JP3071304B2 - Electronic sphygmomanometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic sphygmomanometer. More specifically, the present invention relates to an electronic sphygmomanometer that measures blood pressure using Korotkoff sounds.

[0002]

2. Description of the Related Art In a conventional electronic sphygmomanometer using the Korotkoff sound method, when measuring the blood pressure of a person who has a weak Korotkoff sound (hereinafter referred to as K sound), or when the arm band is poorly wound and above the artery. When the blood pressure is measured in a state where the sensor is shifted, it may be difficult to perform measurement using the K sound method. In such a case, in order to prevent erroneous measurement, it is determined whether or not blood pressure measurement by the K sound method is possible. In a conventional electronic sphygmomanometer using the K-tone method, whether or not this is possible is determined by (1) whether the maximum value of the K-tone signal is greater than a predetermined level, or (2) the K-tone signal having a certain level or more. Was performed by checking the judgment condition of how many beats there are.

[0003]

However, the above-mentioned conventional method for determining whether or not blood pressure can be measured by the K-tone method in an electronic blood pressure monitor has a problem that erroneous determination is highly likely. For example, when the K sound near the systolic blood pressure value is very weak, and the blood pressure of a hypertensive person or the like whose K sound is close to the average blood pressure value and the K sound is normal is measured, the K sound near the systolic blood pressure value can be detected. Instead, the measured value of systolic blood pressure may become a value near the average blood pressure value. That is,
A measurement result that is lower than the actual systolic blood pressure value will be obtained. In this case, the blood pressure measurement by the K-tone method is not accurately performed, but the determination condition described in the above-described conventional technique is satisfied, and the blood pressure measurement by the K-tone method is determined to be “OK”. In some cases. That is, in the conventional electronic blood pressure monitor, there is a problem that reliability in determining whether or not the K sound method can be executed is low.

There is also a phenomenon called an auscultation gap in which the K sound that has begun to be heard becomes inaudible halfway and appears again.
This auscultation gap is common in hypertensive individuals. When such an auscultation gap occurs, the K sound from the beginning of hearing to the auscultation gap is processed as noise, and the measured value of systolic blood pressure may be lower than the actual value. If the K sound signal after the auscultation gap satisfies the above-described determination condition for determining whether the blood pressure can be measured by the K sound method according to the related art, the blood pressure measurement by the K sound method is determined to be “OK”. Also in this case, the blood pressure measurement by the K-tone method is “OK” even though the blood pressure measurement is not correctly performed.
Is determined, the measurement is erroneous.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and determines the measurement state of the K sound blood pressure by checking the level of the K sound based on the pulse wave signal. An object of the present invention is to provide an electronic sphygmomanometer that prevents erroneous measurement of measurement.

[0006]

An electronic sphygmomanometer according to the present invention for achieving the above object has the following arrangement. That is, an electronic sphygmomanometer having a cuff pressure detecting section for detecting cuff pressure and a Korotkoff sound signal detecting section for detecting Korotkoff sound, wherein the cuff pressure signal stores cuff pressure signal data detected by the cuff pressure detecting section. Data storage means, Korotkoff sound signal data storage means for storing Korotkoff sound signal data detected by the Korotkoff sound detection section, and a predetermined level based on the cuff pressure signal data stored in the cuff pressure signal data storage means. Time phase detection means for detecting the time phase of the Korotkoff sound signal that should satisfy the condition,
Extraction means for extracting the Korotkoff sound signal in the time phase detected by the time phase detection means from the Korotkoff sound signal data storage means, and the level of the Korotkoff sound signal extracted by the extraction means is determined by the predetermined level condition. Determining means for determining whether the blood pressure is measured by checking whether the condition is satisfied;

[0007]

