JP2006247215A - Automatic blood pressure measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic blood pressure measuring apparatus of oscillometric type which is capable of highly precisely determining pressure rising deficiency. <P>SOLUTION: This automatic blood pressure measuring apparatus determines whether a rising point of an amplitude A showing the blood-pressure systolic BP<SB>SYS</SB>is formed or not (S8) by determining whether a change rate (d) of the amplitude A of a cuff pulse wave sequentially obtained in a slow depressing process of a cuff pressure PC exceeds a prescribed change rate standard value TH<SB>d</SB>or not, when determination that the blood-pressure systolic BP<SB>SYS</SB>is not determined till a lapse of a prescribed determination standard heart rate TH<SB>N</SB>(S9) from starting the slow depressing is made, determination whether the first amplitude A1 after starting the slow depressing is a prescribed determination standard amplitude TH<SB>A</SB>or more is made (S10), and when the determination is also affirmed, determines it as the pressure rising deficiency, sets a target pressor value PCM to a larger value by a prescribed value ΔP (S11) to immediately increase the blood pressure again. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of an automatic blood pressure measurement device that automatically measures blood pressure values.

  As a blood pressure measuring device that automatically measures a blood pressure value of a living body, an automatic blood pressure measuring device that automatically measures blood pressure by a so-called oscillometric method is known. An oscillometric automatic blood pressure measuring device winds a cuff around a predetermined part of a living body, boosts the pressure of the cuff to a preset pressure target value, and then increases the pressure of the cuff to 3 to 5 mmHg / sec. Decrease the pressure gradually. Then, the cuff pulse wave generated in the cuff during the slow pressure reduction process is sequentially collected, and the blood pressure value is determined using the oscillometric algorithm stored in advance based on the change in the amplitude of the cuff pulse wave. . In the oscillometric algorithm, for example, the maximum blood pressure value is determined as the cuff pressure when the amplitude of the cuff pulse wave suddenly increases, that is, the cuff pressure at the rising point of the amplitude of the cuff pulse wave.

  The boost target pressure value needs to be set to be higher than the maximum blood pressure value. On the other hand, if the boost target pressure value is too high, the pain given to the person to be measured increases. In many cases, a constant value (for example, 180 mmHg) in consideration of such circumstances is used. However, assuming that the target pressure increase value is a constant value, the cuff needs to be increased again in the case of a hypertensive patient having a maximum blood pressure value higher than the target pressure increase value.

As an oscillometric type automatic blood pressure measuring device capable of promptly re-boosting when the pressure is insufficient, for example, a device described in Patent Document 1 has been proposed. The automatic blood pressure measurement device described in Patent Literature 1 determines whether or not the magnitude of the pulse wave initially detected at the start of cuff pressure reduction is greater than a preset criterion value, When it is determined that the initial pulse wave is larger than the determination reference value, the cuff pressure is rapidly increased again. If the pressure increase is insufficient, the pulse wave is relatively large from the beginning of the decrease in the cuff pressure, and therefore the pressure increase is determined based on a comparison between the magnitude of the pulse wave and the determination reference value.
JP 61-130202 A

  As in the automatic blood pressure measurement device described in Patent Document 1, when determining insufficient pressure from a comparison between the magnitude of a pulse wave and a determination reference value, a determination criterion is provided so as to reliably determine insufficient pressure increase while preventing erroneous determination. There is a problem that it is relatively difficult to set the magnitude of the value. That is, as the judgment reference value is set lower, it becomes possible to reliably determine insufficient pressure increase, but on the other hand, it is not insufficient pressure increase, and even if the maximum blood pressure value can be determined even if gradual pressure decrease is continued, The number of cases that are judged increases. Therefore, the judgment reference value is set to be high to some extent so that a case where the boost is not insufficient is not erroneously determined as insufficient boost. However, the higher the criterion value is set, the more often the missing boost is overlooked.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide an oscillometric automatic blood pressure measuring apparatus capable of accurately determining insufficient pressure increase.

  In order to achieve the above object, the present invention includes a cuff wound around a predetermined part of a living body, pressurizes the pressure of the cuff to a preset target pressure value, and then gradually reduces the pressure of the cuff. An automatic blood pressure measurement device of a type that determines a blood pressure value of the living body based on a change in amplitude of a cuff pulse wave generated in the cuff in the process of speed depressurization, and starts slow depressurization of the compression pressure of the cuff Thereafter, amplitude determining means for sequentially determining the amplitude of the cuff pulse wave, blood pressure value determining means for determining a maximum blood pressure value based on a rising point of the amplitude sequentially determined by the amplitude determining means, and compression of the cuff An under-boosting determining means for determining that the boost is insufficient based on the fact that the maximum blood pressure value is not determined by the blood pressure value determining means within a predetermined reference reference number of beats after the start of slow pressure reduction of the pressure; Boost judgment hand If it is determined that the pressure increase is insufficient, the slow pressure reduction of the cuff pressure is stopped, and the pressure increase target pressure is set to a value higher than the pressure increase target pressure value. Re-boosting control means for boosting to a value.

  According to the present invention, based on the fact that the maximum blood pressure value is not actually determined by the blood pressure value determining means within the preset judgment reference number of beats after the start of the gradual pressure reduction of the cuff compression pressure by the pressure increase insufficient determining means. Therefore, it is determined that the pressure increase is insufficient, so that it is possible to reliably determine the pressure increase insufficient.

  Here, in the above-described insufficient pressure increase determination means, it is possible to quickly determine insufficient pressure increase by reducing the judgment reference beat. However, if the highest blood pressure value of the measurement subject is too low, it is determined that the increase in pressure is insufficient even though the increase in pressure is not insufficient. May be. Therefore, preferably, the under-boosting determination means is such that the maximum blood pressure value is not determined by the blood pressure value determining means within a preset reference reference number of beats after the start of gradual pressure reduction of the compression pressure of the cuff, In addition, it is determined that the boost is insufficient based on the fact that the amplitude determined by the amplitude determining means at the beginning of the slow speed decrease is larger than a preset reference amplitude. When the measurement subject's systolic blood pressure value is low, the amplitude at the time of the gradual pressure reduction is small, so that an erroneous determination that is determined as insufficient pressure but not insufficient pressure is prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a circuit configuration of an automatic blood pressure measurement device 10 to which the present invention is applied.

  In FIG. 1, the cuff 12 has a rubber bag in a cloth band bag and is wound around the upper arm portion 14. A pressure sensor 16 and a pressure regulating valve 18 are connected to the cuff 12 via a pipe 20, respectively. An air pump 24 is connected to the pressure regulating valve 18 via a pipe 22. The pressure regulating valve 18 regulates the pressure in the cuff 12 by regulating the high-pressure air generated by the air pump 24 and supplying it to the cuff 12 or exhausting the air in the cuff 12.

  The pressure sensor 16 detects the pressure in the cuff 12 and supplies a pressure signal SP representing the pressure to the static pressure discrimination circuit 26 and the pulse wave discrimination circuit 28, respectively. The static pressure discriminating circuit 26 includes a low-pass filter, and discriminates a cuff pressure signal SC representing a steady pressure included in the pressure signal SP, that is, a compression pressure of the cuff 12 (hereinafter, this pressure is referred to as a cuff pressure PC). The cuff pressure signal SC is supplied to the electronic control unit 32 via the A / D converter 30. The pulse wave discrimination circuit 28 includes a band pass filter having a signal pass band of about 1 to 30 Hz, for example, and discriminates the cuff pulse wave signal SM, which is a vibration component of the pressure signal SP, and converts the cuff pulse wave signal SM to A / This is supplied to the electronic control unit 32 via the D converter 34. The cuff pulse wave signal SM represents a cuff pulse wave because it is transmitted to the cuff 12 from a brachial artery (not shown) and generated in the cuff.

