JPH08322824A - Anesthetic depth detector - Google Patents

Abstract

PURPOSE: To make it possible to objectively detect the anesthetic depth of a living body. CONSTITUTION: A first heart beat period fluctuation signal HFCRR which is the fluctuation component of the heartbeat period generated in approximately synchronization with the respiration of the living body from the fluctuations in the heartbeat periods of the living body detected continuously from a heartbeat period detecting means 50 and the second heartbeat period fluctuation signal LFCRR consisting of the prescribed frequency component lower than this first heartbeat period fluctuation signal HFCRR are extracted by a heartbeat period fluctuation signal extracting means 52. The anesthetic depth DRR of the living body is determined in accordance with the ratio (LFCRR/BFCRR) between the first heartbeat period fluctuation signal HFCRR and the second heartbeat period fluctuation signal LFCRR. Then, the objective or quantitative determination of the anesthetic depth of the living body is made possible and the anesthetic depth of the living body is exactly detected without requiring skill, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the depth of anesthesia in a living body.

[0002]

2. Description of the Related Art When a patient is anesthetized during surgery or the like, it is desired to maintain an appropriate depth of anesthesia in order to protect the patient from the stress. Therefore, conventionally, for example, to monitor changes in the patient's blood pressure, heart rate, respiratory rate, etc., due to surgical stimuli, and to observe the patient's eyelash reflex, pupil size, color tone of the extremities, and body temperature. Based on this, the depth of anesthesia is grasped subjectively or empirically.

[0003]

However, it is necessary to know the depth of anesthesia by the change of the blood pressure value, the heart rate, and the respiratory rate, and the eyelash reflex, the size of the pupil, the color tone of the extremities of the extremities, and the depth of anesthesia by the body temperature. Since it is performed depending on the subjectivity of workers, it requires not only long-term training and skill, but it is not always easy to objectively or accurately grasp the depth of anesthesia. That is, it is an object of the present invention to provide an anesthesia depth detection device capable of objectively detecting the anesthesia depth of a living body.

The present inventors have made various studies based on the above circumstances, and when an anesthetized body is anesthetized, the magnitude of the fluctuation of respiratory synchrony and the blood pressure value contained in the fluctuation component of the heartbeat cycle of the body. The magnitude of fluctuation consisting of frequency components lower than the respiration contained in the fluctuation component of is closely related to the activity level of parasympathetic nerves or sympathetic nerves of the living body,
We found that the depth of anesthesia in a living body can be objectively expressed based on the magnitude of those fluctuations.

[0005]

[First Means for Solving the Problem] The present invention has been made based on such findings, and the gist thereof is an apparatus for detecting anesthesia depth of a living body, a) a heartbeat cycle detecting means for continuously detecting the heartbeat cycle of the living body, and (b) a fluctuation of the heartbeat cycle of the living body continuously detected by the heartbeat cycle detecting means, which is substantially synchronized with the respiration of the living body. Heartbeat cycle fluctuation signal extracting means for extracting a first heartbeat cycle fluctuation signal which is a fluctuation component of the heartbeat cycle generated by the above and a second heartbeat cycle fluctuation signal having a predetermined frequency component lower than the first heartbeat cycle fluctuation component. (C) Anesthesia depth determining means for determining the anesthesia depth of the living body based on the ratio of the first heartbeat cycle fluctuation signal and the second heartbeat cycle fluctuation signal extracted by the heartbeat cycle fluctuation signal extracting means. And are included.

[0006]

In this way, the fluctuation component of the heartbeat cycle that is generated substantially in synchronization with the respiration of the living body is derived from the fluctuation of the heartbeat cycle of the living body continuously detected by the heartbeat cycle detecting means. A certain first heartbeat cycle fluctuation signal and its first
The second heartbeat cycle fluctuation signal composed of a predetermined frequency component lower than the heartbeat cycle fluctuation component is extracted by the heartbeat cycle fluctuation signal extraction means. Then, the anesthesia depth determination means determines the anesthesia depth of the living body based on the ratio between the first heartbeat cycle fluctuation signal and the second heartbeat cycle fluctuation signal. Therefore, the depth of anesthesia of the living body can be determined objectively or quantitatively,
The anesthesia depth of the living body can be accurately detected without requiring skill.

