JP5107535B2 - Blood pressure measurement device - Google Patents

Description

The present invention relates to a blood pressure measurement device, and more particularly to a blood pressure measurement device that performs non-invasive blood pressure measurement using an oscillometric method using an ischemic cuff .

  According to the conventional oscillometric sphygmomanometer, the pressure of the ischemic cuff is gradually increased to a pressure higher than the systolic blood pressure, or is positioned below the ischemic cuff while being lowered from the pressure higher than the systolic blood pressure. Based on the change in the volume of the artery, the vibration of the cuff pressure is detected, and the blood pressure is determined by the change in the amplitude of the vibration.

  The method for obtaining the systolic blood pressure in the blood pressure measurement method using such an ischemic cuff is to increase the pressure of the ischemic cuff above the systolic blood pressure, which is the highest pressure in the artery, while the arterial blood flow stops. By lowering, blood flow is detected and detected.

  On the other hand, according to the Korotkoff method (auscultation method), which is now widely used, the blood pressure is stopped by raising the pressure of the ischemic cuff more than the systolic blood pressure, and then gradually increasing the pressure of the ischemic cuff. The systolic blood pressure value (maximum blood pressure value) is obtained by detecting the Korotkoff sound generated at the timing of lowering and resuming blood flow on the downstream side of the ischemic cuff.

  The oscillometric method is a method of capturing the phenomenon of blood flow resumption as pressure vibration of the ischemic cuff based on the arterial volume change under the ischemic cuff. For this reason, the oscillometric method does not require a sensor (including a stethoscope) for detecting the Korotkoff sound in comparison with the Korotkoff method.

  In the auscultation method, noise (cuff cloth, cuff tube rubbing sound, vibration) generated during blood pressure measurement has a drawback that the frequency component of noise is likely to be erroneously detected because it is close to the frequency component of Korotkoff sound. On the other hand, the frequency component of the pressure fluctuation during the oscillometric measurement is low. In addition, since it is greatly deviated from the noise frequency generated during blood pressure measurement, it is not affected by noise, and it can be measured even if there is a position shift when wearing a cuff with respect to the artery to be measured. Therefore, it is mainly used for automatic blood pressure monitors.

  However, the oscillometric method has a problem in detecting systolic blood pressure (maximum blood pressure value) due to the blood vessel compression characteristics of the Rivaroch cuff used in the ischemic cuff. In other words, the Rivaroch cuff can obtain a compression force reflecting the cuff pressure in the central portion in the width direction, but if it deviates from the central portion, a compression force reflecting the cuff pressure cannot be obtained, and from the central portion to the end of the cuff. The compression force gradually decreases, and the end portion exhibits a characteristic that becomes zero.

  Because of these characteristics, blood flow is stopped at the center of the cuff when the cuff pressure of the ischemic cuff at the timing of measuring systolic blood pressure is close to the systolic blood pressure. become. As a result, a phenomenon occurs in which the blood flow enters and returns from the upstream portion of the ischemic cuff to the central portion of the ischemic cuff in synchronization with the pulsation of the heart. Due to this phenomenon, the pulse wave has already been detected before the generation of the pulse wave used to detect the blood flow resumption phenomenon to the downstream side (forearm side) of the cuff serving as the detection target of the systolic blood pressure.

In addition, when the cuff pressure of the ischemic cuff becomes lower than the systolic blood pressure and the blood flow resumes, a volume change due to the blood flow occurs downstream from the center under the ischemic cuff. for use the cuff pressure is slightly lower than the arterial pressure, blood vessels during the short time, thus quickly closed after opening. At this time, the volume change on the downstream side under the ischemic cuff is very small compared to the volume change on the upstream side.

  The pulse wave detected by the oscillometric method is based on the volume change in which the upstream volume change and the downstream volume change under the above-mentioned ischemic cuff are overlapped. It is very difficult to select and detect this particularly when the blood flow is small. As described above, the oscillometric method causes the deterioration of the S / N ratio in the measurement of systolic blood pressure as compared with the Korotkoff method.

As described above, detection may be difficult due to a change caused by resumption of blood flow. Therefore, conventionally, the following measures have been taken. If the pressure of the ischemic cuff is further lowered from the systolic blood pressure, the downstream volume under the ischemic cuff due to the longer period of time during which the arterial pressure is higher than the pressure of the ischemic cuff during the cardiac cycle As the change increases, the amplitude of the pulse wave gradually increases.