The electronic control unit 32 includes a CPU 36, a ROM 38, a RAM 40, and a so-called microcomputer having an I / O port (not shown). The CPU 36 uses a memory function of the RAM 40 according to a program stored in advance in the ROM 38. However, by executing signal processing, a drive signal is output from the I / O port to control the air pump 24 and the pressure regulating valve 18. The CPU 36 controls the cuff pressure PC by controlling the air pump 24 and the pressure regulating valve 18. Further, the CPU 36 executes the function shown in detail in FIG. 2 to increase the cuff pressure PC to a pressure higher than the measurement subject's maximum blood pressure value BP _SYS, and then gradually decrease the cuff pressure PC. The blood pressure value BP is determined based on the cuff pulse wave obtained sequentially, and the determined blood pressure value BP is displayed on the display 42.

FIG. 2 is a functional block diagram showing the main part of the control function of the CPU 36. The cuff pressure control means 50 controls the pressure regulating valve 18 and the air pump 24 so that the cuff pressure PC is preset to a pressure increase target pressure value PC _M (for example, higher than the maximum blood pressure value BP _SYS in the upper arm portion 14). The pressure is rapidly increased to 180 mmHg), and then the cuff pressure PC is gradually decreased at a gradually decreased pressure rate set to 2 to 3 mmHg / sec until the determination of the blood pressure value BP by the blood pressure value determining means 54 described later is completed. Let Further, the cuff pressure control means 50 also functions as a re-boosting control means, and stops the slow pressure reduction of the cuff pressure PC when it is determined that the cuff pressure PC is insufficiently increased by the pressure increase insufficient determination means 56 described later. Te, and the target pressure preset new target pressure PC _M ie re target pressure value obtained by adding the addition value ΔP has the PC _M, and quickly re-pressurized to the re-target pressure Later, the slow pressure reduction is performed again. The addition value ΔP is previously set that has been set in the initial target pressure PC 10 minutes to several fractions of a range of _M, for example, 50 mmHg. Further, the cuff pressure control means 50 discharges the cuff pressure PC to the atmospheric pressure after the determination of the blood pressure value BP is completed.

  The amplitude determining means 52 determines the amplitude A of the cuff pulse wave represented by the cuff pulse wave signal SM sequentially discriminated by the pulse wave discriminating circuit 28 in the process of gradually decreasing the cuff pressure PC by the cuff pressure control means 50. Each amplitude is determined, and the amplitude A is stored in a predetermined storage area of the RAM 66 together with the cuff pressure PC discriminated by the static pressure discrimination circuit 26 when the amplitude A is determined.

The blood pressure value determining unit 54 changes the amplitude A of the cuff pulse wave sequentially determined by the amplitude determining unit 52 and the cuff pressure signal sequentially collected in the process in which the cuff pressure PC gradually decreases the cuff pressure PC. Based on the SC, a well-known oscillometric algorithm is used to determine the systolic blood pressure value BP _SYS , the systolic blood pressure value BP _DIA , and the mean blood pressure value BP _MEAN, and the determined systolic blood pressure value BP _{SYS and the} like are displayed on the display 42. indicate. In the oscillometric algorithm, the cuff pressure PC when the amplitude A of the cuff pulse wave obtained sequentially increases rapidly, that is, the cuff pressure PC at the rising point of the amplitude A is determined as the maximum blood pressure value BP _SYS . The rising point of the amplitude A is, for example, based on the fact that the rate of change d of the amplitude A is sequentially calculated based on the sequentially obtained amplitude A, and the rate of change _d exceeds a predetermined rate of change reference value THd. decide. The average blood pressure value BP _MEAN is, for example, the cuff pressure PC at the peak point of the envelope obtained by creating an amplitude sequence as shown in FIG. The minimum blood pressure value BP _DIA is the cuff pressure PC at the inflection point (the falling point of the envelope) of the differential curve obtained by differentiating the envelope.

