JP3214213B2 - Electronic sphygmomanometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure value ( calculated cuff pressure).
And the pulse wave amplitude corrected, an electronic sphygmomanometer for calculating a blood pressure value using the calculated cuff pressure and the pulse wave amplitude corrected.

[0002]

2. Description of the Related Art In an electronic sphygmomanometer, the pressure in a cuff is converted into an electric signal, and a pressure value ( calculated cuff pressure) is calculated from the electric signal.
The actual calculated pressure value (calculated cuff pressure) has a non-linear error with respect to (calculated cuff pressure) (a) as shown in (b) or (c) .

[0003]

In the conventional electronic sphygmomanometer, the actual calculated pressure value (calculated cuff pressure) is (b) or
(C) , the calculated pressure value (calculated cuff pressure)
Only corrects. However, if when extracting the pulse wave component from the pressure values, with it means to extract laden pulse wave component nonlinearity errors, for example, in FIG. 6 the pressure characteristics as in (b), however, the pulse wave When the components are extracted, the pulse wave amplitude on the high pressure side becomes larger than the actual pulse wave amplitude and the pulse wave amplitude on the low pressure side becomes smaller than the actual pulse wave amplitude as shown in FIG. Further, in the case with a compression characteristic such as (c) in FIG. 6, the pulse wave amplitude is actually smaller than the high pressure side of the opposite, larger in the low-pressure side. If the blood pressure value is calculated based on the pulse wave amplitude including the non-linear error as described above, there is a problem that an accurate blood pressure value cannot be calculated.

[0004] Accordingly, the present invention has been made to solve such a problem of the prior art, and has as its object to provide an electronic sphygmomanometer capable of calculating a more accurate blood pressure value. .

[0005]

In order to achieve the above object, an electronic sphygmomanometer according to the present invention comprises a cuff and a pressure in the cuff.
Pressure measuring means for converting (cuff pressure) into an electric signal; pressure value converting means for converting the electric signal into a pressure value ( calculated cuff pressure); and pulse wave extracting means for extracting a pulse wave component from the pressure value. Storage means for storing a relationship between the cuff pressure and the calculated cuff pressure calculated by the pressure value conversion means, wherein a relationship between the cuff pressure and the calculated cuff pressure previously stored in the storage means is provided. The calculated cuff pressure and pulse wave amplitude are corrected, and a blood pressure value is calculated using the corrected calculated cuff pressure and pulse wave amplitude.

[0006]

SUMMARY OF] In this electronic blood pressure meter based on the calculated cuff pressure relationship between cuff pressure that has been stored in advance in the storage unit, calculates the cuff pressure and the pulse wave amplitude corrected, corrected calculated cuff pressure and the pulse wave amplitude Since the blood pressure value is calculated by using the equation (1), the corrected pulse wave amplitude hardly includes a non-linear error, and accurate blood pressure value calculation can be performed.

The relationship between the cuff pressure and the calculated cuff pressure stored in the storage means is represented by a function or a numerical table representing the relationship between the two, or a function or a numerical table representing the relationship between the error and the pressure between the two. It is preferable to correct the calculated cuff pressure and the pulse wave amplitude using this. In particular, in addition to the correction of the calculated cuff pressure, the gradient of the relationship between the cuff pressure and the calculated cuff pressure is calculated using the relationship between the cuff pressure and the calculated cuff pressure stored in the storage means, and the pulse wave is calculated using the calculated value. It is convenient to have a pulse wave amplitude correction means for correcting the amplitude.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electronic sphygmomanometer of the present invention will be described below based on embodiments. FIG. 1 is a block diagram showing a schematic configuration of an electronic sphygmomanometer according to one embodiment. This electronic sphygmomanometer has a cuff 1
A pressure sensor (pressure mounting means) 2 for detecting the pressure in the cuff 1 and converting it into an electric signal; and a pressure value converting means (not shown) for converting the electric signal into a pressure value ( calculated cuff pressure). A storage means 3 for storing in advance the relationship between the cuff pressure and the calculated cuff pressure calculated by the pressure value conversion means, and a pulse wave component from the pressure value (calculated cuff pressure) calculated by the pressure value conversion means. Pulse wave extracting means 4 for extracting, pulse wave amplitude calculating means 5 for calculating a pulse wave amplitude from the extracted pulse wave component, and pulse wave based on the relationship between the cuff pressure stored in the storage means 3 and the calculated cuff pressure. Pulse wave amplitude correction means 6 for correcting the wave amplitude, and pressure value correction means 7 for correcting the calculated cuff pressure based on the relationship between the cuff pressure and the calculated cuff pressure also stored in the storage means 3
And blood pressure value determining means 8 for determining a blood pressure value using the corrected pressure value and pulse wave amplitude. Among these, the blood pressure value determining means 8 is configured by an arithmetic processing circuit such as a CPU.

FIG. 2 is a schematic flow chart showing the overall operation of the electronic sphygmomanometer. When the power is turned on, initialization processing of various data and variables is performed (ST1), and the cuff is pressurized by a pressurizing means (pump or the like) (ST2), and whether the pressure of the cuff reaches a target pressurized value is determined. It is determined whether or not the pressure is higher (ST3), and the pressurization is continued until the pressure is reached. After reaching the target pressurization value, a decompression process for evacuating the cuff at a very low speed is performed (ST4), and in the decompression process, a process of determining a blood pressure value (a maximum and a minimum blood pressure value) is performed (ST5), and finally the blood pressure is determined. After determining the value (ST
6) The inside of the cuff is quickly evacuated (ST7), and the blood pressure measurement ends.

The blood pressure value determination process (ST5) in the flowchart of FIG. 2 is performed as follows. In the block diagram of FIG. 1, the pressure in the cuff 1 is converted into an electric signal by a pressure sensor 2, and a pressure value ( calculated cuff pressure) is calculated from the electric signal. The calculated cuff pressure is calculated as described above. Has a non-linear error. However, since the relationship between the cuff pressure and the calculated cuff pressure is stored in the storage means 3 in advance, the calculated cuff pressure is corrected by the pressure value correction means 7 using this storage relation.

On the other hand, a pulse wave component is extracted from the electric signal converted by the pressure sensor 2 by the pulse wave extracting means 4, and then a pulse wave amplitude is calculated by the pulse wave amplitude calculating means 5 from the pulse wave component of one beat. . The pulse wave amplitude extracted here has a non-linear error, and the error is proportional to the gradient in the relationship between the cuff pressure and the calculated cuff pressure, but the relationship between the cuff pressure and the calculated cuff pressure is stored as described above. since 3 are stored in, using the relationship of this, it corrects the pulse wave amplitude in the pulse wave amplitude correction means 6. Then, the blood pressure value determining means 8 determines the blood pressure value based on the corrected cuff pressure and the pulse wave amplitude.

FIG. 3 is a flowchart showing a process of correcting the pulse wave amplitude by the pulse wave amplitude correcting means 6. After the start of blood pressure determining process (refer to ST5 in FIG. 2), it takes in the cuff pressure signal P _C (S
T11), and a digital filtering process on the cuff pressure signal P _C, to separate the pulse wave signal P _W from the cuff pressure signal P _C (ST12). Note that this digital filtering processing is not a main part of the present invention, and a detailed description thereof will be omitted. From the pulse wave signal P _{W for} one beat, the maximum point P of the pulse wave
_WMAX and minimum point P _WMIN are detected (ST13), and pulse wave amplitude W
Is calculated by the following equation (1) (ST14).

W = P _WMAX −P _WMIN (1) Next, a pulse wave amplitude correction value A is obtained (ST15). For this purpose, the relationship between the true pulse wave amplitude W _R and the pulse wave amplitude W calculated in ST14 is defined as: W _R = (1 / A) × W (2) Here, the calculated pulse wave amplitude W has a non-linear error, and the error is proportional to the slope in the relationship between the cuff pressure and the calculated cuff pressure. For example, if the nonlinearity error is 0 as shown in FIG. 6, the gradient in the relationship between the cuff pressure and the calculated cuff pressure is always 1. In FIG. 6, the calculated cuff pressure 200
Assuming that the slope in the relationship between the cuff pressure at mmHg and the calculated cuff pressure is 0.9, the pulse wave amplitude at the calculated cuff pressure of 200 mmHg is about 10% smaller than the true pulse wave amplitude. The relationship between the cuff pressure P _C and the calculated cuff pressure P _C ′ is, as shown in FIG. 6, assuming that the pressure error E is E = P _C ′ −P _C. -Calculated in (3) and stored in the storage means 3 (see FIG. 1) at fixed pressure intervals, for example, at every 16 mmHg. Cuff pressure P _C at the time of the pulse wave amplitude W calculated is between the cuff pressure are stored the pressure error P _C (N) and P _C (N-1) as shown in FIG. 5, P _C (N), P
_C (N-1) of the pressure error is respectively E (N), if E (N-1), the pulse wave amplitude at the cuff pressure range _{[P C (N) -P C (} N-1) ] The correction value A is obtained by the following equation (4) using E (N) and E (N-1).

