JPH02128752A - blood pressure measuring device - Google Patents

Abstract

PURPOSE:To accurately determine maximal blood pressure and mean blood pressure by measuring the change of a liquid amount corresponding to the volumetric change of the membrum as the impedance change of an electric conductive liquid with respect to the electric conductive liquid in the liquid amount control type liquid receiving part surrounding the membrum. CONSTITUTION:In measuring blood pressure, an electrolyte W is supplied to a liquid receiving part 13 and, after the membrum A is inserted in a membrum receiving part B, an AC constant current is allowed to flow between current applying electrodes 17a, 17b. The volumetric change DELTAV of the membrum part corresponds to the change quantity DELTAZ of the impedance Z between voltage detection electrodes 18b, 18c measured by a measuring device 19. The liquid pressure (Pch) of a liquid receiving part 13 is raised by a pressure controller 15 and, when said pressure (Pch) reaches the maximal blood pressure or more, the artery is perfectly closed under pressure and the volumetric change DELTAV of the membrum A is eliminated and the change quantity DELTAZ of the impedance Z is not detected. Thereafter, the Pch is reduced and the Pch obtained when the change quantity DELTAZ of the impedance Z appears as a pulse wave is judged to be the maximal blood pressure. When the Pch is further reduced, the amplitude of the pulse wave of DELTAZ increases to take the max. value and subsequently decreases. The Pch at the amplitude max. point is judged to be mean blood pressure Pam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Applicability Meter) The present invention relates to a method for measuring blood pressure, and in particular to a method for measuring systolic blood pressure and mean blood pressure, and making it possible to accurately determine the measured values. , relating to a blood pressure measurement method.

[Conventional technology]

As a conventional non-invasive blood pressure measuring method, there is a method using a photoplethysmometer as shown in FIG. In this blood pressure measurement method using a photoelectronic plethysmometer, a hydraulic cuff 2 for body cavity compression is attached around the measurement part of the limb L, and the limb L is sandwiched between the central part of the inner surface of the cuff 2. A light source 3 and a light receiving element 4 are used, and the liquid pressure of the cuff 2 can be changed by a pressure controller 5. Since the fluid pressure is recorded by the pressure measuring device 7, changes in the volume of the arterial blood vessels 6 in the limbs due to blood pressure pulsations under various pressure conditions can be detected by the light source 3 and the light receiving element 4. The photoelectric plethysmometer 8 electrically detects the change in the amount of transmitted light.

In other words, by using the volume oscillation method, which measures changes in the amount of transmitted light while gradually changing the fluid pressure in the cuff 2 over time, the fluid pressure in the cuff 2 at the vanishing point of the pulse wave of the amount of transmitted light is determined as the systolic blood pressure. The maximum point of the amplitude of the pulse wave is determined as the mean blood pressure.

Another method that is currently widely used is auscultation, which involves compressing a limb and determining intravascular pressure based on the compression pressure and Korotokoff sounds, which are related to the condition of the blood vessel wall. .

[Problem to be solved by the invention]

By the way, in the method using the conventional photoelectric plethysmometer as described above, the absolute amount of transmitted light is small in relatively thick parts of the body such as arms and legs, so it is difficult to measure the measurement area in relatively thin parts such as fingers. In addition, errors may occur due to scattered light, light that has passed through areas near both ends of the cuff 2 where compression by the cuff 2 is not effective, and light from outside other than the light source. Another problem is that natural light has a negative effect on measurements.

In addition, the conventional auscultation method described above has the problem of poor measurement accuracy, especially poor determination of diastolic blood pressure, and errors that increase due to measurement conditions and individual differences among subjects.Furthermore, the theoretical basis of this method is Another problem is that the mechanism that produces certain Korotkoff sounds has not been fully elucidated.

The present invention aims to solve the above-mentioned problems.The present invention aims to solve the above-mentioned problems.The present invention aims to solve the problems described above. To provide a blood pressure measuring method that enables accurate and simple determination of systolic blood pressure and mean blood pressure by measuring changes in fluid volume corresponding to changes in volume of a body cavity as changes in impedance or admittance of the fluid. With the goal.

