JP2797441B2 - Electronic sphygmomanometer - Google Patents

Description

The present invention relates to an electronic sphygmomanometer that continuously monitors a subject's blood pressure by indirect measurement.

(B) Conventional technology In general, the measurement of blood pressure in critically ill patients or patients undergoing surgery requires a quick measurement and also needs to capture steep blood pressure fluctuations. A so-called method is used. This is a method in which an indwelling needle is inserted into a patient's artery, the arterial pressure is directly measured by a pressure sensor connected to the indwelling needle, and is always displayed.However, this method lacks simplicity. There are many clinically undesirable points such as high invasiveness.

Therefore, in recent years, for example, wearing an arm band (cuff) on the upper arm,
Indirect measurement (Livaloch method) in which the air pressure in the cuff (hereinafter sometimes referred to as cuff pressure) is depressurized or pressurized at a constant speed, and the blood pressure value is determined using cardiovascular information such as Korotkoff sounds and pulse waves generated during that time. An electronic sphygmomanometer that automatically and intermittently performs electronic blood pressure has appeared. This electronic sphygmomanometer requires only a cuff to be worn, so it is safer than the direct method, and the measurement procedure is simple.

(C) Problems to be Solved by the Invention In the electronic blood pressure monitor of the indirect measurement, it is necessary to change the cuff pressure at a predetermined speed over a range from the systolic pressure to the diastolic pressure, so that one measurement is performed. The time required for the measurement ranges from several tens of seconds to one minute or more, and a rapid blood pressure measurement is not possible, and it is difficult to catch a rapid blood pressure change.

In addition, in the above-mentioned electronic sphygmomanometer, since the arterial blood flow is temporarily stopped by the cuff, if the measurement is repeated without a time interval, congestion occurs and accurate measurement cannot be performed. Not preferred.

In addition, in the case of measuring the blood pressure during the depressurization process of the cuff,
The cuff must be pressurized to a pressure higher than the systolic pressure before the pressure is reduced. However, if the pressure is insufficient, the blood pressure value cannot be determined, and there is a problem that the measurement must be performed again.
For these reasons, continuous blood pressure monitoring is still dominated by direct measurement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and significantly reduces measurement time, captures rapid blood pressure oscillations, prevents patient congestion, performs accurate blood pressure measurement, and performs re-measurement due to insufficient pressurization. The purpose of the present invention is to provide an electronic sphygmomanometer that can avoid the problem.

(D) Means for Solving the Problems In order to solve the above problems, the electronic sphygmomanometer of the present invention comprises:
A pressure detecting means for detecting a pressure in the cuff and a pulse wave detecting means for detecting a pulse wave from the subject and outputting a pulse wave signal, wherein the blood pressure value is determined by pressurizing a cuff attached to the subject. A pulse wave parameter characteristic storage unit that stores pulse wave parameter characteristics indicating a relationship between a subject's pulse wave parameter and a blood pressure value, and the pulse wave detection unit when the pressure detected by the pressure detection unit is a predetermined value. Pulse wave parameter calculating means for calculating a pulse wave parameter from the waveform of the pulse wave signal of 1 to 3 beats, and the pulse wave parameter calculated by the pulse wave parameter calculating means and the data stored in the pulse wave parameter characteristic storing means. Blood pressure value determining means for determining the blood pressure value based on

(E) Action The waveform of the pulse wave changes with the cuff pressure, and the change has a predetermined relationship with the blood pressure value. This relationship is approximately constant for a patient if the patient is stable.
Therefore, once this relationship is grasped, the blood pressure value can be expected to be determined simply by detecting the pulse wave and evaluating the waveform.

In the electronic sphygmomanometer of the present invention, the waveform of the pulse wave is evaluated by a plurality of parameters such as pulse wave vibration, pulse wave integration level, waveform width ratio, and flexion rate. Then, a pulse wave parameter characteristic indicating a relationship between the subject's pulse wave parameter and the blood pressure value is stored in the pulse wave parameter characteristic storage unit in advance.

If the relationship between the pulse wave parameter and the blood pressure value is stored, thereafter, the pulse wave of 1 to 3 beats and the cuff pressure at that time are detected, and the pulse wave parameter is calculated for this pulse wave.
A blood pressure value can be determined by applying a predetermined logical calculation to the above relationship.

