JP2807024B2 - Electronic sphygmomanometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sphygmomanometer that employs a vibration method for measuring a blood pressure value from a pulse wave amplitude.

[Conventional technology]

In general, an electronic voltmeter wraps a cuff 32 around a blood pressure measurement site 31 (for example, upper arm) as shown in FIG.
Increase pressure at 32 to occlude the artery. Thereafter, when the pressure is reduced at a very low speed, a pulsation (pulse wave) of the cuff pressure is generated according to the arterial pulsation. FIG. 4 is a graph showing a change in the cuff pressure during the slow speed depressurization process. FIG. 5 is a graph showing a vibration component extracted and separated from the cuff pressure signal of FIG. Hereinafter, the height (pressure difference) of the vibration component is referred to as a pulse wave amplitude. The transition process of the pulse wave amplitude will be described with reference to FIG. In the decompression process, the pulse wave amplitude is initially small (section a), and then gradually increases (section b). After the maximum pulse wave amplitude is shown (time 9), it gradually decreases again (section c). ). At this time, in the cuff pressure decreasing process, the cuff pressure at which the amplitude starts to increase corresponds to the systolic blood pressure P (S) (time 3),
The point where the pulse wave amplitude becomes maximum corresponds to the average blood pressure P (M) (time 9). The principle of determining the blood pressure from this pulse wave amplitude is known as a vibration method or an oscillometric method. Often used. As a method of determining the diastolic blood pressure of the electronic sphygmomanometer based on the vibration method, a decrease rate of the pulse wave amplitude after showing the maximum pulse wave amplitude first, that is, the pulse wave amplitude H (i) and one pulse before A method of calculating the ratio of the pulse wave amplitude H (i-1) to the cuff pressure at which the decrease rate becomes small as the diastolic blood pressure by the relational expression H (i) / H (i-1) Second, systolic blood pressure P
(S) and a method of estimating the diastolic blood pressure P (D) from the mean blood pressure P (M) by a relational expression, P (D) = {3P (M) -P (S)} / 2 (hereinafter referred to as an estimation calculation method and 3)
Then, the pulse wave amplitude H (M) at the time of the average blood pressure P (M) is multiplied by the diastolic blood pressure determination coefficient K, and the product is compared with the pulse wave amplitude in the decompression process that has passed the average blood pressure P (M). (Hereinafter referred to as a pulse wave amplitude comparison method) has been conventionally used.

[Problems to be solved by the invention]

In the conventional method of determining a diastolic blood pressure in the conventional electronic voltmeter, first, when the time series change of the pulse wave is not clear (6th
(Fig. 7, Fig. 7), Secondly, when the time series change of the pulse wave amplitude is disturbed by body movement (artifact) during measurement of the subject, individual differences in the measurement site of the subject, electrical noise, etc. This may cause an error in the diastolic blood pressure value. The present invention is intended to solve the problem caused by the second cause, and will be described using a pulse wave amplitude comparison method and an estimation calculation method as examples. FIG. 9 shows an example in which an incorrect determination of the diastolic blood pressure is made by the pulse wave amplitude comparison method.
In the decompression process, the pulse wave amplitude starts increasing at time 3. The cuff pressure at time 9 indicating the maximum value of the pulse wave amplitude corresponds to the average blood pressure P (M), and the pulse wave amplitude at that time is represented by H
(9). In the depressurization process, the pulse wave amplitude normally undergoes a decreasing process as shown in FIG. 5, but due to the above-mentioned body movement and the like, the pulse wave amplitude differs from the regular decreasing in the regular pulse wave amplitude decreasing process. May occur (time 11). In the process of regularly decreasing the pulse wave amplitude, the pulse wave amplitude at time 11 indicates H '(11), and H (13) indicates a pulse wave amplitude equal to or less than the product of H (9) and the diastolic blood pressure determination coefficient K.
The cuff pressure at the time should be the minimum blood pressure, but if the pulse wave amplitude at time 11 is H (11) as in the example of FIG.
Since the product of (9) and the diastolic blood pressure determination coefficient K is larger than H (11), a diastolic blood pressure value different from H (13) corresponding to the original diastolic blood pressure is determined. FIG. 10 shows an example in which an erroneous determination of the diastolic blood pressure is made in the same manner as described above by the estimation calculation method. In the decompression process, the pulse wave amplitude starts to increase from time 3 in FIG. In the depressurization process, the pulse wave amplitude usually increases as shown in FIG. 5, and the pulse wave amplitude becomes maximum at time 9. Due to the body motion and the like, the pulse wave amplitude may be small as shown at time 8 in FIG. 10 in the process of regularly increasing the pulse wave amplitude. Originally, the 10th that indicates the maximum amplitude
From the cuff pressure P (9) and the systolic blood pressure P (3) at the time 9 in the figure, the diastolic blood pressure P (D) is expressed by a relational expression: P (D) = ｛3 × P (9) −P (3) In this case, in the estimation calculation method, the pulse wave amplitude H (7) at time 7 is set as the maximum amplitude, and the cuff pressure P (7) and the systolic blood pressure P (3 ), The diastolic blood pressure P (D) is erroneously determined by the relational expression P (D) = {3 × P (7) -P (3)} / 2. The present invention
In view of the above, in the process of reducing the cuff pressure, time-series changes in pulse wave amplitude are disturbed due to body movements (artifacts) during measurement of the subject, individual differences in the measurement site of the subject, and electrical noise. In this case, a diastolic blood pressure determination method capable of determining a correct diastolic blood pressure is provided.

