JP5730749B2 - Electronic blood pressure monitor - Google Patents

Description

  The present invention relates to an electronic sphygmomanometer, and more particularly to an electronic sphygmomanometer that reduces the influence of noise and calculates an accurate blood pressure value.

  As methods for measuring blood pressure, the Korotkoff method (auscultation method) and the oscillometric method are known.

  There are two types of sphygmomanometers based on the oscillometric method: a depressurization measurement type sphygmomanometer that measures in the process of depressurization and a pressurization measurement sphygmomanometer that measures in the process of pressurization.

  The measurement principle of the pressure reduction type sphygmomanometer is that after the air is sent to the cuff wrapped around the upper arm of the human body by means of pressure such as a pump, the pressure is gradually reduced by exhaust, and the pressure in the cuff is detected during the process of pressure reduction. Then, extract the pulse wave amplitude of the arterial wave and the remaining static pressure, multiply the maximum value of the pulse wave amplitude by a predetermined ratio, and set the level of the pulse wave amplitude for determining the systolic blood pressure and the diastolic blood pressure, Thereby, the pulse wave is specified, and the systolic blood pressure and the diastolic blood pressure are determined based on the specified pulse wave.

  FIG. 9 and FIG. 10 are diagrams for explaining the specific method, and show the change of the pressure in the cuff of the decompression-type blood pressure monitor. FIG. 9 is a diagram showing the relationship between time (horizontal axis) and pressure in the cuff (vertical axis), and FIG. 10 shows the pressure in the cuff (horizontal axis) and pulse wave amplitude (vertical axis) extracted from FIG. It is a figure which shows a relationship.

  As described above, when the pressure in the cuff wound around the upper arm is increased by pressurizing and then gradually exhausting and lowering, the pressure in the cuff becomes a pulsating component, that is, a pulse wave as shown in FIG. Arise. The height of the pulse wave increases as the pressure in the cuff (cuff pressure) decreases, and decreases after reaching the maximum pulse wave amplitude Hmax. Therefore, the pulse wave detected first in the graph of FIG. 9 is the pulse wave with the higher cuff pressure, and the cuff pressure of the detected pulse wave becomes smaller as time elapses.

Therefore, this is graphed as shown in FIG.
In the figure, the cuff pressure corresponding to the pulse wave amplitude that is 50% of the maximum pulse wave amplitude Hmax with respect to the pulse wave before the maximum pulse wave amplitude Hmax is referred to as a so-called “maximum blood pressure” (hereinafter, the point is referred to as “ The cuff pressure corresponding to the pulse wave amplitude that is 70% of the maximum pulse wave amplitude Hmax with respect to the pulse wave after reaching the maximum pulse wave amplitude Hmax is referred to as a so-called “minimum blood pressure” (referred to as “S” point). Hereinafter, this point is referred to as “D” point). However, the ratio of “50%” or “70%” with respect to “minimum blood pressure” regarding the “maximum blood pressure” may vary depending on the design conditions of the sphygmomanometer.

  By the way, in the blood pressure measurement method as described above, there is a case where a cuff pressure measurement value does not exist at the S point or the D point. In such a case, the maximum blood pressure and the minimum blood pressure cannot be read directly from the measured value.

  As a prior art that can cope with such a problem, there is an electronic blood pressure monitor of Patent Document 1. In the same document, a measured value is selected one point at a point closest to both sides of a point corresponding to the S point or the D point, a linear equation connecting the two points is calculated, and the primary equation and the pulse between the S point or the D point are calculated. The cuff pressure of the maximum blood pressure or the minimum blood pressure is read from the intersection with the wave amplitude. That is, in obtaining the S point or the D point, the above problem can be addressed by interpolating the pulse wave amplitude.

Japanese Examined Patent Publication No. 6-109

  However, if the measurer's body moves during the measurement, or if the cuff's blood vessel compression efficiency changes during the decompression process, local noise occurs, and the two points themselves that cross the S or D point are measured. The value may be inaccurate. In this case, as a matter of course, the interpolated point deviates from the true value, and there is a possibility that accurate calculation of the maximum blood pressure or the minimum blood pressure cannot be performed.

  In addition, when the user decides the measurement time of the day and continuously measures, if the measured blood pressure value fluctuates due to the above causes, the user has a problem with the sphygmomanometer. I'm worried that there might be, and feel anxious.

