JPH0453534A - Respiration detecting method and respiration frequency measuring device - Google Patents

Abstract

PURPOSE:To correctly detect the respiration without any influence of the install condition of a sensor portion by installing an acceleration sensor on the surface of a living body reciprocating in relation to the respiration and detecting the respiration of the living body according to a signal output from the acceleration sensor. CONSTITUTION:The surface 22 of the upper part of the belley reciprocates in relation to the respiration, a plate spring 14 of an acceleration sensor 10 is subjected to distortion with the reciprocation of the surface 22, and the distortion of the plate spring 14 is detected by a semiconductor distortion gauge 18. A signal corresponding to the reciprocation of the surface 22 of the upper part of the belly of the tested person is output from the acceleration sensor 10. The signal is supplied to an apparatus main body 23 to be supplied to CPU 26. According to a program previously stored in ROM 28, signal processing is executed using the storage function of RAM 30. According to a signal supplied from the acceleration sensor 10, the respiration is detected, and the number of respirations per unit time and the respiration waveform are displayed on a CRT display device or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for detecting respiration and a device for measuring respiration rate.

BACKGROUND OF THE INVENTION It may be necessary to monitor a patient's breathing, such as during or after surgery. One method of detecting this respiration has conventionally been to measure the reciprocating motion of the thorax or abdominal wall. The reciprocating motion of the thorax and abdominal wall can be measured, for example, by extracting impedance changes between electrodes attached to the surface of the thorax and abdominal wall, or by measuring impedance changes between electrodes attached to the surface of the thorax and abdominal wall, or by measuring impedance changes between electrodes attached to the surface of the thorax or abdominal wall, or by measuring impedance changes between electrodes attached to the surface of the thorax or abdominal wall, or by measuring It is based on measuring changes in the internal pressure of the sac and changes in the electrical resistance of an electrolyte solution in a rubber tube wrapped around the ribcage and abdominal wall.

Problem to be Solved by the Invention However, when detecting respiration based on impedance changes between the electrodes, if the electrical contact state of the electrodes with the body surface is unstable, respiration cannot be detected accurately. At the same time, there is a drawback that the work of attaching the electrodes requires comparatively much time and skill.

In addition, when a hand or a rubber tube equipped with the above-mentioned rubber sac is wrapped around the body surface and breathing is detected based on changes in the internal pressure of the rubber sac or changes in the electrical resistance of the fluid in the rubber tube, the hand or rubber tube may be wrapped around the body surface. However, if the tightening force is too weak or too strong, breathing cannot be detected accurately, and the work of wrapping the rubber tube with the hand or the rubber tube has the disadvantage of requiring relatively much effort and skill. .

The present invention has been made against the background of the above circumstances, and its purpose is to ensure that detection of respiration is hardly affected by the mounting state of the sensor part for detecting reciprocating movements of the chest and abdominal wall. Moreover, it is an object of the present invention to enable accurate detection of respiration without requiring time and skill for the installation work.

First Means for Solving the Problems The gist of the respiration detection method of the present invention for achieving the above object is to attach an acceleration sensor to the surface of a living body that reciprocates in relation to respiration, and to measure the acceleration of the respiration detection method. The respiration of the living body is detected based on the signal output from the sensor.

Operation and Effect of the First Invention In this way, the reciprocating motion of the surface of the living body that moves reciprocatingly in relation to respiration can be detected based on the signal output from the acceleration sensor attached to the surface of the living body. Breathing can be detected. In this case, since the acceleration sensor is not in electrical contact with the surface of the living body, detection of respiration is not affected by the contact state of the acceleration sensor with the surface of the living body. Furthermore, since the acceleration sensor directly detects the movement of the living body's surface, it is sufficient to simply attach it to the living body's surface.In this way, respiration can be controlled by tightening force on the living body's surface, unlike conventional methods. While detection is completely eliminated from being affected, even if the acceleration sensor is attached to the surface of a living body with a band or the like tightened, the detection of respiration is not affected by the tightening force that much. . As a result, it is possible to suitably prevent the detection of respiration from being affected by the state in which the acceleration sensor is attached to the living body's surface, and accordingly, it is possible to prevent respiration detection from being affected by the attachment state of the acceleration sensor to the living body's surface. can be detected accurately.

Second Means for Solving the Problem Furthermore, the gist of the respiration rate measuring device of the present invention for achieving the above object is as shown in the claim correspondence diagram of FIG. an acceleration sensor attached to the surface of a reciprocating living body; (b) a respiration detection means for detecting respiration of the living body based on a signal output from the acceleration sensor; and (C) a respiration detection means. (d) displaying the number of detected respirations per unit time calculated by the respiration rate calculating means; and display means.

Operation and Effects of the Second Invention According to the respiration rate measuring device configured as described above, the respiration detecting means detects the respiration rate of the living body based on the signal output from the acceleration sensor attached to the surface of the living body that reciprocates in relation to respiration. The number of breaths detected per unit time is calculated by the breathing rate calculation means based on the detected breaths, and the number of detected breaths per unit time is displayed by the display means. Ru. In this case, since the acceleration sensor is not in electrical contact with the surface of the living body, detection of respiration is not affected by the contact state of the acceleration sensor with the surface of the living body. In addition, since the acceleration sensor directly detects the movement of the biological surface,
It is sufficient to simply attach it to the surface of the living body, and in this way, the detection of respiration is completely eliminated from being affected by the clamping force on the surface of the living body, as was the case in the past. Even if the device is worn with a band or the like tightened, the tightening force does not significantly affect the detection of breathing.

As a result, it is possible to suitably prevent the detection of respiration from being affected by the state in which the acceleration sensor is attached to the living body surface. can be accurately detected and the respiratory rate can be accurately measured.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing an example of a respiration rate measuring device of the present invention, which is a respiration detection device showing an application example of the respiration detection method of the present invention. In the figure, 1o is an acceleration sensor. For example, as shown in FIG. 2, the acceleration sensor 1o includes a housing 12, and a soft plate having a longitudinal shape and provided inside the housing 12, and supported at one end in a cantilevered manner by the side wall of the housing 12. Spring 14 and its leaf spring 14
A weight 16 provided at the free end of the plate spring 14 and a semiconductor strain gauge 18 fixed to the longitudinally intermediate portion of the plate spring 14, and a plate provided with the semiconductor strain gauge 18 of the plate spring 14. It is attached to a surface 22 of the subject's upper abdomen, for example, via a double-sided adhesive tape (not shown) on a mounting surface 20 located substantially parallel to the surface.

The surface 22 of the upper abdomen reciprocates in relation to breathing, and as the surface 22 reciprocates, the leaf spring 1 of the acceleration sensor 10
4 is subjected to strain, and the strain of the leaf spring 14 is detected by the semiconductor strain gauge 18. As a result, the acceleration sensor 10
A signal corresponding to the reciprocating movement of the surface 22 of the upper abdominal region of the subject is outputted. Note that the frequency of breathing is, for example, 0.
The size of the leaf spring 14 and the weight 16 are selected to have a sufficiently small spring constant so that the slow reciprocating movement of the upper abdominal surface 22 can be suitably detected. The Rukoto.

The signal output from the acceleration sensor 10 is supplied to the device main body 23 via wiring, and is sent to the C through the A/D converter 24.
It is supplied to PU26. The CPU 26 connects the ROM 2B, RAM 30 . and indicator 32
are connected to the ROM 28 and perform signal processing using the memory function of the RAM 30 according to a program stored in advance in the ROM 28, detect respiration based on the signal supplied from the acceleration sensor 1o, and calculate the respiration per unit time. The number and respiratory waveform are displayed on a display device 32 such as a CRT display device.
to be displayed.

Next, the operation of the respiration detection device configured as described above will be explained according to the flowchart shown in FIG.

First, step S1 is executed, and it is determined whether a starting switch (not shown) has been turned on. If this judgment is negative, the system enters a standby state, but if the judgment is positive, the subsequent step S2 is executed and the signal from the acceleration sensor 10 is read. next,.

Step S3 is executed, and it is determined whether the upper peak of the waveform represented by the signal read in step S2 has been detected. If this judgment is denied, step S
2 and step S3 are repeatedly executed, but if the answer is affirmative, step S4 is executed and step S
It is determined whether the upper peak detected in step 3 is the first upper peak or not. If it is the first upper peak and the determination in step S4 is affirmative, steps S2 and S3 are repeatedly executed, and then the next upper peak is detected. However, if the second and subsequent upper peaks are not the first upper peaks and the determination in step S4 is negative,
Step S5 is executed. Note that FIG. 4 shows an example of the above waveform.

In step S5, the time between the upper peak detected this time and the upper peak detected last time in step S3, that is, the period T of the waveform is determined, and the maximum slope a in the descending portion of the waveform is determined. . wn (corresponding to the maximum speed of movement of the surface 22 during exhalation) and the maximum slope a, p in the rising part of the waveform (corresponding to the maximum speed of movement of the surface 22 during inspiration), respectively, are determined.

Next, step S6 is executed to form the following rules R+ and Rz based on fuzzy reasoning.

The satisfaction level γ++Tz+T:+ that satisfies R3 is determined. That is, FIG. 5, FIG. 6, and FIG. 7 are membership functions fl(T) representing the satisfaction level of satisfying the rules RI, R2, and R3.

FIG. 10 is a diagram showing examples of f z (down) and f z (up), respectively, whose membership functions are RO
It is stored in M2B in advance. And their membership functions f + (T), f z (doivn),
The actual period T determined in step S5 based on f x (up).

Satisfaction level of maximum slope adown+ and maximum slope aup γ1γ2. T3 is calculated for each. In addition, the above membership function f + (Tn, f z
(down).

The value of f z (up), that is, the satisfaction level, is 0 on the vertical axis.
It is expressed as a numerical value of ~1, where 0 means not satisfied at all, and 1 means completely satisfied. When the satisfaction level for each rule R+R2, R3 is 1, it indicates that, for that rule, the waveform obtained from the acceleration sensor 10 is a waveform that suitably corresponds to breathing (hereinafter simply referred to as a breathing waveform). .

R8: "Period T is normal" R2: "Maximum slope a4°w7 is normal" R3:
"The maximum slope aup is normal." In this way, the individual satisfaction level T1. γ2. T.

Once the satisfaction levels γ1. γ2. T.

The smallest value among them is determined as the comprehensive evaluation value A. Next, step S8 is executed, and it is determined whether the comprehensive evaluation value A obtained in step S7 is, for example, 0.6 or more. If this determination is negative, it is determined that the waveform obtained this time is not a respiratory waveform and the process returns to step S2, but if it is affirmative, it is determined that it is a respiratory waveform and the subsequent step S9 is performed. executed. In step S9, the number of breaths per unit time (for example, per minute) is calculated based on the period T determined in step S5. Next, step SIO is executed, and the respiration rate determined in step S9 is displayed on the display 32, and the respiration waveform obtained this time is displayed on the display 32.

Therefore, in this embodiment, steps S2 to S8 are performed by the respiration detection means, step S9 is performed by the respiration rate calculation means, and step S10 and the display 3 are performed by the respiration rate calculation means.
2 correspond to the display means, respectively. In step Sll, it is determined whether or not the start switch has been turned off. If this determination is affirmative, the process is terminated, but if negative, the process returns to step S2 to continue detection of breathing. Ru.

In this way, according to this embodiment, the surface 2 of the upper abdomen of the subject
Based on the signal output from the acceleration sensor 10 attached to the sensor 2, a reciprocating movement of the surface 22 corresponding to respiration can be detected, and thereby the acceleration sensor 10 can be used to detect respiration. In this case, since the acceleration sensor 10 is not in electrical contact with the surface 22, the detection of respiration is not affected by the contact state of the acceleration sensor 10 with the surface 22.

Furthermore, since the acceleration sensor 10 directly detects the movement of the surface 22, it is sufficient to simply attach it to the surface 22, and as a result, the detection of respiration is not influenced by the clamping force applied to the surface of the living body, as in the past. receiving is completely eliminated.

As a result, it is possible to suitably prevent the detection of respiration from being affected by the state in which the acceleration sensor 1O is attached to the surface 22, and accordingly, the attachment work to the surface 22 of the acceleration sensor 1O requires time and skill. Breathing can be detected accurately and the respiratory rate can be measured accurately without any

Furthermore, according to the present embodiment, it is determined whether or not the waveform represented by the signal obtained from the acceleration sensor 10 is a respiratory waveform by using a rule based on fuzzy reasoning. Even if noise is mixed into the signal from the acceleration sensor 10, a respiratory waveform from which the noise has been removed can be suitably detected.

In addition, in the above-mentioned embodiment, the individual satisfaction level r++rz+
Although the minimum value of γ3 is determined as the overall evaluation value A for determining whether the waveform is a respiratory waveform, it is not necessary to do so. For example, the integrated value or average value of individual satisfaction levels can be used as the overall evaluation value. It may also be used as the minimum value or integrated value.

It can also be configured to appropriately combine average values to determine whether or not the waveform is a respiratory waveform.

Furthermore, in the above embodiment, the membership functions f + (T), f z (dow
n).

f3(up) may be determined for each subject based on pre-surgery data, or may be prepared in multiple types depending on conditions such as age and body temperature of the subject. .

Further, in the above-described embodiment, it is determined whether or not the waveform obtained by the acceleration sensor 10 is a respiratory waveform using fuzzy rules, but this is not necessarily necessary. Even if the correlation coefficient between the basic waveform obtained previously or the average waveform of multiple respiratory waveforms obtained up to the previous time and the waveform obtained this time is determined, and whether or not it is a respiratory waveform is determined based on the correlation coefficient. good. Note that a membership function representing the degree of satisfaction with the above-mentioned correlation coefficient may be stored in advance, and the overall evaluation value of the above-described embodiment may be determined by adding the degree of satisfaction related to the actual correlation coefficient.

Further, in the above-described embodiment, the signal from the acceleration sensor 10 was described as being supplied to the device main body 23 via wiring, but it may be supplied to the device main body 23 wirelessly.

Further, in the above-mentioned embodiment, the respiration rate measuring device is configured to include the acceleration sensor 10 and the device main body 23 separately, but as shown in FIG. The sensor 10, a substrate 34 provided with a microcomputer, etc., and a display 36 may be integrally configured.

Further, in the above-mentioned embodiment, the acceleration sensor 10 has the plate spring 14 to which the semiconductor strain gauge 18 is fixed, but other acceleration sensors such as a coil, a magnet provided on the weight, etc. are used. It is also possible to use a so-called servo-type acceleration sensor equipped with a servo type acceleration sensor.

Further, in the above embodiment, only one acceleration sensor 10 is provided, but by providing a plurality of acceleration sensors with different acceleration detection directions, an acceleration vector can be determined, and that vector can be used as a judgment element. It can also be configured to detect breathing.

Further, in the above embodiment, the respiration rate measuring device is configured to display the respiration waveform as well, but the respiration waveform does not have to be displayed.

Furthermore, in the above-mentioned embodiment, the acceleration sensor 10 is attached to the surface 22 of the subject's upper abdomen, but it is not necessary to do so, and any living body surface that moves back and forth in relation to breathing can be attached to the thorax. It may be attached to a surface or the like, or may be attached with a band or the like. Even if the acceleration sensor is attached to the surface of a living body by tightening it with a band, etc., since the acceleration sensor directly detects the movement of the surface of the living body, the detection of respiration may be affected by the tightening force. There's not much you can receive.

In addition, various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of the respiration rate measuring device of the present invention, and is a diagram showing a state in which an acceleration sensor is attached. FIG. 2 is an enlarged view of the acceleration sensor shown in FIG. 1, with a portion thereof cut away. FIG. 3 is a flowchart for explaining the operation of the apparatus shown in FIG. FIG. 4 is a diagram showing an example of a waveform represented by a signal from the acceleration sensor shown in FIG. 1. FIGS. 5 to 7 are diagrams showing examples of membership functions used when determining individual satisfaction levels in step S6 of the flowchart of FIG. 3, respectively. 8th
The figure is a perspective view showing another example of the respiration rate measuring device of the present invention. FIG. 9 is a diagram corresponding to the second claim of the present invention. 10: Acceleration sensor 22: Surface (Steps 82 to S8): (Respiration detection means) Step S9: (Respiration rate detection means) (Step 310, Display 32.36): (Display means)

Claims (2)

[Claims] (1) A respiration detection method in which an acceleration sensor is attached to the surface of a living body that reciprocates in relation to respiration, and the respiration of the living body is detected based on a signal output from the acceleration sensor. (2) an acceleration sensor attached to the surface of a living body that reciprocates in relation to respiration; a respiration detection means for detecting the respiration of the living body based on a signal output from the acceleration sensor; a breathing rate calculation means for calculating the number of detected breaths per unit time based on the detected breathing; and a display means for displaying the number of detected breaths per unit time calculated by the breathing rate calculation means. A respiration rate measuring device comprising: