JP2005261505A - Blood pressure measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blood pressure measuring apparatus which determines a precise systolic blood pressure. <P>SOLUTION: The apparatus has a cuff 12, which is wrapped around a prescribed site of a living body and is equipped with a first rubber bladder 18 provided to compress an artery and a second rubber bladder 14 provided inside the first rubber bladder 18 on the downstream side of the first rubber bladder 18 and having a width narrower than that of the first rubber bladder 18, and measures a systolic blood pressure BP<SB>SYS</SB>in a process of gradually decreasing pressure for gradually decreasing the pressure in the first rubber bladder 18. The apparatus includes a blood pressure determining means 64 for determining the systolic blood pressure BP<SB>SYS</SB>from the fact that a delayed time Δt of a second pulse wave M<SB>2</SB>produced at the second rubber bladder 14 to a first pulse wave M<SB>1</SB>produced at the first rubber bladder 18 is larger than a predetermined specific judgement reference value TH. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oscillometric blood pressure measurement device that includes an inflatable bag for compression and an inflatable bag for pulse wave detection in a single cuff in order to improve the accuracy of blood pressure measurement. It is.

  An oscillometric blood pressure measuring device boosts the pressure in an inflatable bag provided in a cuff wound around a predetermined part of a living body to a compression pressure set in advance as a pressure that can completely stop the artery under the cuff. After that, in the process of gradually decreasing the pressure at a predetermined speed, the pressure in the expansion bag is sequentially detected, and the pulse wave is sequentially discriminated from the pressure change in the expansion bag that is sequentially detected, and the sequential discrimination is performed. In general, a method of detecting the compression pressure at the rising point of the envelope obtained by connecting the amplitudes of the pulse waves (that is, when the amplitude suddenly increases) and determining the pressure as the maximum blood pressure value is common.

  However, in the blood pressure measurement device, since the rising point of the envelope of the amplitude is unclear, the determined maximum blood pressure value may be inaccurate. For example, when the blood flow is low or the arterial blood vessel is hard, the change in pulse wave amplitude is small even when the cuff pressure decreases and the blood flow begins to flow. The rising point of is likely to be unclear.

In order to solve the above problems, an inflatable bag for detecting a pulse wave is provided at a downstream position in the cuff, in addition to the inflatable bag for compressing an artery, and the inflatable for detecting the pulse wave is provided. It is considered to measure the blood pressure value based on the amplitude of the pulse wave transmitted to the bag (for example, Patent Documents 1 and 2). In this way, in a state where the pressure of the cuff is higher than the maximum blood pressure value, even if there is a pulsation upstream in the range where the cuff is wound, the pulsation is downstream in the cuff. It is not transmitted directly to the expansion bag for pulse wave detection provided on the side. Therefore, since the rise of the pulse wave generated in the expansion bag for detecting the pulse wave becomes relatively clear, the maximum blood pressure value is determined based only on the amplitude of the pulse wave generated in the expansion bag for detecting the pulse wave. However, an accurate and accurate systolic blood pressure value can be obtained as compared with the case where there is only one inflatable bag.
JP 2001-070262 A JP 2001-333888 A

  However, even when the amplitude of the pulse wave generated in the expansion bag for detecting the pulse wave is used, the rising point may be unclear. For example, in the measurement at the ankle, the rising point tends to be unclear. This is because the pulse wave generated upstream of the cuff at a pressure higher than the maximum blood pressure value is not directly transmitted to the inflation bag for detecting the pulse wave, but via the inflation bag for compression. This is because it is indirectly transmitted to the expansion bag for detecting the pulse wave. Therefore, the accuracy of the systolic blood pressure value determined based only on the pulse wave generated in the expansion bag for detecting the pulse wave is insufficient.

  The present invention has been made in the background as described above, and an object thereof is to provide a blood pressure measurement device capable of obtaining an accurate maximum blood pressure value.

  In order to solve the above-mentioned problem, in Patent Document 1, the amplitude difference between the amplitude of the pulse wave generated in the inflatable bag for compression and the amplitude of the pulse wave generated in the inflatable bag for detecting the pulse wave is calculated. The maximum blood pressure value is determined based on the amplitude difference. In Patent Document 2, the amplitude of the pulse wave generated in the inflatable bag for compression and the amplitude of the pulse wave generated in the inflatable bag for detecting the pulse wave are disclosed. An amplitude ratio with the amplitude is calculated, and the systolic blood pressure value is determined based on the amplitude ratio, but the present invention is an invention that achieves the above object by a configuration different from that.