[Means for solving the problem]

The gist of the present invention for achieving the above object is to determine a temporary diastolic blood pressure P (d) from a systolic blood pressure P (S) measured in a cuff pressure decreasing process and an average blood pressure P (M) using a relational expression P (d). ) = {3 × P (M) −P (S)} / 2, and the comparison pulse wave amplitude H (D) is calculated as the pulse wave amplitude H at the time of the average blood pressure P (M). (M) and a second diastolic blood pressure determining means which is calculated from the diastolic blood pressure determining coefficient K by a relational expression H (D) = H (M) × K.

[Action]

In this electronic voltmeter, the cuff pressure P during the cuff pressure change process is
(I) is equal to or less than the provisional diastolic blood pressure P (d) calculated by the first diastolic blood pressure determining means, and the pulse wave amplitude H (i)
Is the cuff pressure P (i) when the amplitude becomes equal to or smaller than the comparison pulse wave amplitude H (D) calculated by the second diastolic blood pressure determining means, as the diastolic blood pressure P (D).

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples.

FIG. 2 shows an embodiment of blood pressure measurement by an electronic voltmeter.
A cuff 32 for blocking arterial blood is attached to the blood pressure measurement site 31 (for example, the upper arm) of the subject, a rubber tube 33 is connected to a part of the cuff 32, and the other end of the rubber tube 33 is connected to the measuring instrument body 34. The fluid (for example, air) can move between the cuff 32 and the measuring instrument main body 34 via the rubber tube 33. Hereinafter, a circuit in which a fluid (for example, air) moves is referred to as a fluid circuit. FIG. 3 is a block diagram showing a configuration inside the main body. First, the fluid circuit in the measuring instrument body 34 will be described. The fluid circuit in the measuring instrument body 34 is branched into four. The first is a pressure sensor 35 for converting the pressure in the cuff 32 into an electric signal, and the second is a slow exhaust valve 39 for gradually reducing the pressure in the cuff 32.
The third is a quick exhaust valve 40 for rapidly reducing the pressure in the cuff 32, and the fourth is a pressurizing pump 41 for increasing the pressure in the cuff 32. Next, an electric circuit in the measuring instrument body 34 will be described. The analog electric signal of the pressure converted by the pressure sensor 35 is converted to an A / D converter 36.
Is converted into a digital signal. The digital signal is input to a microcomputer 37 including a CPU, a ROM, a RAM, and the like. In addition, microcomputer 37
A control signal for turning on / off the pressurizing pump 41 for pressurizing the cuff 32 and a control signal for turning on / off the quick exhaust valve 40 are output from the control unit. On the front surface of the measuring instrument body 34, an operation switch unit 42 configured to control a blood pressure measurement by the electronic voltmeter and configured by a power switch, a start switch, a pressurization upper limit setting switch, and the like is disposed. The signal is input to the microcomputer 37. Similarly, a display 38 for displaying a measurement result or the like is arranged on the front surface of the measuring instrument body 34, and a display data signal is output from the microcomputer 37. Measuring instrument body
The power supply unit 43 is built in the
When power is required for the operation of the power supply, power is supplied from the power supply unit 43. Although the present embodiment is a method in which cuff pressure is generally called an automatic type by the pressurizing pump 41, it is also applicable to a method in which cuff pressure is generally called manually in which a cuff pressure is manually generated.

FIG. 8 is a flowchart showing the flow of blood pressure measurement. Blood pressure measurement is started by the operation switch unit 42 (ST
0), the cuff pressure is increased by the pressure pump 41 (ST1).
During pressurization, the quick exhaust valve 40 is closed. When the cuff pressure reaches a predetermined pressure set by the operation switch section 42 before the start of measurement (ST2), the pressurizing pump 41 stops pressurizing (ST2).
3), the cuff pressure starts to decrease due to the slow exhaust valve 39 (ST
Four). As shown in FIG. 4, vibration (pulse wave) is generated in the cuff pressure according to the arterial pulsation, and the systolic blood pressure (ST5), the average blood pressure P (M) (ST6) and the diastolic blood pressure ( ST
7) is determined, the result is displayed on the display unit 38 (ST8), the rapid exhaust valve 40 is opened, the pressure of the cuff 32 pressing the measurement site is removed (ST9), and the blood pressure measurement ends (ST10). .

FIG. 4 is a view showing a change in the cuff pressure during the slow pressure reduction process. FIG. 5 is a diagram showing a vibration component extracted and separated from the cuff pressure signal of FIG.

FIG. 1 is a flowchart showing the flow of blood pressure measurement according to the present invention. The process from the start of measurement (ST0) to the determination of systolic blood pressure (ST5) is the same as that shown in FIG. As for the method of determining the systolic blood pressure, similar to the method of determining the diastolic blood pressure, an actual measurement method in which the cuff pressure at the time when the rate of increase of the pulse wave amplitude for each beat becomes the maximum is the maximum blood pressure, and the maximum pulse wave amplitude H (M ) Is multiplied by the maximum blood pressure determination coefficient G, and there is a pulse wave amplitude comparison method in which the cuff pressure when the pulse wave amplitude exceeds the product of H (M) and G is set as the maximum blood pressure.
In this embodiment, a pulse wave amplitude comparison method was used. FIG. 11 is a diagram showing a logic (algorithm) for determining systolic blood pressure using the pulse wave amplitude comparison method. The algorithm for determining systolic blood pressure will be described with reference to FIG. As a preparation stage, the maximum pulse wave amplitude H (M), the pressure P (M) at the maximum pulse wave amplitude, and the counters i and j are cleared to zero (ST1).
1). When the pulse wave is detected (ST12), the pulse wave start cuff pressure P is set to P
In (i), the pulse wave amplitude H is stored in H (i) (ST13),
i is incremented by one (ST14), and when i is 1 (ST14)
15) Return to ST12. H if i is not 1 (ST15)
It is determined whether (i) does not exceed H (M) (ST16),
If not, shift to ST18. If it exceeds, the maximum pulse wave amplitude H (M) is updated (ST17). The counter j is cleared to zero (ST18), and it is determined whether or not H (j) exceeds the product of the systolic blood pressure determination coefficient G and the maximum pulse wave amplitude H (M) (ST19). j is incremented by 1 (ST20), and it is determined whether j is equal to i (ST20).
21) If not equal, return to ST19. ST if equal
Return to 12. In ST19, H (j) is the maximum pulse wave amplitude H
The pulse wave start cuff pressure P (j) when the product exceeds the product of (M) and the systolic blood pressure determination coefficient G is set as the systolic blood pressure P (S) (ST2
2).

