JPS592730A - Hemomanometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blood pressure monitor that measures blood pressure using Korotkoff sounds, and its purpose is to display the condition when blood pressure measurement is performed under good conditions. Other objectives are to reliably detect the second phase of voiced sounds in Korotkoff sounds, to display blood pressure measurements in good conditions, to enable blood pressure measurements to be performed in correct conditions, and to provide guidance on measurement techniques. , the purpose is to improve.

Currently, the standard clinical method for general indirect blood pressure measurement is the Koro
It is based on the auscultation method by Mr. Tkov.

This method involves wrapping a cuff around the subject's upper arm, injecting all the air into the cuff, and lowering the expected systolic blood pressure by 20 to
Apply a high pressure of 30 wHg to compress the brachial artery and stop blood flow. Next, the air pressure in the cuff band, that is, the cuff pressure 1 to 2 to
Evacuate slowly at a rate of 3 mHg/l1ec. Eventually,
When the cuff pressure reaches the systolic pressure, the brachial artery opens slightly,
Blood flow begins to flow. At this time, a damped vibration called a sound (hereinafter abbreviated as sound) is generated in the lateral direction of the blood vessel wall.

As the cuff pressure is further lowered, the sound continues to occur in synchronization with the pulse, but it eventually disappears when the artery becomes sufficiently voluminous and the blood flow becomes constant. The cuff pressure when the sound first occurs is the systolic blood pressure, and the cuff pressure before it disappears, that is, when the sound last occurs, is the diastolic blood pressure.

The characteristics of the K sound are 5 as shown in Figure 1 by Mr. Swan.
It was shown that there are three points and four phases. first,
A weak crisp clear tone is heard (first phase), then a dull tone occurs (second phase), then it becomes a crisp clear tone again (third phase), and then suddenly becomes a weak pure tone (fourth phase). The first point is when you first hear the sound, and the second to fourth points are the transitions of each phase.
The fifth point is the point where the K sound disappears (actually, the last point). Generally, the first point is the systolic blood pressure and the fifth point is the diastolic blood pressure.

In conventional blood pressure measurements, the phase of sound is generally not controlled. Also, actually measure it ^
As a result, there were many cases in which the first phase transitioned to the third phase without generating the second phase of voiced sounds. Therefore, when measuring by raising the arm before applying pressure, and then lowering the arm after applying pressure,
When measuring by clenching and opening the hand several times before applying pressure, the second phase of dullness occurs in most cases, and the K sound does not change correctly from the first sum to the fourth phase. Understood. Also, when second-phase voiced sounds occur, the amplitude of the sound becomes larger than when it does not occur, and S/
It was found that the N ratio was increased, making it easier to measure blood pressure, and reducing the number of measurements required, resulting in reliable measurements.

The present invention has been made in view of this point, and by detecting and displaying whether or not the second phase of voiced sounds has occurred,
This allows you to see if blood pressure measurements are being taken under good conditions, and to ensure reliable blood pressure measurements.

On the other hand, the clear sound waveform of the K sound is as shown in Figure 2(a), and the turbid sound waveform is as shown in Figure 2(b). Figure 2(a),
In (b), (a) is the output of the crab sound sensor, and (I) is the output that has been passed through a filter in the crab sound region (approximately 20 to 200 Hz). The voiced sound is considered to be a small signal portion in the latter half of the K sound signal. Therefore, by paying attention to this time lag, it is possible to detect voiced sounds. The present invention will be explained in detail below with reference to Examples.

In Fig. 3, (1) is a sound sensor (K sound sensor), which is made up of a microphone, etc., and receives a signal as shown in Fig. 4 (a) detected by the sound sensor fi+. Only the sound signal is detected through a filter (K blue filter i2) as shown in FIG. 4(b).

The sound signal is passed through the first shibrator (3) to the fourth
An output as shown in Figure (C) is obtained and the signal as shown in Figure 14 (D) is obtained by passing through the entire expansion circuit (4). This signal is input to the control circuit (5). The process up to this point is the same as the conventional sound detection method.

Next, a circuit for detecting all voiced sounds will be explained. A certain period of time (approximately 10~1QQ) from the rise of the output of the expansion circuit (4)
msec) through a delay circuit (6) that generates a delayed signal J8 as shown in FIG.
7), a gate signal is generated for a certain period of time (approximately 10 to 200 rnsec) from the fall of the delayed signal, as shown in FIG. 4(f). On the other hand, a signal as shown in FIG. 4(g) is obtained by passing through the second comparator (8) which adjusts the output of the K-blue filter (2) to a level suitable for detecting voiced sounds. This signal, the gate signal, and the tAND gate (9) are used to detect all the dull sounds in the sound as shown in Figure 4 (h), and the control circuit (5
). In addition, the pressure in the cuff band (lO) is detected by a pressure transducer (Ill) and input to the control circuit (5).In the control circuit (5), the output of the tension circuit (4) is first generated. The pressure transducer (the cuff pressure obtained from the river) is displayed as the systolic blood pressure value, and the cuff pressure when it occurred last is displayed on the display as the diastolic blood pressure value.
A voiced sound was detected during the continuous generation of K sounds, and the AND gate (9)
When the output is obtained, the second phase of dullness is detected by a part of the display 021 or another display either immediately or after the blood pressure measurement is completed, and the paper indicates that the blood pressure measurement was performed in good condition. The present invention provides an indication when the second phase of the Korotkoff sound is detected, so it is possible to know whether the blood pressure measurement was performed under good conditions, and reliable blood pressure measurement is possible. A gate signal generating circuit is provided which has a Rotkoff sound filter and generates a gate signal for a certain period of time after a certain period of time from the rise of the Korotkoff sound, and the output of the gate signal generator circuit is Since the second phase of the voiced sound in the Korotkoff sound is detected, the second phase of the voiced sound in the Korotkoff sound can be reliably detected, blood pressure measurement can be displayed in a good state, and blood pressure measurement can be performed in the correct state. This has the effect of being able to provide guidance on measurement techniques and funding for improvement.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram of the] 0 Tokoff sound, Figure 2 <-), (b) is a waveform diagram of the clear and voiced sounds of the Roto] F sound, and Figure 3 is a block circuit of an embodiment of the present invention. Figure, Figure 4(a)~
(hl is the same signal waveform diagram as above. tl+...]0t]F sound secessor, +21-:]O) Knock sound filter, (5)・Control circuit, (6)・Delay circuit,
(7)・Gate signal generation circuit, 02)・Display device. Agent Patent Attorney Ishi 1) Long Figure 2 (B) ~,! -(b)+ (0) (b) Figure 3/1: ■ Figure 4 (h)

Claims (1)

[Scope of Claims] ill A sphygmomanometer for measuring blood pressure using Korotkoff sounds, characterized in that a display is displayed when a second-phase dullness of the Korotkoff sounds is detected. (2) A gate signal generation circuit is provided which has a Korotkoff sound filter that detects only the Korotkoff sound signal and a Korotkoff sound signal, and generates a gate signal for a certain period of time after a certain period of time from the rise of the Korotkoff sound, and the gate signal generation circuit 2. The blood pressure monitor according to claim 1, wherein the second phase of the voiced sound in the sound is detected by the output of [0]].