JPH11146868A - Blood pressure measurement device - Google Patents

Abstract

(57) [Summary] [Problem] To always pressurize at the optimum pressure regardless of the patient's current blood pressure. An electrocardiogram electrode detects an R wave as a time interval detection reference point on a pulse wave of an aorta of a living body, and a pulse oximeter probe detects a pulse on a peripheral blood vessel which appears later than the pulse wave of the aorta. Detect waves. The CPU 1 calculates the pulse wave propagation time from the R wave to the pulse wave on the peripheral blood vessel side, calculates the systolic pressure based on the pulse wave propagation time, adds the systolic pressure and a predetermined pressure, and pressurizes the cuff 2. Calculate the pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood pressure measuring device for measuring blood pressure using a cuff, and more particularly to a blood pressure measuring device suitable for monitoring biological information such as an electrocardiogram and a pulse wave in addition to blood pressure. .

[0002]

2. Description of the Related Art Conventionally, in a blood pressure measuring device of this kind, pressurized air more than a cuff wound around an arm or the like by a fixed pressure of, for example, about 50 mmHg more than a systolic pressure (systolic blood pressure value) at the previous measurement. Is supplied from a pressurizing pump to block the blood in the arm, etc., and then the pressurized air is exhausted at a very low speed from an exhaust valve to reduce the pressure in the cuff. During this exhaust, the pressure in the cuff is measured by a pressure sensor. In addition, a pulse wave component is drawn based on the pressure, a pulse wave amplitude value is calculated from the pulse wave component, and a blood pressure is calculated based on the pulse wave amplitude value and the cuff pressure. In addition, it is also known that the pressure and Korotkoff sound are simultaneously measured during exhaust instead of the pulse wave component, and the measured pressure at the time of appearance is determined as the systolic blood pressure value, and the measured pressure at the time of disappearance is determined as the minimum blood pressure value. Have been.

[0003]

By the way, the blood pressure of a patient including the systolic pressure (systolic blood pressure value) is not always constant but fluctuates constantly. However, in the above-mentioned conventional blood pressure measurement device, blood is blocked by supplying pressurized air obtained by adding a constant pressure to the systolic pressure at the previous measurement, so that the patient's blood pressure is significantly higher than at the previous measurement. In this case, the pressurization becomes insufficient with respect to the previous systolic pressure, and the measurement cannot be performed. Therefore, there is a problem in that the apparatus again starts measurement and pressurization, thereby causing pain to the patient.
Furthermore, since the blood pressure value cannot be immediately known due to the remeasurement operation, normal patient monitoring cannot be performed. In addition, when the blood pressure of the patient is lower than normal, pressure is applied more than necessary, which again causes a problem to the patient.

[0004] In view of the above-mentioned conventional problems, an object of the present invention is to provide a blood pressure measuring device which can always pressurize at an optimum pressure regardless of the current blood pressure of a patient.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a blood pressure measuring apparatus for measuring a blood pressure by pressurizing a cuff. A time interval detecting reference point detecting means for detecting a reference point, a pulse wave detecting means for detecting a peripheral vascular pulse wave appearing later than the aortic pulse wave, the time interval detecting reference point detecting means and the pulse wave Pulse wave transit time detecting means for detecting a pulse wave transit time based on each detection output of the detecting means, and a systole for calculating a systolic pressure based on the pulse wave transit time detected by the pulse wave transit time detecting means A pressure calculating unit that adds the systolic pressure calculated by the systolic pressure calculating unit and a predetermined pressure to calculate a pressurized pressure of the cuff.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a pulse wave transit time measuring device according to the present invention, FIG. 2 is a waveform diagram showing main measurement signals of the pulse wave transit time measuring device of FIG. 1, and FIG. 4 is a flowchart for explaining the operation at the time of blood pressure measurement.

In FIG. 1, a cuff 2 is mounted on the upper arm or finger of a subject to measure blood pressure. In this mounted state, the cuff 2 is pressurized by a pressurizing pump 4 until the upper arm or finger of the subject is blocked, and then an exhaust valve is provided. The pressure is reduced via 3. Pressure sensor 5
Detects a signal including the pressure in the cuff 2, and a cuff pressure detection and amplification section 6 detects and amplifies a pressure signal from the signal detected by the pressure sensor 5. This pressure signal is supplied to the A / D converter 7
Is converted into a digital signal, and this digital pressure signal is taken into the CPU 1. The pressurizing pump 4 and the exhaust valve 3 are controlled by the CPU 1 via the output interface 8.