In the above arrangement, the cuff pressure signal and the Korotkoff sound signal detected by the cuff pressure detecting section and the Korotkoff sound signal detecting section are stored in the cuff pressure data storing means and the Korotkoff sound data storing means, respectively. The time phase detection means detects a time phase at which a Korotkoff sound satisfying a predetermined level condition should be detected based on the cuff pressure signal stored in the cuff pressure data storage means. The extracting means extracts the Korotkoff sound signal in the time phase detected by the time phase detecting means from the Korotkoff sound signal data storage. Then, it is determined whether or not the extracted Korotkoff sound signal satisfies the predetermined level condition. That is, by checking whether the Korotkoff sound signal in the time phase that should satisfy the predetermined level condition, which is obtained based on the cuff pressure data, satisfies this level condition, it is possible to determine the measurement state in the blood pressure measurement by the Korotkoff sound method. Is what you do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of the electronic sphygmomanometer of the present embodiment. In the figure, 1 is CP
U controls the entire electronic blood pressure monitor. 2 is ROM
And stores a program describing the execution procedure of various processes of the CPU 1, various initial values, and the like. Reference numeral 3 denotes a RAM for auxiliary storage, which has an area for storing various data as described below.

Reference numeral 31 denotes an L value storage unit, which is a pulse wave amplitude value (L) calculated from the cuff pressure measured by the electronic sphygmomanometer.
Value). Reference numeral 32 denotes an Lmax storage unit, which stores the maximum pulse wave amplitude value (Lmax). Reference numeral 33 denotes a blood pressure measurement value storage unit which stores a systolic blood pressure value (O-SYS) and a diastolic blood pressure value (O-SYS) obtained by an oscillometric method (OSC method).
DIA), systolic blood pressure value (KS) determined by the K-tone method
YS), the diastolic blood pressure value (K-DIA), and the like. 34
Is a K sound signal presence / absence determination level (K _L ) storage unit for storing a comparator level (K _L ) for determining the presence / absence of a K sound. Reference numeral 35 denotes a K sound signal storage unit which stores the magnitude of the K sound signal detected by the present electronic sphygmomanometer. Also,
An O-SYSL storage unit 36 stores a systolic blood pressure recognition comparator level (O-SYSL) used when obtaining a systolic blood pressure value by the OSC method. 37 is O-DAI
L storage unit, which is a diastolic blood pressure recognition comparator level (O-DI
AL).

Reference numeral 4 denotes a cuff pressure detecting unit, and a pressure sensor 4
The pressure value from 1 is amplified by the amplifier 42, and the cuff pressure is converted into a digital value by the A / D converter 43 and output.
Reference numeral 5 denotes a K sound detecting unit, which detects the K sound picked up by the microphone 51.
After the sound signal is amplified by the amplifier 52, the A / D converter 5
3 converts the K sound signal into a digital value and outputs it.
Here, the A / D converters 43 and 53 include 8-bit A / D converters. Reference numeral 6 denotes a cuff pressure control unit, which includes an exhaust valve for controlling the pressure of the cuff (arm band) 7 and the like. Note that the cuff 7 is automatically pressurized or depressurized by the cuff pressure control unit. Reference numeral 7 denotes a cuff (arm band) which is wrapped around the upper arm of the subject to measure blood pressure. Reference numeral 8 denotes a display unit that displays the detected systolic blood pressure value, diastolic blood pressure value, insufficient pressure, inability to perform measurement by the K-tone method, and the like, and notifies the user of the measurement state. The components of the above configuration are mutually connected by a bus 9 to exchange data.

In this embodiment, a pulse wave amplitude value is extracted from the pulse wave signal detected by the cuff pressure detecting section 4 and is used as a pulse wave signal level. FIG. 2 is a diagram illustrating a part of the pressure value waveform detected by the cuff pressure detection unit. The maximum value (201 to 205) of the pulse wave amplitude in each beat is extracted and set as the pulse wave amplitude value L of each beat. Note that there are various methods for handling the pulse wave signal, for example, obtaining the area of the hatched portion 206 and setting the value of the pulse wave signal level in the beat, and any method may be used. In the example, a pulse wave amplitude value is used as one example. Therefore, the above-mentioned pulse wave amplitude value is stored in the L value storage unit 31 corresponding to each beat.

FIG. 3 is a diagram showing a portion of the K sound signal waveform detected by the K sound detecting section 5. In this embodiment, the difference between the maximum value and the minimum value of the K sound signal of each beat (301 to 303).
05) is the K sound level of each beat. The K sound signal storage unit stores the K sound signal waveform and the K sound level corresponding to each beat. BN is a base noise, which is a signal output from the K sound detector 5 in a time phase in which no K sound exists.