  Therefore, Cited Document 1 also has room for improvement in terms of calculating the maximum blood pressure or the minimum blood pressure with high accuracy.

  The present invention has been made in view of the background art as described above. In an electronic sphygmomanometer that calculates blood pressure by an oscillometric method, the accuracy of interpolation with respect to detected pulse wave amplitude is improved, and It is possible to provide the user with correct blood pressure measurement results, and to reduce blood pressure fluctuations using an electronic sphygmomanometer and an electronic sphygmomanometer that can relieve the user's anxiety by reducing variations in measured values. The purpose is to provide a measurement method.

In order to solve the above-described problems, an electronic sphygmomanometer according to the present invention includes a cuff for applying pressure to a blood vessel, a pressurizing unit for supplying pressurized air to the cuff, a decompression unit for reducing the pressure of the cuff, and a cuff. A cuff pressure detecting means for detecting the internal pressure, a pulse wave detecting means for detecting the pulse wave amplitude based on the detection value of the cuff pressure detecting means, and a blood pressure value based on the pressure in the cuff and the pulse wave amplitude. An electronic sphygmomanometer having a blood pressure determination means, wherein the blood pressure determination means is a maximum amplitude pulse wave detection means for extracting a maximum pulse wave amplitude detected by the pulse wave detection means, and is subtracted from the maximum pulse wave amplitude by a certain percentage. The pulse wave amplitude level that determines the blood pressure value is calculated, and one or more of the measured values on one side are selected as the first measured value group from the pulse wave amplitude level, and the measurement on the other side is selected. Select multiple values as the second measured value group, And any one point of the measurement value group and a second pulse wave amplitude linear expression calculating means for calculating two or more as a plurality of interpolated linear expression of the linear combinations connecting the any one point of the measurement value group And a blood pressure value is calculated based on the cuff pressure corresponding to the pulse wave amplitude level for each of the plurality of linear interpolation equations.

  According to the present invention, three or more measurement points are extracted according to the pulse wave amplitude level, a plurality of interpolation equations are calculated from the measurement points, and the plurality of interpolation equations and the blood pressure determining pulse wave level are calculated. Since the maximum blood pressure and the minimum blood pressure are calculated, the influence of local noise in blood pressure measurement can be reduced, and a correct measurement value can be obtained. As a result, the variation in blood pressure value for each measurement is also reduced.

  Preferably, the blood pressure determination unit calculates a blood pressure value by obtaining a cuff pressure corresponding to the pulse wave amplitude level for each of the plurality of linear interpolation equations and averaging the cuff pressure.

  In this case, since the maximum blood pressure and minimum blood pressure are calculated by averaging a plurality of interpolation values obtained from a plurality of interpolation equations, the influence of local noise in blood pressure measurement can be reduced and correct measurement is performed. A value can be obtained. As a result, the variation in blood pressure value for each measurement is also reduced.

Preferably, the pulse wave amplitude primary expression calculating means selects two points as the first measurement value group from the measurement values on one side with the pulse wave amplitude level as a boundary, and the measurement value on the other side. Are selected as the second measured value group, and four of the combinations of straight lines connecting any one point of the first measured value group and any one point of the second measured value group. Is calculated as a linear interpolation equation .

  According to the electronic sphygmomanometer and the blood pressure measurement method of the present invention, it is possible to improve the accuracy of interpolation with respect to the detected pulse wave amplitude, and to provide the user with the correct measurement result of the maximum blood pressure and the minimum blood pressure, By reducing the variation in the measured values, the user's anxiety can be eliminated.

It is a functional block diagram of the electronic sphygmomanometer according to the first embodiment of the present invention. It is a functional block diagram of the principal part in FIG. It is a flowchart of the systolic blood pressure / minimum blood pressure calculation concerning the 1st Embodiment of this invention. The selected measurement points are shown in the graph showing the relationship between the cuff pressure and the pulse wave amplitude in the calculation of the systolic blood pressure and the systolic blood pressure according to the first embodiment of the present invention. In the graph showing the relationship between the cuff pressure and the pulse wave amplitude in the blood pressure calculation according to the first embodiment of the present invention, two approximate lines connecting the measurement points are shown. It is a graph of the principal part in FIG. In the graph showing the relationship between the cuff pressure and the pulse wave amplitude in the blood pressure calculation according to the second embodiment of the present invention, four approximate lines connecting the measurement points are shown. It is a graph of the principal part in FIG. It is a graph for demonstrating the relationship of the time-cuff pressure of a pressure reduction type | mold blood pressure meter. It is a figure for demonstrating the method of calculating | requiring the maximum blood pressure and the minimum blood pressure from the graph of a cuff pressure-pulse wave amplitude.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, with reference to FIG. 1 and FIG. 2, the structure of the electronic blood pressure monitor 100 concerning embodiment of this invention is demonstrated.

  An electronic sphygmomanometer 100 shown in FIG. 1 includes a cuff 1, a cuff pressure adjusting unit 3, a pressure signal converting unit 4, an operating unit 5, a control unit 6 and a display unit 7.

  The cuff 1 is a bag for tightening the blood vessel of the subject by applying pressure to the upper arm of the subject, and is connected to the cuff pressure adjusting means 3 and the pressure signal converting means 4 by a tube 2.

  The cuff pressure adjusting means 3 sends air to the cuff 1 and applies pressure to the subject's upper arm, an exhaust valve 3b for discharging the air in the cuff 1, and a constant air pressure in the cuff. And a pressure reducing valve 3c that reduces the speed.

  The pressure signal conversion means 4 detects the pressure in the cuff 1 and converts it into an electrical signal. The pressurizing pump 3a, the exhaust valve 3b, and the pressure signal converting means 4 are connected to the control means 6, respectively. Further, the operation means 5, the display means 7, and the buzzer 8 are connected to the control means 6.

  As shown in FIG. 2, the control unit 6 includes a CPU, a storage unit such as a ROM and a RAM (not shown), and also includes a pulse wave detection unit 61, a cuff pressure detection unit 62, and a blood pressure determination unit 63. Here, the pulse wave detecting means 61 detects the pulse wave based on the pressure signal from the pressure signal converting means 4 and detects the magnitude of the pulse wave amplitude. The cuff pressure detecting means 62 detects the cuff pressure based on the pressure signal from the pressure signal converting means 4. Furthermore, the blood pressure determining unit 63 receives signals from the pulse wave detecting unit 61 and the cuff pressure detecting unit 62, and determines the blood pressure based on the pulse wave amplitude and the cuff pressure corresponding to the pulse wave amplitude.

  Next, the operation of the electronic sphygmomanometer 100 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  In this electronic sphygmomanometer, the operator attaches the cuff 1 to the subject's upper arm so that the blood vessel of the subject can be tightened, and operates the operation means 5 to turn on the power. When the power is turned on, the control means 6 causes the pressure signal conversion means 4 to start detecting the pressure in the cuff 1 and output the pressure signal.

  Further, when the start of blood pressure measurement is instructed by the operation means 5, the control means 6 starts the pressurizing pump 3a to send air to the cuff 1, and then the pressure in the cuff 1 is stored in the RAM. When the pressurization set value is reached, the pressurization pump 3a is stopped, and then the air in the cuff 1 is gradually discharged and decompressed by the pressure reducing valve 3c.

As the pressure is reduced, the pressure in the cuff 1 decreases, the blood vessels of the subject are relaxed, and blood begins to flow.
When the blood vessel is relaxed and approaches the maximum blood pressure, the blood vessel starts to vibrate. Therefore, the pulse wave detection means 61 detects the pulse wave amplitude in conjunction with the heartbeat. The pulse wave amplitude gradually increases as the cuff pressure decreases, and when the blood vessel compressed by the cuff is loosened and returned to the original blood flow, the pulse wave amplitude rapidly decreases and cannot be detected (see FIG. 4). ).

  According to the blood pressure measurement method according to the present embodiment, the blood pressure determining unit 63 determines the blood pressure based on the pulse wave amplitude that changes as the cuff pressure decreases and the cuff pressure corresponding to the pulse wave amplitude that changes. .

(First embodiment)
Next, details of the blood pressure determining means 63 of the electronic sphygmomanometer 100 according to the first embodiment will be described with reference to FIGS. 2 to 6.

  Referring to FIG. 2, blood pressure determining means 63 includes maximum amplitude pulse wave detecting means 63a, measurement point extracting means 63b, pulse wave amplitude primary expression calculating means 63c, and blood pressure value calculating means 63d.

  Referring also to FIG. 3, the maximum amplitude pulse wave detection means 63a that has received the pulse wave amplitude detection data from the pulse wave detection means 61 extracts the maximum amplitude pulse wave Hmax (mmHg) from the data (S302).

