JPH05115445A - System for detecting dynamic state of peripheral circulation - Google Patents

Abstract

PURPOSE:To provide the system for detecting the dynamic state of the peripheral circulation which can quantitatively measure the dynamic state of the peripheral circulation of a living body at every period of artificial respirations and can predict the shock state of the living body in an earlier period when the living body is subjected to the artificial respirations by an artificial respirator. CONSTITUTION:The temporary change, generated in synchronization with the periods of the artificial respirations, in the photoelectric pulse waves expressed by the intensity of the light cast to the patient's forehead and reflected from the region where the peripheral blood vessel exists is detected in a step SB 4 and the delay time td of the point of the time when this temporary change is detected from the point of the time when the inhalation at every period of the artificial respirations completes is detected in a step SB 6. The dynamic state of the peripheral circulation is determined in accordance with the delay time td from a predetermined relation in a step SB 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peripheral circulatory dynamics detecting device for detecting the peripheral circulatory dynamics of a living body being artificially respired by an artificial respirator.

[0002]

2. Description of the Related Art When a patient's blood circulation is deteriorated due to bleeding or drugs during or after surgery, the patient may be in a shock and may be in a dangerous state. It is known that the shock condition is predicted by estimating the blood circulation dynamics from a predetermined blood analysis value or the like.

[0003]

By the way, since the deterioration of the blood circulation of the living body usually begins to appear from the peripheral blood vessels, in order to predict the shock state of the patient at an earlier stage, the arteriole system located near the body surface is considered. It has been considered to measure the hemodynamics of a patient in the peripheral blood vessels. That is,
Although attempts have been made experimentally to measure peripheral circulatory dynamics using lasers, plethysmographs, etc., quantitative measurement of peripheral circulatory dynamics has not yet been achieved.

As a result of various investigations by the present inventor, when artificial respiration is given to a patient by an artificial respirator, the photoelectric pulse wave due to the reflected light of the light applied to the forehead or the like affects the respiratory cycle of the artificial respiration. It was found that the delay time at the time when the change of the photoplethysmogram with respect to the reference time point within one cycle of the artificial respiration changes while changing temporarily synchronously, depending on the blood circulation dynamics of peripheral blood vessels.

The present invention has been made on the basis of such knowledge, and its object is to artificially determine the peripheral circulatory dynamics of a living body when the living body is artificially ventilated by an artificial respirator. It is an object of the present invention to provide a peripheral circulatory dynamics detecting device capable of quantitatively measuring each respiratory cycle and predicting a shock state of a living body at an earlier stage.

[0006]

Means for Solving the Problem The gist of the present invention for achieving such an object is to detect peripheral circulatory dynamics for detecting peripheral circulatory dynamics of an organism being artificially respired by an artificial respirator. An apparatus comprising: (a) a light-emitting element and a light-receiving element, and the light emitted from the light-emitting element toward the surface of the living body is reflected by the peripheral blood vessel in the living body to the light-receiving element. Photoelectric pulse wave detection means for detecting the photoelectric pulse wave represented by the intensity of the reflected light by receiving the light, and (b) detecting a temporary change in the photoelectric pulse wave that occurs in synchronization with the respiratory cycle by the artificial respiration. Pulse wave change detecting means for: (c) a temporary change of the photoelectric pulse wave with respect to a predetermined reference time point in one cycle of the artificial respiration in order to determine the blood circulation dynamics in the peripheral blood vessel. The delay time when Lies in the fact that includes a delay time detecting means that out. FIG. 8 is a claim correspondence diagram.