[0014] However, a _{P C (N) -P C (} N-1) = 16. Using pulse wave amplitude correction value A obtained by the equation (4), calculates the correction pulse wave amplitude W _A (ST16). The corrected pulse wave amplitude W _A is obtained by using the equation (2), W _A = (1 / A) × W (5)

Actually, the slope in the relationship between the cuff pressure and the calculated cuff pressure continuously changes in a curved line as shown by the broken line in FIG. 5, so that the pulse wave amplitude correction value A also changes continuously. However, when the pulse wave amplitude correction value A is obtained as in Expression (4),
The correction value A is calculated so as to change linearly as shown by the solid line in FIG. 5, and the pulse wave amplitude correction value A is one in the above cuff pressure range. Therefore, if the cuff pressure is P _C (N) or P
_The closer to _C (N-1), the larger the error. However, this can be solved by reducing the pressure interval when storing the pressure error E in the storage means 3 according to the magnitude of the pressure error E, that is, by reducing the pressure interval from 16 mmHg in the above example.

In the above embodiment, the correction of the pulse wave amplitude is determined from the relationship between the pressure and the error between the cuff pressure and the calculated cuff pressure. However, a function or a function representing the relationship between the cuff pressure and the calculated cuff pressure is obtained. It may be obtained using a numerical table.

[0017]

As described above, the electronic sphygmomanometer of the present invention corrects the calculated cuff pressure and the pulse wave amplitude based on the relationship between the cuff pressure and the calculated cuff pressure stored in the storage means in advance. Because the blood pressure value is calculated using the corrected calculated cuff pressure and the pulse wave amplitude, the corrected pulse wave amplitude contains almost non-linear errors compared to the case where only the pressure value is corrected as in the conventional case. Therefore, a more accurate blood pressure value can be calculated.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an electronic sphygmomanometer according to one embodiment.

FIG. 2 is a schematic flowchart showing an overall operation of the electronic sphygmomanometer of the embodiment.

FIG. 3 is a flowchart showing a pulse wave amplitude correction process in the blood pressure value determination process in the flowchart of FIG. 2;

FIG. 4 is a diagram showing a relationship between cuff pressure and pressure error stored in storage means in the electronic sphygmomanometer of the embodiment.

FIG. 5 is a diagram showing a calculation example of a pulse wave amplitude correction value in the electronic sphygmomanometer of the embodiment.

FIG. 6 is a diagram showing a relationship between an actual cuff pressure and a calculated cuff pressure.

FIG. 7 is a diagram comparing a pulse wave amplitude before correction with a pulse wave amplitude after correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cuff 2 Pressure sensor (pressure measuring means) 3 Storage means 4 Pulse wave extracting means 5 Pulse wave amplitude calculating means 6 Pulse wave amplitude correcting means 7 Pressure value correcting means 8 Blood pressure value determining means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-311933 (JP, A) JP-A-5-329113 (JP, A) JP-A-62-268531 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) A61B 5/022-5/0295

Claims (3)

(57) [Claims] 1. A cuff; a pressure measuring means for converting a pressure (cuff pressure) in the cuff into an electric signal; a pressure value converting means for converting the electric signal into a pressure value ( calculated cuff pressure); An electronic sphygmomanometer comprising: a pulse wave extracting unit that extracts a pulse wave component from a value; and a storage unit that stores a relationship between the cuff pressure and the cuff pressure calculated by the pressure value conversion unit. Based on the relationship between the cuff pressure and the calculated cuff pressure stored in the corrected cuff pressure and pulse wave amplitude,
An electronic sphygmomanometer, wherein a blood pressure value is calculated using the corrected calculated cuff pressure and pulse wave amplitude. 2. The relationship between the cuff pressure and the calculated cuff pressure stored in the storage means is a function or a numerical table representing the relationship between the two, or a function or a numerical table representing the relationship between the error and the pressure between the two. 2. The electronic sphygmomanometer according to claim 1, wherein the calculated cuff pressure and the pulse wave amplitude are corrected using the calculated values. 3. A slope in the relationship between the cuff pressure and the calculated cuff pressure is calculated using the relationship between the cuff pressure and the calculated cuff pressure stored in the storage means, and the pulse wave amplitude is corrected using the calculated value. 2. The apparatus according to claim 1, further comprising pulse wave amplitude correction means.
Electronic blood pressure monitor as described.