Here, the ratio (corresponding to 0.5 or 0.7 in FIG. 10) for calculating the systolic blood pressure “SBP” (Systemic Blood Pressure) and the systolic blood pressure “DBP” (Diastrotic Blood Pressure) from Hmax, The maximum blood pressure determination ratio α, the minimum blood pressure determination ratio β, and the pulse wave amplitude levels that determine the blood pressure for calculating SBP and DBP are defined as Hs = Hmax × α and Hd = Hmax × β, respectively. Specific values of can be set to, for example, 0.5 and 0.7, respectively.

  FIG. 4 shows the relationship between these variables and the measured blood pressure data. In the figure, the horizontal axis is the cuff pressure Pc, the vertical axis is the pulse wave amplitude H, and the envelope for the measurement point is also indicated by a dotted line. Reference signs A to D indicate specific measurement points.

  In FIG. 4, when SBP is taken as an example, if there is a measurement point at the intersection of the envelope and H = Hs, it is ideal to set the cuff pressure at that measurement point as the maximum blood pressure SBP. Does not have a measuring point. In this case, a method of obtaining by interpolation based on other measurement points is conceivable. Conventionally, a linear expression is obtained from measurement points A and B before and after Hs, and this linear expression and a straight line H = Hs are obtained. SBP was calculated from the intersection of

  However, in this method, when a disturbance such as noise is superimposed on the measurement point A or the measurement point B, the intersection point becomes a value deviating from the true value of SBP. FIG. 4 shows a case where, for example, the measurement point B is a measured value that is shifted from the predicted envelope in a direction in which the pulse wave amplitude is small.

  In the present embodiment, in order to avoid such a problem, in the graph plotting the relationship between the cuff pressure and the pulse wave amplitude, the straight line H = Hs (H = Hd) is added to each of the nearest points above and below the straight line. Then, one point measured before or after the two points is selected, and a total of two straight lines connecting the two points located above and below and one point are obtained, and these straight lines and H = Hs (H = Hd ) Is calculated, two maximal blood pressure interpolation values (minimum blood pressure interpolation values) are obtained from the intersection, and the average value of these interpolation values is determined as the maximal blood pressure SBP (minimum blood pressure DBP). (See FIGS. 4 and 5).

  Referring to FIGS. 2 and 3 again, the measurement point extraction means 63b that has received Hmax multiplies Hmax by α and β to calculate Hs and Hd (S304).

  Then, one point measured before or after the two points is extracted as a measurement point for obtaining the linear interpolation equation (S306) by adding each point closest to the top and bottom across the straight line of H = Hs and H = Hd. ).

  In the following description, the blood pressure calculation method according to this embodiment when measuring the maximum blood pressure will be described, but the minimum blood pressure can also be calculated by the same method.

  Referring to FIG. 4, in the present embodiment, a case where one point of A is selected as the closest measurement point of H = Hs and two points of B and D are selected as the measurement points for obtaining the linear interpolation formula. Show.

Next, referring to FIG. 2, FIG. 3 and FIG. 5, the pulse wave amplitude primary expression calculating means 63c combines the upper one point A and the lower two points B and D to obtain an interpolation primary expression for interpolation. (1) Calculate using the formula.
H = a × Pc + b (1)
Here, a and b are coefficients, and the pulse wave amplitude primary expression calculating means 63c calculates these coefficients from the A, B and D coordinate data.

  As shown in FIG. 5, two linear expressions for interpolation are obtained: L1 from the combination of point A and point B, and L2 from the combination of point A and point D (S308).

Next, the blood pressure value calculation means 63d that has received the above two formulas calculates two intersections of the respective formulas and H = Hs (S310). Specifically, in FIG. 5, intersection points P1 and P2 with H = Hs are calculated for the interpolation straight lines L1 and L2.

Next, the blood pressure value calculating means 63d calculates the cuff pressures Pcs1 and Pcs2 at the respective points from the intersection points P1 and P2, and determines the average value thereof as the maximum blood pressure <SBP> (S312 and S314). That is,
<SBP> = (Pcs1 + Pcs2) / 2 (2)
It is.

  In FIG. 5, a point on H = Hs corresponding to <SBP> is indicated as P0, and <SBP> is indicated by a perpendicular line extending from P0 on the Pc axis.