  According to a first aspect of the present invention for achieving the above object, a cuff wound around a predetermined part of a living body is provided with a first inflating bag provided to compress an artery in the predetermined part, and the first inflating bag. A slow pressure change process that is provided on the inner side downstream of the first inflatable bag and has a second inflatable bag having a narrower width than the first inflatable bag, and gradually changes the pressure in the first inflatable bag. The blood pressure measuring device for measuring the blood pressure value of the living body based on the pulse wave transmitted from the living body to the second inflating bag, the second inflating bag against the pulse wave generated in the first inflating bag It includes blood pressure value determining means for determining a maximum blood pressure value of the living body based on a delay time of the generated pulse wave being larger than a predetermined judgment reference value set in advance.

  In the first aspect of the invention, the downstream side means the downstream side when the cuff is divided into an upstream side and a downstream side.

  Further, the second invention provides a predetermined gradual pressure decrease start pressure that is set to a value higher than the maximum blood pressure value, in order to determine the maximum blood pressure value by the blood pressure value determining means. In the blood pressure measurement device according to the first aspect of the present invention, the compression pressure control means further includes a compression pressure control means for stepping up to a pressure and then gradually decreasing the pressure, wherein the delay time is greater than the determination reference value. Based on this, the pressure in the first expansion bag is rapidly discharged.

  Further, the third aspect of the present invention provides a predetermined gradual pressure drop start pressure in which the pressure in the first inflation bag is set to a value higher than the maximum blood pressure value in order to determine the maximum blood pressure value by the blood pressure value determining means. In the blood pressure measurement device according to the first aspect of the present invention, further comprising a compression pressure control means for stepping up and then stepping down gradually, the first delay time in the step of stepping down the pressure in the first inflation bag is determined. The delay time does not become larger than the judgment reference value when the pressure is larger than the reference value or until the pressure in the first inflatable bag reaches a preset maximum blood pressure lower limit value in the slow pressure reduction process. In the case where the pressurization pressure control means determines that the pressure increase is insufficient by the pressure increase insufficient determination means, and stops the slow pressure reduction, The slow pressure decrease starting pressure After re-boosting remote to a predetermined value higher pressures, again, characterized by starting the slow decreasing.

  According to the first invention, the systolic blood pressure value is determined by the blood pressure value determining means based on the delay time of the pulse wave generated in the second expansion bag with respect to the pulse wave generated in the first expansion bag. As will be described in detail later, this delay time is almost zero when the cuff winding site is hemostatically stopped by the first inflatable bag, but the compression pressure of the first inflating bag is an artery in the cuff winding site. There is a delay time near the maximum blood pressure. Therefore, if the systolic blood pressure value is determined based on the delay time as in the present invention, an accurate systolic blood pressure value can be obtained.

  In the first invention, the maximum blood pressure value can be determined if it is determined that the delay time is smaller than the determination reference value at the beginning of the gradual pressure reduction and then the delay time is longer than the determination reference value. Therefore, when the average blood pressure value and the minimum blood pressure value are unnecessary, the pressure in the first inflating bag is quickly discharged based on the fact that the delay time is larger than the judgment reference value as in the second invention. The pressure reduces the measurement time and reduces the patient's pain due to cuff compression.

  According to the third aspect of the present invention, the insufficient pressure increase determination means determines that the increase in pressure is insufficient during the slow pressure decrease, and when the insufficient pressure increase is determined, the slow pressure decrease is stopped and the first slow decrease is started. Since the slow pressure reduction is resumed after the pressure is increased again to a pressure higher than the pressure, an accurate maximum blood pressure value can be obtained relatively quickly even for a patient having a high maximum blood pressure value.

