JPH0239249B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention detects Korotkoff sounds, their expression,
This invention relates to a sphygmomanometer that measures blood pressure with a lapse of time.

[Background Art] The currently common standard clinical method for non-invasive blood pressure measurement is based on Korotkoff's auscultation method. This method involves wrapping a cuff around the upper arm of the human body, injecting air into the ischemic cuff inside the cuff, applying pressure to 20 to 30 mmHg higher than the expected systolic blood pressure, and compressing the artery to stop blood flow. . Next, the air pressure inside the ischemic cuff is gradually exhausted at a rate of 2 to 3 mmHg/sec. If you press the stethoscope lightly on the artery near the fingertip side of the cuff, you will soon begin to hear Korotkoff sounds. Swan showed that the characteristics of this Korotkoff sound can be divided into five points and four phases. At first, a clear tapping sound is heard (phase), then it becomes a dull sound (phase),
It becomes a clear sound again (phase), and suddenly becomes a weak dull tone (phase). The point at which the first Korotkoff sound begins to be heard is the Swan's first point (S ₁ point), the change of each phase is the Swan's second to fourth points (S ₂ to S ₄ ), and the point at which the Korotkoff sound disappears ( Actually the last point heard)
is the fifth point (S ₅ points).

Generally, the cuff internal pressure at point _S1 is taken as the systolic blood pressure, and _S5
The blood pressure at that point is considered the lowest blood pressure. However, regarding diastolic blood pressure, there is also a theory that uses _S4 points. Therefore, recently it has been recommended to write S ₄ points and S ₅ points together, such as 142/82/78 (S ₁ point = 142 mmHg, S ₄ points = 82 mmHg, S ₅ points = 78 mmHg). Also, if you hear Korotkoff sounds even if the cuff internal pressure is 0 mmHg,
A score of ₄ is considered the minimum blood pressure.
From the above points, it is very useful to know the S ₄ points at the same time as the S ₁ and S ₅ points.

[Object of the Invention] The present invention has been provided in view of the above points, and provides a blood pressure monitor that can accurately detect and display the S ₄ point that closely matches the Swan's 4th point (S ₄ point) judged by a doctor. The purpose is to provide

[Disclosure of the Invention] Examples of the present invention will be described below with reference to the drawings.
FIG. 1 shows a block diagram, in which numeral 1 is a compression means for compressing the upper arm of the body, and 2 is a pressure reduction means, which increases or reduces the pressure of the compression means 1 on the arm cuff. Reference numeral 3 indicates a pressure value detection means for detecting the pressure value of the compression means 1, and reference numeral 4 indicates a Korotkoff sound detection means for detecting a Korotkoff sound based on a signal from the compression means 1. Reference numeral 5 denotes a blood pressure determining means, which detects the appearance and disappearance of Korotkoff sounds from the Korotkoff sound detecting means 4 and determines the pressure value at that time as the maximum or diastolic blood pressure value. Reference numeral 6 denotes display means for displaying the maximum and diastolic blood pressure values obtained by the blood pressure determination means 5. In addition, the blood pressure determination means 5 determines the point in time when the Korotkoff sound attenuates to 1/2 or less compared to the Korotkoff sound one beat before.
S Swan _4th point detected as 4 points (Swan 4th point)
Point detection means 7 are provided. And this S ₄
The pressure value of the compression means 1 at the point is displayed on the display means 6 as the diastolic blood pressure (S ₄ ).
Note that the pressure value at point _S1 is displayed on the display means 6 as the systolic blood pressure, and the pressure value at point _S5 is displayed as the diastolic blood pressure ( _S5 ), as in the conventional art.

By the way, we inventors investigated the characteristics of the Korotkoff sound based on the S ₄ points judged by doctors, and found that the peak value of the Korotkoff sound initially became smaller by more than 1/2 compared to the peak value one beat before. It was found that by capturing the points, it was possible to obtain an _S4 score that closely matched the _S4 score determined by the doctor. Also, the peak value of the Korotkoff sound after ₄ points of S usually becomes smaller. Although there are some cases where the size grows somewhat and then becomes smaller, we also found that it does not become extremely large. Furthermore, at point S ₄ , the pressure value of compression means 1 is 0 mmHg.
Although there are very rare cases where it is heard even after the age, the S ₄ point has never been less than 30 mmHg including those cases.

