JP2000041959A - Cardiac output monitoring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cardiac output monitoring instrument which can monitor easily and continuously change in the cardiac output of a living body. SOLUTION: When a photoelectric pulse wave of the peripheral part of an organism is detected by means of a photoelectric pulse sensor 40, a pulse wave area indicating blood flow rate of the peripheral part is calculated from the photoelectric pulse wave detected by means of the photoelectric pulse wave sensor 40 and the product of the pulse wave area and the heart rate calculated by a heart rate information calculating means 66 is calculated as a pseudo- cardiac output changing in relation to change in the cardiac output in a pseudo- cardiac output calculating means 68 and the changing value of the pseudo- cardiac output is calculated in a changing value calculating means 70 and the changing value is displayed on a displaying tool 36 by a changing value displaying means 74. Therefore, as the changing value of the pseudo-cardiac output changing in relation to the change in the cardiac output is displayed on the displaying tool 36, the change in the cardiac output of the organism can be easily and continuously monitored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cardiac output monitoring apparatus for continuously monitoring the cardiac output of a living body based on the fluctuation of the pulse wave in the peripheral part of the living body.

[0002]

2. Description of the Related Art Monitoring the volume of blood output from the heart is extremely important in monitoring the condition of a patient.
If blood output from the heart decreases, urgent treatment is required. The minute volume, ie, the cardiac output, which indicates the amount of blood output from the heart per minute, is calculated based on the Fick's principle using the oxygen collection amount O ₂ per minute and the oxygen content A of the arterial blood.
And the oxygen content V of the mixed venous blood divided by the difference (AV). Also, inject dyes or radioisotopes from a part of the living body, detect changes in transmitted light using a densitometer, and indirectly obtain the concentration curve of the dyes using the dilution method. Can be.

[0003]

However, when calculating the cardiac output using the Fick principle described above, the oxygen collection amount O ₂ per minute and the oxygen content A of the arterial blood can be easily measured, but it is difficult to measure them. It is difficult to measure the oxygen content V of venous blood. For example, to directly measure oxygen content V of mixed venous blood, pulmonary artery blood must be collected by placing a catheter in the pulmonary artery or right ventricle. . Even in the indirect method, mixed venous blood is obtained by retrieving alveolar gas after rebreathing a gas of appropriate composition or by collecting continuous arterial blood during rebreathing and measuring the change in gas content. Or a method of estimating the oxygen content V of the arterial blood and the oxygen content V of the mixed venous blood based on the composition of the gas in the capsule by further rebreathing a gas such as acetylene from the capsule briefly. Difference (A-
The method of calculating V) must be used. Therefore,
It was difficult to continuously monitor the patient's cardiac output. In addition, the method of measuring cardiac output by the dilution method also requires a dye or a radioisotope to be injected from a part of the living body, so that the device becomes complicated and large,
It was difficult to continuously monitor the patient's cardiac output.

[0004] Therefore, in monitoring the condition of a patient, a blood pressure value is generally used as a substitute value of the cardiac output. When monitoring the blood pressure value for a relatively long time, generally, a cuff wound around a part of the living body is used, and the blood pressure value of the living body is measured by changing the compression pressure by the cuff. A blood pressure monitoring device is used in which the blood pressure measuring means is automatically activated at a predetermined cycle. This is because the blood pressure measurement value measured by the blood pressure measurement means using the cuff can be relatively reliable.

However, when monitoring the patient's condition by measuring the blood pressure by the blood pressure monitoring device, if the automatic activation cycle is shortened in order to eliminate the delay in blood pressure monitoring, the frequency of pressing the cuff against the living body increases. There is a drawback that a large burden is imposed on the living body, and if the frequency of compression by the cuff becomes extremely high, congestion may occur and an accurate blood pressure value may not be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cardiac output capable of easily and continuously monitoring a change in cardiac output of a living body. It is to provide a quantity monitoring device.

The inventor of the present invention has conducted various studies on the background described above, and has found that the peripheral blood flow per unit time changes in close relation to the change in cardiac output of a living body. . The present invention has been made based on such findings.

[0008]

That is, the gist of the present invention to achieve the above object is a cardiac output monitoring device for monitoring cardiac output of a living body, comprising (a) )
A plethysmogram detecting device for detecting a plethysmogram in the peripheral part of the living body, and (b) a pulse wave area calculating means for calculating an area of the plethysmogram detected by the plethysmogram detecting device, (c) Heart rate information calculating means for calculating heart rate information related to the heart rate of the living body; and (d) heartbeat volume calculated by the pulse wave area calculating means and heart rate calculated by the heart rate information calculating means. A pseudo cardiac output calculating means for sequentially calculating a pseudo cardiac output which is a product of the numerical information, and (e) calculating a change value of the pseudo cardiac output calculated by the pseudo cardiac output calculating means. Change value calculation means, and (f) change value display means for displaying the change value calculated by the change value calculation means on a display,
To include.