After the start of the slow pressure reduction of the cuff pressure PC by the cuff pressure control means 50, the blood pressure value determination means 56 determines the maximum blood pressure value BP _SYS within the preset judgment reference beat number TH _N. If the amplitude A determined by the amplitude determining means 52 at the beginning of the slow depressurization of the cuff pressure PC is larger than the preset reference amplitude TH _A , the pressure is insufficient. judge. The determination reference beat number TH _N is determined in advance based on experiments, and is, for example, 3 to 10 beats (more specifically, 5 beats). In addition, the amplitude A at the beginning of the slow pressure reduction is the amplitude A at any point in time from the start of the slow pressure reduction until the determination reference beat number TH _N elapses, or the above determination criterion from the start of the slow pressure reduction. Although it is the average amplitude A in an arbitrary period until the beat number TH _N elapses, in the following description, it is assumed that it is the first amplitude A after the start of the slow speed reduction. The reference amplitude TH _A is a weak cuff generated when the pulsation generated on the upstream side of the cuff 12 is transmitted to the upstream end of the cuff 12 when the artery under the cuff 12 is completely driven. greater than the amplitude a of the pulse wave, and, when the measured person is hypertensive patient, the cuff pressure PC is relatively amplitude large cuff pulse wave detected in a state that is with the original target pressure PC _M It is set based on experiments so as to be lower than A.

4, an envelope derived from the amplitude A of the slow decreasing the beginning of the cuff pulse wave, and determines the reference amplitude TH _A, is a diagram schematically showing the relationship between the criteria beats TH _N. FIG. 4A shows an example in which the person being measured is a hypertensive patient and the pressurization is insufficient. As shown in FIG. 4 (a), the maximum blood pressure value BP _SYS is not determined by the determination reference beat number TH _N , and the amplitude A at the beginning of the slow pressure reduction is larger than the determination reference amplitude TH _A. It is correctly determined that there is a shortage. FIG. 4B shows an example in which the blood pressure BP of the measurement subject is slightly high, but the pressure increase is not insufficient. As shown in FIG. 4 (b), since the systolic blood pressure value BP _SYS has been determined up to the determination reference beat number TH _N , it is not determined that the pressurization is insufficient. Note that FIG. 4B shows a case where the initial amplitude A at the start of the gradual pressure reduction is larger than the determination reference amplitude TH _A , so that the apparatus described in Patent Document 1 is erroneously determined to be insufficient in boosting. . FIG. 4C shows an example where the measurement subject is a hypotension patient. As shown in FIG. 4 (c), since the systolic blood pressure value BP _SYS has not been determined by the determination reference beat number TH _N , it is determined that the increase in pressure is insufficient due to the determination based only on this. Is smaller than the determination reference amplitude TH _A, it is not determined that the boost is insufficient.

  FIG. 5 is a flowchart showing a main part of the control operation of the CPU 36 shown in the functional block diagram of FIG.

First, in step S1 (hereinafter, step is omitted), the air pump 24 is activated and the pressure regulating valve 18 is controlled to start the rapid pressure increase of the cuff pressure PC. Subsequently, at S2, the cuff pressure PC is determined whether exceeds the target pressure PC _M set to 180 mmHg. While the determination of S2 is denied, the determination of S2 is repeatedly executed and the rapid increase of the cuff pressure PC is continued. On the other hand, if the determination in S2 is affirmative, in S3, the air pump 24 is stopped and the pressure regulating valve 18 is controlled to start the slow pressure reduction at about 3 mmHg / sec of the cuff pressure PC. .

  In S4, the cuff pulse wave signal SM supplied from the pulse wave discrimination circuit 28 and the cuff pressure signal SC supplied from the static pressure discrimination circuit 26 are read for one beat. In subsequent S5, “1” is added to the beat number N.