Here, the operation of the electronic blood pressure monitor of the present embodiment will be described with reference to FIG.
As described above, in the present embodiment, the case where the blood pressure measurement point B deviates from the envelope predicted from other measurement points is illustrated. That is, the point on the envelope corresponding to Pc at the measurement point B is B ′, and the measurement point B has a pulse wave amplitude lower than that due to the influence of noise or the like.

  In this case, the true value SBP0 of the systolic blood pressure SBP is close to the intersection of the straight line H = Hs and the straight line connecting the measurement point B ′ and the measurement point D. Even when only one interpolation formula is used, the interpolation formula is If the measurement points to be obtained are B ′ and D, there is no problem.

  However, in the case where the measurement point is B, when the number of interpolation equations is one, the selected measurement points are A and B, so the maximum blood pressure obtained by this interpolation is from the intersection point P1 to SBP1. In this case, the difference between the measured value SBP1 and the true value SBP0 is ΔPc1 shown in FIG.

  On the other hand, since the systolic blood pressure obtained by the present embodiment is <SBP> obtained from the intersection point P0, the difference between the measured value <SBP> and the true value SBP0 is ΔPc2 shown in FIG. 6, and in principle ΔPc2 < ΔPc1. Therefore, according to the present embodiment, the measured values of the systolic blood pressure and the diastolic blood pressure are made closer to the true value even when the measurement point for calculating the interpolation formula deviates from the originally predicted measurement value due to noise or the like. Is possible.

  In other words, in the present embodiment, even if the measurement point is made redundant and the noise is superimposed on a certain measurement point to deviate from the overall envelope, the deviation is corrected by the measurement point close to the other envelope. It can also be said.

  The minimum blood pressure <DBP> can also be obtained by interpolation in the same manner as the above-described maximum blood pressure <SBP>. According to the electronic sphygmomanometer of the present embodiment, it is closer to the true value and has less error. The maximum blood pressure / minimum blood pressure can be displayed on the display means 7 by operating the operation means 5.

  As described above, according to the present embodiment, the maximum blood pressure and the minimum blood pressure are calculated by averaging a plurality of interpolation values obtained from a plurality of interpolation formulas, thereby reducing the influence of local noise in blood pressure measurement. As a result, it is possible to provide the user with a correct measurement value of the maximum blood pressure and the minimum blood pressure.

  In addition, by reducing the influence of local noise, there is an effect that variation in blood pressure values for each measurement is reduced. In this case, since the variation of the blood pressure value is large, the user does not worry about the malfunction of the blood pressure monitor, and the user's anxiety about the blood pressure monitor can be solved.

(Second Embodiment)
An electronic sphygmomanometer 100 according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8.

  In the present embodiment, in the relationship between the cuff pressure and the pulse wave amplitude shown in FIG. 4, when A, B, C, and D are selected as measurement points for obtaining a linear interpolation equation, that is, A, C This is an embodiment in the case where two points B and D are selected closest to the lower side.

  In the flowchart of calculating the systolic blood pressure / diastolic blood pressure of this embodiment, in FIG. 3, the number of measurement points for obtaining the interpolation primary expression is changed from 3 to 4 (S306), and the pulse wave amplitude primary expression number is changed from 2 expressions to 4 expressions. It is read as an expression (S308).

  According to the read flow of FIG. 3, the pulse wave amplitude primary expression calculating means 63 c obtains the coefficients a and b of the expression (1) from the coordinate data of A, B, C and D, and as shown in FIG. Four formulas are obtained: L1 from the combination of A and point B, L2 from the combination of point A and point D, L3 from the combination of point C and point B, and L4 from the combination of point C and point D (S308). .

  Next, the blood pressure value calculation means 63d that has received the above four formulas calculates four intersections of the respective formulas and H = Hs (S310). Specifically, in FIG. 7, intersection points P1 to P4 with H = Hs are calculated for the interpolation straight lines L1 to L4.

Next, the blood pressure value calculating means 63d obtains the cuff pressures Pcs1 to Pcs4 at the respective points from the intersection points P1 to P4, and determines the average value thereof as the maximum blood pressure <SBP> ′ (S312 and S314). That is,
<SBP> ′ = (Pcs1 + Pcs2 + Pcs3 + Pcs4) / 4 (3)
It is.

  In FIG. 7, a point on H = Hs corresponding to <SBP> ′ is indicated as P 0 ′, and a vertical line extending from P 0 ′ on the Pc axis indicates <SBP> ′.