[0009]

In this way, when the volume pulse wave in the peripheral part of the living body is detected by the volume pulse wave detection device, the volume pulse detected by the volume pulse wave detection device by the pulse wave area calculation means. The pulse wave area indicating the peripheral blood flow is calculated from the wave, and the product of the pulse wave area and the heart rate information calculated by the heart rate information calculating means is calculated by the pseudo cardiac output calculating means. The change in the pseudo cardiac output is calculated by the change value calculating means, and the change value is displayed on the display by the change value display means. You. Therefore, since the change value of the pseudo cardiac output which changes in relation to the change of the cardiac output is displayed on the display, it is possible to easily and continuously monitor the change of the cardiac output of the living body. it can.

Preferably, the change value display means graphically displays the change value calculated by the change value calculation means on a display. This has the advantage that the magnitude of the change value, that is, the change in cardiac output can be easily recognized.

Preferably, the cardiac output monitoring device comprises: a blood pressure measuring means for measuring a blood pressure value of the living body using a cuff for changing a compression pressure on a part of the living body; A blood pressure measurement activation unit that activates the blood pressure measurement by the blood pressure measurement unit based on the fact that the change value calculated by the calculation unit exceeds a predetermined determination reference range. With this configuration, when the change value of the pseudo cardiac output calculated by the change value calculation means exceeds a predetermined reference range, the blood pressure measurement using the cuff by the blood pressure measurement means starts immediately. Therefore, there is an advantage that a highly reliable blood pressure measurement value by the cuff is automatically obtained at the time of determining a change in cardiac output of the living body.

[0012] Preferably, the cardiac output monitoring device is configured to determine whether a change value of the pseudo cardiac output calculated by the change value calculating means exceeds a predetermined reference range. And abnormal display means for displaying an abnormal change in the pseudo cardiac output. In this way, the abnormal value of the change in the pseudo cardiac output that changes in relation to the change in the cardiac output is displayed, so that it is easy to recognize that the cardiac output of the living body has changed abnormally. There are advantages that can be done.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating a configuration of a cardiac output monitoring device 8 to which the present invention is applied.

In FIG. 1, a cardiac output monitoring device 8 includes a rubber bag in a cloth band-shaped bag, for example, the upper arm 1 of a patient.
2, a pressure sensor 14 and a switching valve 1 connected to the cuff 10 via a pipe 20, respectively.
6 and an air pump 18. The switching valve 16 has three states: a pressure supply state in which the supply of pressure into the cuff 10 is allowed, a slow discharge state in which the cuff 10 is gradually discharged, and a rapid discharge state in which the cuff 10 is rapidly discharged. It is configured to be switchable between two states.

The pressure sensor 14 detects the pressure in the cuff 10 and outputs a pressure signal SP representing the pressure to the static pressure discriminating circuit 22.
And the pulse wave discrimination circuit 24. Static pressure filter circuit 22 includes a low pass filter, steady pressure or cuff pressure P _C to discriminate the cuff pressure signal SK representative of the in the cuff pressure signal SK to the A / D converter 2 is included in the pressure signal SP
6 to the electronic control unit 28.

The pulse wave discriminating circuit 24 includes a band pass filter, and a pulse wave signal SM which is a vibration component of the pressure signal SP.
₁ is discriminated in frequency and the pulse wave signal SM ₁ is supplied to the electronic control unit 28 via the A / D converter 29. The cuff pulse wave represented by the pulse wave signal SM ₁ is a pressure vibration wave, that is, a cuff pulse wave generated from a brachial artery (not shown) and transmitted to the cuff 10 in synchronization with the heartbeat of the patient. 14 and the pulse wave discrimination circuit 24 function as a cuff pulse wave sensor.

The electronic control unit 28 includes a CPU 30, R
The microcomputer 30 includes a so-called microcomputer having an OM 32, a RAM 34, an I / O port (not shown), and the like. The CPU 30 executes signal processing using a storage function of the RAM 34 according to a program stored in the ROM 32 in advance. Thus, a drive signal is output from the I / O port to control the switching valve 16 and the air pump 18 and to control the display contents of the display 36.

The photoelectric pulse wave sensor 40 functioning as a volume pulse wave detecting device is configured in the same manner as that used for detecting a pulse, for example, for detecting a volume pulse wave (plethysmograph) of a peripheral blood vessel of a living body. In the housing 42 capable of accommodating a part of a living body such as a fingertip, red light or infrared light in a wavelength band that can be reflected by hemoglobin, preferably a wavelength of about 800 nm that is not affected by oxygen saturation. And a light receiving element 46 provided on the side of the housing 42 facing the light emitting element 44 and detecting light transmitted through a part of the living body. And outputs a photoelectric pulse wave signal SM ₂ corresponding to the blood volume in the capillary, and supplies the signal to the electronic control device 28 via the A / D converter 48. Since the photoelectric pulse wave signal SM ₂ is a signal that pulsates every beat in accordance with the amount of hemoglobin in the peripheral capillaries, that is, the blood volume, the photoelectric pulse wave sensor 40 detects a heartbeat signal of a living body. It also functions as a heartbeat signal detection device.