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

  In FIG. 1, a cuff 12 is for winding a living ankle 19 (see FIG. 2), and a cuff generally used for blood pressure measurement at the ankle is a second rubber that functions as a second inflatable bag. The difference is that a sac 14 is provided. That is, the cuff 12 includes a belt-shaped armband bag 16 configured to be suitably wound around the ankle of a living body with a cloth that is not extensible and has a relatively high rigidity, and the inside of the armband bag 16, A first rubber sac 18 having a predetermined length (for example, 2/3 times the average length of the ankle circumference) whose width direction is slightly shorter than the armband bag 16 and whose longitudinal direction is shorter than the circumference length of the ankle. And. The first rubber sac 18 functions as a first inflatable bag and is mainly used to compress and occlude the blood vessel at the site around which the cuff 12 is wound.

  Further, in the armband bag 16, when the cuff 12 is wound around the ankle 19, the first rubber has a length in the longitudinal direction at a position that becomes the downstream end inside the first rubber bag 18. The width of the first rubber sac 18 is substantially equal to or smaller than a fraction of the width of the first rubber sac 18 (for example, about one fourth to one sixth of the first rubber sac 18). A second rubber sac 14 is provided. The second rubber sac 14 is mainly used for detecting the pulsation of the artery at the site where the cuff 12 is wound.

  In FIG. 2, the cuff 12 configured as described above is wound around the ankle 19 of the living body, and the artery 20 where the cuff 12 is wound is occluded by the compression pressure from the first rubber sac 18. It is a figure which shows a state. In this state, the artery 20 only slightly pulsates at the upstream end of the cuff 12, and at least downstream of the center of the cuff 12 in the width direction (left-right direction in FIG. 2), the artery 20 does not pulsate. . Therefore, the pulsation of the artery 20, that is, the pressure pulse wave is directly transmitted from the body surface 21 to the first rubber sac 18, thereby generating a pulse wave (pressure vibration) in the first rubber sac 18. Only the pulsation of the artery 20 is indirectly transmitted to the sac 14 via the first rubber sac 18. A shielding plate 22 is provided between the first rubber sac 18 and the second rubber sac 14 in order to prevent vibration generated in the first rubber sac 18 from being transmitted to the second rubber sac 14. However, even if the shielding plate 22 is provided, the pulse wave from the first rubber sac 18 is transmitted to the second rubber sac 14 without being completely shielded. The shielding plate 22 is substantially the same size as the second rubber sac 14 in the width direction and the longitudinal direction, and is made of a relatively hard flexible material having a thickness of about 0.3 mm. . The cuff 12 in FIG. 1 is shown with the shielding plate 22 omitted.

  Returning to FIG. 1, the first rubber bladder 18 is connected to a switching valve 24 and a first pressure sensor 25 via a pipe 23, and the switching valve 24 is connected to an air pump 28 via a pipe 26. The second rubber bladder 14 is also connected to the second pressure sensor 32 and the switching valve 24 via a pipe 30 branched from the pipe 23 connected to the first rubber bladder 18. The pipe 30 connected to the rubber bag 14 is made thinner than the pipe 23 connected to the first rubber bag 18 and functions as a throttle device.

  The switching valve 24 is in a pressure supply state that allows the supply of pressure into the cuff 12 (that is, in the first rubber bag 18 and the second rubber bag 14), a slow exhaust pressure state in which the inside of the cuff 12 is gradually discharged, And it is comprised so that it can switch to three states of the rapid exhaust pressure state which exhausts the inside of the cuff 12 rapidly.

The first pressure sensor 25 detects the pressure P ₁ in the first rubber bag 18 and supplies a first pressure signal SP ₁ representing the pressure to the static pressure discrimination circuit 34 and the pulse wave discrimination circuit 36, respectively. The static pressure discriminating circuit 34 includes a low-pass filter, discriminates a steady pressure included in the first pressure signal SP ₁ , that is, the first cuff pressure signal SK ₁ representing the first cuff pressure PK _1, and the first cuff pressure signal SK. ₁ is supplied to the electronic control unit 40 via the A / D converter 38. The pulse wave discriminating circuit 36 includes a band-pass filter, and discriminates the pulse wave signal SM ₁ that is a vibration component of the first pressure signal SP ₁ in terms of frequency and passes the pulse wave signal SM ₁ through the A / D converter 42. Supply to the electronic control unit 40. This pulse wave signal SM ₁ is a pressure vibration generated in the first rubber sac 18 when the pulsation of the artery 20 under the cuff 12 is transmitted to the first rubber sac 18 and represents the first pulse wave M ₁ . .