[Means to solve the problem]

In order to achieve the above-mentioned object, the blood pressure measuring method of the present invention includes a method for measuring blood pressure formed between a rigid outer cylinder made of an electrically insulating material and a flexible inner cylinder made of an electrically insulating material disposed inside the outer cylinder. A conductive liquid is stored in the liquid volume-adjustable liquid storage part, and the body cavity is inserted into the body limb receiving part inside the inner cylinder, and then the fluid pressure in the liquid storage part is adjusted sequentially over time. While gradually increasing or decreasing the impedance or admittance, the change in impedance or admittance accompanying the change in the amount of the liquid in a predetermined length of the liquid storage section is measured, and the measured impedance pulse wave or It is characterized in that the fluid pressure at the vanishing point of the admittance pulse wave is determined to be the systolic blood pressure.

Further, the present invention is characterized in that the maximum amplitude point of the impedance pulse wave or admittance pulse wave is determined to be the average blood pressure.

(Function) In the above-described blood pressure measuring method of the present invention, after the body cavity is inserted into the body limb receiving part inside the flexible inner cylinder, the fluid pressure in the liquid storage part between the outer cylinder and the inner cylinder is measured. An operation is performed to gradually increase or decrease the value over time.

Then, while performing the above operation, an impedance pulse wave or an admittance pulse wave is measured in accordance with a change in liquid volume corresponding to a change in the body/limb volume of liquid within a predetermined length range of the liquid storage section.

Based on the results of such measurements, it is determined that the fluid pressure at the vanishing point of the impedance pulse wave or admittance pulse wave is the systolic blood pressure.

Also, a determination is made that the fluid pressure at the maximum amplitude point of the impedance pulse wave or admittance pulse wave is the average blood pressure.

〔Example〕

Hereinafter, a blood pressure measuring method as an embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a schematic vertical cross-sectional view of a limb volume measuring device used for the measurement, and FIG. FIG. 2(b) is a graph recording the change over time in the liquid pressure in the liquid storage section. FIG. 2(b) is a graph recording the change over time in the impedance pulse wave for the electrolytic solution in the liquid storage section.

As shown in FIG. 1, a rigid outer cylinder 11 is mounted on a base member 10.
is installed, and a flexible inner cylinder 12 is arranged inside the outer cylinder 11, and the peripheral edges of the 7 flange-shaped ends 12a and 12b at both ends of the inner cylinder 12 are connected to the ends of the outer cylinder 11. It is installed in a liquid-tight manner on the inner surface of the unit.

In this way, the liquid volume adjustable liquid storage section 13 is formed between the outer cylinder 11 and the inner cylinder 12, and the liquid storage section 13 is
It is communicated with the electrolyte tank 14.

That is, an electrolytic solution W as a conductive liquid is supplied into the liquid storage part 13, and as this electrolytic solution, physiological saline or a saline solution with a lower concentration is used. It will be done.

In addition, a pressure controller 15 is connected to the gas phase portion of the electrolyte tank 14, and the pressure controller 15 is connected to the electrolyte tank 14 in response to a detection signal from a sensor 16 that detects the liquid pressure in the liquid storage portion 13. By supplying operating pressure to the hydraulic pressure, control is performed to maintain the hydraulic pressure at a predetermined value. That is, the electrolytic solution tank 14, the pressure controller 15, and the sensor 16 constitute a fluid pressure regulating means.

The outer cylinder 11 is made of an electrically insulating material such as bulk acrylic, and the inner cylinder 12 is a flexible member such as a rubber tube that has a body cavity receiving part B for receiving the body cavity A inside. . And, on the inner circumference of the outer cylinder 11,
A pair of current applying electrodes 171° 17'b and four voltage detecting electrodes 18a, 18b, 18c between the same electrodes 17a, 17b are spaced apart from each other in the longitudinal direction.
18d are arranged, and these electrodes can be connected to required terminals of a measuring instrument 19 for measuring impedance or admittance.