After the systolic blood pressure, determine the diastolic blood pressure. The algorithm for determining the diastolic blood pressure will be described with reference to FIG.
From the start of measurement (ST0) to the determination of systolic blood pressure (ST5),
It is the same as shown in the figure. When the pulse wave is detected (ST23), the pulse wave start cuff pressure P is set to P (i), and the pulse wave amplitude H is set to H (i).
To memory (ST24) and increment i by one (ST25)
It is determined whether H (i) does not exceed H (M) (ST
26) If not, move to ST28. If it exceeds, H (M) is updated (ST27). Temporary diastolic blood pressure P
(D) is calculated by the relational expression, P (d) = {3 × P (M) −P (S)} / 2 (ST28), and the maximum pulse wave amplitude H (M) and the diastolic blood pressure determination coefficient K are calculated. Multiply and compare pulse wave amplitude H (D) (ST
29). Here, the value of the diastolic blood pressure determination coefficient K and its determination method will be described. After the cuff is wound around the blood pressure measurement site of the blood pressure measurement person and the pressure of the cuff is increased above the systolic blood pressure, the change in the cuff pressure P (i) in the process of gradually reducing the cuff pressure is recorded, and auscultation is simultaneously performed. The minimum blood pressure P (D) and the average blood pressure P (M) are determined by the method. Diastolic blood pressure P determined by auscultation
The pulse wave amplitude at the time (D), that is, the value of the comparison pulse wave amplitude H (D) and the value of the pulse wave amplitude H (M) at the time of the mean blood pressure P (M) are calculated by comparing the pulse wave amplitude H (D) with the mean pulse pressure. Pulse wave amplitude H at P (M)
The value of the diastolic blood pressure determination coefficient K is obtained by substituting into a relational expression between (M) and the diastolic blood pressure determination coefficient K, H (D) = H (M) × K. The diastolic blood pressure determination coefficient K indicates 0.5 to 0.8, and this value is, for example,
It is determined for each blood pressure measurement site of the subject, such as a wrist or finger. First
Returning to the explanation of the figure, the cuff pressure P (i) is
(D) is determined (ST30), and P (i) is
If it exceeds (d), return to ST23. P (i) is P
(D) In the following cases, the pulse wave amplitude H (i) is
It is determined whether (D) is exceeded (ST31). If H (i) exceeds H (D), the process returns to ST23. If H (i) is equal to or lower than H (D), the pulse wave start cuff pressure P (i) is set as the minimum blood pressure P (D) (ST32). The process from the blood pressure display after the determination of the diastolic blood pressure (ST8) to the end of the measurement (ST10) is the same as in FIG. With reference to FIGS. 9 and 10, an algorithm will be described in which the present invention can avoid a mistake in determining the diastolic blood pressure caused by only one of the pulse wave amplitude comparison method and the estimation calculation method when determining the diastolic blood pressure. First, the pulse wave amplitude comparison method will be described with reference to FIG. In the pulse wave amplitude comparison method alone,
When an extremely small pulse wave is measured from the regular pulse wave amplitude decreasing process as at time 11 in FIG. 9, the product of the pulse wave amplitude H (9) indicating the maximum pulse wave amplitude and the diastolic blood pressure determination coefficient K is If it was greater than H (11), the cuff pressure at H (11) was taken as the diastolic blood pressure P (D). However, as in the present invention, if the diastolic blood pressure is determined by the logical product of the estimation calculation method, the cuff pressure P (i) becomes P (M) (= P (9)) and the systolic blood pressure P
Since the diastolic blood pressure is not determined unless it becomes lower than the provisional systolic blood pressure calculated by (S), the example of FIG. 9 can be avoided. In addition, with only the estimation calculation method, when a significantly small pulse wave is measured from the regular rising process of the pulse wave amplitude as at time 8 in FIG. 10, the maximum pulse wave amplitude H (M) [= H (7)]
Even if an erroneous diastolic blood pressure is calculated by the relational expression P (D) = {3 × P (7) -P (S)}, the diastolic blood pressure P (D) is calculated by If the diastolic blood pressure is determined by the logical product of the pulse wave amplitude comparison method as in the present invention, the pulse wave amplitude H at time 8 in FIG. 10 is obtained from the product of the maximum pulse wave amplitude H (7) and the diastolic blood pressure determination coefficient K.
Since (8) is large, the mistake of determining the diastolic blood pressure at time 8 in FIG. 10 can be avoided.