The subsequent S6 corresponds to the amplitude determining means 52, and based on the cuff pulse wave signal SM for one beat read in S4, the amplitude A of the cuff pulse wave represented by the cuff pulse wave signal SM is determined. Subsequently, at S7, the amplitude A (and _{A N)} determined above S6, based on _{(a A N-1} to) the amplitude A determined in S6 in the previous pulse and the amplitude from the formula 1 A The rate of change d is calculated.
(Formula 1) d = (A _N −A _N−1 ) / A _N−1

In subsequent S8, the change rate calculated in S7 d is, by determining whether the rate of change reference value TH _d is greater than that has been set in advance, determines whether the rising point of the amplitude A has occurred . If the determination in S8 is negative, in subsequent S9, it is further determined whether or not the beat number _{N is} greater than a preset reference beat number TH _N. If the determination is negative at the beginning of the slow pressure reduction, the process from S4 onward is executed again. On the other hand, if the determination in S9 is affirmative, or target pressure PC _M is less than the systolic blood pressure value _{BP SYS,} because target pressure PC _M is the case significantly greater than the systolic blood pressure value _{BP SYS} In order to determine which one of them, in the subsequent S10, it is further determined whether or not the amplitude A1 of the first cuff pulse wave is greater than a preset criterion amplitude TH _A after the start of the slow pressure reduction. .

If the determination in S10 is denied, the target pressure PC _M is significantly greater than the systolic blood pressure value BP _SYS, yet, since the case where the rising point of the amplitude A has not occurred, the S4 follows Run repeatedly. On the other hand, if the determination in S10 is affirmative, it is considered that the boost target pressure value PC _M is smaller than the systolic blood pressure value BP _SYS. Therefore, in the subsequent S11, a predetermined addition value ΔP is added to the boost target pressure value PC _M. after the added value as a new target pressure PC _M ie re target pressure, executes S1 follows again. As a result, the slow depressurization of the cuff pressure PC started in S3 is stopped, and the cuff pressure PC is rapidly increased to the re-pressurization target pressure value.

If the determination in S8 is affirmative, that is, if the rising point of the amplitude A has occurred, the cuff pressure PC at that time is determined as the maximum blood pressure value BP _SYS in S12, and in the subsequent S13, the above-described oscilloscope is determined. By executing the metric algorithm, the mean blood pressure value BP _MEAN and the minimum blood pressure value BP _DIA are determined.

In the subsequent S14, the maximum blood pressure value BP _SYS , the average blood pressure value BP _MEAN and the minimum blood pressure value BP _DIA determined in S12 or S13 are displayed on the display 42, and in the subsequent S15, the pressure control valve 18 is controlled to control the cuff. Pressure PC is exhausted to atmospheric pressure. In FIG. 5, S1 to S3, S11, and S15 correspond to the cuff pressure control means 50, and among them, S1 to S2 and S11 also correspond to the re-boosting control means. S7 to S8 and S12 to S14 correspond to the blood pressure value determining means 54, and S8 to S10 correspond to the insufficient pressure increase determining means 56.

As described above, according to this embodiment, by the step-up shortage determination unit 56 (S8 to S10), after the slow decreasing the start of cuff pressure PC, preset criteria beats TH blood pressure determining means within _N 54 (S7 to S8, S12 to S14), it is determined that the boost is insufficient based on the fact that the systolic blood pressure value BP _SYS is not actually determined. Therefore, it is possible to reliably determine the insufficient boost.

Further, according to the present embodiment, the pressure increase deficiency determining means 56 actually uses the blood pressure value determining means 54 (S7 to S8, S12 to S14) within the predetermined reference pulse rate TH _N to actually increase the maximum blood pressure value BP _SYS. Is not determined, and when the amplitude A determined by the amplitude determining means 52 (S6) at the beginning of the slow pressure reduction is larger than the determination reference amplitude TH _A , it is determined that the boost is insufficient. In addition, erroneous determination that is determined as insufficient boosting is prevented.

  As mentioned above, although one Embodiment of this invention was described in detail based on drawing, this invention is applied also in another aspect.

