JPH02126830A - Non-open type automatic blood pressure measuring device - Google Patents

Abstract

PURPOSE:To measure a maximum and a minimum blood pressure value with high precision by detecting with the non-invasion method and processing stable blood flow signals with amplitude of vibration in accurate correlation with reduced cuff pressure and in a high S/N ratio. CONSTITUTION:An ultrasonic blood flowmeter 13, by the non-invasion method, detects blood flow by application of a probe 13a to portion of an artery which is on the peripheral side of a cuff 11. A starter 16 is set to initialize a microcomputer 20 and also to take in blood flow signals digitized prior to pressurization, so that data of moving averaged amplitudes is originated. After a predetermined period of time has elapsed, the cuff is pressurized to a predetermined pressurization value and thereafter pressure reduction is initiated. During the pressure reduction process, the microcomputer 20 averages the top and bottom values of the vibrational blood flow signals and also performs moving average treatment of this averaged data. Detection of blood flow starting and returning points THTL is performed simultaneously with the arithmetic process, and a displayer 15 then displays cuff pressures corresponding to the respective points, as maximum and minimum blood pressure values.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a non-invasive method for detecting systolic blood pressure and diastolic blood pressure in a non-invasive manner during the decompression process after pressurization by attaching a cuff to a part of a living body. This invention relates to an automatic blood pressure measuring device.

(Prior art) This type of automatic blood pressure measuring device uses the Korotkoff sound recognition method, which first detects the Korotkoff sound with a microphone during the decompression process and measures the cuff pressure when the sound starts and disappears, and the It is interpreted as a pulse wave caused by pulsation, which is a vibration in the cuff's internal pressure.

There is a so-called oscillometric method based on changes in this vibration.

(Problem to be solved by the invention) However, the former method is easily affected by noise;
Furthermore, the Korotkoff sounds may disappear or may not disappear even if the blood pressure drops below the diastolic blood pressure, which poses a problem in measurement accuracy. vk
According to this method, the above-mentioned problem caused by the instability of Korotkoff sound generation can be solved, or the pulse wave at different points in the cuff width direction can be detected in order to detect the pulse wave as a pressure change inside the cuff. This results in additive detection, and there is still a problem with measurement accuracy. Furthermore, since it is difficult to detect the diastolic blood pressure value from the vibration itself, there remains a problem in terms of accuracy since the diastolic blood pressure value is estimated by calculation from the average blood pressure value.

Therefore, an object of the present invention is to provide a non-invasive automatic blood pressure measuring device based on a novel method that enables blood pressure measurement with higher precision.

(Means for Solving the Problems) In order to achieve this object, the present invention provides a cafe that is attached to a part of a living body and that is pressurized by the pressure control unit 1a and then depressurized for measurement. , a blood flow meter 2 that non-invasively detects the blood flow in the afferent or distal artery of the cuff, and a blood flow meter 2 that detects the rising point of the blood flow signal output by the blood flow meter 2 in the process of reducing the cuff pressure. blood flow rise point detection means 3; blood flow return point detection means 4 for detecting the point at which the blood flow signal returns to a steady state in the subsequent pressure reduction process; and systolic blood pressure for holding the cuff pressure at the rise point as the systolic blood pressure value. It is provided with a holding means 5, a diastolic blood pressure holding means 6 for holding the cuff pressure at the time of return as a diastolic blood pressure value, and an output means 7 for displaying or printing out these held systolic and diastolic blood pressure values.

The blood flow start point detection means and the blood flow return point detection means detect the blood flow start point and blood flow from the averaged blood flow signal obtained by smoothing the pulsation component of the blood flow signal, or from the top or bottom value thereof. One possibility is to detect the point of return.

(Function) When measuring blood pressure, the pressure control unit 1a pressurizes the cafe, and then the pressure is reduced for blood flow measurement.

During this pressure reduction process (Fig. 2a), the blood flow signal detected by the blood flow meter (Fig. 2b) has a high S/N ratio, and the vibration amplitude gradually increases from the state where blood flow is blocked. The vibration amplitude becomes the largest, and as the pressure reduction continues, a steady state is gradually reached in which pulsations of a constant vibration amplitude are superimposed on the DC component.

The blood flow rising point detecting means 3 detects the rising point of the blood flow signal at which blood starts to flow from the blocked state, and causes the systolic blood pressure holding means 5 to hold the cafe pressure value at this point as the systolic blood pressure value.

On the other hand, the blood flow return time detection means 4 detects the time point when the vibration amplitude returns to a steady state as the blood flow return time point, causes the diastolic blood pressure holding means 6 to hold the diastolic blood pressure value, and causes the output means 7 to instruct the diastolic blood pressure value.

Incidentally, as shown in FIG. 2C, the pulse wave signal caused by the cuff internal pressure vibration obtained by the oscillometric method also has poor correlation with the S/N ratio and cuff pressure change compared to the blood flow signal.

(Embodiment of the Invention) FIG. 3 shows a circuit configuration of a non-invasive automatic blood pressure measuring device according to an embodiment of the present invention using a microcomputer (hereinafter referred to as microcomputer) 20.
is a cuff attached to the upper arm of the person to be measured, and is pressurized and depressurized by a pressurization control unit 12 in a well-known manner. 13 is a probe set on the -E arm adjacent to the distal side of the cuff 11! This is an ultrasonic blood flow meter equipped with 3a. 14 is an A/D converter that digitizes blood flow signals, and 15 is a numerical display for systolic and diastolic blood pressure. A recorder can also be used instead of this output means. 16 is a start switch.

The pressurization control section 12 pressurizes the compressed air to a predetermined pressure value using the pressurization pump according to a command from the microcomputer 20, and then gradually exhausts and depressurizes the compressed air by controlling the exhaust valve.
The exhaust valve is fully opened in response to a command issued by the system when detecting diastolic blood pressure. During this time, cuff pressure data detected by the built-in pressure sensor is sent to the microcomputer 2°.

In the microcomputer 20, the CPU 20a operates according to the program stored in the ROI 120b, and sends and receives control signals or data to and from each of the above-mentioned units 12, 14 to 16 via the built-in I10 board, and determines the blood flow start point and blood flow according to the present invention. It functions as a flow return point detection means and a systolic and diastolic blood pressure maintaining means. That is, the RAM 20c stores the amplitude data of the blood flow signal (Fig. 4a) and the cuff pressure data (Fig. 4b) in chronological order, and the CPO 20a takes in the timer signal of the timer 20d based on these stored data. TsutsuRO! lI2
The following arithmetic processing is performed according to the program stored in 0b.

That is, first, the top and bottom values of the input amplitude data are sequentially detected to create averaged amplitude data (Fig. 4C), which is similarly temporally correlated with the cuff pressure data and stored in the RAM2.
Store it in 0c. Furthermore, by heating for 0.1 seconds, for example, create moving averaged amplitude data for 4 seconds (Fig. 4 d),
The data is stored in the RAM 20c in a temporally corresponding manner again. Furthermore, moving averaged amplitude data before the start of pressurization is also created, its 1% value is calculated, and an operation start signal is sent to the pressurization control section 12. Then, the time when the moving averaged data in the pressure reduction process increases from the cutoff state to the above-mentioned 1% value is detected as the blood flow rise time T, and the cuff pressure at this time is held as the systolic blood pressure value and displayed on the display 15. to be displayed. Furthermore, in the subsequent pressure reduction process, the rate of increase of the moving average data of the blood flow signal, that is, differential data is created.

The point in time when this rate of increase once increases and then decreases to 1% of its maximum value is detected as the blood flow return point TL, and the cuff pressure at that point is held as the diastolic blood pressure value and displayed on the display 15.

Next, the operation of the non-invasive automatic blood pressure measuring device configured as described above will be explained.

The ultrasonic blood flow meter 13 non-invasively detects blood flow by applying a probe 13a to an artery on the distal side of the cuff 11. When the start switch 16 is set, the microcomputer 20 is initialized and takes in the digitized blood flow signal before the start of pressurization to create moving averaged amplitude data. Then, after a predetermined period of time has elapsed and the pressure has been increased to a predetermined pressurization value, depressurization is started. During this pressure reduction process, the microcomputer 20 averages the top and bottom values of the oscillatory blood flow signal and performs moving average processing on this averaged data as described above (FIG. 4 a to d). In parallel, the blood flow rise time TN and blood flow return time TL are detected using the above processing method, and the corresponding cuff pressures are detected and held as the systolic and diastolic blood pressure values, and are displayed on the display 15. . After detecting the diastolic blood pressure value, the cuff pressure suddenly decreases by fully opening the exhaust valve and the measurement ends.

According to blood pressure measurement using this blood flow detection method, the amplitude of the pulsation signal changes smoothly in response to cuff pressure.

Moreover, since the moving average follows cuff decompression with high precision, the highest and lowest pressures can be detected with high precision directly from the self-flow signal.

In addition, the blood flow detection method according to the present invention does not average the top or bottom values of the oscillating waveform of the blood flow signal, but directly moves and averages five values at a time to create envelope data. The point in time when the blood flow exceeds a predetermined envelope level that slightly increases from the blocked state is detected as the blood flow rise point, and the predetermined envelope level slightly increases from the steady state envelope level in the large pulsation state of the mean blood pressure region. It is also possible to detect the point in time as the point in time when the blood flow returned.

(Effects of the Invention) As described above, according to the present invention, it is possible to noninvasively detect and process a blood flow signal that has a high S/N ratio and a stable blood flow signal in which the vibration amplitude is more accurately correlated with the reduction in cuff pressure. Accordingly, the systolic and diastolic blood pressure values can be directly detected from the pulsation signal, and both blood pressure values can be measured with high precision.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a non-invasive automatic blood pressure measuring device according to the present invention, FIG. 2 is a diagram explaining its operation, and FIG. 3 is a diagram showing the non-invasive automatic blood pressure measuring device according to an embodiment of the present invention. The diagram showing the configuration of the embodiment and FIG. 4 are diagrams explaining the operation of the embodiment. Figure M3 cause

Claims (1)

[Claims] 1) A cuff that is attached to a part of a living body and pressurized, and then decompressed for measurement, and a non-invasive way to measure blood flow in an artery on the afferent side or distal side of the cuff. a blood flow meter for detecting; a blood flow rise time detection means for detecting a rise point of a blood flow signal outputted by the blood flow meter during a cuff pressure reduction process; and a steady state of the blood flow signal during the subsequent pressure reduction process. blood flow return point detecting means for detecting the point of return to blood flow; systolic blood pressure holding means for holding the cuff pressure at the rising point as a systolic blood pressure value; A non-invasive automatic blood pressure measurement device comprising blood pressure holding means and output means for displaying or printing out the held maximum and diastolic blood pressure values. 2) A claim characterized in that the blood flow rise point detection means and the blood flow return time detection means detect the blood flow rise time and the blood flow return time from an averaged blood flow signal obtained by smoothing the pulsating component of the blood flow signal. Item 1. The non-invasive automatic blood pressure measuring device according to item 1. 3) The blood flow rise point detection means and the blood flow return time detection means detect the blood flow rise time and the blood flow return time from the top or bottom value of the pulsation component of the blood flow signal, according to claim 1. The non-invasive automatic blood pressure measuring device described above.