FIG. 2 is a specific circuit diagram of the present invention, and FIG. 3 is a timing chart. In addition, Fig. 2 shows A to Z, a
-h correspond to A to Z and a to h in FIG.
In other words, A to Z, a to h in Figure 3 are A to A in Figure 2.
It shows waveforms at point Z and points a to h. This will be explained in detail below. Now, by wrapping the arm cuff 9 around the upper arm 8 of the body and pressurizing the pressure ball 58, the arm cuff 9
Air is pumped into the ischemic cuff inside through the conduit 57, and the pressure is increased to 20 to 30 mmHg higher than the expected systolic blood pressure value. The compression means 1 is composed of the arm cuff 9, the compression ball 58, and the like. Next, the exhaust gas is gradually evacuated at a rate of 2 to 3 mmHg by the exhaust adjustment valve 59 constituting the pressure adjustment means 2. Here, the pressure value within the ischemic cuff is detected by a pressure transducer 60 connected by a conduit 57 and input into a control circuit 64 through an A/D converter 61. Pressure transducer 60, A/D
The pressure value detection means 3 is composed of the converter 61 and the like. On the other hand, a signal containing a Korotkoff sound (K sound) as shown in FIG. 3A is detected by a Korotkoff sound sensor 10 made of a microphone or the like built into the cuff 9 and a Korotkoff sound detection circuit 11. This signal A is passed through the Korotkoff sound filter 12 and becomes a signal B containing only Korotkoff sounds, and the comparator 13
After signals above a certain level are distinguished as Korotkoff sounds by the waveform shaping circuit 14, the signals C
is obtained, and the Korotkoff tone logic circuit 66
is input. In addition, the above Korotkoff sound detection circuit 1
1, Korotkoff sound filter 12, comparator 1
3. The Korotkoff sound detection means 4 is composed of the waveform shaping circuit 14 and the like.

Next, the Korotkoff tone logic circuit 66 will be explained. That is, in the Korotkoff tone logic circuit 66, the rising edge of the signal C is
(approximately 300 msec), Korotkoff sound pulse E
At the third rising edge of the Korotkoff sound pulse E, J is input to the control circuit 64.
- Set the output G of the K flip-flop 25 to high level. On the other hand, the signal C is input to the retriggerable monostable multi 17. This retriggerable monostable multi 17 detects the rising edge of signal C and
If a ~4sec pulse is generated and the next pulse does not rise within that time and the output G of the JK flip-flop 25 reaches a high level, it is considered noise and resets the Korotkov sound count. be. Next, the OR gate 26 performs a logical sum on the signals G and F, and the OR gate 26
and the reset signal D from the reset switch 15 are NANDed by a NAND gate 27,
The signal from this NAND gate 27 is input to the control circuit 64 as the S ₁ point determination signal H. On the other hand, the signal G is inputted to the reset input of the latch circuit 28, and the signal F is inputted as the set input, and the output thereof is obtained as the _S5 point determination signal I and inputted to the control circuit 64. Here, the reset signal D is set to a high level at all times by the reset switch 15, and is set to a low level by pressing the reset switch 15 at the start of measurement or when noise occurs, thereby resetting the Korotkoff sound logic circuit 66. This is to return to the initial state.

Next, the swan fourth point detection means 7 will be explained. In the Swan fourth point detection circuit 67, which is the Swan fourth point detection means 7, the Korotkoff sound pulse E
is input to the monostable multi 29, and a check pulse J of a certain period of time is obtained from its falling edge. The inverted output Q of the signal J is input to the monostable multi 31,
Reset pulse K for a certain period of time from its rise
get. On the other hand, the T flip-flop 30 obtains an output L that is inverted every time the Korotkoff sound pulse E falls. By ANDing the signal L and the inverted signals of the signals J and K with an AND gate 34, a signal O is obtained, and by ANDing the inverted signals of the signals J, K, and L with an AND gate 35, a signal P is obtained. get. The above signal O is analog switch 3
It is input to the control terminal of 8. In this analog switch 38, only the high section of the signal O is passed through the Korotkoff sound signal B to obtain the signal Q.
The signal is input to a double peak hold circuit 40 and a double peak hold circuit 42 . Similarly, the analog switch 39 obtains a signal R through which only the high section of the signal P passes the Korotkoff sound signal B, and inputs it to the 1x peak hold circuit 44 and the 2x peak hold circuit 46. Here, 1x peak hold circuit 4
0,44 is the operand as shown in Figure 4a.
The double peak hold circuits ₄₂ , ₄₆ are composed of operational amplifiers _OP3 , _OP4 , resistors 68, 69, etc., as shown in FIG. 4b. Here, the resistance values of the resistors 68 and 69 are set equal, and the gain is doubled.