[0007]

A second aspect of the present invention for achieving the above object is an apparatus for detecting anesthesia depth of a living body, comprising: (a) the living body Continuous blood pressure detection means for continuously detecting the blood pressure value of (b)
From the fluctuation of the blood pressure value of the living body continuously detected by the continuous blood pressure detecting means, a blood pressure value fluctuation signal extracting means for extracting a blood pressure value fluctuation signal which is a predetermined frequency component lower than the respiration of the living body, and (c ) Anesthesia depth determining means for determining anesthesia depth of the living body based on the strength of the blood pressure value fluctuation signal.

[0008]

With the above arrangement, the blood pressure value of the living body is continuously detected by the continuous blood pressure detecting means.
When the blood pressure value fluctuation signal which is a predetermined frequency component lower than the respiration of the living body is extracted by the blood pressure value fluctuation signal extraction means from the fluctuation of the blood pressure value of the living body detected continuously,
The anesthesia depth determination means determines the anesthesia depth of the living body based on the strength of the blood pressure value fluctuation signal. Therefore, the anesthesia depth of the living body can be determined objectively or quantitatively, and the anesthesia depth of the living body can be accurately detected without requiring skill.

[0009]

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

FIG. 1 is a diagram showing an example of the configuration of the anesthesia depth detection device of the present invention. In the figure, the electrocardiographic induction device 10 is
Equipped with a plurality of electrodes 12 attached to a living body, a well-known electrocardiographic induction signal that is continuously generated in synchronization with a heartbeat from a living body that has undergone general anesthesia with an inhalation anesthetic such as isoflurane is A / Operation control device 1 via D converter 14
6 is sequentially supplied to the CPU 18.

The continuous blood pressure measuring device 20 is equipped with a pressure pulse wave detection probe 22 which is pressed against an artery of a living body such as a carotid artery, a radial artery, a dorsalis pedis artery by a wearing band or the like (not shown). The applied blood pressure value of the living body is continuously detected for each beat, and a blood pressure value signal representing the blood pressure value is sequentially supplied to the CPU 18 of the arithmetic unit 16 via the A / D converter 24. This continuous blood pressure measuring device 20 is disclosed in, for example, Japanese Patent Laid-Open No.
It is configured similarly to the blood pressure monitoring device described in Japanese Patent Publication No. 253196.

The arithmetic and control unit 16 includes a CPU 18, R
A so-called microcomputer including the OM 26, the RAM 28, etc., which processes an input signal, that is, an electrocardiographic induction signal and a blood pressure value signal in accordance with a program stored in advance in the ROM 26 while utilizing a temporary storage function of the RAM 28, to obtain an anesthesia depth of a living body. D is displayed on the display 30.

FIG. 2 is a functional block diagram showing the control function of the arithmetic and control unit 16. In the figure, the heartbeat cycle detection means 50 continuously detects the heartbeat cycle T _RR of the living body under anesthesia by calculating the time interval of the electrocardiographic waveform, for example, the time interval between R waves. The heartbeat cycle T _RR thus continuously detected has fluctuation (variation) as shown in FIG. 3, for example.