The ECG electrode 1 is attached to the subject's chest or the like to detect a signal including an ECG signal. The electrocardiogram signal is converted into a digital signal by the A / D converter 11, and the digital electrocardiogram signal is taken into the CPU 1. Here, the analog electrocardiogram signal has the top value of the R wave as shown in FIG. 2 (a), and the aortic pressure is the R value as shown in FIG. 2 (b).
The top value of the wave becomes the bottom value, rises relatively steeply slightly after the bottom value, and then falls relatively slowly.

Returning to FIG. 1, the pulse oximeter probe 12 is attached to a finger or the like to measure the concentration of oxygen dissolved in the blood, and although it is not shown, the probe has a wavelength λ1 that affects the hemoglobin in the blood. LED that outputs light
1, a phototransistor provided to face LED1 so as to detect light of wavelength λ1, LED2 outputting light of wavelength λ2 which does not affect hemoglobin, and LED2 so as to detect light of wavelength λ2. It is composed of phototransistors provided to face each other. Then, each pair of the LED and the phototransistor is mounted so as to face each other according to the size of the measurement site of the subject.

[0010] The LED control section 13 has an L of wavelength λ1.
The current applied to the ED1 is controlled, and the LED control unit 14 controls the current applied to the LED2 having the wavelength λ2. The photoelectric pulse wave signal detection / amplification unit 15 detects and amplifies a pulse wave signal from the output signal of the phototransistor having the wavelength λ1, and the photoelectric pulse wave signal detection / amplification unit 16 calculates the pulse wave signal from the output signal of the phototransistor having the wavelength λ2. Detect and amplify the signal. The output signals of the photoelectric pulse wave signal detection / amplification units 15 and 16 are converted into digital signals by A / D converters 17 and 18, respectively.
It is taken into 1.

As shown in FIG. 2C, the analog pulse wave signal on the peripheral blood vessel side such as a finger or an ear has its bottom value slightly delayed from the bottom value of the aortic pressure shown in FIG. 2B. This delay time is called a pulse wave propagation time. In this case, based on the R wave of the electrocardiogram waveform shown in FIG. 2A, the pulse wave propagation time is the time from the appearance of the top value of the R wave to the appearance of the bottom value of the pulse wave on the peripheral blood vessel side. Becomes

When measuring blood pressure using the pulse wave transit time, the blood pressure is measured in advance using another method such as a cuff,
It is necessary to calibrate by referring to this measurement result. After performing this calibration, for example, when the blood pressure rises, the pulse wave transit time becomes shorter. Therefore, the blood pressure value can be obtained by correcting the pulse wave transit time at this time and the time difference between the pulse wave transit times at the time of calibration. . The blood pressure value P can be obtained by the following equation. P = αT + β where T is the pulse wave transit time, α and β are parameters unique to the subject, and the parameters α and β can be obtained when the pulse wave transit time T is calibrated. , The blood pressure P and the pulse wave transit time T are measured.

Here, the resting blood pressure P and the pulse wave transit time T
Are P1 and T1, respectively, and the blood pressure P and the pulse wave transit time T during the exercise load are P2 and T2, respectively.
P2 is given by: P1 = αT1 + β (1) P2 = αT2 + β (2) By measuring these P1, T1, P2 and T2, the parameters α and β can be obtained.
Therefore, the blood pressure P can be obtained by measuring the pulse wave propagation time T by obtaining the parameters α and β in advance for each subject. Note that the parameters α and β need not be at rest and during exercise load, but may be at the time when two different blood pressure values appear.

The input unit 19 is used to instruct the pulse wave transit time, and to use the calibration blood pressure values P1 and P2 used for calibration.
Used for inputting the information. C is stored in the ROM 20 in advance.
The program of PU1 is stored, and RAM 21 stores
It is used as a work area. The CPU 1 executes a processing program based on input signals from the A / D converters 7, 11, 17, 18 and the input unit 19, and outputs the processing result to the display 22 and the output interface 8. That is, as shown in detail in FIG. 3, when measuring the blood pressure, the CPU 1 controls the pressurizing pump 4 and the exhaust valve 3 at regular time intervals and at the time of operating the blood pressure measuring key of the input unit 19, thereby controlling the electrocardiographic electrode 9 and the pulse oximeter. By taking in signals from three systems of the probe 12 and the pressure sensor 5, the blood pressure value is measured and displayed on the display 22. Also, at the time of measuring the heart rate, the heart rate is calculated by taking in the signal from the system of the electrocardiogram electrode 9 and displayed on the display 22 together with the electrocardiogram waveform.
By taking in the signal from the system, the oxygen saturation is calculated, and the pulse wave is measured and displayed on the display 22.

Next, the operation of the CPU 1 when measuring the blood pressure will be described with reference to FIG. First, the non-invasive blood pressure (N) is determined by determining whether the blood pressure measurement time or the blood pressure measurement key has been operated.
It is determined whether or not it is time to start measuring IBP (Non Invasive Blood Pressure) (step S1). In step S2 and subsequent steps, first,
The signal from the system of the electrocardiogram electrode 9 is taken and FIG.
2 is detected, and then a signal from the system of the pulse oximeter probe 12 is acquired to
By detecting a pulse wave signal as shown in FIG.
The pulse wave propagation time T1 from the wave to the bottom value of the pulse wave signal is calculated (step S2).

Next, the NIBP calculation value BP1 is calculated by the following equation: BP1 = α × T1 + β (Step S)
3) Then, the following equation BP2 = BP1 + 50 [mmHg] The pressurization pressure BP2 is calculated (step S4). Next, the arm or the like is blocked by supplying the air having the pressurized pressure BP2 into the cuff 2 from the pressurizing pump 4, and then the pressurized air is exhausted from the exhaust valve 3 at a low speed to reduce the pressure in the cuff 2. During the evacuation, the pressure in the cuff 2 is measured by the pressure sensor 5, and a pulse wave component is drawn based on the pressure.
Next, a pulse wave amplitude value is calculated from the pulse wave component, and a non-invasive blood pressure (NIBP) is calculated based on the pulse wave amplitude value and the cuff pressure (step S5). Next, the blood pressure display process is executed (step S6), and the blood pressure measurement process ends.

[0017]

As described above, according to the first aspect of the present invention, the pulse wave transit time is detected without invasion, and the systolic pressure is calculated based on the pulse wave transit time. Since the pressurizing pressure of the cuff is calculated by adding the pressure and the predetermined pressure, the pressurizing can always be performed at the optimum pressure regardless of the current blood pressure of the patient.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a pulse wave transit time measuring apparatus according to the present invention.

FIG. 2 is a waveform diagram showing main measurement signals of the pulse wave transit time measuring device of FIG.

FIG. 3 is a flowchart for explaining the operation of the CPU in FIG. 1 when measuring blood pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Cuff 3 Exhaust valve 4 Pressure pump 5 Pressure sensor 8 Output interface 9 Electrocardiogram electrode 10 Electrocardiogram signal detection amplification part 12 Probe for pulse oximeter 15, 16 Photoelectric pulse wave signal detection amplification part 19 Input part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Rie Tanaka 1-31-4 Nishi-Ochiai, Shinjuku-ku, Tokyo Inside Photoelectric Industries, Inc. (72) Inventor Chen Wenxi 1-31, Nishi-Ochiai, Shinjuku-ku, Tokyo No. 4 Japan Photovoltaic Industry Co., Ltd.

Claims (1)

[Claims] 1. A blood pressure measuring device for measuring a blood pressure by pressurizing a cuff, comprising: a time interval detection reference point detecting means for detecting a time interval detection reference point on a pulse wave of an aorta of a living body; Pulse wave detecting means for detecting a pulse wave on the peripheral blood vessel side appearing late; pulse wave propagation time for detecting a pulse wave propagation time based on each detection output of the time interval detection reference point detecting means and the pulse wave detecting means. Detecting means; systolic pressure calculating means for calculating a systolic pressure based on the pulse wave transit time detected by the pulse wave transit time detecting means; and a predetermined systolic pressure calculated by the systolic pressure calculating means. Means for calculating the pressurized pressure of the cuff by adding pressure.