Signal M is obtained by ANDing signals K and L at AND gate 33, and transistors 41,
47 to drive the 1x peak hold circuit 40, 2
The double peak hold circuit 46 is reset, and the Korotkoff sound signal B is inputted via the analog switches 38 and 39. Similarly, the inverted outputs of the signals K and L are ANDed by the AND gate 36,
Obtain signal N. This signal N causes transistor 4 to
5, 43, and 1x peak hold circuit 4
4. Reset the 2x peak hold circuit 42,
Korotkoff sound signal B is connected to each peak hold circuit 4
4,42. The output S of the 1x peak hold circuit 40 is input to the non-inverting input terminal of the operational amplifier 48, and the output V of the 2x peak hold circuit 46 is input to the inverting input terminal of the operational amplifier 48, so that the signals S and V are compared. It is done.
When the signal S is larger, the operational amplifier 48
The output of the signal V becomes high level, and when the signal V is larger, the output becomes low level. The output of this operational amplifier 48 is an AND gate 3 that ANDs signals J and L.
The AND gate 50 performs an AND operation on the output W of 2 to obtain an output Y. Similarly, the signals T and U are input to the operational amplifier 49, and the output thereof is ANDed with the output X of the AND gate 37, which ANDs the inverted output of the signal L and the signal J, and the AND gate 51 obtains the output Z. . The output a of the OR gate 52 which ORs the signals Y and Z is the S _4- point detection pulse, which is input to the set terminal of the latch circuit 53.

Here, K ₁ of the first Korotkoff sound signal B (the third
Since the signal P is at a high level (P in Fig. 3) at the time when the signal P in Fig. B) is input, the analog switch 3
9 is turned on and Korotkov sound filter 12 to K ₁
is input to the 1x peak hold circuit 44 (FIG. 3R). In this 1x peak hold circuit 44,
The level of _K1 is held as is (Figure 3 U). Next, the signal O becomes high level (FIG. 3 O), turning on the analog switch 38, and K ₂ of the Korotkoff sound signal B is input to the double peak hold circuit 42 (FIG. 3 Q). In this double peak hold circuit 42, the level of _K2 is amplified twice and held (T in FIG. 3). The signal T is then compared by the operational amplifier 49, but in this case, since the signal T is higher, the output of the operational amplifier 49 becomes low level. Both peak hold circuits 42 and 44 are then reset by the pulse of signal N. Next, K ₃ is input as signal P and K ₄ as signal O is input to both peak hold circuits 44 and 42 and compared in the same manner as above. Also, a small level of noise
N ₁ and K ₅ of the Korotkoff sound signal B are compared.
Next, K ₆ and K ₇ are compared, in this case K ₇
(S ₄ points) level is more than 1/2 lower than K ₆ , signal T
When comparing and U, the signal U is larger (T, U in FIG. 3), so the output of the operational amplifier 49 becomes high level, and the signal Z is obtained from the AND gate 51 (Z in FIG. 3). In addition, the above is K ₁ and K ₂ , K ₃ and K ₄ , N ₁
This is a comparison of K ₅ and K 5, K ₆ and K ₇ (S ₄ points), but next we will explain the case of comparing K ₂ and K ₃ , K ₄ and N ₁ , and K ₅ and K ₆ . .