As described above, since the electronic blood pressure monitor of the present invention only needs to detect one pulse wave in principle, the measurement time can be greatly reduced, and a rapid change in blood pressure can be detected, and the patient can be monitored. Blood pressure can be prevented and accurate blood pressure measurement can be performed. Also, when detecting a pulse wave, it is necessary to pressurize the cuff, but the pressure at that time only needs to be able to detect the pulse wave,
Since it is not necessary to set strictly, there is almost no possibility that measurement becomes impossible due to insufficient pressurization.

(F) Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 8 is a block diagram illustrating the configuration of the electronic blood pressure monitor of this embodiment. Reference numeral 2 denotes a cuff attached to the upper arm of the subject. The cuff 2 is connected to an exhaust valve 3, a pressurizing pump (pressure adjusting means) 4, and a pressure sensor (pressure detecting means) 5. The exhaust valve 3 and the pressure pump 4 are controlled by the MPU 10. After an output signal of the pressure sensor 4 (hereinafter referred to as a cuff pressure signal) is amplified by an amplifier 6, one of the output signals is directly input to an analog / digital (A / D) converter 8 to be converted into a digital signal and taken into the MPU 10. . On the other hand, the cuff pressure signal is input to the band pass filter 7 and a pulse wave signal is detected. This pulse wave signal is also digitally converted by the A / D converter 8 and taken into the MPU 10.

The MPU 10 has a function of determining a blood pressure value from the amplitude of a pulse wave obtained during the slow depressurization process of the cuff 2 (normal measurement), a function of calculating a pulse wave parameter, a function of determining a pulse wave parameter obtained by the normal measurement and a relative pressure (cuff). The relationship between the pressure and the difference between the blood pressure value and the blood pressure value determined by the normal measurement (hereinafter simply referred to as a characteristic function) is stored in the memory 10a.
, A function of calculating a membership function based on pulse wave parameters and characteristic functions obtained by short-time measurement described later, a function of determining a blood pressure value from these membership functions, and the like.

The display 9 is connected to the MPU 10, and the determined blood pressure value and the like are displayed. Although not shown, a printer may be connected to print out the blood pressure value.

Next, the overall operation of the continuous blood pressure monitoring device of the embodiment will be described below with reference to FIG.

First, normal measurement is performed [Step (hereinafter referred to as ST) 1]. In this normal measurement, after the cuff 2 is rapidly pressurized to a predetermined initial pressure, the pulse wave is obtained based on the amplitude of the pulse wave obtained during the evacuation process of the cuff 2 (this amplitude also serves as one of the pulse wave parameters). While determining the blood pressure value, the pulse wave parameter is also calculated during that time, and the pulse wave parameter and the relative pressure are stored in the memory.
Remember in 10a.

In ST2, it is determined whether or not a predetermined time (measurement interval) has elapsed after the end of the normal measurement. If this determination is NO, the process waits in ST2, and if YES, the process branches to ST3.

In ST3, a short-time measurement is performed. In this short-time measurement, after the cuff 2 is pressurized to a predetermined pressure, several pulse waves are detected to determine a blood pressure value.

In ST4, when the blood pressure value appearing in the short-time measurement of ST3 has a large variation compared to the blood pressure value of the previous measurement, or when the blood pressure value exceeds or falls below a preset warning value, the process branches to ST5, and not so. In this case, branch to ST6. In ST5, an emergency measurement is performed, and this measurement is the same as the normal measurement. At this time, the initial pressure is set to a value as low as possible within a range where it can be measured, based on the systolic pressure obtained by the previous short-time measurement so that the blood pressure value can be obtained more quickly.

In ST6, it is determined whether or not the measurement has been completed. This judgment is YES
In the case of, the measurement ends, and in the case of NO, the process branches to ST7. In ST7, it is determined whether the short-time measurement has been performed a predetermined number of times. If the determination is YES, the process branches to ST1, and if NO, the process branches to ST2. That is, a normal measurement is performed every predetermined number of times, and the characteristic function is retaken.

Next, the details of the normal measurement will be described with reference to FIGS.
This will be described with reference to the drawings.