[0007]

In the peripheral circulatory dynamics detecting apparatus having such a configuration, the photoelectric pulse wave detecting means irradiates light from the light emitting element toward the surface of the living body being artificially respired by the artificial respirator, and The reflected light from the part where the peripheral blood vessel is located in the living body is received by the light receiving element, so that the photoelectric pulse wave represented by the intensity of the reflected light is detected and the photoelectric pulse wave generated in synchronization with the respiratory cycle by artificial respiration is detected. A temporary change in the photoelectric pulse wave is detected by the pulse wave change detecting means. Then, the delay time detecting means detects the delay time at the time when the change of the photoelectric pulse wave is detected with respect to the predetermined reference time within one cycle of the artificial respiration. This delay time quantitatively represents the blood circulation dynamics of the peripheral blood vessels, and the peripheral circulation dynamics are judged based on this delay time.

[0008]

As described above, according to the peripheral circulatory dynamics detecting apparatus of the present invention, the photoelectric pulse wave due to the reflected light from the site where the peripheral blood vessel is located with respect to a predetermined reference time within one cycle of artificial respiration. Based on the delay time at the time when a temporary change is detected, the blood circulation dynamics can be quantitatively measured in the peripheral blood vessels where the shock state begins to appear, so that the shock state of the living body can be predicted early. Moreover,
Since the peripheral circulatory dynamics based on the delay time can be measured in real time for each cycle of artificial respiration, the shock state of the living body can be predicted even earlier.

[0009]

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

FIG. 3 is a diagram showing the construction of the peripheral circulation dynamics detecting apparatus of the present invention. In the figure, 10 is a photoelectric pulse wave detection probe (hereinafter, simply referred to as a probe),
For example, it is worn in close contact with a wearing band or the like (not shown) on the surface 12 of the patient's forehead during or after surgery. The probe 10 includes a container-shaped housing 14 that is open in one direction, a plurality of light-emitting elements 16 such as LEDs that are provided on the outer peripheral side of the inner surface of the bottom of the housing 14, and the inner surface of the bottom of the housing 14. The light receiving element 18 provided in the central portion and including a photodiode, a phototransistor, etc., the transparent resin 20 integrally provided in the housing 14 and covering the light emitting element 16 and the light receiving element 18, and the light emitting element 16 in the housing 14. And the light receiving element 18, and the light emitting element 1
And a ring-shaped light shielding member 22 that shields the light emitted from the surface 6 toward the surface 12 and reflected from the surface 12 toward the light receiving element 18.

The plurality of light emitting elements 16 are, for example, 660.
The red light having a wavelength of about nm is emitted, and the reflected light from the site where the peripheral blood vessel is located in the forehead of the light emitted from the light emitting elements 16 toward the surface 12 is the common light receiving element 18. Are respectively received by. The light receiving element 18 outputs a photoelectric pulse wave signal SM having a magnitude corresponding to the amount of received light to the low pass filter 26 via the amplifier 24. The low-pass filter 26 removes noise having a frequency higher than the frequency of the pulse wave from the inputted photoelectric pulse wave signal SM, and the photoelectric pulse wave signal SM from which the noise is removed is passed through the A / D converter 28. Supply to the I / O port 30. In this embodiment, the probe 10 including the light emitting element 16 and the light receiving element 18 constitutes photoelectric pulse wave detecting means.

On the other hand, the patient is given artificial respiration by means of an artificial respirator (not shown) equipped with endotracheal intubation and the like, and the endotracheal intubation and the like has a pressure (artificial respiration) in the patient's respiratory tract. A pressure sensor 32 for detecting pressure P is provided. The pressure signal SP output from the pressure sensor 32 is sequentially supplied to the I / O port 30 via the amplifier 34 and the A / D converter 36.

The I / O port 30 has a CPU 38, a ROM 40, a RAM 42, and a C via a data bus line.
Each of them is connected to a display device 44 such as an RT display device. The CPU 38 executes signal processing according to a program stored in advance in the ROM 40 while utilizing the storage function of the RAM 42, and detects the maximum value P _max of the artificial respiration pressure P for each cycle of artificial respiration based on the pressure signal SP. At the same time, the photoelectric pulse wave signal S input from the light receiving element 18
A temporary change in the photoplethysmographic wave represented by M that occurs after the detection of the maximum value P _max in synchronization with the artificial respiration cycle is detected, and the maximum value P at the time when the temporary change in the photoplethysmographic wave is detected.
_{While the} delay time t _d with respect to the time point at which _max is detected (time point at which inspiration is completed) is sequentially detected, the peripheral circulatory dynamics of the patient is determined from a predetermined relationship based on the delay time t _d , and the determined peripheral The circulatory dynamics are displayed on the display 44.

Next, the operation of the peripheral circulation dynamics detecting apparatus constructed as above will be described with reference to the flow charts of FIGS.

The light emitting element 16 is turned on and the operation of the ventilator is started. Then, when the peripheral circulatory dynamics detection device is powered on and a manual start switch (not shown) is turned on, an initial process (not shown) is executed to clear flags F ₁ and F _{2 (} to be described later) and the like. 1
The photoelectric pulse wave routine and the artificial respiration routine of FIG. 2 are processed in parallel.

In the artificial respiration routine of FIG. 2, first, step SA1 is executed to read the pressure signal SP representing the artificial respiration pressure P. Next, step SA for detecting the maximum value P _max of the artificial respiration pressure P for each respiratory cycle.
After the P _max detection routine of _No. 2 is executed, step SA
3 is executed and it is determined whether or not the maximum value P _max is detected. If this determination is denied, steps SA1 to SA3 are repeatedly executed,
If the determination in step SA3 is affirmative, step SA4 is executed to store the detection time of the maximum value P _max , and then step SA5 is executed to determine the maximum value P _max.
Flag F to indicate that the _max detection time has been stored
₁ of the content is set to "1".

Next, step SA6 is executed to determine whether or not the content of the flag F ₂ described later is "1", that is, whether the delay time t _d is obtained in the photoelectric pulse wave routine described later. To be judged. If this judgment is negative, step SA6 although are repeatedly executed standby state, if the sought delay time t _d determined in step SA6 is positive, is the following step SA7 is executed After the contents of the flags F ₁ and F ₂ are cleared together, steps SA1 and thereafter are executed again. As a result, the stored content of the detection time of the maximum value P _max is sequentially updated for each respiratory cycle.

On the other hand, in the photoelectric pulse wave routine shown in FIG.
After the photoelectric pulse wave signal SM from S is read, step S
B2 is executed to determine whether or not one beat of the photoelectric pulse wave is detected. If this judgment is denied, step S
B1 and step SB2 are repeatedly executed, but if the determination in step SB2 is affirmative, step S2 is executed.
B3 is executed to determine whether the content of the flag F ₁ is "1", that is, whether the maximum value P _max of the artificial respiration pressure P is detected and the detection time is stored. If this determination is denied, steps SB1 to SB3 are repeatedly executed.

When the determination at step SB3 is affirmative, the pulse wave change detection routine at step SB4 is executed. In this pulse wave change detection routine, for example, the upper peak value or amplitude of the photoelectric pulse wave detected in this cycle is the upper peak value or amplitude of the photoelectric pulse wave detected in the previous multiple cycles. Based on the fact that the maximum value P _max is greater than a predetermined value by a predetermined value or more, a temporary change in the photoelectric pulse wave after the detection of the maximum value P _max is detected. In the present embodiment, the above step SB4, more accurately, the step SB of the ROM 40 is performed.
4 is stored and a predetermined portion of the CPU 38 and the RAM 42 for executing the step SB4 corresponds to the pulse wave change detecting means. Next, step SB5 is executed to determine whether or not a temporary change in the photoelectric pulse wave is detected. If this determination is negative, steps SB1 to SB5 are repeatedly executed, but if a temporary change in the photoelectric pulse wave is detected and the determination at step SB5 is positive, the subsequent step SB
6 is executed.