  FIG. 8 shows the relationship between <SBP> ′, true value SBP0, and systolic blood pressure SBP1 obtained from one interpolation equation, as in FIG.

FIG. 8 shows that the difference ΔPc2 ′ between <SBP> ′ and the true value SBP0 is smaller than the difference ΔPc1 between SBP1 and the true value SBP0.
Therefore, according to the present embodiment, even when the measurement point for calculating the interpolation formula is deviated from the originally predicted measurement value due to noise or the like, it is possible to make the measurement values of the maximum blood pressure and the minimum blood pressure closer to the true value. In addition, by making the number of linear interpolation equations larger than that in the first embodiment, the measured value can be made closer to the true value.

  In the above embodiment, two measurement points measured before and after the pulse wave amplitude level straight line H = Hs (H = Hd) for determining the blood pressure value are measured as two measurement points for obtaining the interpolation linear expression. Although the case where four points are selected and the blood pressure value is obtained from four intersections by four straight lines has been described as an example, two or more measurement points before and after the pulse wave amplitude level for determining the blood pressure value are selected. May be.

  In that case, if the selected number of measurement points measured before the pulse wave amplitude level for determining the blood pressure value is M and the selected number of measurement points measured after the pulse wave amplitude level for determining the blood pressure value is N, The number of straight lines is M × N. In this way, the measured value can be made more accurate. For example, when three lines are selected in the upper and lower positions of the straight line H = Hs (H = Hd) and two lines are selected below, the number of linear interpolation equations is six.

  Furthermore, the selection of the measurement point for obtaining the linear interpolation equation does not need to be closest to the straight line H = Hs (H = Hd), and may be selected by skipping the closest point according to a predetermined rule.

  In addition, a part of the predetermined number of measurement points may be selected as appropriate according to the measurement conditions, etc., and the primary interpolation equation is the measurement point measured before the pulse wave amplitude level for determining the blood pressure value. What is necessary is just to calculate from the measurement point measured behind.

1 Cuff 2 Tube 3 Cuff pressure adjusting means 3a Pressure pump 3b Exhaust valve 3c Pressure reducing valve 4 Pressure signal converting means 5 Operating means 6 Control means 7 Display means 8 Buzzer 61 Pulse wave detecting means 62 Cuff pressure detecting means 63 Blood pressure determining means 63a Maximum amplitude pulse wave detection means 63b Measurement point extraction means 63c Pulse wave amplitude primary expression calculation means 63d Blood pressure value calculation means 100 Electronic sphygmomanometer

Claims (3)

A cuff for applying pressure to the blood vessel, a pressurizing means for supplying pressurized air to the cuff, a depressurizing means for reducing the pressure of the cuff, a cuff pressure detecting means for detecting the pressure in the cuff, and An electronic sphygmomanometer having a pulse wave detection unit that detects a pulse wave amplitude based on a detection value of a cuff pressure detection unit, and a blood pressure determination unit that determines a blood pressure value based on the pressure in the cuff and the pulse wave amplitude. There,
The blood pressure determining means includes a maximum amplitude pulse wave detecting means for extracting a maximum pulse wave amplitude detected by the pulse wave detecting means, and a pulse wave amplitude level for determining a blood pressure value obtained by subtracting a certain percentage from the maximum pulse wave amplitude. Calculate and select one or more of the measured values on one side as the first measured value group with the pulse wave amplitude level as a boundary, and the second measured from the measured values on the other side Select as a value group, and two or more of the combinations of straight lines connecting any one point of the first measurement value group and any one point of the second measurement value group as a plurality of interpolation linear expressions An electronic sphygmomanometer, comprising: a pulse wave amplitude primary expression calculating unit that calculates a blood pressure value for each of the plurality of interpolation primary expressions based on a cuff pressure corresponding to the pulse wave amplitude level .   The blood pressure determination means calculates a blood pressure value by obtaining a cuff pressure corresponding to the pulse wave amplitude level for each of the plurality of linear interpolation equations and averaging the cuff pressure. The electronic blood pressure monitor as described. The pulse wave amplitude primary expression calculating means selects two points from the measured values on one side as the first measured value group with the pulse wave amplitude level as a boundary, and two points from the measured values on the other side. Are selected as the second measurement value group, and four of the combinations of straight lines connecting any one point of the first measurement value group and any one point of the second measurement value group are interpolated to primary. The electronic sphygmomanometer according to claim 1, wherein the electronic sphygmomanometer is calculated as an equation .

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