First, the outline of the blood pressure determination in the normal measurement process will be described with reference to FIG. The pulse wave amplitude AMP gradually increases with the evacuation of the cuff at a very low speed, and decreases again after taking the maximum value _Amax . On the increasing side of the pulse wave amplitude, the cuff pressure _Pc corresponding to the amplitude of 50% of _Amax is determined as the systolic pressure SYS, and the cuff pressure corresponding to the amplitude of 70% of _Amax on the decreasing side of the pulse wave amplitude. _Pc diastolic pressure
Determined as DIA. Of course, the method of normal measurement is not limited to this. Although the blood pressure value may be determined using the Korotkoff sound, it is still necessary to detect a pulse wave and calculate and store a pulse wave parameter. Hereinafter, specific processing will be described.

First, the MPU 10 closes the exhaust valve 3 and sets the pressure pump 4
(ST201, see FIG. 11). MPU10 is
A cuff pressure signal is fetched from the A / D converter 8 (ST202), and it is determined whether or not the cuff pressure has reached a predetermined initial pressure (ST203).
If the determination is NO, the process branches to ST202, and if the determination is YES, the process branches to ST202.
Branch to ST204. This initial pressure needs to be slightly higher than the patient's systolic pressure and needs to be set in advance.

In ST204, the MPU 10 stops the pressurizing pump 4 and puts the exhaust valve 3 into the low-speed exhaust state (ST205). Then, both the counter n and the pulse wave amplitude maximum value A _max are set to zero (ST20).
6).

In ST207, MPU 10 captures the cuff signal and further captures the pulse wave signal (ST208). The MPU ₁₀ applies the threshold value TH0 to the pulse wave signal P _W to divide the pulse wave signal P _W into beats (ST2
09, Figure 6). Then, MPU 10 determines whether the breakpoint T _n has been detected, in the case of NO branches to ST207, to continue the detection of the cuff pressure and the pulse wave.

If the determination in ST210 is YES, the process branches to ST211 and sets n to 1
Increment. Then, in ST212, the pulse wave parameters (amplitude AMP, integration level RAV, waveform width ratio WID and flexion rate CON) and the average P _c (n) of the cuff pressure are calculated for the n-th pulse wave, This is stored in the memory 10a.
The calculation process of the pulse wave parameter will be described later.

In ST213, the MPU 10 determines the amplitude AM for the n-th pulse wave.
It is determined whether P (n) is equal to or greater than _Amax . When the determination is NO, the process branches to ST215, and when the determination is YES, the process branches to ST214. In ST214, this AMP (n) is set as a new _Amax .
Then, in ST215, it is determined whether or not AMP (n) is less than 70% of _Amax . If this determination is NO, the process branches to ST207 to detect the next pulse wave. On the other hand, if this determination is YES, the process branches to ST216 and shifts to determining a blood pressure value.

In ST216, the MPU 10 determines the cuff pressure P _c (n) corresponding to the pulse wave when the determination in ST215 is YES as the diastolic pressure DIA. In the next ST217, the counter n is set to n at this time.
In the following ST218, this m is decremented by 1, and AMP (m)
Is smaller than 50% of _Amax . This judgment is NO
In the case of, the process branches to ST218 to continue searching for AMP (n).

If the determination in ST219 is YES, the flow branches to ST220, and the cuff pressure P _c (m) corresponding to m is set as the systolic pressure SYS. In ST221, the MPU 10 puts the exhaust valve 3 into the rapid exhaust state, and releases the patient's upper arm from compression. Further, in ST222, MPU 10 causes display 9 to display SYS and DIA.

Processing after ST223, the relative pressure P _CS, a calculation of P _CD.
First, the counter k is set to 1 (ST223), this k is incremented by 1 (ST224), and the relative pressure P _CS (k) with respect to the systolic pressure SYS is calculated by the following formula (1) (ST225).

P _CS (k) = The _{P c (k) -SYS ... (} 1), to calculate the relative pressure P _CD for diastolic pressure DIA (k) by the following equation (2) (ST 226).

P _CD (k) = P _c (k) −DIA (2) The ST227 determines whether or not k has become equal to n.
If the determination is NO, the process branches to ST224 to continue the process. If the determination is YES, the normal measurement ends, and the process returns to the main routine in FIG. Obtained, of course
P _CS, P _CD is stored in the memory 10a.

Next, the short-time measurement processing will be described. Before that, the calculation processing of the pulse wave parameter will be described with reference to FIGS. 5 and 10. FIG.

In the continuous blood pressure monitoring apparatus of this embodiment, four types of pulse wave parameters, that is, a pulse wave amplitude AMP, an integration level RAV, a waveform width ratio WID, and a flexion rate CON are employed. Of course, the pulse wave parameters are not limited to these four.

First, the MPU 10 determines the time T at which the pulse wave Pw (t) becomes maximum and minimum.
_max and T _min are searched, and the maximum pulse wave value Pw _max and the minimum pulse wave value Pw _min corresponding to T _max and T _min are stored in the memory 10a [ST101, see (a) in FIG. 5]. And from Pw _max
The pulse wave amplitude AMP is calculated by subtracting Pw _min (ST102).

Next, an integral level RAV [%], which is a value obtained by normalizing the time average of the pulse wave Pw (t) with the amplitude AMP, is calculated by the following equation (3) [ST103, see FIG. 5 (b)]. .

Subsequently, the waveform width ratio WID [%] is calculated.
04-ST108, see FIG. 5 (c)], and this WID is the pulse wave Pw.
The maximum value Pw _max predetermined time to decrease to the threshold TH ₁ than the appearance of (t), a normalized value in a cycle of the pulse wave (T _ne -T _st).

First, to set the threshold TH ₁ by the following equation (4),
X in this equation (4) is a constant that is predetermined in the range of 0 to 1 (ST104).

TH ₁ = Pw _min + AMP × x (4) Next, the time t is set to T _max (ST105), and the sampling width Δt is added to this t (ST106), and the pulse wave P _W for this t is added.
(T) determines whether it is TH ₁ below (ST 107).
When the determination in ST107 is NO, the process branches to ST106, and when the determination is YES, the process branches to ST108. In ST108, the following equation (5) is used.
Calculate WID.

Here, T _dec is the time a Pw (t) ≦ TH _1.

Finally, calculate the bending ratio CON [%] (ST109 to ST11).
1). This CON is a reference connecting the maximum point and the minimum point of the pulse wave at a point T _cen which internally _divides the time section [T _max , T _min ] between the maximum point and the minimum point in one beat at a predetermined ratio y. Straight line L and pulse wave
This is a relative ratio to Pw (t).

First, T _cen is obtained by the following equation (6) (ST10
9). Here, y is a constant preset in the range of 0 to 1.

T _cen = T _max + (T _en −T _max ) × y (6) Next, the level Ref of the reference straight line L at T _cen is calculated by the following equation (7) (ST110).

Ref = Pw _max −AMP × y (7) Then, CON is calculated by the following equation (8).

Now, short-time measurement will be described. First, the pressurization set value is set to the average value of the systolic pressure and the diastolic pressure [(SYS + DIA) / 2] obtained by the immediately preceding normal measurement or short-time measurement (ST301, see FIG. 12). Note that the pressurization set value for the short-time measurement may be between the storage period pressure and the diastolic pressure, and does not need to be set strictly.

Next, the cuff 2 is pressurized to this pressurization set value (ST30).
2). The following processing from ST303 to ST309 may be performed while the cuff pressure _Pc is kept at this pressurization set value, or may be performed in the state of slow exhaust.

In ST303, the counter i is set to zero, and in the next ST304, this i is incremented. In ST305, the previous ST2
As in step 09, the pulse wave is divided for each beat, and pulse wave parameters AMP, RAV, WID, and CON are calculated for the separated pulse waves and stored in the memory 10a. The cuff pressure P _c at that time is also stored in memory 1
It is stored in 0a (ST307).

In ST308, it is determined whether or not i has reached a predetermined number.
This determination number is set so that pulse waves of two or three beats can be detected. In short-time measurement, in principle, it is only necessary to detect a pulse wave for one beat, but actually, for reasons such as body movement,
Since accurate pulse wave parameters may not be obtained, in this embodiment, several pulse waves are detected, the pulse wave parameters are calculated for each pulse wave, and the arithmetic average value is calculated.

In ST309, the average values of pulse wave parameters V _amp , V _rav , V
_wid, calculates an average value _c of V _con and the cuff pressure, which is stored in the memory 10a, the exhaust valve 3 as quick exhaust state, to release from compressing the upper arm (ST 310).

In ST311, the membership function is calculated by applying the data to the pulse wave parameters. In ST312, the membership functions are subjected to logical calculation, and the blood pressure values SYS, D
Determine the IA. Details of the processing of ST311 and ST3T12 will be described later.

Finally, the determined blood pressure values SYS and DIA are displayed on the display 9 (ST313), and the short-time measurement is terminated.

Next, ST311 membership function calculation processing and ST311
Twelve logical calculation processes will be described. In the following description,
Although only the case of the systolic pressure will be described, the same applies to the case of the diastolic pressure.