  Also, depending on the degree of congestion, if the intravascular pressure in the peripheral region is greater than the cuff pressure for ischemia than the cuff for ischemia, a baroreflex occurs from the periphery, and the pulse wave suddenly increases from this cuff pressure due to this reflection. Become. As the ischemic cuff pressure is further reduced, the time during which the intravascular pressure at the peripheral site becomes larger than the internal pressure of the ischemic cuff becomes longer, and immediately before the time when the blood vessel is closed, the upstream portion and the peripheral portion of the ischemic cuff These blood vessels are fully opened at the same time, and the amplitude of the pulse wave is maximized.

  The volume change at this time is a change upstream of the cuff center corresponding to 50% of the blood vessel volume under the ischemic cuff at the time of systolic blood pressure measurement. Approximately twice the pulse wave amplitude during systolic blood pressure measurement. Utilizing this, a method is adopted in which the systolic blood pressure is set at a timing at which the pulse wave amplitude is about 50% of the maximum pulse wave amplitude.

However, this ratio depends on the upstream and downstream volume imbalances, cuff compliance differences, the degree of increase in intravascular pressure at the peripheral site, timing Affected by. In addition, the increase in intravascular pressure at this peripheral site is influenced by the degree of congestion due to the short repetition time of blood pressure measurement. Has an effect.

A double cuff system has been devised to solve these problems. This double cuff method is a method in which an ischemic cuff used for blood vessel compression and a detection cuff for detecting only a pulse wave at a central portion under the ischemic cuff are provided separately from the ischemic function. According to this double cuff method, the influence of the pulse wave based on the upstream volume change under the ischemic cuff at the time of measuring the systolic blood pressure, which is a problem in the oscillometric method, can be reduced. It is possible to detect a volume change downstream of the ischemic cuff with a good S / N ratio. (Patent Document 1)
However, at the detection timing of systolic blood pressure, the blood flow entering the upstream side under the ischemic cuff may enter the immediate vicinity of the pulse wave detection cuff, which is detected by the pulse wave detection cuff. since there is provided a pulse wave detection cuff under ischemia cuff, notably pulse wave detection cuff oscillation of the cuff based on the upstream volume change of the under cuff ischemia detected by ischemia cuff is in contact In some cases, the S / N ratio in the measurement of systolic blood pressure may be deteriorated.

Therefore, a backing is provided to improve the compression performance of the pulse wave detection cuff so that the blood flow entering from the upstream side of the pulse wave detection cuff does not approach when the blood vessel is closed by the ischemic cuff. Install a cushioning material for damping the transmission pulse wave from the ischemic cuff between the pulse wave detection cuff and the ischemic cuff, and further to dump the pulse wave upstream under the ischemic cuff Proposals for providing cushioning materials have also been made. (Patent Document 2)
However, according to this proposal, the compression force of the pulse wave detection cuff can be improved, but there is a limit to the extent to which the ischemic point is separated from the pulse wave detection cuff. In addition, since there is a limit to the damping characteristics of the members used, the relatively high frequency components of the pulse wave can be attenuated, but there are cases where the low components cannot be sufficiently attenuated. For this reason, the systolic blood pressure may not be detected with a good S / N ratio.
JP 2004-195056 A Japanese Patent Laid-Open No. 2004-321251

  Therefore, the present invention has been made in view of such a situation, and more effectively eliminating the influence of the volume change in the upstream portion of the ischemic cuff relative to the pulse wave detection cuff by the oscillometric method, The purpose is to improve the S / N ratio for detection of blood pressure.

In order to solve the above-described problem, a blood pressure measurement device according to the present invention has the following configuration. That is,
A cuff body attached to the blood pressure measurement site;
A blood pressure measuring device comprising: a main body portion that controls pressurization and decompression of the cuff main body,
The cuff body is
An ischemic cuff that compresses the artery at the site of blood pressure measurement;
A sub-cuff disposed closer to the heart than the substantially central portion below the ischemic cuff;
A pipe branched and connected to the cuff for ischemia and the sub-cuff;
A fluid resistor connected between the pipe and the sub-cuff;
A check valve connected in parallel with the fluid resistor between the pipe and the sub-cuff;
The main body is
A cuff pressure detector connected to said pipe,
Pressurizing means for pressurizing the ischemic cuff and the sub- cuff through the pipe ;
A decompression control unit for decompressing the ischemic cuff and the sub- cuff via the pipe;
A pulse wave detection unit that is electrically connected to the cuff pressure detection unit and detects a detection pulse wave signal from a detection cuff pressure signal of the cuff pressure detection unit;
A blood pressure detection unit that determines a blood pressure value based on the detected pulse wave signal detected by the pulse wave detection unit and the detected cuff pressure signal of the cuff pressure detection unit in the decompression process by the decompression control unit ;
A blood pressure display unit for displaying a blood pressure value from the blood pressure detection unit ,
The check valve is controlled to be opened when the pressurizing unit pressurizes to a pressure higher than the systolic blood pressure, and closed when pressurization by the pressurizing unit is stopped. It is characterized by .