The second pressure sensor 32 detects the pressure P ₂ in the second rubber bladder 14 and supplies a second pressure signal SP ₂ representing the pressure to the pulse wave discrimination circuit 44. The pulse-wave filter circuit 44 is configured similarly to the pulse-wave filter circuit 36 connected to the first pressure sensor 25, a pulse wave signal SM ₂ is a vibration component of the second pressure signal SP ₂ Frequency manner After discrimination, the pulse wave signal SM ₂ is supplied to the electronic control unit 40 via the A / D converter 45. This pulse wave signal SM ₂ represents the second pulse wave M ₂ generated in the second rubber bag 14.

The electronic control unit 40 includes a CPU 46, a ROM 48, a RAM 50, and a so-called microcomputer having an I / O port (not shown). The CPU 46 has a storage function of the RAM 50 according to a program stored in the ROM 48 in advance. By executing signal processing while using it, a drive signal is output from the I / O port to control the switching valve 24 and the air pump 28. In the control process of the switch valve 24 and the air pump 28, the pulse wave signal _SM 1 supplied from the first pressure signal SP ₁ and the pulse-wave filter circuit 36, 44 supplied from the static-pressure filter circuit 34, SM ₂ Based on this, the systolic blood pressure value BP _SYS is determined, and the determined systolic blood pressure value BP _SYS is displayed on the display 52.

FIG. 3 is a functional block diagram for explaining the main part of the control function of the electronic control unit 40. In the figure, the compression pressure control means 60 drives the air pump 28 and switches the switching valve 24 to the pressure supply state, whereby the pressure in the cuff 12 wound around the ankle 19 of the living body (that is, the first rubber). pressure) in the pressure and in the second rubber bag 14 in the sac 18 is quickly increased, based on the first cuff pressure signal SK ₁ supplied from the static-pressure filter circuit 34, pressing pressure of the first rubber bag 18 is given If it is determined that the slow pressure decrease starting pressure P _CM (for example, a pressure value of about 240 mmHg) has been reached, then the air pump 28 is stopped and the switching valve 24 is switched to the slow exhaust pressure state. As a result, the pressure in the cuff 12 is gradually reduced at a speed set in advance to about 3 mmHg / sec. However, if it is determined that the boosted shortage by boosting shortage determination unit 66 to be described later, to stop the slow decreasing immediately the predetermined slow decreasing starting pressure P _CM further predetermined value α than (e.g., 30 mmHg) After the pressure in the cuff 12 is increased again to a value as high as possible, the above-mentioned slow pressure reduction is resumed. When the systolic blood pressure value BP _SYS is determined by the blood pressure value determining means 64 described later, the pressure in the cuff 12 is rapidly exhausted by switching the switching valve 24 to the rapid exhaust pressure state.

The delay time calculation means 62 gradually reduces the pressure in the cuff 12 based on the pulse wave signals SM ₁ and SM ₂ sequentially supplied from the two pulse wave discrimination circuits 36 and 44 by the compression pressure control means 60. allowed are sequentially determining the occurrence time of the first pulse wave M ₁ and a predetermined delay time calculation point of the second pulse wave M ₂ are sequentially detected in the process it is. The delay time calculation point is a peak in this embodiment, but may be another part of the pulse wave such as a rising point. Further, the delay time calculating means 62 calculates the time difference between the occurrence times of the peaks of the first pulse wave M ₁ and the second pulse wave M ₂ (that is, the delay time calculation point) as the delay time Δt.

The blood pressure value determining unit 64 sequentially determines whether or not the delay time Δt sequentially calculated by the delay time calculating unit 62 is greater than a preset determination reference value TH, and the delay time Δt is greater than the determination reference value TH. Is changed from a small state to a state larger than the determination reference value TH, the compression pressure of the first expansion bag 18 at that time, that is, the first cuff pressure PK ₁ is changed to the first cuff from the static pressure discriminating circuit 34. Based on the pressure signal SK ₁ , the first cuff pressure PK ₁ is determined as the maximum blood pressure value BP _SYS . Then, the determined systolic blood pressure value BP _SYS is displayed on the display 52.