Note that receivers 20g and 20b for the limbs A are provided at both ends of the base member 10, respectively.

Then, the internal pressure Pcb and impedance of the liquid storage section 13 are simultaneously measured and recorded by the pressure sensor 16 and the measuring instrument 19.

When measuring the blood pressure of a desired part of the body limb A using the body cavity volume measuring device having the above-described configuration, first, the liquid storage section 13 is
An appropriate amount of electrolyte W is supplied to the body cavity A, and then, after the body cavity A is inserted into the body cavity receiving part B, the current applying electrodes 17s and 17b
A required alternating current constant current is applied in between. The volume change ΔV of the body cavity where the blood pressure is to be measured is calculated as follows using the change ΔZ of the mutual impedance 2 between the voltage detection electrodes 18b and 18c measured by the measuring device 19 due to the change in fluid volume. expressed.

ΔV=(P,・Ly/2・Δ2) In other words, the volume change ΔV of the body cavity corresponds to the impedance change Δ2.In this way, in this method, the change in the volume of the body cavity is caused by the electrical It is converted into a digital signal.

In addition, in the above formula, P is the specific resistance of the electrolytic solution W, and L is
is the distance between the voltage detection electrodes 18b and 18c.

After the above-mentioned operation is performed, the pressure controller 15 then adjusts the hydraulic pressure (Pch) in the liquid storage section 13.
An operation is performed to raise the artery in limb A until it is completely compressed and closed. Figure 2(i).

As shown in (b), when Pch reaches the systolic blood pressure or higher, the artery is completely compressed and closed (see reference numeral 21), so the volume change ΔV of limb A due to blood pressure pulsation disappears, and therefore the impedance , the change ΔZ is not detected.

After that, the pressure controller 15
When blood begins to flow into the artery as the pressure gradually decreases, a volume change ΔV of the limb A occurs due to the blood pressure pulsation, and accordingly, a minute amplitude appears in the impedance 2. This minute amplitude, that is, the change in impedance Δ
Pcl+ when Z appears as a pulse wave is the systolic blood pressure Pis
(See reference numeral 22).

As Pcb is further decreased, the amplitude of the pulse wave of Δ2 gradually increases as the blood flow increases, reaches a maximum value, and then decreases. Pch at this maximum amplitude point (see reference numeral 23) is determined to be the mean blood pressure Psm. This is because, due to the nonlinearity of the pressure/volume characteristics of blood vessels, arterial blood pressure is at its most extensible state when the intravascular pressure and extravascular pressure are equal, and the volume change in response to a change in pressure is maximum. .

The diastolic blood pressure P xd (see numeral 24) is determined by Feb and Δ
Although it cannot be determined directly from the change in 2, it can be calculated using the following formula.

Psdm(3Pa1l-Pu5)/2In addition, Pcl
An appropriate speed for reducing + is about 3 to 5 am) Ig/l heartbeat.

In addition, in this example, the systolic blood pressure and mean blood pressure are determined from the impedance pulse wave, but even in the determination method using the admittance pulse wave, the admittance can be easily obtained as the reciprocal of the impedance, so the impedance measurement Systolic blood pressure and mean blood pressure can be determined using the same operations as in the case of .

Furthermore, in this embodiment, first, the hydraulic pressure Pch is changed to the systolic blood pressure Pss.
Measurements have been carried out by increasing the Pch pressure to a higher level and then reducing the pressure from there.However, if you measure the impedance pulse wave in the same way while gradually increasing the Pch pressure from a low pressure, the systolic blood pressure and the average Blood pressure can be determined.

In this way, in this embodiment, the systolic blood pressure and the mean blood pressure can be measured without relying on the amount of light that passes through the limb A as in the past, and therefore, it is not affected by external influences such as natural light. Moreover, the body limbs to be measured are not limited to particularly thin parts, and any part of the body can be measured.

Furthermore, the measurement accuracy is improved by converting volume changes due to blood pressure pulsations in the limbs into electrical impedance pulse waves or admittance pulse waves, and the operation requires only the operation of the pressure controller 15, so no skill is required. This method has the advantage that systolic blood pressure and mean blood pressure can be measured accurately and easily because there are no differences among individuals.