  In addition, a first backing member including a backing material is disposed between the ischemic cuff and the sub-cuff.

  Further, a second backing member including a backing material is disposed between the ischemic cuff and the cuff body.

  Further features of the present invention will become apparent from the best mode for carrying out the present invention and the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the reduction | decrease change of the compression pressure which arises toward the cuff end from the cuff center part of the compression pressure which is a fault of the Rivaroch cuff used for the ischemic cuff can be eliminated. Specifically, it is reinforced with the compression force of the sub-cuff to which the same pressure as the ischemic cuff is applied to prevent blood from flowing into the upstream part under the ischemic cuff at the timing of systolic blood pressure measurement. The volume change generated by the blood flowing from the upstream side toward the center of the cuff for ischemia is guarded by the sub-cuff, and further attenuated moderately by the fluid resistor connected to the sub-cuff, and the volume change to the ischemic cuff It is possible to accurately detect only the pulse wave change due to the volume change on the downstream side under the ischemic cuff based on the resumption of blood flow by improving the S / N ratio.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a blood pressure measurement device according to an embodiment of the present invention.

  According to the embodiment of the figure, a blood pressure measurement cuff 100 (hereinafter referred to as a cuff) for detecting a pulse wave includes a cuff cloth 5 serving as a cuff body mounted on an arm serving as a blood pressure measurement site, and blood pressure measurement. There is provided a cuff 1 for ischemia that compresses the artery K at the site, and a sub-cuff 3 that is disposed on the heart H side from a substantially central portion below the cuff 1 for ischemia. Further, a pipe 6 connected to the ischemic cuff 1 and the sub-cuff 3 through branch portions 6a, 6b, 6c, 6d as shown in the figure is provided, and between the branch portions 6b, 6d of the pipe 6 is provided. A fluid resistor 11 such as an orifice is connected.

  The sub-cuff 3 is disposed on the side in contact with the living body so as to be positioned between the upstream end of the ischemic cuff 1 and the central portion of the ischemic cuff. The size of the sub-cuff 3 is not limited to the illustrated size, and a part of the sub-cuff 3 may protrude on the left side of the ischemic cuff 1 in the upstream side (heart side) from the central portion of the ischemic cuff. The cuff 1 may have the same overall length in the vertical direction.

  The blood pressure measurement device shown in FIG. 1 is composed of a device body 10 and a cuff 100 attached to a blood pressure measurement site.

  As shown in the figure, the cuff 100 is attached so that the upstream portion of the cuff is on the left ventricle side where the blood flow of the artery at the blood pressure measurement site flows. This cuff 100 is configured by providing a cuff cloth 5 that wraps the entire cuff with the cuff 1 for ischemia and the sub-cuff 3 connected via the fluid resistor 11, and the cuff 100 is wound around the blood pressure measurement unit. It has a hook-and-loop fastener (not shown) for fixing later. In addition, the cuff 100 may be provided with a backing member made of a backing material, which will be described later, between the cuff cloth 5 and the cuff on the side opposite to the surface of the cuff 1 that contacts the living body.

  On the other hand, the pipe 7 may be further connected from the branch portions 6 b and 6 d of the pipe 6. By connecting a check valve 21 connected in parallel with the fluid resistor 11 to the pipe 7, the cuff When the pressure of 100 is applied, the check valve 21 bypasses the fluid resistor 11 so that the sub-cuff 3 can be pressurized within a short time.

  By enabling the pressurization in this way, for example, when the size of the arm of the blood pressure measurement person is increased and the volume of the sub-cuff has to be set large, when the pressurization is performed via the fluid resistor 11, the sub-cuff 3 is It is comprised so that it can prevent not fully expanding.

  The cuff 100 and the main body 10 are detachably connected by a connector 38, but may be integrated piping.

  In order to eliminate the pulse wave detected by the sub-cuff 3, a fluid resistor 11 is connected between the ischemic cuff 1 and the sub-cuff 3 as shown in the figure. Note that the S / N ratio of the systolic blood pressure measurement is improved by setting the capacity B of the sub-cuff 3 to a maximum (A / 2) ml, where the capacity of the cuff 1 for ischemia is Aml.

  On the other hand, a pressurization control unit 19 for controlling the air pressure from the pump 18 and a decompression control unit 20 for performing decompression exhaust control are piped on the pipe 7 of the cuff 100 as shown in the figure.

  The pipe 7 is connected to a cuff pressure detection unit 13 including a pressure sensor. From the output of the cuff pressure detection unit 13, a pulse wave detection unit 14 that detects a pulse wave superimposed on the output is connected. The blood pressure value is determined by the blood pressure detecting unit 15 based on the detected cuff pressure signal from the cuff pressure detecting unit 13 and the detected pulse wave signal from the pulse wave detecting unit 14, and the determined blood pressure value is displayed on the liquid crystal display. The blood pressure display unit 16 provided with a device or the like is configured to display.

  Further, the main body 10 includes a power source unit 17 such as a battery. The main unit 10 controls the above-described pump and each control unit, and controls a CPU including a ROM, a RAM, and the like that store various control programs readable by a computer. Power is supplied.

  Here, either or both of the fluid resistor 11 and the check valve 21 are disposed in the main body 10 and connected to the sub-cuff 3 via a separate pipe so that the cuff 100 can be reduced in size and weight. Anyway. Each of the detection units 13, 14, 15 and the display unit 16, and the control units 19 and 20 are built in a CPU 70 (not shown) and can execute a predetermined program.

  2A is a cross-sectional view after the cuff 100 is broken in the width direction and attached to the measurement site. FIG. 2B is an enlarged piping diagram for explaining the operation.

  In FIG. 2A, a first backing member 30 including a backing material is disposed between the ischemic cuff 1 and the sub-cuff 3 in order to enhance the compression characteristics of the sub-cuff 3. A second backing member 40 including a backing material is disposed between the ischemic cuff 1 and the cuff cloth 5.

  In FIG. 2 (a), the sub-cuff 3 is reinforced with the same pressure as the ischemic cuff 1, and the blood K1 is prevented from flowing into the upstream part under the ischemic cuff 1 at the timing of the systolic blood pressure measurement. The volume change generated by the blood K1 flowing from the upstream side of the cuff toward the central part of the cuff for crushing is guarded by the sub-cuff 3, and further attenuated by a fluid resistor connected to the sub-cuff 3 Since the volume change can be prevented from being transmitted to the cuff 1, it is possible to accurately detect only the pulse wave change due to the volume change downstream of the ischemic cuff 1 based on the resumption of blood flow with an improved S / N ratio. Became.

  The cuff 100 configured as described above can be used for various blood pressure measurement devices. For example, according to the blood pressure measurement device shown in FIG. 1, the stored control program is read out by a computer, and the blood pressure measurement routine of FIG. It can operate like a flowchart.

  First, when the blood pressure apparatus is activated, pressurization is started by the pressurization control unit in step S1, and pressurization is performed in the direction of the arrow shown by the broken line in FIG. 2B, and the process proceeds to step S2. In this step S2, 20-30 mmHg higher than the expected systolic blood pressure is set as a set pressure, and it is checked by the signal of the cuff pressure detection unit whether the pressure of the cuff 1 for ischemia has reached the set pressure. Run until. When the pressure of the cuff 1 for ischemia reaches the set pressure, the pressurization control unit stops pressurization in step S3. Here, when an electromagnetic valve is used as the check valve 21, the opening operation is performed in step S1, and the closing operation synchronized with the stop operation is performed in step S3.

  Subsequently, the process proceeds to step S4, and the pressure reduction control unit uses the signal from the cuff pressure detection unit to start the pressure reduction in the arrow direction indicated by the solid line in FIG. 2B so that the pressure reduction rate becomes 2 to 3 mmHg / sec. Is done. Subsequently, in step S5, the detection of the pulse wave is started from the signal from the cuff pressure detector. The pulse wave signal detected by the pulse wave detection unit is sent to a storage unit in the blood pressure detection unit, and the cuff pressure and the pulse wave amplitude are stored as a set. In step S6, the blood pressure detection unit detects the maximum value of the pulse wave amplitude, detects that the pulse wave amplitude continuously decreases, and detects the previous pulse wave that starts decreasing as the pulse wave maximum value. To do.