The operation of the electronic sphygmomanometer according to the above configuration will be described below.

FIG. 8 is a flowchart showing a measurement procedure by the electronic sphygmomanometer according to the present embodiment.

When the blood pressure measurement is started, step S21
, The initial value setting such as setting the cuff pressure value to zero is executed. Then, in step S22, the cuff pressure control unit 6
Pressurization of the cuff 7 is started. The value of the cuff pressure is detected through the cuff pressure detector 4. In step S23, it is determined whether or not the value of the detected cuff pressure exceeds a predetermined value.
If the cuff pressure exceeds a predetermined value, step S24
Proceed to. If the cuff pressure does not exceed the predetermined value, the process returns to step S22, and the pressurization of the cuff is continued. It is assumed that the predetermined value used in step S23 is stored in the ROM 2 in advance.

In step S24, the cuff pressure controller 6 starts reducing the pressure of the cuff 7. Then, the detection of the pulse wave signal and the K sound signal is started together with the pressure reduction. In step S25, a pulse wave signal is detected, and a pulse wave amplitude value L of each beat is obtained.
1 is stored. The pulse wave signal is extracted from a change in the cuff pressure detected by the pressure sensor 41. Step S
At 26, the K sound signal of each beat is detected and stored in the K sound signal storage unit 35, and the K sound level value is stored in the K sound signal storage unit 35 in association with each beat. The K sound signal is detected by the microphone 51.

In step S27, step S25
The pulse wave amplitude value L obtained in step (1) is stored in the O-DIAL storage unit 37.
-DIAL), the step S28
The exhaust is performed and the cuff 7 is released. If the pulse wave amplitude value L is larger than O-DIAL in step S27, the process returns to step S25, and the above-described processing is repeated.
The detection of the value and the K sound signal is continued.

FIG. 4 is a flowchart showing a blood pressure measurement operation by the electronic sphygmomanometer of the present embodiment. After the power supply of the present electronic sphygmomanometer is turned on and the cuff 7 is wound around the upper arm of the subject and preparation for blood pressure measurement is completed, the blood pressure measurement is started by pressing a switch for starting blood pressure measurement.

When the blood pressure measurement is started, first, in step S
In 1, the pulse wave amplitude value and the K sound signal are measured and stored in the L value storage unit 31 and the K sound signal storage unit 35, respectively. The pulse wave amplitude value and the K sound signal are obtained from the signal outputs from the cuff pressure detector 4 and the K sound detector 5, respectively. still,
For the processing in step S1, the one input based on the flowchart in FIG. 8 is used.

Next, in step S2, it is checked whether blood pressure measurement by the K sound method is possible. This is executed based on the pulse wave amplitude value and the K sound signal measured in step S1. The processing in step S2 will be described later in detail with reference to the flowchart in FIG. Step S2
If it is determined that blood pressure measurement by the K-tone method is not possible, the process proceeds from step S3 to step S4, and the display unit 8 displays that blood pressure measurement by the K-tone method is not possible. Then, in step S5, a blood pressure value is extracted by the oscillometric method. The extracted maximum and minimum blood pressure measurement values are stored in the blood pressure measurement value storage unit 33. Then, in step S6, the measured blood pressure value is displayed on the display unit 8, and the present blood pressure measurement process ends. Hereinafter, a method of extracting a blood pressure value by the oscillometric method will be briefly described.

FIG. 5 is a diagram for explaining a method of determining the maximum / minimum blood pressure value by the oscillometric method. The systolic blood pressure value is obtained by converting the data in the L value storage unit 31 into the maximum pulse wave amplitude value Lmax.
To find the first beat is smaller than the value of the O-sysl hypertension direction from beat a ₁ having a. Here, O-SYSL
Is a systolic blood pressure recognition comparator level stored in the O-SYSL storage unit 36. Then, the blood pressure value at the low blood pressure side beat x1 of _one of the detected beats is set as the systolic blood pressure value. Furthermore, diastolic blood pressure value, the L value storage unit 31 from the beat a ₁ having a maximum pulse wave amplitude value Lmax hypotension direction O-D
Search for the first beat that is less than the value of IAL. Here, O-DIAL is the diastolic blood pressure recognition comparator level stored in the O-DIAL storage unit 37. Then, the diastolic blood pressure blood pressure values in beats y ₁ of one hypertensive side of the detected beat.