For example, in the illustrated embodiment, each time the re-boosting is superimposed, the additional value ΔP i.e. constant value has been added value a new target pressure to target pressure PC _M (i.e. re-target pressure) However, the difference between the reboosting target pressure value and the previous boosting target pressure value need not be constant. For example, the reboosting target pressure value so that the difference from the previous boosting target pressure value gradually decreases. A value may be set.

Further, in the above-described embodiment, the insufficient pressure increase determination unit 56 determines that the maximum blood pressure value BP _SYS is not actually determined by the blood pressure value determination unit 54 within the preset reference reference beat number TH _N. When the amplitude A determined by the amplitude determining means 52 at the beginning of the step-down is larger than the judgment reference amplitude TH _A, it is judged that the boosting is insufficient. However, only the former condition, that is, the judgment reference beat number TH set in advance is determined. Insufficient pressurization may be determined only from the fact that the maximum blood pressure value BP _SYS is not actually determined by the blood pressure value determining means 54 within _N. In this case as well, in the device described in Patent Document 1, the determination reference amplitude TH _A is too high, so that it is determined that the boost is not insufficient but the determination reference amplitude TH _A is not sufficient. Therefore, even if it is determined that the boost is insufficient even though the boost is not insufficient, it is possible to correctly determine whether the boost is insufficient.

  In the above-described embodiment, the cuff 12 is wound around the upper arm portion 14, but may be wound around other portions such as a thigh and an ankle.

  The present invention can be modified in various other ways without departing from the spirit of the present invention.

It is a block diagram which shows the circuit structure of the automatic blood pressure measuring device to which this invention was applied. It is a functional block diagram which shows the principal part of the control function of CPU of FIG. It is a figure which shows an example of the amplitude row | line | column comprised by the amplitude of a cuff pulse wave. An envelope derived from the amplitude A of the slow decreasing the beginning of the cuff pulse wave, and determines the reference amplitude TH _A, is a diagram schematically showing the relationship between the criteria beats TH _N. It is a flowchart which shows the principal part of the control action of CPU shown in the functional block diagram of FIG.

Explanation of symbols

10: Automatic blood pressure measuring device 12: Cuff 50: Cuff pressure control means (re-boosting control means)
52: Amplitude determination means 54: Blood pressure value determination means 56: Insufficient pressure increase determination means

Claims (2)

A cuff wound around a predetermined part of the living body is provided, and the cuff is generated in the cuff in the process of increasing the compression pressure of the cuff to a preset pressure increase target pressure value and then gradually decreasing the compression pressure of the cuff. An automatic blood pressure measurement device of a type that determines a blood pressure value of the living body based on a change in amplitude of a cuff pulse wave,
An amplitude determining means for sequentially determining the amplitude of the cuff pulse wave after the start of gradual pressure reduction of the compression pressure of the cuff;
A blood pressure value determining means for determining a systolic blood pressure value based on the rising point of the amplitude sequentially determined by the amplitude determining means;
Insufficient boost determination for determining insufficient pressure based on the fact that the maximum blood pressure value is not determined by the blood pressure value determination means within a predetermined reference reference number of beats after the start of gradual pressure reduction of the compression pressure of the cuff Means,
When it is determined that the pressure increase is insufficient by the pressure increase determination means, the slow pressure reduction of the cuff pressure is stopped, and the pressure of the cuff is set to a value higher than the target pressure value. An automatic blood pressure measurement device comprising: a re-boosting control means for boosting to a re-boosting target pressure value. The insufficient pressure increase determination means is configured to determine a maximum blood pressure value that is not determined by the blood pressure value determination means within a predetermined reference reference number of beats after the start of the slow decrease of the compression pressure of the cuff. 2. The automatic blood pressure according to claim 1, wherein the amplitude determined by the amplitude determining means is determined to be insufficient for boosting based on being larger than a preset criterion amplitude. measuring device.

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