Thus systolic blood pressure BP _SYS determined by indicates the systolic blood pressure BP _SYS good correlation measured by auscultation, about 40 patients in the experiment of measuring the systolic blood pressure value BP _SYS according to the present invention and the auscultatory method The correlation coefficient R between them was 0.95. Here, considering the reason that the blood pressure value determining means 64 can determine the maximum blood pressure value BP _SYS based on the delay time Δt between the first pulse wave M ₁ and the second pulse wave M ₂ , the following will be given. Can be estimated.

In a state where the cuff winding site is stopped, the first pulse wave M ₁ generated in the first rubber sac 18 is directly transmitted from the body surface 21 by the pulsation of the artery 20 generated at the upstream end of the cuff 12. On the other hand, the second pulse wave M ₂ generated in the second rubber sac 14 is generated at the upstream end of the cuff 12 because the second rubber sac 14 is provided on the downstream side of the cuff 12. The pulsation of the artery 20 is not transmitted directly, but is only transmitted indirectly via the first rubber sac 14. Accordingly, since the first pulse M ₁ phase generated in the first rubber bag 18 and the second pulse wave M ₂ phases generated in the second rubber bag 14 is equal, the delay time Δt is substantially zero in hemostasis .

In contrast, immediately after the compression pressure of the cuff 12 becomes smaller than the maximum blood pressure value BP _SYS of the artery 20 and the blood flow of the artery 20 is resumed under the cuff 12, the internal pressure of the artery 20 is the highest pressure (that is, the highest pressure). Only during the period near the high blood pressure BP _SYS ), blood flow is generated in the artery 20 under the cuff 12. In such a state, in the state where the internal pressure of the artery 20 is near the minimum blood pressure value (the diastole of the heart), as shown in FIG. 2 described above, most of the artery 20 under the cuff 12 is occluded. However, as the internal pressure of the artery 20 increases, the occluded portion decreases to become as shown in FIG. 4A, and when the internal pressure of the artery 20 further increases to the maximum pressure (cardiac systole), As shown in 4 (b), the closed portion disappears. Then, the pressure pulse wave from the artery 20 is directly transmitted to the second rubber sac 14 as shown in FIG. 4 (b) because the artery 20 is opened just below the second rubber sac 14. It is when it is in a state. On the other hand, the pressure pulse wave from the artery 20 is directly transmitted to the first rubber sac 18 from before the state shown in FIG. Therefore, it is the first pulse wave _{M 1} and the second pulse wave _{M 2} to the delay time Δt occurs.

In addition, when the compression pressure of the cuff 12 is reduced, the occlusion section in the artery 20 is eliminated, and incompressible blood is constantly flowing, the pressure change upstream is instantaneously transmitted downstream. since the so that, again, there is no delay time Δt between the first pulse wave M ₁ and the second pulse wave M _2.

FIG. 5 shows the first pulse wave M ₁ , the second pulse wave M ₂ , and the pressure P ₁ in the first rubber sac 18 obtained in the slow pressure reduction process in the blood pressure measurement with the cuff 12 shown in FIG. 1 wound around the ankle. The pulse wave indicated by BP _SYS is a pulse wave for which the maximum blood pressure value BP _SYS is determined. FIG. 6 is a graph showing the delay time Δt calculated from the pulse waves M ₁ and M ₂ obtained in the same experiment as FIG. Note that the horizontal axis in FIG. 6 is a pulse wave that is sequentially obtained in the slow pressure reduction process from the left side, and BP _SYS indicates a pulse wave when the maximum blood pressure value BP _SYS is determined.

As shown in FIGS. 5 and 6, only a limited part of the delay time Δt calculated from the pulse waves M ₁ and M ₂ sequentially obtained in the slow pressure reduction process shows a relatively large value. . The above results are supported by the results of this experiment. From this experimental result, the criterion value TH is set to 10 msec, for example, as shown in FIG. 6, and as a result, the systolic blood pressure value BP is based on the pulse wave shown by BP _SYS shown in FIGS. _SYS is determined.