First, the analog switch 38 is opened by the signal O (FIG. 3 O), and K ₂ is input to the 1x peak hold circuit 40 and held (FIG. 3 Q,
S). Next, the analog switch 39 is opened by the signal P (FIG. 3 P), and K ₃ is input to the double peak hold circuit 46 and held (FIG. 3 R, V). The signals S(K ₂ ) and V(K ₃ ) are compared by the operational amplifier 48, but in this case, the signal V is 2
Since it is amplified twice, it is larger than S, and the output of the operational amplifier 48 is at a low level. and signal M
Both peak hold circuits 40 and 46 are reset by the reset pulse (FIG. 3M). Similar to the above, next K ₄ and N ₁ will be compared. Since the level of N ₁ is less than 1/2 of the level of K ₄ one beat before, the signal S is larger than the level of K 4.
The output of No. 8 becomes high level. Therefore, the output Y of the AND gate 50 becomes high level, and Y
Obtain the pulse shown in . Furthermore, this signal Y is S ₄
Since it is not a point, it is reset as described below. Moreover, the Korotkoff sound signal B mentioned above has K ₁ and K ₂ ,
They are compared sequentially for each shot, such as K ₂ and K ₃ , K ₃ and K ₄ , and so on.

On the other hand, the comparator 54 detects the Korotkoff sound signal B at a level Va or higher, which is higher than the Korotkoff sound detection level of the comparator 13.
Obtain signal b. This signal b is applied to the AND gate 55
The signal G is ANDed with the signal G, and the output c of the AND gate 55 is obtained. Then, an OR gate 56 performs an OR operation on the signal c and the signal I to obtain a signal d. Furthermore, the output f of the comparator 62 that detects that the output signal e of the pressure transducer 60 is 30 mmHg, and the signal d
The OR gate 63 performs an OR with the output g, which is input to the reset terminal of the latch circuit 53. The output h of the latch circuit 53 is inputted to the control circuit 64 as an S ₄ -point detection signal.

By configuring the S _4- point detection circuit 67 as described above, the peak value is compared for each Korotkoff sound pulse E, and the peak value is 1/1 compared to the previous one.
When it becomes 2 or less, it is detected as S ₄ points. However, as mentioned above, when the Korotkoff sound level is high, such as noise N ₁ , and a small noise occurs next, this noise N ₁
A comparison is made with K ₄ and N ₁ is set as the S ₄ point, resulting in an erroneous detection. However, in this circuit, since the Korotkoff sound level of the next _K5 is large, the latch circuit 53 is activated by the low level of the signal g.
is reset (Fig. 3g, h), and the once detected S _4- point detection signal h cancels _N1 as noise. Also, as in N ₂ , after the S ₅ points are confirmed and the pressure inside the ischemic cuff in the arm cuff 9 falls below 30 mmHg, even if a large noise occurs,
The _S4 points already determined by _N2 are not reset. In other words, after determining S ₅ points,
S ₅ -point determination signal I becomes high level (I in Figure 3),
Continuing to supply a high level signal to the reset terminal of the latch circuit 53 via the OR gates 56 and 63,
S The latch circuit 53 cannot be reset even if a large noise is input after _{the 5} points are determined.
In addition, the comparator 54, the OR gates 56, 6
3. The latch circuits 28, 53, etc. constitute reset inoperability means. In this way, even if noise occurs during or after blood pressure measurement, the Swan's fourth point can be detected with high accuracy without malfunction.
Even if it sounds like mmHg, the fourth Swan point can be detected and can be taken as the diastolic blood pressure.

Next, in the control circuit 64, while the _S1 point determination signal H is at a low level, the pressure transducer 60 and the A/D
The pressure value in the ischemic cuff in the cuff 9 obtained by the converter 61 is displayed on the display 65 as the systolic blood pressure (S ₁ point).
Display section, diastolic blood pressure (S ₄ points) display section, diastolic blood pressure (S _{5 points)}
Point) Always displayed on the display. Here, when the first Korotkoff sound occurs in the Korotkoff sound pulse E, the pressure value at that time is displayed on the systolic blood pressure (S ₁ point) display section, and unless the S ₁ point determination signal becomes low level, the pressure value at that time is displayed as the systolic blood pressure value. Confirmed as after that,
Every time the Korotkoff sound of Korotkoff sound pulse E is input, the pressure value at that time is displayed on the diastolic blood pressure (S ₄ points) and (S ₅ points) display section. When the _S4 point detection signal h becomes high level, the pressure value displayed at that time is displayed as the _S4 point on the diastolic blood pressure ( _S4 point) display section. Here, when the S _4- point detection signal h becomes low level, it is canceled as a malfunction. In the example of FIG. 3, the S ₄ points once determined are canceled due to the noise N ₁ , and K ₇ is detected and determined again as the S ₄ points. Next, when the S ₅ point determination signal I becomes high level, the pressure value displayed at that time is displayed as the S ₅ point on the diastolic blood pressure (S ₅ point) display section and confirmed. S When the _5- point determination signal I becomes high level, it means that the measurement has been completed, and this is notified by the display 65 or sound. When the measurement is finished, the measurer fully opens the exhaust adjustment valve 59 to remove the air from the ischemic cuff in the arm cuff 9, and finishes the measurement. The displayed value on the display 65 remains until the next measurement is performed (reset switch 15).