On the other hand, if it is determined in step S2 that blood pressure measurement by the K-tone method is possible, the process proceeds from step S3 to step S7 to check whether or not auscultation gap has occurred. The determination of the auscultation gap is performed based on the L value and the K sound signal stored in the L value storage unit 31 and the K sound signal storage unit 35, respectively. still,
The check for the occurrence of this auscultation gap is shown in FIGS.
2 will be described later in detail. If it is determined in step S7 that the auscultation gap has not occurred, the process proceeds from step S8 to step S9, and the display unit 8 displays that there is no auscultation gap. Then, in step S10,
The systolic blood pressure value and the diastolic blood pressure value are obtained by the K sound method, and these are displayed on the display unit 8 as measurement results in step S11.

An example of determining a blood pressure value by the K sound method will be described below. FIG. 6 is a diagram for explaining a method of determining a systolic blood pressure value and a diastolic blood pressure value by the K sound method. First, it is assumed that an appropriately set value (K _L ) is stored in the K sound signal presence / absence determination level storage unit 34. Note that the K _L is intended to be set on the basis of the base noise (BN), the setting method will be described later. Find the K sound level data of K sound signal storage unit 35 in the high blood pressure direction than beat a ₂ having a maximum K sound level, first K sound level find smaller beats than K _L. Then, the systolic blood pressure value in beats x ₂ of one hypotensive side of the beat. Moreover, than beat a ₂ having a maximum K sound level searching K sound signal storage unit 35 to the low pressure side, the first K sound find smaller beats than K _L. Then, the diastolic blood pressure blood pressure values in beats y ₂ of one hypertension side of the beat.

On the other hand, if the occurrence of the auscultation gap is detected in step S7, the process proceeds from step S8 to step S12, and a display indicating that the auscultation gap has occurred is displayed on the display unit 8.
Then, in step S13, the blood pressure value is extracted by the K-tone method by a method taking the auscultation gap into consideration, and step S14
Displays the blood pressure value on the display unit 8.

A method considering the auscultation gap will be described below. FIG. 7 is a diagram illustrating a method of determining a blood pressure measurement value by the K sound method when an auscultation gap occurs. Maximum K sound level Searches hypertension direction from having beat a ₃ a, K sound level for the second time to detect a smaller beats than K _L. And
A blood pressure value in beat x ₃ in one hypotensive side of the detected beat the systolic blood pressure value. Moreover, than beat a ₃ having a maximum K sound level search hypotension direction, first K sound level to detect smaller beats than K _L. Then, the diastolic blood pressure blood pressure values in beats y ₃ of one hypertensive side of the detected beat.

Next, a method for checking whether or not blood pressure can be measured by the K-tone method in step S2 will be described in detail with reference to FIGS.

FIG. 9 is a flowchart showing a processing procedure for determining whether or not blood pressure measurement by the K sound method is possible.
FIG. 10 is a diagram showing the contents of data stored in the L value storage unit 31 and the K signal storage unit 35.

In step S41, the maximum pulse wave amplitude value Lmax is detected from the L value storage unit 31 and the Lmax storage unit 32
To memorize. A beat having this Lmax is defined as a beat a. Next, in step S42, Lmax of 60
The value of% is calculated and set as comp1. Step S
At 43, a search is made on the hypertension side from the pulse a having Lmax, and a pulse p _{1 which} first has a pulse wave amplitude value less than comp1
Is detected. Then, the K sound level extracted from the K sound signal storage unit 35 in the beat p beat p ₁ than one hypotensive side in step S44, which is referred to as K (p). Based on the magnitude of the K sound level K (p), it is determined whether or not blood pressure measurement by the K sound method is possible.