First, the outline of the membership function calculation will be described with reference to FIG. FIG. 3A shows an example of the amplitude AMP characteristic function obtained by the normal measurement. In the subsequent short-time measurement, the amplitude of the pulse wave captured at the cuff pressure _Pc was V
_If it were _amp1 , this cuff pressure _Pc would be systolic pressure SYS
It is more likely that it is near either _PCS11 higher or _PCS12 lower.

This is represented by a membership function as shown in FIG. 3 (b). In this figure, the horizontal axis is the relative cuff pressure.
A P _CS, the vertical axis represents the probability relative cuff pressure P _CS during the pulse wave capture its value. In this embodiment, the shape of the membership function curve is a triangle having a vertex (maximum point) at a point (intersection) equal to _Vamp of the pulse wave characteristic function and a base having a predetermined width.

There may be a plurality of intersections, and there are as many triangles as the number of intersections. For example, in the case of FIG. 3B, since there are two intersections, there are also two triangles. In addition, these triangles may partially overlap as shown in FIG. 3 (c), and the maximum value is taken as one membership function in the embodiment. Further, since the data stored in the memory 10a is discrete, in this embodiment, the membership function is calculated with higher accuracy by performing a linear interpolation operation.

In the above description, the pulse wave amplitude has been described as an example, but the same applies to other parameters. The value of the maximum point of the membership function and the width of the base of the triangle can be set in consideration of the weight and reproducibility of each pulse wave parameter, but in this embodiment, it is assumed that each pulse wave parameter is unified. .

Next, specific processing will be described. First, the pointer x
_Is set to the minimum value P _CSmin of the relative cuff pressure P _CS and the counter j is set to 1. (ST401). The pointer x is incremented by 1 (ST 402), it determines whether the intersection of the characteristic function AMP and V _{# 038} of the pulse wave amplitude obtained [ST 403, in FIG. 1 (a) refer to Fig. When the determination is NO, the process branches to ST402, and when the determination is YES, the process branches to ST404.

In ST404, as shown in FIG. 4, X _c (j) is linearly interpolated by the following equation (9).

Further, from this X _c (j), the membership function φ _amp
(P _CS , X _c (j)) is calculated by the following equation (10).

That is, an isosceles triangle having a base of 20 mmHg centered at X _c (j).

In ST406, j is incremented by 1, and in ST407, x is incremented.
_Determines whether the relative cuff pressure has reached the maximum value _PCSmax . When the determination is NO, the process branches to ST402, and when the determination is YES, the process branches to ST408.

There are two or more intersections and a plurality of membership functions φ _amp (P _CS , X _c (1)), ..., φ _amp (P _CS , X _c (j))
Is calculated, a membership function Φ _amp (P _CS ) having the largest value is calculated (ST408).

Φ _amp (P _CS ) = MAX [φ _amp (P _CS , X _c (1)), ..., φ _amp (P _CS , X _c (j)) For ST409, ST410, and ST111, Φ _amp (P _CS ) Similarly,
Membership function, Φ _rav (P _CS ), Φ _wid (P _CS ), Φ _con
(P _CS ) is calculated. Now, for example, amplitude AMP, integration level RA
The characteristic functions of V, waveform width ratio WID and bending ratio CON are the second
If the results of the short-time measurement are V _amp , V _rav , V _wid , and V _{con as} shown in (a), (b), (c), and (d) in the _figure , the membership function Φ _amp (P _CS ) , Φ _rav (P _CS ), Φ _wid (P
_CS ) and Φ _con (P _CS ) are (a) and (b) in FIG. 1, respectively.
(C) and (d) are obtained.

Next, logical calculation processing will be described. The outline of this logical calculation is the membership function Φ _amp (P _CS ), Φ
_{rav (P CS), Φ wid} (P CS), to calculate the [Phi _con minimum value becomes [Phi of _{(P CS) (P CS)} , a relative cuff pressure P _CS to the maximum value of the Φ (P _CS) Determine and find systolic pressure SYS (1st
See figure).

First, the pointer x is set to the minimum value P _CSmin of the relative cuff pressure, and the initial value of Φ _max is set to 0 (ST501, see FIG. 14). Next, x is incremented by one (ST502), and the membership function Φ (x) is calculated by the following equation (12) (ST503).

Φ (x) = MIN [Φ _amp (x), Φ _rav (x), Φ _wid (x), Φ _con (x)] (12) The ST504 determines whether this Φ (x) is larger than Φ _max Is determined. When the determination is NO, the process branches to ST506, and when the determination is YES, the process branches to ST505. In ST505, x at this time is x
_max Distant, Φ a (x) and Φ _max. In ST506, it is determined whether or not x has reached the maximum value P _CSmax of the relative cuff pressure, and if this determination is NO, the process branches to ST502;
Branch to 7. In ST507, based on the following equation (13),
Calculate systolic pressure SYS.

SYS = _c + _Xmax (13) where _c is the cuff pressure detected during the short-time measurement.

(G) Effects of the Invention As described above, the electronic sphygmomanometer of the present invention determines the blood pressure value by pressurizing a cuff attached to a subject, and includes a pressure detecting means for detecting a pressure in the cuff. ,
A pulse wave detection unit that detects a pulse wave from the subject and outputs a pulse wave signal, and a pulse wave parameter characteristic storage unit that stores pulse wave parameter characteristics indicating a relationship between the subject's pulse wave parameter and blood pressure value in advance, Pulse wave parameter calculating means for calculating a pulse wave parameter from the waveform of the pulse wave signal of 1 to 3 beats from the pulse wave detecting means when the pressure detected by the pressure detecting means is a predetermined value; Blood pressure value determining means for determining the blood pressure value based on the pulse wave parameter calculated by the means and the data stored in the pulse wave parameter characteristic storing means.

Therefore, it is only necessary to detect 1 to 3 pulse waves,
The measurement time can be greatly reduced, rapid blood pressure fluctuations can be captured, and there is an advantage that blood pressure in patients can be prevented and accurate blood pressure measurement can be performed. Less is. Therefore, the features of the indirect measurement, which are easy to operate and excellent in safety, can be fully utilized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a membership function of the continuous blood pressure monitoring device of the present invention. FIG. 2 is a diagram illustrating an example of a characteristic function of a pulse wave parameter of the continuous blood pressure monitoring device.
FIG. 3 is a view for explaining a process of calculating a membership function from a characteristic function of pulse wave amplitude of the continuous blood pressure monitoring device, and FIG. 4 is an interpolation calculation for calculating a membership function of the continuous blood pressure monitoring device. FIG. 5 is a waveform diagram illustrating calculation of a pulse wave parameter in the continuous blood pressure monitoring device, FIG. 6 is a waveform diagram illustrating a pulse wave separation process of the continuous blood pressure monitoring device, FIG. FIG. 8 is a diagram for explaining blood pressure value determination in a normal measurement process of the continuous blood pressure monitoring device, and FIG.
9 is a block diagram illustrating the configuration of the continuous blood pressure monitoring device, and FIG.
The figure is a flowchart illustrating the overall operation of the continuous blood pressure monitoring device, FIG. 10 is a flowchart illustrating the pulse wave parameter calculation processing of the continuous blood pressure monitoring device, and FIG. FIG. 12 is a flowchart illustrating a normal measurement, FIG. 12 is a flowchart illustrating a short-time measurement process of the continuous blood pressure monitoring device, and FIG.
FIG. 13 is a flowchart illustrating a membership function calculation process of the continuous blood pressure monitoring device, and FIG. 14 is a flowchart illustrating a logical calculation process of the continuous blood pressure monitoring device. 2: Cuff, 3: Exhaust valve, 4: Pressure pump, 5: Pressure sensor, 7: Band pass filter, 10: MPU.

Claims (1)

(57) [Claims] An electronic sphygmomanometer for determining a blood pressure value by pressurizing a cuff attached to a subject, a pressure detecting means for detecting a pressure in the cuff, and a pulse wave signal detecting a pulse wave from the subject. Pulse wave detecting means for outputting a pulse wave parameter characteristic indicating a relationship between the subject's pulse wave parameter and the blood pressure value; a pulse wave parameter characteristic storing means storing in advance the pressure detected by the pressure detecting means; A pulse wave parameter calculating means for calculating a pulse wave parameter from the waveform of the pulse wave signal of 1 to 3 beats from the pulse wave detecting means; a pulse wave parameter calculated by the pulse wave parameter calculating means and the pulse wave parameter An electronic sphygmomanometer provided with blood pressure value determining means for determining the blood pressure value based on data stored in a characteristic storing means.