  Then, it progresses to step S7, the pulse wave which becomes 60% or less of a pulse wave maximum value is detected in a blood pressure detection part, and the cuff pressure at that time is determined as a diastolic blood pressure (minimum blood pressure value). When the diastolic blood pressure is determined, the process proceeds to step S8, where rapid exhaust is performed by the decompression control unit. In step S9, from the data in which the cuff pressure and the pulse wave amplitude recorded in the blood pressure detection unit are a set, a change in which the pulse wave amplitude is suddenly increased by 50% or more after the start of pressure reduction is performed. The detected pressure value of the pulse wave whose amplitude suddenly increases is determined as the systolic blood pressure. When determined in this way, in step S10, the systolic blood pressure value and the diastolic blood pressure value are displayed on the blood pressure display unit, and the series of blood pressure measurement operations is terminated.

  FIG. 4 shows the pulse wave amplitude and cuff pressure stored in the blood pressure determination unit in time series. (A) shows the detected pulse wave amplitude change when the sub-cuff is not used, and (b) shows the detected pulse wave amplitude change when the sub-cuff of the present invention is used.

  As shown in the figure, compared with the waveform of FIG. 4A, the waveform of FIG. 4B has a clear pulse wave amplitude change at the systolic blood pressure detection timing.

  As described above, even when the cuff pressure for ischemia is higher than the systolic blood pressure, the blood flow entering the lower cuff upstream of the cuff for cuff can be blocked by the sub-cuff. Detection was possible with a good S / N ratio, and the determination accuracy of the systolic blood pressure value could be improved.

It is a block diagram which shows the blood pressure measuring device of one Embodiment of this invention. (A) is sectional drawing of the cuff 100 of FIG. 1, (b) is an enlarged piping figure. 2 is an operation explanatory flowchart of the blood pressure measurement device in FIG. 1. (A) is the detected pulse wave amplitude change when the sub-cuff is not used, and (b) is the detected pulse wave amplitude change when using the sub-cuff of the present invention, the pulse wave amplitude and the cuff pressure stored in the blood pressure determining unit. It is the chart which displayed chronologically.

Explanation of symbols

1 Cuff for ischemia 3 Sub cuff 5 Cuff cloth 6 and 7 Pipe 11 Fluid resistor 21 Check valve 10 Body 100 Cuff (blood pressure measurement cuff)

Claims (3)

A cuff body attached to the blood pressure measurement site;
A blood pressure measuring device comprising: a main body portion that controls pressurization and decompression of the cuff main body,
The cuff body is
An ischemic cuff that compresses the artery at the site of blood pressure measurement;
A sub-cuff disposed closer to the heart than the substantially central portion below the ischemic cuff;
A pipe branched and connected to the cuff for ischemia and the sub-cuff;
A fluid resistor connected between the pipe and the sub-cuff;
A check valve connected in parallel with the fluid resistor between the pipe and the sub-cuff;
The main body is
A cuff pressure detector connected to said pipe,
Pressurizing means for pressurizing the ischemic cuff and the sub- cuff through the pipe ;
A decompression control unit for decompressing the ischemic cuff and the sub- cuff via the pipe;
A pulse wave detection unit that is electrically connected to the cuff pressure detection unit and detects a detection pulse wave signal from a detection cuff pressure signal of the cuff pressure detection unit;
A blood pressure detection unit that determines a blood pressure value based on the detected pulse wave signal detected by the pulse wave detection unit and the detected cuff pressure signal of the cuff pressure detection unit in the decompression process by the decompression control unit ;
A blood pressure display unit for displaying a blood pressure value from the blood pressure detection unit ,
The check valve is controlled to be opened when the pressurizing unit pressurizes to a pressure higher than the systolic blood pressure, and closed when pressurization by the pressurizing unit is stopped. A blood pressure measuring device characterized by the above.   The blood pressure measurement device according to claim 1, wherein a first backing member including a backing material is disposed between the ischemic cuff and the sub-cuff.   The blood pressure measurement device according to claim 1, wherein a second backing member including a backing material is disposed between the cuff for ischemia and the cuff body.

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