The heartbeat cycle fluctuation signal extracting means 52 is a fluctuation component of the heartbeat cycle which is generated substantially in synchronization with the respiration of the living body from the fluctuation of the heartbeat cycle T _RR of the living body continuously detected by the heartbeat cycle detecting means 50. The first heartbeat cycle fluctuation signal H that is
FC _RR and a second heartbeat cycle fluctuation signal LF composed of a predetermined frequency component lower than the first heartbeat cycle fluctuation signal HFC _RR
Extract C _RR . This heartbeat cycle fluctuation signal extraction means 52
Then, the fluctuation of the heartbeat period T _RR is subjected to frequency analysis by using, for example, a fast Fourier transform (FFT) method or an autoregressive (AR) method, and a peak generated near the respiratory frequency band of the living body (for example, 0.25 Hz). The signal strength (signal power) of the frequency component having is output as the first heartbeat cycle fluctuation signal HFC _RR , and the vicinity of the frequency band of about 1/3 to 1/4 of the respiratory frequency of the living body (for example, 0.0
The signal strength (signal power) of the frequency component having the peak occurring at 7 Hz) is output as the second heartbeat cycle fluctuation signal LFC _RR . FIG. 4 shows the signal strengths of the first heartbeat cycle fluctuation signal HFC _RR , the second heartbeat cycle fluctuation signal LFC _RR , and the 0 Hz frequency component (DC component) signal DC _RR extracted from the fluctuations of the heartbeat cycle T _RR. Shows.

The first anesthesia depth determining means 54 included in the anesthesia depth determining means 62 is the heartbeat cycle fluctuation signal extracting means 5 described above.
The ratio of the first heartbeat cycle fluctuation signal HFC _RR and the second heartbeat cycle fluctuation signal LFC _RR extracted by 2 (LFC _RR / HFC
_RR ) to determine the anesthesia depth D _{RR of the} living body. The first anesthesia depth determination means 54 uses the actual ratio (LFC _RR / HFC) based on the relationship stored in advance shown in FIG. 5, for example.
_RR ) to determine the depth of anesthesia D _RR .

[0016] Due to the buffering from the respiratory center to the circulatory center at the brainstem level and the respiratory fluctuation of the afferent signal from the cardiopulmonary receptors, the activity of the cardiac vagus nerve, which is a centrifugal path from the circulatory center, is respirable. It is considered that fluctuations occur, and fluctuations appearing in the frequency of sinus node firing occur at a signal intensity (signal power) of a frequency component having a peak near the respiratory frequency band of the living body (for example, 0.25 Hz), that is, a first heartbeat cycle fluctuation signal. H
It is considered to be FC _RR . Respiratory variability also occurs in the sympathetic nerves that control the sinus node, but since heart rate control by the sympathetic nerve has the characteristic of a low-pass filter, only heart rate variability of an extremely low frequency of 0.15 Hz or less can be transmitted. HFC which is normal respiratory frequency without
_RR is mediated exclusively by the vagus nerve. Therefore, HF
The amplitude or signal strength of C _RR is proportional to the level of cardiac vagal activity and can be a selective and quantitative index of cardiac vagal activity. On the other hand, the second heartbeat cycle fluctuation signal L composed of a frequency component of about a fraction of the first heartbeat cycle fluctuation signal HFC _RR.
It is thought that FC _RR appears in heart rate variability via the baroreceptor reflex mechanism of blood pressure. The reflex afferents are the aortic sinus nerve and the efferents are the cardiac parasympathetic nerve and sympathetic nerve. Since it is proportional to the product of baroreceptor sensitivity, the evaluation of sympathetic nerve activity level is limited to the case where baroreceptor reflex sensitivity can be processed to be constant. Then, by using the ratio (LFC _RR / HFC _RR ),
It can be closely related to the nerve activity level without the influence of individual differences. The relationship in FIG. 5 is based on such a thing, and is experimentally obtained in advance.

Further, the continuous blood pressure detecting means 56 is constituted by, for example, the continuous blood pressure measuring device 22 and continuously detects the blood pressure value of the living body. The blood pressure value fluctuation signal extraction means 58 uses the blood pressure value of the living body continuously detected by the continuous blood pressure detection means 56, for example, the systolic blood pressure value P _SYS.
From fluctuation, and extracts the blood pressure fluctuation signal LFC _SYS is a predetermined frequency component lower than the breath of the living body. Also in the blood pressure value fluctuation signal extracting means 58, the fluctuation of the blood pressure value P _SYS is subjected to frequency analysis by using, for example, the fast Fourier transform (FFT) method or the autoregressive (AR) method, and ⅓ of the respiratory frequency of the living body. The signal strength (signal power) of a frequency component having a peak generated in the vicinity of a frequency band of about 1/4 (for example, 0.07 Hz) is output as a blood pressure value fluctuation signal LFC _{SY S.}

The second anesthesia depth determining means 60 included in the anesthesia depth determining means 62 has an anesthesia depth D _{SYS of the} living body based on the intensity of the blood pressure value fluctuation signal LFC _SYS from the relationship stored in advance as shown in FIG. 6, for example. To decide. Since the blood pressure value fluctuation signal LFC _SYS , which constitutes the fluctuation of blood pressure value, is considered to be derived from the delay element of the sympathetic vasomotor control system, its amplitude (signal strength) is quantified for vasomotor sympathetic nerve activity. Can be used as a dynamic indicator. The relationship in FIG. 6 is based on such a thing, and is experimentally obtained in advance.

FIG. 7 is a flow chart for explaining the main part of the control operation of the arithmetic and control unit 16 and shows a routine executed in synchronization with the pulse cycle or the input cycle of the blood pressure value.

In FIG. 7, the heartbeat period detecting means 50 is shown.
In SA1 corresponding to, the heartbeat cycle T _RR is calculated by calculating the time interval between the R waves of the electrocardiographic waveform input from the electrocardiographic induction device 10. Next, in SA2 corresponding to the heartbeat period fluctuation signal extraction means 52, for example, the fluctuation (fluctuation) of the fluctuation component of the heartbeat period T _RR that is sequentially calculated is determined by, for example, a fast Fourier transform (FFT) method or autoregression (AR). Near the respiratory frequency band of the living body (for example, 0.25 Hz) by performing frequency analysis using the method
The signal strength (signal power) of the frequency component having the peak occurring at the peak is extracted as the first heartbeat cycle fluctuation signal HFC _RR , and the vicinity of the frequency band of about 1/3 to 1/4 of the respiratory frequency of the living body (for example, 0. The signal strength (signal power) of the frequency component having the peak occurring at 07 Hz) is extracted as the second heartbeat cycle fluctuation signal LFC _RR .

Next, in SA3 corresponding to the first depth of anesthesia determination means 54, for example, the first heartbeat cycle fluctuation signal HFC _RR and the second heartbeat cycle fluctuation extracted in SA2 from the previously stored relationship shown in FIG. The anesthesia depth D _{RR of the} living body is determined based on the ratio with the signal LFC _RR (LFC _RR / HFC _RR ).

Next, at SA4, the continuous blood pressure measuring device 20
The blood pressure value P _SYS input from is read and
In SA5 corresponding to the blood pressure value fluctuation signal extraction means 58, frequency analysis is performed on the fluctuation of the blood pressure value P _{SYS by} , for example, a fast Fourier transform (FFT) method or an autoregressive (AR) method, so that the biological The signal strength (signal power) of a frequency component having a peak in the vicinity of a frequency band (for example, 0.07 Hz) of about 1/3 to 1/4 of the respiratory frequency is extracted as the blood pressure value fluctuation signal LFC _SYS .

[0023] Then, the in the second anesthetic depth determining means SA6 corresponding to 60, for example on the basis of a predetermined stored relationship shown in FIG. 6 in blood pressure fluctuation signal LFC _SYS which is extracted in SA5, biological depth of anesthesia D _SYS is determined.

At SA7, a more reliable depth of anesthesia D is determined from the depth of anesthesia D _RR determined based on the fluctuation of the heartbeat cycle and the depth of anesthesia D _SYS determined based on the fluctuation of the blood pressure value. . For example, when the values of the anesthesia depths D _RR and D _SYS are greatly different from each other, which one is an abnormal value is determined from the progress until then, and the value considered to be a normal value is the anesthesia depth D. It is determined.
When the values of the anesthesia depths D _RR and D _SYS are not so different, the average value of the two is determined as the anesthesia depth D. Then, at SA8, the anesthesia depth D determined at SA7 is quantitatively displayed on the display 30 by a numeral or a trend graph. This anesthesia depth D is expressed by a number by dividing the horizontal axis of FIG. 5 or 6 into predetermined units.

As described above, according to this embodiment,
It is continuously detected by SA1 corresponding to the period detection means 50.
Fluctuation of the heartbeat cycle of the living body is almost synchronized with the breathing of the living body
First heartbeat cycle change, which is a fluctuation component of the heartbeat cycle that occurs
Motion signal HFC_RRAnd its first heartbeat cycle fluctuation signal HFC_RR
Second heartbeat cycle fluctuation consisting of a predetermined frequency component lower than
Signal LFC_RRCorrespond to the heartbeat period fluctuation signal extraction means 52.
It is extracted by the corresponding SA2. And the first anesthesia depth
The first heartbeat cycle is determined by SA3 corresponding to the determining means 54.
Fluctuating signal HFC_RRAnd the second heartbeat cycle fluctuation signal LFC_RR
Ratio with (LFC _RR/ HFC_RR) Based on the depth of anesthesia of the living body
Degree D_RRIs determined. Therefore, objective or quantitative
The anesthesia depth of the living body D_RRThe anesthesia depth D of the living body_RR
Can be accurately detected without requiring skill
It

Further, according to this embodiment, the blood pressure value P _SYS of the living body is continuously detected by the continuous blood pressure detecting means 56,
From the fluctuation of the continuously detected blood pressure value P _SYS of the living body, the blood pressure value fluctuation signal LFC _SYS which is a predetermined frequency component lower than the respiration of the living body is converted into the blood pressure value fluctuation signal extraction means 58.
When extracted by SA5 corresponding to, the blood pressure value fluctuation signal LF is obtained by SA6 corresponding to the anesthesia depth determining means 60.
The anesthesia depth D _{SYS of the} living body is determined based on the strength of C _SYS . Therefore, objective or quantitatively be determined anesthetic depth D _SYS of the living body, can be accurately detected without requiring such skill the anesthetic depth D _SYS of the living body.

Further, according to this embodiment, in SA7 corresponding to the anesthesia depth determining means 62, the anesthesia depth D _RR determined from the fluctuation of the heartbeat cycle T _RR and the anesthesia depth determined from the fluctuation of the blood pressure value P _SYS. Since a more reliable depth of anesthesia D is finally determined based on D _SYS , the indicator 3
The reliability of the anesthesia depth D quantitatively displayed at 0 is further enhanced.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other modes.

For example, in the above-described embodiment, the heartbeat period T
Means 50 for obtaining anesthesia depth D _RR from fluctuation of _RR ,
52, 54 and fluctuation of blood pressure value P _SYS to depth of anesthesia D
Means 56, 58 and 60 for determining _SYS were provided, but even if either one is removed, the function of detecting the depth of anesthesia can be obtained.

Further, in the above-mentioned embodiment, the electrocardiographic induction device 1 is used.
The heartbeat cycle T _RR of the living body was continuously detected by calculating the cycle of the electrocardiographically induced waveform (ECG) induced by 0, for example, the interval of the R wave every beat, but the well-known cuff Or a pulse wave sensor for calculating the pulse wave cycle detected from the artery of the living body for each pulse wave, or for calculating the pulse wave cycle detected by the photoelectric pulse wave sensor for each pulse wave May be provided. In short, it suffices if a heartbeat cycle detecting means for continuously detecting the heartbeat cycle of the living body is provided. For example, when the heartbeat cycle is detected from the pressure pulse wave detected by the pressure pulse wave detection probe 22 of the continuous blood pressure measurement device 20, the electrocardiographic induction device 1
0 becomes unnecessary.

Further, as the heartbeat period T _RR or blood pressure value P _SYS or the depth of anesthesia D _RR or D _SYS in the above-mentioned embodiment, the value obtained for each beat is averaged within a predetermined period to obtain a moving average. Values may be used.

Further, the heartbeat period fluctuation signal extracting means 52 and the blood pressure value fluctuation signal extracting means 58 of the above-mentioned embodiment may be constituted by a digital filter for discriminating a low frequency microvibration signal.

In the above embodiment, the depth of anesthesia D _SYS
Although the fluctuation of the systolic blood pressure value P _SYS detected by the continuous blood pressure detecting means 56 is used to determine the fluctuation, the fluctuation of the mean blood pressure value P _MEAN or the minimum blood pressure value P _DIA detected by the continuous blood pressure detecting means 56 is used. Can be used.

In the above-described embodiment, the anesthesia depth D _{RR of the} living body is determined from the ratio (LFC _RR / HFC _RR ) of the first heartbeat cycle fluctuation signal HFC _RR and the second heartbeat cycle fluctuation signal LFC _RR to determine the blood pressure. The anesthesia depth D _{SYS of the} living body was determined from the intensity of the value fluctuation signal LFC _SYS , but their ratio (LFC _RR
/ HFC _RR ) or the blood pressure value fluctuation signal LFC _SYS may be corrected or corrected by other parameters. In short, the ratio of the first heartbeat cycle fluctuation signal HFC _RR and the second heartbeat cycle fluctuation signal LFC _RR (LFC _RR / HFC _RR )
On the basis of the determined anesthetic depth D _RR of the biological, anesthetic depth of a living body based on the intensity of the blood pressure fluctuation signal LFC _SYS D _SYS
Should be determined.

Although not described one by one, the present invention can be variously modified and changed within the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the anesthesia depth detection device of the present invention, and is a block diagram showing the configuration.

FIG. 2 is a functional block diagram illustrating a main part of a control function of the anesthesia depth detection device in FIG.

FIG. 3 is a diagram showing fluctuations in a heartbeat cycle T _RR detected in the anesthesia depth detection device of FIG.

4 is a first heartbeat cycle fluctuation signal HFC _RR , a second heartbeat cycle fluctuation signal LFC _RR , and a heartbeat cycle DC component DC _RR extracted from fluctuations of the heartbeat cycle T _RR detected by the anesthesia depth detection device of FIG. 1. It is a figure which respectively shows.

FIG. 5: Anesthesia depth D _RR in the anesthesia depth detection device of FIG.
FIG. 6 is a diagram showing a relationship used for determining

6 is an anesthesia depth D in the anesthesia depth detection device of FIG.
FIG. 6 is a diagram showing relationships used to determine _SYS .

FIG. 7 is a flowchart illustrating a main part of control operation of the anesthesia depth detection device in FIG.

[Explanation of symbols]

 50: Heartbeat cycle detecting means 52: Heartbeat cycle fluctuation signal extracting means 54: First anesthesia depth determining means 56: Continuous blood pressure detecting means 58: Blood pressure value fluctuation signal extracting means 60: Second anesthesia depth determining means

Claims (2)

[Claims] 1. An apparatus for detecting a depth of anesthesia in a living body, comprising: a heartbeat cycle detecting means for continuously detecting a heartbeat cycle of the living body; and a living body detected continuously by the heartbeat cycle detecting means. A second heartbeat cycle fluctuation signal, which is a fluctuation component of the heartbeat cycle that is generated substantially in synchronization with the respiration of the living body due to fluctuations in the heartbeat cycle, and a second frequency component that is a predetermined frequency component lower than the first heartbeat cycle fluctuation component. Heartbeat cycle fluctuation signal extraction means for extracting a heartbeat cycle fluctuation signal, and the first pulse signal extracted by the heartbeat cycle fluctuation signal extraction means
An anesthesia depth detection device, comprising: anesthesia depth determination means for determining anesthesia depth of the living body based on a ratio between a heartbeat period fluctuation signal and the second heartbeat period fluctuation signal. 2. An apparatus for detecting a depth of anesthesia in a living body, comprising: a continuous blood pressure detecting means for continuously detecting a blood pressure value of the living body; and a body pressure continuously detected by the continuous blood pressure detecting means. From the fluctuation of the blood pressure value, a blood pressure value fluctuation signal extracting means for extracting a blood pressure value fluctuation signal which is a predetermined frequency component lower than the respiration of the living body, and the anesthesia depth of the living body based on the strength of the blood pressure value fluctuation signal. An anesthesia depth detection device, comprising: anesthesia depth determination means for determining.