〔Effect of the invention〕

As detailed above, according to the blood pressure measurement method of the present invention,
The following effects or advantages can be obtained.

(1) Unlike the conventional photoplethysmometer method, systolic blood pressure and mean blood pressure can be measured without relying on the amount of light that passes through the limbs, so there is no external influence such as natural light. Furthermore, the body limb to be measured is not limited to particularly thin parts, and any part of the body can be measured.

(2) Measurement accuracy is improved because changes in volume due to blood pressure pulsations in the body cavity are converted into electrical impedance pulse waves or admittance pulse waves.

(3) Since the measurement operation only requires changing the fluid pressure in the fluid storage section, no skill is required and there are no individual differences, making it possible to accurately and easily measure systolic blood pressure and mean blood pressure. can.

[Brief explanation of the drawing]

Fig. 1 is a schematic vertical cross-sectional view of a body limb volume measuring device used for the measurement, and Fig. 2 (1) is a graph recording changes over time in the liquid pressure in the liquid storage section of the above device. (b)
3 is a graph recording the change in impedance pulse wave over time for the electrolytic solution in the liquid storage section, and FIG. 3 is a schematic diagram showing a conventional photoelectric plethysmometer. 1. Body limb, 2. Cuff, 3. Light source, 4. Light receiving element, 5. Pressure controller, 6. Arterial blood vessel,
7. Pressure measuring device, 8. Photoelectric plethysmometer, 10.
Base member, 11... Outer cylinder, 12... Flexible inner cylinder, 12
g, 12b...7 flange-like end, 13...liquid volume adjustable liquid storage section, 14...electrolyte tank, 15...pressure controller, 16...sensor 17a, 17b-
- Current applying electrodes, 18g, 18b, 18c, 18d - Voltage detection electrode, 19... Measuring device, 20a, 20b... Receiving part, 21... Arterial pressure closure area, 22... Systolic blood pressure point, 23
・・Mean blood pressure point, 24・・Minimum blood pressure point, A・・Limb, B
... Limb receiving part, W... Electrolyte. Agent Patent attorney Yoshi Iinuma Intention Kodo Adachi Hideyuki Abe No. 3 Diagram procedural amendment 1 Indication of the case 1984 Patent application No. 284688 2 Name of the invention Blood pressure measurement method 3 Person making the amendment Address related to the case Name Address Name 4 Agent Postal Code Address Odakyu Shinanomachi Apartment Room 706, 5-3 Minamimotomachi, Shinjuku-ku, Tokyo

Claims (2)

[Claims] (1) The liquid volume adjustable liquid storage section formed between a rigid outer cylinder made of an electrically insulating material and a flexible inner cylinder made of an electrically insulating material disposed inside the outer cylinder is electrically conductive. After storing the liquid and inserting the body limb into the body limb receiving part inside the inner cylinder, the liquid pressure in the liquid storing part is gradually increased or decreased gradually over time. While changing the impedance or admittance of the liquid along a predetermined length of the liquid storage section, the change in impedance or admittance is measured, and the liquid pressure at the vanishing point of the measured impedance pulse wave or admittance pulse wave is measured. A blood pressure measurement method characterized by determining systolic blood pressure. (2) The liquid volume adjustable liquid storage section formed between the rigid outer cylinder made of electrically insulating material and the flexible inner cylinder made of electrically insulating material disposed inside the outer cylinder has electrical conductivity. After storing the liquid and inserting the body limb into the body limb receiving part inside the inner cylinder, the liquid pressure in the liquid storing part is gradually increased or decreased gradually over time. While changing the impedance or admittance of the liquid in a predetermined length of the liquid storage section, the change in impedance or admittance accompanying the change in the amount of the liquid is measured, and the change in the impedance or admittance of the liquid at the maximum point of the amplitude of the measured impedance pulse wave or admittance pulse wave is measured. A blood pressure measurement method characterized by determining blood pressure as an average blood pressure.