 155 for optional wired connection. A protective cover 250 is connected to the holder on the upper side, which is shaped to fit the observer's fingers (from the index finger to the little finger). The position of the fingers is defined so that the pads'fingers sedbjb čiffi more ”· constant on the optical sensors 120. The cover 250 has built-in light sources 111, 112, 113 and 114. Each of them consists of at least two sets of LEDs; the sets of diodes differ in the wavelength of the light emitted. A display unit, such as a line LCD display 140, is attached to the top or side of the cover 150. Also, a switch 165 for attaching the device to a battery power supply is attached to the side 250 of the cover;

Figure 3 shows a flow diagram for detecting the moment when the measurement should start;

Figure 4 shows a flow diagram for performing a measurement;

Figure 5 shows a flow chart for calculating blood and vascular parameters and current blood pressure.

Figure 2 shows the physical design of the device according to the invention, while Figure 1 shows the electrical connection of the individual elements of the device. In the embodiment, it is important that the optical sensors 121, 122, 123 and 124 are mounted on the bracket 200 in a closed row and that they are longitudinally aligned with the light sources 111, 112, 113 and 114 in the cover 250. The cover 250 takes into account different finger dimensions. that it leaves enough space for the maximum thick fingers, which are therefore inserted close to each other during the measurement. The thinner fingers in the cover do not lie close together, but the design of the cover with partitions between the fingers ensures that the grips are distributed along the entire length of the optical sensors 120. The shape of the cover 250 in the device according to the invention provides additional protection from ambient light. closed at the back - lowered to the bracket 200.

Turning on the switch 165 supplies power to the microcontroller 100, which begins to perform a process to prepare for the measurement. The procedure is shown in Figure 3. After switching on the device, the initialization block 305 is performed, which creates the data structures and connections necessary for further interrupting operation of the microcontroller 100. The IR lights are then pulsed at a frequency of several tens of times per second (block 310). At the same time, responses to illumination from IR lamps (block 315) are received and digitized from all channels (photodiodes) in the light sensors. In block 320, a check is made as to whether the brightness on a predetermined number of channels may have decreased by a predetermined percentage, for example on half of the channels by a quarter of the maximum illumination. Until this happens, the loop with blocks 310, 315 and 320 is repeated. However, if the check shows that the condition for the decrease in brightness has been met, this is taken as a sign to start the measurement. Namely, a sudden drop in the perceived light intensity is expected to occur when the observer inserts his fingers between the lights 110 and the light sensors 120. The start of the measurement is indicated in block 325.

The general measurement procedure is described in Figure 4. First, the lOtf microcontroller changes * Lamp control 110. Periodically, it starts pulsing lights of different wavelengths, for example first red and then infrared, and then pauses for a short time (block 405). With light sensors 120, it captures light intensity values in all phases: first in illuminations of different wavelengths, for example in R-illumination and then in IR illumination, and finally during dimming of light sources, when it actually detects ambient light intensity (block 410 ). First, in block 415, it is checked whether the overwritten number of channels detects a reduced brightness, which means that the fingers are still inserted above the light sensors 120 (checking similar to block 320 in Figure 3). If the condition is not met, the device according to the invention returns to the standby state, which means that only the IR lights are switched on with a reduced sampling frequency (entry point A in front of block 310 in Figure 3). If the condition is met, the measurement is continued.

Data acquisition runs in parallel from all K optical channels, i. photodiode. Period oz. the frequency of repetitions of all phases by capturing different lights is determined according to the properties or. the frequency content of PPG signals, for example at 100 Hz. The duration of illumination with a single wavelength, ie the width of the pulses activating the lamps 110, is significantly shorter than the duration of one period of illumination, but must last long enough for the microcontroller 100 to cause all K channels in the light sensors. This can take at, say, K = 512 around 100 ps. By sampling the light sensors, signal vectors with values for K light channels at each moment are formed /:

Ii (t) = [/ i, i (t) J2, i [tX - ^, iW] ^T n ε {/?, //?, ...}, (10) so that every 4, (/) ; k = 1, ..., K corresponds to the signal /, (/) in equation (3).

At the same time, the microcontroller 100 also samples in block 420 the accelerations measured with the multi-axis accelerometer 130, so that in the case of the three-axis version:

P (t) = VpKO + Py (0 + Pf (O> ⁽¹¹ ) where p _x (t), p _y (t) and p _z (t) are the accelerations measured during the tv accelerometer directions x, y and z.

In block 425, it is checked whether the change in acceleration kp (t) at the moment t reaches a peak and at the same time exceeds a predetermined value corresponding to the lowest accelerations when a movement caused by a sudden descent of external pressure on the observer's fingers occurs in the device according to the invention. If the condition is met, a predetermined time interval begins to be counted down, for example for 0.5 s (comparison block 430), and the time index at the maximum change in acceleration is remembered as t _mp . In any case, the loop continues with the prescribed period with illumination and sampling of light signals and accelerations in blocks 405, 410, 415, 420. In block * 430 * the countdown of the time interval is set after the detection of the maximum change in accelerations, max (Ap (?)). When this interval expires, the calculation of blood and vascular parameters and current blood pressure is triggered (block 435). After calculating and displaying the results, the measurement is continued so that block 405 is reactivated in the loop.

The analysis of the captured signals triggered by block 435 is shown in Figure 5. In block 505, the start of the time interval for signal analysis is first ordered. From the moment the maximum change in acceleration was found, i. from t _mp , we go back in time until the acceleration changes Δρ (Ζ) drop to a pre-prescribed tolerance band. This moment is defined as the initial time of the observed interval. It then locates the process started in block 510 on the observed interval between all signals 7 _k , (/); k = 1, ..., K, i = R, IR, ... of the one most suitable for further analysis. The search involves the simultaneous verification of signals for individual wavelengths, such as R- and 77? -Signals, in each channel separately. We are looking for a channel in which, at the same time, light perceptions decrease the fastest from the beginning of the observed interval onwards. As said, the interval found with the greatest changes in accelerations means a situation in which an external force suddenly pressed, pressing on the vessels of the observed person, for example, when the refrigerator door was opened. As this causes blood flow to begin, the translucency of the fingers usually decreases. However, it may happen that the observer does not press with all his fingers equally hard on the light sensors 120, so the measured light signals are not all of the same quality or. they do not have the same good resolution. For the best possible results, it is necessary to find a channel where the events are most pronounced and therefore also with the highest resolution. The best channel is denoted by the index k ₀ .

The signal in the optimal channel k _{0 is} written as /, (/) for simplicity and to match the notation in equations (1) to (9); i = R, IR, ..., without the designation of the selected channel. In block 515, the change in blood volume is calculated with respect to the left side of equations (8) and (9) - the resulting function is proportional to AK (/). Block 520 finds the minimum in this function and sets the starting point of the time axis t = 0 in the corresponding time moment. At the same time, it defines the difference between the beginning of the observed interval and this moment as time t _kl . In block 525, the search continues from t = 0 onwards, looking for the moment when the function A7 (t) approaches the value 0 with a predetermined tolerance. We denote this moment as t _k2 .

The calculation continues in block 530, which takes the course of the signals ze {R, IR, ...} and with the selected best fit method, for example with the smallest square deviations, we calculate the model parameters a, and = ate ^b d-, t = 0 , ..., t _k2 , i & {R, IR, ...}.

Similarly, in block 535, the model parameters c, and d, are estimated:

= _c . _e d _it . _{t =} _ _t ^ o, _{Z e {7ζ IR>} (13)

By equalizing the right-hand sides of equations (12) and (9) and (13) and (8) and taking into account all the samples from both intervals, the average oxygen saturation rate of blood is estimated in block 540, i. c ₀ , and with its help from equations (12) and (13) of volume V _m and Po, taking into account the model parameters a, and c ,.

The following is an estimate of the external pressure P-. The fingers are laid via optical sensors 120 having known dimensions M x L. At the length M there are K channels (photodiode) so that each channel occupies -

To length units. In block 545, the signals /, () are taken according to equation (10); t = -t _kl , ..., t _k , ie {R, IR, ...} and estimate how many of them have, at all wavelengths of light, over the entire observed range of sample values below a pre-selected threshold that assumes that the light in the channel is obscured by a finger inserted in the cover 250. If such channels are K-_, the area with which the fingers cover the optical sensors is equal to L - K _z . Since j ^e is known in advance, with what force is necessary to pull it comes to a sudden failure of pressure by the meter on the fingers, from this information to estimate the maximum external pressure:

(14) if F represents the maximum tractive force.

From the exponent on the right side of equation (8) and the model parameter d, we can calculate the coefficient of maximum compressibility C _m (block 550). When C _{m is} known, the internal current blood pressure P _n (block 555) is determined from equation (9) and model parameter bj.

Claims (15)

PATENT APPLICATIONS 1. An instantaneous non-invasive blood pressure and vascular and blood parameters meter is characterized in that a computer device that measures non-invasively, unobtrusively or unobtrusively and is used in conjunction with at least one primary non-biomedical function that causes human fingers to come into contact with frequent contact with it, consisting of: a. a bracket (200) allowing the device to be placed under the cover (250), b. an integrated computer comprising at least one microcontroller (100) with at least one analog-to-digital converter, at least one display unit (140) and at least one communication unit (150) with an optional wired connection (155), c. a photoplethysmograph comprising several light sources with several different wavelengths (110) and several line light sensors with several photodiodes (120), the output signals of which are amplified by several operational amplifiers (125), d. accelerometer (130) for measuring accelerations in several spatial directions, and e. power supply units (160) with power switch (165). Device according to Claim 1, characterized in that it is inserted into elements of household appliances, household appliances or furniture, the essential property of which is to perform their primary function by a sudden shift of position only when pressed with a sufficiently large, always the same force. . Device according to Claim 1, characterized in that it is inserted into a dedicated, self-contained housing which is mechanically supported and further comprises such a mechanical, pneumatic, hydraulic or electrically guided barrier that when applied to it at a certain force it suddenly gives way and does not prevents more movement of the device. Device according to claim 1, characterized in that the lid (250) is designed to fit anatomically to the fingers of a human hand and to be partially or completely closed at the back. Device according to claim 1, characterized in that light sources (110) are arranged in the cover (250) on the upper inner side, in several sources of several different wavelengths for each finger. Device according to claim 1, ........... characterized in that the cover (250) is firmly connected to the carrier (200) so that the line light sensors (120) on the carrier (200) are aligned with the light sources (110) in the cover (250), namely the source (111) with sensor (121), source (112) with sensor (122), source (113) with sensor (123) and source (114) with sensor (124). Device according to claim 1, characterized in that the light sensors (120) are raised so high above the surface of the carrier (200) that human fingers, when pushed under the cover (250), sit only on the line light sensors (120) and do not rely on other elements of the meter. Device according to claim 1, characterized in that the microcontroller (100) controls the light sources (110) and samples the photoplethysmographic signals from the optical sensors (120), which are previously amplified, if necessary, by operational amplifiers (125). Device according to claim 1, characterized in that the accelerometer (130) is firmly connected to the carrier (200) and that it measures the accelerations in several spatial directions if the device is moved. Device according to Claim 1, characterized in that the measuring parameters are selected from a set consisting of blood oxygen saturation, the coefficient of maximum vascular flexibility, maximum vascular volume, vascular volume at equal internal and external pressure on the vessel wall and current blood pressure. 11. Instant non-invasive blood pressure and vascular and blood parameters meter, the method of which is characterized in that the microcontroller (100) monitors photoplethysmographic measurements and detects accelerations and performs the following steps: a. determining the measuring interval, b. calculation of external pressure on veins, c. determination of blood volume in blood vessels, d. assessment of the optical values of tissues and vascular parameters from a set of melfanic: * k ethnic ethnics or physiological quantities, and e. assessment of current blood pressure. Method according to claim 11, characterized in that the measuring interval is determined between: a. detecting the start of the measurement when an infrared light flux intermittently coming from the lamp (110) to the optical sensor (120) is interrupted, and b. detecting the end of the measurement when the lamp (110) is no longer obscured and the light sensor (120) passes into saturation. Method according to claim 11, characterized in that the external pressure on the veins is calculated by estimating: a. the number of optical channels obscured by fingers at the light sensor (120), b. the surface of the finger-covered parts of the optical sensors (120) and c. the pressure with which the surface of the covered parts of the optical sensors (120) presses on the fingers. Method according to claim 11, characterized in that it determines the optical values of the tissues and the parameters of the vessels by: a. by measuring photoplethysmographic signals with a light sensor (120) within the duration of the measuring interval, b. determination of changes in blood volume from measured photoplethysmographic signals, c. modeling changes in blood volume using an exponential model, so that the optimal match of the model response with the photoplethysmographic signal curve is sought, d. by calculating the model parameters in the exponential model for each different type of light used from the lamps (110). The method according to claim 11, characterized in that by means of the calculated exponential model and the estimated external pressure on the veins, it determines: ······ · φ _β a. blood oxygen saturation, coefficient of maximal vascular compressibility and Tfitiksrmalno · · vascular volume and b. current internal blood pressure in the veins.