Returning to FIG. 3, the under-pressurization determining means 66 is based on the delay time Δt calculated in the process in which the pressure P ₁ in the first rubber bag 18 is gradually reduced by the compression pressure control means 60. It is determined whether the cuff pressure PK ₁ is insufficiently increased. As described above, if a pressure higher than the slow decreasing starting pressure P _CM is systolic blood pressure value BP _SYS, sequentially delay time Δt calculated in slow decreasing process, initially less than the criterion value TH Thereafter, the change once exceeds the judgment reference value TH and again becomes smaller than the judgment reference value TH. On the other hand, if the slow decreasing starting pressure P _CM is slightly lower than the systolic blood pressure value BP _SYS, the delay time Δt which is initially calculated in the slow decreasing process becomes larger than the criterion value TH, the slow If the step-down start pressure P _CM is further low, it does not exceed the determination reference value TH delay time Delta] t. Thus, step-up shortage determination unit 66, if the first delay time Δt in the slow decreasing process is greater than the determination reference value TH, or a systolic blood pressure lower limit value P _L of the first cuff pressure PK ₁ is set in advance By the time, when the delay time Δt has not become larger than the determination reference value TH, it is determined that the pressure increase is insufficient, and the pressure increase control unit 60 is instructed to perform the second pressure increase. Here, the maximum blood pressure lower limit value P _L is set to a pressure at which the maximum blood pressure value BP _SYS is hardly lower than that. For example, it is set to the lower limit value of the fluctuation range of the systolic blood pressure value BP _SYS obtained experimentally, or a value lower by about several tens of mmHg.

  FIG. 7 is a flowchart for explaining a main part of the control operation in the electronic control device 40 of the automatic blood pressure measurement device 10. The routine shown in FIG. 7 is executed by operating a measurement start switch (not shown).

  In FIG. 7, first, in step S <b> 1 (hereinafter, step is omitted), the air pump 28 is started and the switching valve 24 is switched to the rapid pressure increasing state, whereby the cuff 12 is started to increase pressure. That is, supply of pressure into the first rubber sac 18 and the second rubber sac 14 provided in the cuff 12 is started.

Continued In S2, whether the first cuff pressure PK ₁ becomes cuff 12 slow decreasing starting pressure P _{CM (e.g.,} about 240 mmHg) preliminarily set pressing pressure the blood flow can be prevented under the artery 20 or determined Is done. If this determination is negative, the determination is repeated until the determination in S2 is affirmed, during which the pressure of the cuff 12 is continuously increased.

On the other hand, if the determination in S2 is affirmative, in the subsequent S3, the air pump 28 is stopped, the switching valve 24 is switched to the slow exhaust pressure state, and the compression pressure of the cuff 12 is set in advance. The pressure is gradually reduced at a speed of about 3 mmHg / sec. That is, slow decreasing of the pressure P ₂ of the pressure P ₁ and the second rubber bag 14 in the first rubber bag 18 is started.

In subsequent S4, the first cuff pressure PK ₁ supplied from the static pressure discriminating circuit 34, the pulse wave signal SM ₁ supplied from the pulse wave discriminating circuit 36, and the pulse wave signal SM ₂ supplied from the pulse wave discriminating circuit 44. Is read. In subsequent S5, it is determined whether or not those signals have been read for one beat. If the determination in S5 is negative, S4 and the subsequent steps are repeatedly executed, so that every predetermined sampling period. The reading of the signal is repeated.

On the other hand, if the determination in S5 is affirmed, S6 to S7 corresponding to the delay time calculating means 62 are executed. First, in S6, the first pulse wave M ₁ and the second pulse M ₂ of one beat that has been read by the repetition of the S4 to S5, respectively, the peak is determined, the subsequent S7, the two peaks The time difference is calculated as the delay time Δt.

In subsequent S8, it is determined whether or not the delay time Δt calculated in S7 is greater than a preset determination reference value TH. If this judgment is negative, in S13, whether the first cuff pressure PK ₁ is greater than the systolic blood pressure lower limit P _L is further determined. When this determination is affirmed, the above S4 and subsequent steps are repeatedly executed. Thereby, reading of the signal in the process of gradually decreasing the pressure of the cuff 12 is continued.

On the other hand, when the determination in S13 is negative, i.e., if the first cuff pressure PK ₁ is the systolic blood pressure lower limit value P _L despite lower than, not systolic blood pressure BP _SYS is yet determined the execution in S14, after the predetermined value α to the original slow decreasing starting pressure P _CM (e.g. 30 mmHg) is the value that is added is set as a new slow decreasing starting pressure P _CM, step S1 follows again Is done. In this case, the slow decreasing is stopped immediately after a new rapid re boosted until the set slow decreasing starting pressure P _CM is performed, the slow decreasing is resumed.

If the determination in S8 is affirmative, it is determined in subsequent S9 whether or not the delay time Δt has been calculated first. This determination is in boosted insufficient even if it is affirmative, the by S14 is executed, the initial slow decreasing starting pressure P _CM to a predetermined value α is added value a new slow decreasing starting pressure P After being set as _CM , S1 and subsequent steps are executed again. In FIG. 7, S 8 to S 9 and S 13 correspond to the pressure increase insufficient determination means 66.

On the other hand, if the determination in S9 is negative, in S10, the first cuff pressure PK ₁ when the pulse wave in which the determination in S8 is affirmed is generated (for example, a section for one pulse wave) first average value and the cuff pressure PK ₁ in its predetermined portion of the pulse wave (e.g., peak) first cuff pressure PK ₁ when generation) is determined in systolic blood pressure value _{BP SYS,} in the subsequent S11, determination in S10 The obtained maximum blood pressure value BP _SYS is displayed on the display 52. In FIG. 7, S8 to S11 correspond to the blood pressure value determining means 64.

  In the subsequent S12, the switching valve 24 is switched to the rapid exhaust pressure state to release the pressure in the cuff 12, and then this routine is terminated. In FIG. 7, S1 to S3 and S12 correspond to the compression pressure control means 60.

According to the above-described embodiment, the systolic blood pressure value BP _SYS is generated in the second rubber sac 14 with respect to the first pulse wave M ₁ generated in the first rubber sac 18 by the blood pressure value determining means 64 (S8 to S11). since is determined based on the delay time Δt of the pulse wave M _2, it is possible to obtain an accurate systolic blood pressure BP _SYS.

  Further, according to the present embodiment, when it is determined that the delay time Δt exceeds the determination reference value TH, the pressure in the first rubber bag 18 is rapidly discharged, so that the measurement time is shortened and the cuff is cuffed. The patient's pain due to twelve pressures is also reduced.

Further, according to the present embodiment, the insufficient pressure increase determination means 66 determines that the increase in pressure is insufficient during the gradual pressure decrease, and if it is determined that the increase in pressure is insufficient, the gradual pressure decrease is stopped and the first gradual pressure decrease. after being re-pressurized to a pressure higher than the starting pressure P _CM, since the slow decreasing is resumed, even patient systolic blood pressure BP _SYS is high to obtain a relatively fast accurate systolic blood pressure BP _SYS be able to.

  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 above-described embodiment, only the maximum blood pressure value BP _SYS is determined as the blood pressure value BP. However, in addition to the maximum blood pressure value BP _SYS , the average blood pressure value BP _MEAN and the minimum blood pressure value BP _DIA may be determined. . The average blood pressure value BP _MEAN and the minimum blood pressure value BP _DIA are determined by a conventional oscillometric algorithm.

In the above-described embodiment, the systolic blood pressure value BP _SYS is determined in the process in which the compression pressure of the cuff 12 is gradually reduced. However, the compression pressure of the cuff 12 is gradually increased and the pressure is gradually increased. The systolic blood pressure value BP _SYS may be determined on the basis of the signal obtained in step ( _b ).

  In the above-described embodiment, the cuff 12 is attached to the ankle 19, but may be configured to be wound around other than the ankle 19. For example, it may be configured to be wound around the thigh and the upper arm.

  In the above-described embodiment, the length of the second rubber bladder 14 in the longitudinal direction is substantially equal to the length of the first rubber bladder 18 in the longitudinal direction. However, since the second rubber sac 14 is for detecting a pulse wave from the artery 20 at the site around which the cuff 12 is wound, the second rubber sac 14 only needs to be positioned above the artery 20. The length in the longitudinal direction of the two rubber bladders 14 may be shorter than the length in the longitudinal direction of the first rubber bladder 18.