[Effects of the Invention] As described above, the present invention includes a compression means for compressing an artery of the body, a pressure adjustment means for adjusting the pressure of the compression means, a pressure value detection means for detecting the pressure value of the compression means, and a pressure value detection means for detecting the pressure value of the compression means. Korotkoff sound detection means for detecting Korotkoff sounds emitted from the affected arteries; and blood pressure determination means for detecting the appearance and disappearance of Korotkoff sounds from the Korotkoff sound detection means and determining the pressure value at that time as systolic blood pressure or diastolic blood pressure. In a sphygmomanometer comprising a display means for displaying a blood pressure value based on a signal from a blood pressure determination means, the point at which the amplitude of the Korotkoff sound attenuates to a predetermined amount or less compared to the Korotkoff sound one beat before is defined as Swan 4th.
If the amplitude of the next detected Korotkoff sound is greater than or equal to a predetermined amount compared to the Korotkoff sound at the Swan fourth point, the Swan fourth point detection means resets the Swan fourth point. Since the pressure value of the compression means at the fourth Swan point is displayed on the display means as the diastolic blood pressure, the amplitude of the Korotkoff sound one beat before can be determined by the Swan fourth point detection means. A point attenuated to a predetermined amount or less compared to the Korotkoff sound is detected as the Swan's fourth point, and if the amplitude of the next detected Korotkoff sound is at least a predetermined amount compared to the Korotkoff sound at the Swan's fourth point, the above-mentioned By resetting the Swan 4th point of
This has the effect of accurately detecting and displaying points.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the above, Fig. 3 is a timing chart of the same, and Fig. 4 a and b are of the 1x and 2x peak hold circuits of the same. It is a specific circuit diagram. 1 is a compression means, 2 is a pressurization/depression means, 3 is a compression detection means, 4 is a Korotkoff sound detection means, 5 is a blood pressure determination means, 6 is a display means, and 7 is a Swan fourth point detection means.

Claims (1)

[Scope of Claims] 1. A compression means for compressing an artery of the body, a pressure adjustment means for adjusting or decreasing the pressure of the compression means, a pressure value detection means for detecting the pressure value of the compression means, and a Korotkoff pressure emitted from the compressed artery. Korotkoff sound detection means for detecting sounds; blood pressure determination means for detecting the appearance and disappearance of Korotkoff sounds from the Korotkoff sound detection means and determining the pressure values at that time as systolic blood pressure and diastolic blood pressure; In a sphygmomanometer comprising a display means for displaying a blood pressure value using a signal, the point where the amplitude of the Korotkoff sound attenuates to a predetermined amount or less compared to the Korotkoff sound one beat before is detected as the fourth Swan point, and then The blood pressure determining means is provided with a swan fourth point detection means for resetting the swan fourth point if the amplitude of the detected Korotkoff sound is more than a predetermined amount compared to the Korotkoff sound at the swan fourth point; A blood pressure monitor characterized in that pressure values of the compression means at four points are displayed as the diastolic blood pressure on a display means. 2. When the pressure value of the pressure value detection means becomes approximately 30 mmHg or less and after the swan 4th point is determined, the swan 4th point detection means is equipped with a reset deactivation means that disables the reset means of the swan 4th point detection means. A blood pressure monitor according to claim 1, characterized in that the blood pressure monitor is provided with: