JPH01214338A - Blood pressure monitoring method - Google Patents

Abstract

PURPOSE:To enhance the measuring accuracy of blood pressure by calculating the average value of the magnitudes of a plurality of arterial pulses while measuring an actual blood pressure value to determine the relation preliminarily calculated on the basis of the blood pressure value and the average value of a plurality of arterial pulses and determining a blood pressure value on the basis of the arterial pulses from the determined relation. CONSTITUTION:A pulse wave sensor 32 detects an arterial pulse from the radial artery and supplies a pulse wave signal SM to a CPU 24 through an A/D converter 34. A predetermined number of pulse waves are successively stored in the ring buffer mounted in a RAM 28 and the corresponding relation between the average value of the magnitudes of a predetermined number of pulse waves in the ring buffer and an actual blood pressure value is calculated in the CPU 24. A pressure sensor 14 detects the pressure in a cuff 10 to output a cuff pressure signal SP showing cuff pressure P to the CPU 24. The CPU 24 determines actual maximal and minimal blood pressure values and continuously determines a blood pressure value on the basis of a series of pulse waves from the corresponding relation between the actual blood pressure value and the magnitude of the arterial pulse detected by the pulse wave sensor 32 and a blood pressure display device 29 successively and continuously displays a bar graph 25 showing the maximal and minimal blood pressure values.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a blood pressure monitoring method that reduces the influence of breathing during blood pressure measurement.

Conventional technology For example, a cuff is wrapped around a part of a living body such as the upper arm, and the actual blood pressure value is measured based on the pulsation synchronized with the heartbeat that occurs during the process of gradually increasing or decreasing the pressure inside the cuff. such as the radial artery located near the wrist,
Arterial waves are detected by applying moderate pressure to arteries that are relatively close to the surface of the living body, and the correspondence between these actual blood pressure values and the actual magnitude of arterial waves is determined in advance and the corresponding relationship is determined. For this reason, a blood pressure monitoring method has been considered in which blood pressure values are continuously estimated and monitored based on arterial waves.

Problems to be Solved by the Invention However, in the conventional method as described above, there have been cases where sufficient accuracy of the blood pressure value determined based on the actual arterial wave from the predetermined relationship cannot be obtained.

Means for Solving the Problems The inventor of the present invention has conducted various studies based on the above-mentioned circumstances, and has discovered that the magnitude of arterial waves changes in synchronization with the respiration of living organisms. The present invention has been made based on this knowledge.

That is, the gist of the present invention is to provide a blood pressure monitoring method in which the arterial waves generated from the arteries of the living body are determined, and the blood pressure value of the living body is determined based on the arterial waves of the living body from a predetermined relationship. (b) calculating the average value of the magnitude of the plurality of arterial waves obtained in this step; an average value calculation step; (a blood pressure measurement step of measuring the blood pressure value of the living body using a Cl cuff; and [d) determining the relationship based on the blood pressure value and the average value of the magnitude of a plurality of arterial waves. and a relationship determination step.

In this way, the average value of the magnitude of a plurality of arterial waves obtained within a period of time equal to or longer than the respiratory cycle of the living body is calculated in the average value calculation step, and the blood pressure is In the measurement step, the actual blood pressure value of the living body is measured, and in the relationship determination step, a predetermined relationship is determined based on the actual blood pressure value and the average value of a plurality of arterial waves. Based on the relationship, the blood pressure value of the living body is determined based on the arterial wave. Therefore, according to the present invention, since the relationship determined in the relationship determination step is hardly affected by the respiration of the living body, the relationship between the arterial wave and the blood pressure value is prevented from being deviated due to the influence of respiration.
This has the effect of significantly improving the accuracy of blood pressure measurement compared to conventional methods.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram illustrating the configuration of a blood pressure monitoring device in which the blood pressure monitoring method of this embodiment is adopted. 10 is provided with a microphone 12 inside. The cuff 10 also includes a pressure sensor 14. Switching valve 1
6. and an electric pump 18 are connected to each other via piping 19. The microphone 12 detects pulse sounds (Korotkoff sounds) generated from the upper arm of the living body, and supplies a pulse sound signal SO representing the pulse sounds to the bandpass filter 20 .

The bandpass filter 20 passes a signal having a frequency component of, for example, about 30 to 80 Hz,
The passed pulse sound signal SO is converted to CP via the A/D converter 22.
Supply to U24.

The pressure sensor 14 detects the pressure inside the cuff 10 (cuff pressure P) and sends a cuff pressure signal SP representing the cuff pressure P to the CPU 24.
Output to. The switching valve 16 connects the cuff 10 and the electric pump 18.
The cuff pressure P is adjusted by switching between three states: a pressure supply state, a rate-limiting evacuation state, and a rapid evacuation state. That is, in the pressure supply state, the rate-limiting exhaust port and the rapid exhaust port of the switching valve 16 are closed, pressure is supplied from the electric pump 18 to the cuff 10, and when the cuff pressure P reaches a predetermined target cuff pressure. Switching to a rate-limiting exhaust state, the inside of the cuff 1O is exhausted from a rate-limiting exhaust port equipped with a restriction at a predetermined speed suitable for a predetermined blood pressure measurement,
At the same time as the blood pressure value is determined during the rate-determining blood pressure reduction period of the cuff 10, the state is switched to a rapid evacuation state, and the inside of the cuff 10 is rapidly evacuated from the rapid evacuation port.

The CPU 24 connects the ROM 26 .
RAM28. They are connected to the I10 port 27, and the R
Execute signal processing while using the temporary memory function of AM28, and send 0 to the drive circuit 31 connected to the electric pump 18.
By supplying the N10FF signal and controlling the power supply to the electric pump 18 from the drive circuit 31, the start and stop of the electric pump 18 is controlled, and the switching valve 1
The cuff pressure P is adjusted as described above by outputting a command signal to 6 to execute the switching operation.

At the same time, the CPU 24 executes a series of blood pressure measurement operations,
Based on the pulse sound signal SO and the cuff pressure signal SP, the cuff pressure P when the Korotkoff sound occurs and disappears is determined as the actual systolic blood pressure value and diastolic blood pressure value, respectively, and the actual blood pressure value and the pulse as described later are determined. A correspondence relationship between the magnitude of the arterial wave detected by the wave sensor 32 is determined, and based on the correspondence relationship, a blood pressure value is continuously determined based on a series of pulse waves detected by the pulse wave sensor 32. According to the display signal supplied from the CPU 24, the blood pressure display 29 operates on a horizontal axis 21 and a vertical axis 2 as shown in FIG.
A bar graph 25 whose upper end A and lower end B represent the systolic blood pressure value and the diastolic blood pressure value, respectively, is sequentially and continuously displayed on a cathode ray tube provided with a two-dimensional chart where 3 represents time and blood pressure (tm Hg), respectively. It has become.

Further, a pulse wave sensor 32 is connected to the CPU 24 via an A/D converter 34. As shown in FIG. 3, a pulse wave sensor 32 composed of a semiconductor strain sensor or a piezoelectric element for converting arterial pulsation into an electrical signal has a band 3 provided with a pair of fasteners (not shown) at both ends thereof.
The band 36 is attached to the radial bone near the wrist of the living body, where it is easy to collect arterial waves. The radial artery located on the bone is locally pressed with a constant pressure of about 10 to 100 mHg. That is, the pulse wave sensor 32 detects an arterial wave from the radial artery, and supplies a pulse wave signal SM representing the arterial wave to the CPU 24 via the A/D converter 34. Further, a predetermined number of pulse waves represented by the pulse wave signal SM are sequentially stored in a ring buffer provided in the RAM 28, and the CPU 24 determines the magnitude of the predetermined number of pulse waves in the ring buffer. The correspondence relationship between the average value of blood pressure and the actual blood pressure value can now be determined.

In this embodiment, the number of ring buffers in the RAM 28 is eight, but this number is equal to or an integral multiple of the respiratory cycle (twice in this embodiment). This is the number of pulse waves that occur within approximately the corresponding period. Further, the pulse wave sensor 32 is attached to the arm on the side around which the cuff 10 is wound. Also, CPU24
is a pulse signal C of a predetermined frequency from a clock signal source 38.
K is supplied.

The operation of this embodiment will be explained below according to the flowchart of FIG.

First, when a power switch (not shown) is turned on, step S1 is executed, and it is determined whether a start/stop button (not shown) has been pressed, that is, whether a start/stop signal is being supplied to the CPU 24. When the activation stop signal is output after the cuff 10 is wrapped around the upper arm of the living body, step S2 is executed, and the count content T of the timer is reset to zero, after which the clock signal is supplied again from the clock signal source 38. The counting of pulse signals GK is started. Subsequently, step S3 is executed, and each time a pulse wave is detected by the pulse wave sensor 32, the detected pulse wave is stored in the ring buffer in the RAM 28, and the subsequent step S4 is executed.
In this step, it is determined whether the pulse wave detected by the pulse wave sensor 32 has reached the predetermined number, that is, eight beats. That is, the determination in step S4 is denied until eight consecutive pulse waves are detected and stored in the ring buffer, and step S3 is executed each time. When the pulse waves are sequentially stored, the determination in step S4 is affirmed, and the storage operation of the ring buffer is stopped, and at the same time, the subsequent step S5 is executed. Here, as described above, since the period during which eight pulse waves are generated approximately corresponds to twice the respiratory cycle, in this embodiment, step S3 corresponds to the step of obtaining a plurality of arterial waves.

In step S5, the switching valve 16 is switched so that the pressure is supplied so that the electric pump 18 supplies the cuff lO.
Pressure fluid is supplied to.

This increases the cuff pressure P, and in step S6 it is determined whether the cuff pressure P has reached a predetermined target cuff pressure P1. This target cuff pressure P1 is a pressure higher than the expected systolic blood pressure value of the living body, for example, 180
When the cuff pressure P reaches the target cuff pressure P, step S7 is executed, the electric pump 18 is stopped, and the switching valve 16 is switched to the rate-limiting exhaust state. Cuff pressure P is gradually lowered.

Next, in step S8, a blood pressure measurement routine corresponding to the blood pressure measurement process of this embodiment is executed, and the cuff 10 is
The actual systolic blood pressure value H (lmHg) and diastolic blood pressure value L are determined from the cuff pressure signal SP based on the occurrence and extinction of the Korotkoff sound represented by the pulse sound signal SO during the rate-limiting blood pressure lowering period.
(mHg) is determined and these actual blood pressure values H and L are stored in RAM 28. When step S8 is completed, step S9 is executed to determine whether the systolic and diastolic blood pressure values have been determined, and when both the systolic and diastolic blood pressure values are determined, step SIO is immediately executed to switch The valve 16 is switched to the rapid evacuation state and the inside of the cuff 10 is rapidly evacuated, but if the determination is negative, step S8 is executed again and blood pressure measurement is performed.

In the following step Sll, a series of eight pulse waves M+ and Mz stored in step S7 are stored.

...The average value A1.8 of each maximum value of M, and the average value A1, 7 of each minimum value are calculated, and the maximum value is calculated based on the average value A□8 and A @ i , , respectively. A relational expression for determining the hypertension value sys and the diastolic blood pressure value DIA: %The constant and a in the formula %() are determined. In other words,
The constants and a are calculated by substituting the actual blood pressure values H and L determined in chip S8 into the systolic blood pressure value SYS and the diastolic blood pressure value DIA. Here, since it is known that a proportional relationship exists between the systolic blood pressure value and the highest value of the pulse wave, and between the diastolic blood pressure value and the lowest value of the pulse wave, the constant and a are the same as the blood pressure value. In the case where the Y axis is the Y axis and the magnitude of the pulse wave is the X axis, the slope and the intercept of the Y axis are respectively shown. Note that by adding the Y-intercept a, the blood pressure value does not necessarily become zero even when the magnitude of the pulse wave is zero, so the relationship between the blood pressure value and the pulse wave becomes accurate. Therefore, in this embodiment, step Sll corresponds to the average value calculation step and the relationship determination step.

Next, in step S12, it is determined whether or not a pulse wave has been detected since the end of compression of the living body by the cuff 10. If it is determined that a pulse wave has been detected, the process continues (step 3).
13 is executed, the pulse wave M immediately after the end of the compression is read, and the highest value m□8 and lowest values m and i of the pulse wave M are determined. Then, in step S14, since K and a have already been determined in step 311, these maximum values m□. and the lowest value m1
, 7 into the old formulas (1) and (2), we get
The systolic blood pressure value SYS and the diastolic blood pressure value DIA are estimated, and in step S15, the systolic blood pressure value S
Y and the diastolic blood pressure value DIA are displayed by the blood pressure display 29.

In step S16, it is determined whether the start/stop push button has been operated again. If it is determined that the re-operation has been performed, the process returns to step S1, but if it is determined that the re-operation has not been performed, step 317 is executed and the count content T of the timer is set to the predetermined count content T. . It is determined whether or not it has been reached. This counting content T0 corresponds to the time interval at which K and a are determined again in order to correct the correspondence determined in step S11, and is set to, for example, about 5 to 10 minutes. Therefore, the count content T is T. If it reaches To, steps 82 and subsequent steps will be executed again, but at this stage, the count content T has not yet reached To, so step 31
2 and below are executed, and a series of pulse waves M, following M9. 1M
Each time 11... is detected, the systolic blood pressure value SYS and the diastolic blood pressure value DIA are estimated and displayed in series.

As described above, in the process of repeating the operations from step 312 onwards, when it is determined in step S17 that the count content T of the timer has reached To, steps from 82 onwards are executed again, and a new The determined actual systolic blood pressure value H and diastolic blood pressure value,
A series of pulse waves 8 stored in step S3 immediately before the start of compression of the living body by the cuff 10 in step S5
Average value of each of the highest and lowest values A @@z
and A m i Fl ', step S
In ll, the constants and a of the correspondence relations (1) and (2) are determined again. Then, based on the new correspondence equations (1) and (2), the blood pressure value is continuously determined based on the highest and lowest values of the pulse wave detected after the end of the compression, and the determined blood pressure value is displayed. It will be done.

As described above, by employing the blood pressure monitoring method of this embodiment, eight pulse waves obtained within a time period longer than the breathing cycle of the living body, that is, a time approximately equivalent to two breathing cycles. Average value A of each of the highest and lowest values,
, 8 and A, ifi are calculated, and the actual blood pressure values H and L of the living body are measured, and the actual blood pressure value H
and L and average value A. Based on X and A, i and
The correspondence relationship between the systolic blood pressure value SYS and the diastolic blood pressure value DIA and the highest and lowest values of the pulse wave is determined, and based on the correspondence relationship, the blood pressure values SYS and DIA are determined based on the pulse wave detected after the end of compression by the cuff 10. is determined. Therefore, according to this embodiment, the correspondence between the blood pressure value and the pulse wave size is determined using the average value of eight pulse waves generated within a time period longer than the breathing cycle of the living body. The correspondence relationship is hardly affected by the breathing of the living body, and the accuracy of blood pressure measurement can be significantly improved compared to conventional methods.

Furthermore, according to this embodiment, the blood pressure value can be monitored simply by compressing a part of the living body at regular time intervals, compared to a method that continuously compresses a part of the living body at a relatively high pressure. As a result, even when blood pressure is measured continuously over a long period of time, pain caused to the living body such as discomfort and congestion can be significantly reduced. Further, according to this embodiment, the systolic blood pressure value and the diastolic blood pressure value of the living body can be measured simultaneously and continuously for each pulse of the artery, so there is an advantage that highly dense medical information can be obtained. In addition, in this example, it is of course possible to configure so that only either the systolic blood pressure value or the diastolic blood pressure value is continuously measured, or the average blood pressure value that is the average value thereof or other blood pressure values It can also be configured to measure continuously.

Next, another embodiment of the present invention will be described. In the following embodiments, parts common to those in the above-described embodiments are designated by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5, a state in which the correspondence relationship between the blood pressure value determined in step Sll and the pulse wave is considered to have deviated, such as body movement of the pulse wave detection unit near the wrist or a change in peripheral blood flow resistance. If the relationship is determined from the pulse wave, step 318 may be provided to recalculate the relationship. When the pressure condition of the pulse wave sensor 32 changes due to body movement of the pulse wave detection unit, or when the peripheral blood flow resistance changes due to contraction or expansion of peripheral blood vessels, the brachial blood pressure value and the pulse wave of the radial artery change. This is because the correspondence relationship with the blood pressure value determined based on this value deviates. The step 318 is provided, for example, between steps S13 and 31-4 in FIG. 4, and determines whether the radial pulse wave is abnormal. In this step S18, for example, regarding the body movement of the pulse wave detection unit, the amplitude of the radial pulse wave and the magnitude from the base line (for example, the zero volt line) to the peak value of the radial pulse wave are determined in units of time (for example, 5 seconds). It is determined that there is an abnormality when there is a change of 50% or more within the range. Alternatively, an abnormality is determined when the generation timing of the radial pulse wave deviates, for example, by 30% or more from the normal generation cycle. Regarding changes in peripheral blood flow resistance, as shown in Figure 6, values indicating the position of the notch with respect to the radial pulse wave (for example, the size A from the notch to the upper peak value) /When the size B) from the notch to the lower peak value changes by 30% or more within a unit time, it is determined to be abnormal. Alternatively, an abnormality is determined when the rate of change (slope) of a portion of the radial pulse wave corresponding to the diastole phase (falling portion C after the notch) changes significantly.

Although one embodiment of the present invention has been described above based on the drawings,
The present invention can also be suitably implemented in other embodiments.

In the above embodiment, the pulse wave was collected from the radial artery near the wrist of the living body, but it is easier to collect the pulse wave from other organs such as the carotid artery or dorsalis pedis artery, which are located relatively close to the surface of the living body. It is also possible to detect pulse waves from the arteries of the patient.

Furthermore, in the above embodiment, the number of pulse waves stored to calculate the average values A 1lllx and A +a i is 8, that is, the pulse waves occur within a time approximately equivalent to the length of two breathing cycles. However, in short, 3 to 4 pulse waves obtained within a time period equivalent to the respiratory cycle, or a greater number of pulse waves, preferably a number of pulse waves occurring within a time period that is an integral multiple of the respiratory cycle. It would be good if the waves could be memorized.

Further, in the above-described embodiment, the cuff 10 and the pulse wave sensor 32 were worn on the same arm, but the cuff 10 and the pulse wave sensor 32 can be worn on different arms. That is, in the above embodiment, when the upper arm is compressed by the cuff 10 during blood pressure measurement, the pulse wave detected by the pulse wave sensor 32 is small (distorted), so the blood pressure value and the pulse wave size are The storage of pulse waves by the ring buffer for determining the correspondence between the cuff 10 and the body was stopped immediately before the cuff 10 compressed the living body. By attaching the pulse wave sensors 32 to different arms, a predetermined number of the latest pulse waves are always stored until the correspondence is determined regardless of the compression by the cuff 10, and the highest value and the highest value of the predetermined number of pulse waves are stored. Using the average value of each of the lowest values, it is possible to determine the correspondence between the blood pressure value and the magnitude of the pulse wave.

Further, in the above embodiment, the pulse wave sensor 32 is fixed on the radial artery near the wrist by the band 36 and is pressed against the radial artery with a constant pressing force.
On the other hand, for example, a cuff can be wrapped around the fingers of a living person's hand.
The cuff pressure is raised to a predetermined pressure, and a pressure sensor connected to the cuff detects the pressure vibration waves generated within the cuff in synchronization with the pulse of the living body, and a pulse wave signal corresponding to the pressure vibration waves is detected by the pressure sensor. The sensor may output the information to the CPU 24. At this time, the pressure supply to the cuff is controlled by a pressure regulating valve, and the CPU 24 calculates the magnitude of the pulse wave signal, such as amplitude and signal power, and detects whether or not the magnitude is saturated. When the cuff pressure reaches saturation, a command signal is output to the pressure regulating valve to maintain the cuff pressure at that point. Note that the cuff pressure is not changed so that the magnitude of the pulse wave signal is saturated (it is also possible to control the pressure inside the cuff so that it reaches a predetermined suitable pressure).

In addition, instead of the band 36, a fluid container that accommodates the pulse wave sensor 32, and a diaphragm such as rubber that fixes the pulse wave sensor 32 so as to come into contact with the biological surface within the fluid container and seals the inside of the fluid container. The fluid container and diaphragm are fixed directly above the artery on the surface of the living body, and when pressure fluid whose pressure is regulated by a pressure regulating valve or the like is supplied into the fluid container, the pulse wave sensor 32 is activated by the action of the diaphragm. It is also possible to detect the pulse wave by pressing with a suitable pressing force. Also,
By providing the pulse wave sensor 32 inside the fluid container, on the fluid container, or outside the fluid container, and by blocking the contact surface of the fluid container with the living body with the diaphragm, the pulse wave sensor 32 is connected to the fluid in the fluid container and through the diaphragm. A pressure vibration wave corresponding to the wave may be detected by the pulse wave sensor 32.

For example, by fixing electrodes at two positions separated by a predetermined distance on a part of a living body such as a finger and passing a weak current through the finger, a vibration wave corresponding to a pulse wave can be generated from the impedance generated between the two electrodes. It may also be detected. Further, a light projector and a light receiver are provided above and below a relatively thin part such as a finger, and the light receiver receives the light projected to pass through the artery located in that part,
Pulsation in the artery can also be detected from changes in the wavelength of the received light.

In addition, in the above-mentioned example, the correspondence relationship between the actual blood pressure value and the pulse wave size is calculated on the premise that they are in a proportional relationship, but the blood pressure value is a quadratic function of the pulse wave size. The blood pressure value and the pulse wave size of the living body being measured can be determined from among multiple types of data maps that express the correspondence relationship between the blood pressure value and the thickness of the pulse wave programmed in advance. There is no problem in finding the correspondence in other ways, such as finding the correspondence by selecting one data map based on the data map.

In addition, in the above embodiment, the slope K and the Y-intercept a were used in the correspondence between the blood pressure value and the pulse wave size, but even if only the slope K is used, the accuracy of blood pressure measurement is sufficient. It can be obtained. In this case, the average value A, x of the systolic blood pressure value SYS and the highest value of the pulse wave, and the average value A of the diastolic blood pressure value DIA and the lowest value of the pulse wave.
Two types of slopes K may be obtained by assuming that the proportional relationships with n are different.

Furthermore, in the above-mentioned embodiment, in the blood pressure measurement process, a positional method was adopted in which the blood pressure value was determined during the blood pressure lowering process of the cuff 10 based on the generation and disappearance of Korotkoff sounds collected by the microphone 12. , the oscillometric method that determines blood pressure values based on changes in the size of the pulse waves of the living body, and the ultrasound method that uses ultrasound to detect waves on the arterial surface wall and determines blood pressure values according to changes in the size of the waves. It is also possible to adopt other blood pressure measurement methods such as the above-mentioned method, and it is also possible to measure blood pressure during the process of increasing the pressure of the cuff 10.

In addition, in step S13 described above, the maximum value m, , X and the minimum value m, i, regarding one pulse wave were determined, but the number obtained within a time equal to or an integral multiple of the respiratory cycle, For example, m of 8 consecutive pulse waves,
It may be determined by taking a moving average of X, m, and in. In this way, the influence of negative layer breathing is removed, making it possible to monitor blood pressure with high accuracy.

Further, in the above embodiment, the continuously measured systolic and diastolic blood pressure values are displayed on the cathode ray tube, but they may also be printed and recorded on recording paper such as a chart at the same time. Various other display means or storage means may be employed.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the configuration of a blood pressure monitoring device that employs a blood pressure monitoring method that is an embodiment of the present invention. FIG. 2 is a diagram showing an example of the trend of blood pressure displayed on the blood pressure display device in FIG. 1. FIG. 3 is a diagram showing a state in which the pulse wave sensor shown in FIG. 1 is attached to the wrist of a living body. FIG. 4 is a flowchart illustrating the operation of the apparatus of FIG. 2. FIG. 5 is a flowchart illustrating the main part of the operation of an apparatus employing another embodiment of the present invention. FIG. 6 is a diagram illustrating the notch position of the pulse wave or the portion corresponding to the diastolic phase of the heart. 10: Cuff applicant Korin Electronics Co., Ltd. Figure 2 Figure 4

Claims (1)

[Scope of Claims] A blood pressure monitoring method in which an arterial wave generated from an artery of a living body is determined and a blood pressure value of the living body is determined based on the arterial wave of the living body from a predetermined relationship, comprising: a step of obtaining a plurality of arterial waves within a period of time equal to or longer than the respiration cycle of a living body; an average value calculation step of calculating an average value of the plurality of arterial waves obtained in the step; A blood pressure monitoring method comprising: a blood pressure measuring step of measuring a blood pressure value of a living body; and a relationship determining step of determining the relationship based on the blood pressure value and the average value of the plurality of arterial waves.