〔The invention's effect〕

According to the present invention, in an electronic sphygmomanometer of a vibration method in which blood pressure is determined by vibration of a cuff pressure, a body movement (artifact) during measurement of a subject, individual differences in a measurement site of the subject, electric noise, and the like. Disturbs the time-series changes in pulse wave amplitude,
Even when an error occurs in the determination of the diastolic blood pressure, the amplitude of the pulse wave caused by the arterial pulsation of the cuff pressure is determined by the systolic blood pressure P (S) and the average blood pressure P measured during the pressure change process in the decompression process.
(M) and P (d) = ｛3 × P (M) −P
(S) The first diastolic blood pressure determining means for calculating the provisional diastolic blood pressure P (d) from｝ / 2, and the comparison pulse wave amplitude H (D) is calculated as the average blood pressure P (d).
And a second diastolic blood pressure determining means which is calculated from a relational expression from the pulse wave amplitude H (M) at (M) and the diastolic blood pressure determining coefficient K, H (D) = H (M) × K. The cuff pressure P (i) during the change process is equal to or less than the provisional diastolic blood pressure P (d) calculated by the first diastolic blood pressure determining means, and the pulse wave amplitude H (i) is determined by the second diastolic blood pressure determination. The time series change of the pulse wave amplitude is disturbed by setting the cuff pressure P (i) at the time when the pulse wave amplitude becomes equal to or smaller than the comparison pulse wave amplitude H (D) calculated by the means as the diastolic blood pressure P (D). However, the diastolic blood pressure can be determined accurately.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for determining a diastolic blood pressure according to the present invention, FIG. 2 is an embodiment of blood pressure measurement, FIG. 3 is a block diagram of the same, and FIG. FIG. 5 is a diagram showing the vibration of the cuff pressure, and FIG. 5 is a diagram showing the vibration extracted and separated from FIG. 4, which is a case showing an ideal vibration change. FIG. 6 is a diagram showing the extracted and separated vibrations, and FIG. 7 is a diagram showing the extracted and separated pulse waves when the maximum pulse wave amplitude is small, and FIG. FIG. 9 is a flow chart showing the flow of blood pressure measurement. FIG. 9 shows an example in which a diastolic blood pressure is erroneously determined by the pulse wave amplitude comparison method.
FIG. 10 is an example in which a diastolic blood pressure is erroneously determined by the estimation calculation method, and FIG. 11 is a flowchart showing a method of determining the systolic blood pressure by the pulse wave amplitude comparison method. Blood pressure measurement site ... 31, Cuff ... 32, Pressure sensor ... 35, A / D converter ... 36, Slow exhaust valve ... 39, Quick exhaust valve ... 40, Pressurizing pump 41.

Claims (1)

(57) [Claims] 1. A cuff attached to a blood pressure measurement site of a subject, a pressurizing pump for increasing a pressure in the cuff,
A slow exhaust valve for gradually reducing the pressure in the cuff, a quick exhaust valve for rapidly reducing the pressure in the cuff after measurement is completed, and a conversion of the pressure in the cuff to an electric signal Pressure sensor, an A / D converter for converting a signal of the pressure sensor into a digital value, a pulse wave amplitude detecting means for detecting a pulse wave amplitude in a pressure change process of the cuff, and the pulse wave amplitude detecting means. In an electronic voltmeter including a blood pressure value determining means for determining a blood pressure from the cuff pressure detected by the pressure sensor, the blood pressure value determining means measures a provisional diastolic blood pressure P (d) in a cuff pressure changing process. First diastolic blood pressure determining means which is calculated from a systolic blood pressure P (S) and an average blood pressure P (M) by a relational expression, P (d) = {3 × P (M) -P (S)} / 2; Comparison pulse wave amplitude H (D) with pulse wave at mean blood pressure P (M) A second diastolic blood pressure determining means for calculating the relational expression from the width H (M) and the diastolic blood pressure determining coefficient K by the following equation: H (D) = H (M) × K, and the cuff pressure P during the pressure change process. (I) is not more than the provisional diastolic blood pressure P (d) calculated by the first diastolic blood pressure determining means, and the pulse wave amplitude H (i) is calculated by the second diastolic blood pressure determining means. An electronic voltmeter, wherein the cuff pressure P (i) when the amplitude becomes equal to or smaller than the comparison pulse wave amplitude H (D) is set as the minimum blood pressure.