  In the above-described embodiment, the pipe 30 functions as a throttling device by being made thinner than the pipe 23. However, instead of reducing the diameter of the pipe 30 as described above, an orifice is provided in the middle of the pipe 30. May be provided.

Further, in the above-described embodiment, by using the thin pipe 30 functioning as the throttle device, the pressure P ₁ in the first rubber bladder 18 and the second rubber bladder 14 with one air pump 28 and one switching valve 24. Although the internal pressure P ₂ was controlled simultaneously, separate air pumps and switching valves may be provided for the first rubber bladder 18 and the second rubber bladder 14, respectively.

  In the above-described embodiment, the second rubber sac 14 is positioned on the most downstream side of the cuff 12. However, the second rubber sac 14 is within the range of the downstream side of the cuff 12. It may be located on the upstream side.

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

It is a block diagram explaining the circuit structure of the blood pressure measuring device which is one Example of this invention. It is a figure which shows the state by which the cuff of FIG. 1 was mounted | worn with the ankle of the biological body, and the artery of the site | part in which the cuff was wound is obstruct | occluded. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus in the Example of FIG. It is a figure which shows the obstruction | occlusion state of an artery when the compression pressure of a cuff is near a maximum blood pressure value, (a) shows the case where the internal pressure of an artery is between the minimum pressure and the maximum pressure, (b) Indicates the case where the internal pressure of the artery is the highest pressure. 1 shows a part of the first pulse wave M ₁ , the second pulse wave M ₂ , and the pressure P ₁ in the first rubber sac 18 obtained in the slow pressure reduction process in the blood pressure measurement in which the cuff 12 shown in FIG. 1 is wound around the ankle. FIG. 6 is a graph showing a delay time Δt calculated from pulse waves M ₁ and M ₂ obtained in the same experiment as FIG. It is a flowchart explaining the principal part of the control action | operation in the electronic controller in the Example of FIG.

Explanation of symbols

10: Automatic blood pressure measuring device 12: Cuff 14: Second rubber sac (second inflatable bag)
18: First rubber bag (first inflatable bag)
60: Compression pressure control means 64: Blood pressure value determination means 66: Pressure increase insufficient determination means

Claims (3)

A cuff wound around a predetermined part of the living body is provided with a first inflatable bag provided for compressing an artery in the predetermined part, and provided on the downstream side of the first inflatable bag inside the first inflatable bag. A second inflatable bag having a width narrower than that of the first inflatable bag, and is transmitted from the living body to the second inflatable bag in a slow pressure changing process for gradually changing the pressure in the first inflatable bag. A blood pressure measurement device for measuring a blood pressure value of the living body based on a pulse wave,
The blood pressure that determines the maximum blood pressure value of the living body based on the delay time of the pulse wave generated in the second inflatable bag with respect to the pulse wave generated in the first inflatable bag being larger than a predetermined judgment reference value set in advance. A blood pressure measuring apparatus comprising a value determining means. In order to determine the systolic blood pressure value by the blood pressure value determining means, the pressure in the first inflatable bag is rapidly increased to a predetermined gradual pressure decrease starting pressure set to a value higher than the systolic blood pressure value, The blood pressure measurement device according to claim 1, further comprising a compression pressure control means for gradually lowering pressure.
The blood pressure measurement device according to claim 1, wherein the compression pressure control means rapidly discharges the pressure in the first inflatable bag based on the delay time being greater than the determination reference value. In order to determine the systolic blood pressure value by the blood pressure value determining means, the pressure in the first inflatable bag is rapidly increased to a predetermined gradual pressure decrease starting pressure set to a value higher than the systolic blood pressure value, The blood pressure measurement device according to claim 1, further comprising a compression pressure control means for gradually lowering pressure.
When the first delay time in the slow depressurization process of the pressure in the first expansion bag is larger than the judgment reference value, or the pressure in the first expansion bag is preset in the slow depressurization process When the delay time does not become greater than the determination reference value before reaching the maximum blood pressure lower limit value, including an under-pressurization determining means for determining an under-pressurization,
When the compression pressure control means determines that the pressure increase is insufficient by the pressure increase insufficient determination means, after stopping the slow pressure reduction and re-pressurizing to a pressure higher than the slow pressure decrease start pressure by a predetermined value The blood pressure measurement device is characterized in that slow pressure reduction is started again.

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