In step SB6, the delay time t _d at the time when the temporary change of the photoelectric pulse wave occurs with respect to the time when the maximum value P _max of the artificial respiration pressure P is detected is calculated and stored. In this embodiment, this step SB
6. More precisely, the portion of the ROM 40 in which the step SB6 is stored and the predetermined portion of the CPU 38 and the RAM 42 for executing the step SB6 correspond to the delay time detecting means. Next, step SB7 is executed,
After the content of the flag F ₂ is set to "1" to indicate that the delay time t _d has been obtained, step SB8 is executed, whereby the delay time t _d obtained at step SB6 is calculated. Te, for example, peripheral hemodynamics in patients from a predetermined relationship between peripheral hemodynamics and delay time t _d as shown in FIG. 4 are determined. In FIG. 4, the peripheral circulatory dynamics is represented by a numerical value within the range of 0 to 100, for example, and the lower the numerical value, the worse the peripheral hemodynamics. Note that FIG. 5 is a diagram showing an example of the delay time t _{d in} the case where the peripheral hemodynamics are favorable in relation to the artificial respiration waveform and the photoelectric pulse waveform, and FIG. 6 is the delay in the case where the peripheral hemodynamics deteriorate. an example of a time t _d is a graph showing the relationship between the artificial respiration waveform and the photoelectric pulse wave.

Next, step SB9 is executed, and the numerical value representing the peripheral circulatory dynamics determined in step SB8 is displayed as a trend on the display 44, and then steps SB1 and thereafter are executed again. As a result, the numerical value indicating the peripheral circulatory dynamics is trend-displayed on the display unit 44 for each respiratory cycle of artificial respiration, and the doctor, the nurse or the like grasps the peripheral circulatory dynamics of the patient from the display content of the display unit 44. In addition, it is possible to determine whether or not the patient is in a shock state for each respiratory cycle of artificial respiration based on the peripheral circulatory dynamics. FIG. 7 shows an example of the trend display of the peripheral circulation dynamics. Note that, in FIG. 7, the trend display of the peripheral circulatory dynamics is drawn as a curve for convenience.

As described above, according to the present embodiment, at the time when the maximum value P _max of the artificial respiration pressure P for each respiratory cycle is detected, the photoelectric pulse wave is temporarily generated by the reflected light from the part of the forehead where the peripheral blood vessel is located. Predicting the shock state of a patient at an early stage because it is possible to quantitatively measure the hemodynamics in the peripheral blood vessels where the shock state begins to appear, based on the delay time t _d at the time when a dynamic change is detected. You can Moreover, since the measurement of the peripheral circulation dynamics based on the delay time t _d can be performed in real time for each breathing cycle of artificial respiration, the shock state can be predicted earlier.

Further, according to the present embodiment, since the numerical value representing the determined peripheral circulation dynamics is displayed in a trend, there is an advantage that the temporal change of the peripheral circulation dynamics can be seen.

Further, according to the present embodiment, the photoelectric pulse wave is detected by irradiating the red light from the plurality of light emitting elements 16 toward the surface 12 of the forehead over a relatively large area. Therefore, compared with the case where photoelectric pulse wave is detected by irradiating a single point on the surface of the living body with laser light,
There is an advantage that the photoplethysmogram can be detected more accurately and the peripheral circulation dynamics can be detected more accurately.

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 embodiment, the probe 10
Is attached to the patient's forehead, but the effect of the present invention can be obtained even when it is attached to a site other than the forehead.

Further, in the above-described embodiment, the inspiration completion time is used as the reference time in one cycle of artificial respiration, but it is not always necessary, and for example, the inspiration start time may be used as the reference time. is there.

In the above embodiment, the time point when the maximum value P _max of the artificial respiration pressure P is detected is set as the reference time point (the time point when the inspiration is completed), but the tidal volume has been delivered to the lungs of the patient. There is no problem even if the time point is set as the reference time point (time point when the intake is completed).

Further, in the above-mentioned embodiment, the predetermined relationship between the delay time t _d and the peripheral circulatory dynamics is used that changes linearly, but it is not always necessary, for example, a step-like shape. What changes in a curved shape may be used.

In the above embodiment, the peripheral circulation dynamics obtained from the predetermined relationship based on the delay time t _d are displayed quantitatively, but the peripheral circulation dynamics are predetermined. It is also possible to determine whether or not the shock state of the patient is present and the degree thereof based on whether or not the value has exceeded and to display the determined presence or absence and degree of the shock state in place of or in addition to the peripheral circulatory dynamics. Then, by displaying the delay time t _d , the displayed delay time t
_It is also possible that a doctor or the like determines the peripheral hemodynamics based on _d to determine the shock state of the patient. It should be noted that instead of directly displaying the delay time t _d , the artificial respiration waveform and the photoelectric pulse waveform may be displayed in parallel as shown in FIG. 5 and the like, and the delay time t _d may be read from both waveforms. Good.

Further, in the above embodiment, in addition to or instead of displaying the peripheral circulation dynamics, a predetermined alarm sound or the like is output when the peripheral circulation dynamics deteriorates by a predetermined limit or more. You may.

In the above-mentioned embodiment, the numerical value indicating the peripheral circulatory dynamics is displayed as a trend, but it is not always necessary. For example, the numerical value is numerically displayed and the displayed value is sequentially updated. In any case, the effect of the present invention can be obtained.

Further, in the above embodiment, the light emitting element 16 for emitting light of one wavelength is provided, but it is not always necessary. For example, two kinds of light emitting elements for emitting light of two wavelengths are provided. A conventional reflection oximeter provided may be diverted to detect peripheral circulation dynamics.

Further, in the above-mentioned embodiment, red light having a wavelength of about 660 nm is used for detecting the photoelectric pulse wave, but other light can be used.

In addition, it goes without saying that the present invention can be embodied in variously modified forms without departing from the spirit thereof.

[Brief description of drawings]

1 is a flow chart for explaining the operation of the apparatus of FIG.

2 is a flow chart for explaining the operation of the apparatus of FIG. 3, which is executed in parallel with the flow chart of FIG.

FIG. 3 is a diagram showing an example of the peripheral circulatory dynamics detection device of the present invention, and is a block diagram showing the configuration.

FIG. 4 is a diagram showing an example of a predetermined relationship between peripheral hemodynamics and delay time t _d used in the flowchart of FIG.

FIG. 5: Delay time t when peripheral circulatory dynamics are good
_It is a figure showing _d in relation with an artificial respiration waveform and a photoelectric pulse waveform, and is a figure showing an example.

FIG. 6 is a diagram showing a delay time t _d in the case where peripheral circulation dynamics are deteriorated in relation to an artificial respiration waveform and a photoelectric pulse waveform, and is a diagram showing an example.

FIG. 7 is a diagram showing a display example of peripheral circulation dynamics.

FIG. 8 is a claim correspondence diagram.

[Explanation of symbols]

 10 Photoelectric pulse wave detection probe (photoelectric pulse wave detection means) 12 Surface 16 Light emitting element 18 Light receiving element

Claims (1)

[Claims] 1. A peripheral circulatory dynamics detection device for detecting peripheral circulatory dynamics of a living body being artificially respired by an artificial respirator, comprising a light emitting element and a light receiving element, wherein the light emitting element Photoelectric pulse wave detection means for detecting the photoelectric pulse wave represented by the intensity of the reflected light by receiving the reflected light of the light radiated toward the surface from the portion where the peripheral blood vessel in the living body is located by the light receiving element. A pulse wave change detection means for detecting a temporary change of the photoelectric pulse wave that occurs in synchronization with the respiratory cycle due to the artificial respiration, and to determine the blood circulation dynamics in the peripheral blood vessel, the artificial respiration A peripheral circulatory dynamics detecting device comprising: a delay time detecting means for detecting a delay time at the time of occurrence of the temporary change of the photoelectric pulse wave with respect to a predetermined reference time of one cycle.