In step S45, the base noise
(BN) is detected. The detection of this BN is done by first detecting the cuff pressure.
Cuff vibration superimposed on the cuff pressure detected by outlet 4
A time phase in which no K sound is generated by an arterial wave is detected. Soshi
The K sound detector 5 in the time phase when this K sound is not generated
Let these K sound detection outputs be BN (see FIG. 3). Next,
In step S46, to determine the presence or absence of the K sound signal
Comparator level K_LSet. In this embodiment
In this case, an 8-bit A / D converter taking a value of 0 to 255
By adding 10 to the converted BN value,_L To
decide. That is, K _L = BN + 10.

At step S47, the comparator level K
Comparing the _L and K sound signal level K (p), K _L is K
If it is smaller than (p), the process proceeds to step S48, and it is assumed that the blood pressure can be measured by the K sound method. Also, K _L is K
If it is larger than (p), the process proceeds to step S49, and it is determined that blood pressure measurement by the K sound method cannot be performed. That is, if the K sound signal level has a value as shown in FIG. 10B, it is determined that measurement by the K sound method is possible. However, at the K sound level as shown in FIG. 10C, it is determined that measurement by the K sound method is impossible.

As described above, the present electronic sphygmomanometer checks the level of the K sound on the basis that the pulse wave amplitude value L is a beat (time phase) in which a K sound having a predetermined level or more should exist in a beat of comp1 or more. By doing so, it is determined whether or not blood pressure can be measured by the K sound method.

Next, a method of detecting the occurrence of an auscultation gap by the present electronic sphygmomanometer (step S7 in the flowchart of FIG. 4 described above) will be described in detail with reference to FIGS.

FIG. 11 is a flowchart showing a processing procedure for detecting occurrence of an auscultation gap by the electronic sphygmomanometer of the present embodiment. FIG. 12 is a diagram showing the contents of data stored in the L value storage unit 31 and the K signal storage unit 35. It should be noted that the K sound level shown in FIG. 12 indicates that the auscultation gap has occurred.

In step S61, the Lmax value stored in the Lmax storage unit 32 is read. And L
A value of 80% of max is calculated and set as comp2. Note that the value of Lmax used here was obtained in step S41 of the above-described flowchart of FIG. In step S62, searches the blood pressure side than beat a having Lmax, detects the first a pulse wave amplitude value of less than comp2 beat r _1. Then, the K sound level extracted from the K sound signal storage unit 35 in the beat r beat r ₁ than one hypotensive side in step S63, which is referred to as K (r). The presence or absence of the auscultation gap is determined based on the magnitude of the K sound level K (r).

For the determination of the auscultation gap, the aforementioned step S44
Use the K sound level K (p) extracted in. In step S64, the K sound signal level K (p) and the K sound signal level K
If K (r) is larger than K (p), the process proceeds to step S68, and it is determined that the auscultation gap has not occurred. If K (r) is smaller than K (p), the flow advances to step S69 to determine that an auscultation gap has occurred.

As described above, the pulse wave amplitude value L becomes comp2
An auscultation gap occurs during the following phases:
The occurrence of the auscultation gap is detected by checking the K sound in this phase. The vicinity where the pulse amplitude value is equal to or less than comp2 is a position corresponding to the second point of the swan, and the auscultation gap frequently occurs at the second point of the swan. Thus, the auscultation gap can be detected in the manner described above.

As described above, according to the electronic sphygmomanometer of the present embodiment, the pulse (time phase) in which the blood flow under the cuff is sufficient to generate the K sound (that is, the pulse wave amplitude value L is greater than or equal to comp1) Time phase) and the loudness of the K sound in this time phase is detected, so that the loudness of the K sound can be determined stably without being affected by noise and the like, and the determination of whether or not to implement the K sound method can be made. Reliability is improved.

In particular, it is possible to confirm the attenuation of the K sound signal in the vicinity of the first point of the swan (a position where the pulse wave amplitude value L is less than or equal to comp1) unique to a hypertensive patient, and the reliability in the state where the K sound detection is uncertain. Low blood pressure measurement can be prevented.

Further, two points between the systolic blood pressure and the average blood pressure (that is, a pulse at which the pulse wave amplitude value L is equal to or less than comp1 and a comp)
The auscultation gap can be detected by comparing the loudness of the K sound at a beat of 2 or less). By changing the method of detecting systolic blood pressure based on the information on the presence or absence of the auscultation gap, there is an effect that erroneous measurement due to the auscultation gap can be prevented.

The setting of the level values of comp1 and compm2 is determined empirically and is not limited to the setting values of the present embodiment. Further, in the above-described embodiment, the possibility of performing the K-tone method and the presence or absence of the auscultation gap are confirmed using one K-tone level value in the vicinity of comp1 and comp2, but the present invention is not limited to this.
For example, the K sound level values of several beats in the vicinity where the pulse wave amplitude value L is equal to or less than comp1 may be extracted to determine whether the K sound method is to be performed. Further, there are various other methods for setting each comparator level (such as K _L ) and for determining a blood pressure value by the K-tone method or the oscillometric method, and are limited to the method performed in this embodiment. is not.

[0042]

As described above, according to the electronic sphygmomanometer according to the present invention, the measurement state of blood pressure is determined by checking the level of the K sound based on the pulse wave signal. It is possible to prevent erroneous measurement of the blood pressure measurement, and the reliability of the blood pressure measurement in the K-tone method is improved.

[0043]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an electronic sphygmomanometer of the present embodiment.

FIG. 2 is a diagram illustrating a part of a pressure value waveform detected by a cuff pressure detection unit.

FIG. 3 is a diagram illustrating a part of a K sound signal waveform detected by a K sound detection unit 5;

FIG. 4 is a flowchart illustrating a blood pressure measurement operation by the electronic sphygmomanometer according to the present embodiment.

FIG. 5 is a diagram for explaining a method of determining a systolic / diastolic blood pressure value by an oscillometric method.

FIG. 6 is a diagram illustrating a method of determining a maximum blood pressure value and a minimum blood pressure value by the K sound method.

FIG. 7 is a diagram illustrating a method of determining a blood pressure measurement value by the K sound method when an auscultation gap occurs.

FIG. 8 is a flowchart illustrating a procedure of measuring a pulse wave signal and a K sound signal by the electronic sphygmomanometer according to the present embodiment.

FIG. 9 is a flowchart showing a processing procedure for determining whether or not blood pressure measurement by the K sound method is possible.

FIG. 10 is a diagram showing the contents of data stored in an L value storage unit 31 and a K signal storage unit 35.

FIG. 11 is a flowchart illustrating a processing procedure for detecting occurrence of an auscultation gap by the electronic sphygmomanometer according to the present embodiment.

FIG. 12 is a diagram showing the contents of data stored in an L value storage unit 31 and a K signal storage unit 35;

[Description of Signs] 1 CPU 2 ROM 3 RAM 4 Cuff pressure detection unit 5 K sound detection unit 6 Cuff pressure control unit 7 Cuff (arm band) 8 Display unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-123535 (JP, A) JP-A-62-152432 (JP, A) JP-A-61-247430 (JP, A) JP-A-61-247430 249225 (JP, A) JP-A-60-179039 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5/022-5/0295

Claims (1)

(57) [Claims] 1. An electronic sphygmomanometer having a cuff pressure detecting section for detecting a cuff pressure and a Korotkoff sound signal detecting section for detecting a Korotkoff sound, wherein cuff pressure signal data detected by the cuff pressure detecting section is stored. Cuff pressure signal data storage means, Korotkoff sound signal data storage means for storing Korotkoff sound signal data detected by the Korotkoff sound detection unit, and cuff pressure signal data stored in the cuff pressure signal data storage means. Time phase detecting means for detecting a time phase of a Korotkoff sound signal which should satisfy a predetermined level condition; extracting means for extracting a Korotkoff sound signal in the time phase detected by the time phase detecting means from the Korotkoff sound signal data storage means Whether the level of the Korotkoff sound signal extracted by the extraction means satisfies the predetermined level condition Electronic sphygmomanometer characterized by comprising a determination means for measuring the state of the blood pressure by checking.