FIG. 2 is a functional block diagram illustrating a main part of the control function of the electronic control unit 28 in the cardiac output monitoring device 8. In FIG. 2, the blood pressure measuring means 60
The blood pressure measurement is activated at every preset blood pressure measurement cycle,
For example, the cuff pressure control means 62 changes the compression pressure of the cuff 10 wound around the upper arm of the living body to a predetermined target pressure value P.
_The pulse wave signal S is sequentially sampled during a slow down period in which the pressure is rapidly increased to _CM (for example, a pressure value of approximately 180 mmHg) and then slowly reduced at a speed of approximately 3 mmHg / sec.
Using a well-known oscillometric method based on the change in the amplitude of the pulse wave represented by M ₁ , determine a systolic blood pressure value BP _SYS , an average blood pressure value BP _MEAN , a diastolic blood pressure value BP _{DIA, and the} like,
The determined systolic blood pressure value BP _SYS and the average blood pressure value BP
_MEAN and the diastolic blood pressure value BP _DIA are displayed on the display 36.

The pulse wave area calculating means 64 calculates the area S of the volume pulse wave of the peripheral blood vessel detected by the photoelectric pulse wave sensor 40. Since the pulse wave signal SM ₂ output from the photoelectric pulse wave sensor 40 pulsates every beat as shown in FIG. 3, the pulse wave area calculating means 64 outputs the pulse wave signal SM ₂ , for example. calculating the intensity per one heartbeat, or the pulse wave area S representing the peripheral blood flow by two or more beats of the integration for every predetermined number of beats (adding the sampling values of the pulse wave signal SM _2). Alternatively, it is surrounded by a pulse wave and an area of a portion exceeding a predetermined reference value indicated by a predetermined broken line B, or a line connecting a rising point of a peak indicated by a dashed line C to a rising point of the next peak. The area of the fluctuation component of the pulse wave may be mainly calculated by, for example, calculating the area of the range every beat or every predetermined number of beats equal to or more than two.

The heart rate information calculating means 66 calculates heart rate information relating to the heart rate of the living body, that is, heart rate cycle TH, heart rate HR, pulse cycle TP, pulse rate PR, etc., from the heart rate signal detected by the heart rate signal detecting device. For example, the heartbeat period TH (sec) from the interval for example peak interval between the predetermined portion of the resulting pulse wave from the detected photoelectric pulse-wave signal SM ₂ is measured by the pulse wave sensor 40, further heart rate HR (times / min
) Is calculated from the relationship HR = 60 / TH.

The pseudo cardiac output calculating means 68 is the product of the peripheral pulse wave area S calculated by the pulse wave area calculating means 64 and the heart rate information calculated by the heart rate information calculating means 66. The pseudo cardiac output SS is calculated. The pseudo cardiac output SS represents the blood flow per unit time that changes in proportion to the cardiac output of the living body. For example, the pulse wave area calculation is performed so as to represent the blood flow per minute. The pulse wave area S for one beat calculated by the means 64 and the heart rate HR calculated by the heart rate information calculating means 66 (beats / min)
(= S × HR) is calculated as the pseudo cardiac output SS.

The change value calculating means 70 calculates a change value ΔS of the pseudo cardiac output calculated by the pseudo cardiac output calculating means 68.
Calculate S. The change value ΔSS is, for example, a change rate or a change amount with respect to the moving average value SS _{AV of} the pseudo cardiac output or the pseudo cardiac output SS determined based on the pulse wave before a predetermined number of beats. Since the pseudo cardiac output SS is proportional to the cardiac output of the living body, the change value ΔSS indicates a change in the cardiac output of the living body.

The blood pressure measurement activating means 72 calculates the change value ΔS of the pseudo cardiac output calculated by the change value calculating means 70.
It also functions as a change value abnormality judging means for judging abnormality of S, judges whether the change value ΔSS has exceeded a predetermined judgment reference range, and judges whether the change value ΔSS has exceeded the judgment reference range. Based on the above, the blood pressure measuring means 60
Activate blood pressure measurement by. For example, the pseudo cardiac output S
Moving average value of S SS _AV [= (SS _in +... + SS
_i-1 + SS _i ) / (n + 1)] or an abnormality in the change value ΔSS based on whether or not a predetermined value or a predetermined ratio has changed from the pseudo cardiac output SS calculated at the time of blood pressure measurement by the previous cuff. Is determined, and when it is determined that the change value ΔSS is abnormal, the blood pressure measurement by the blood pressure measurement means 60 is started.

The change value display means 74 is provided by the change value calculation means 7.
The change value ΔSS of the pseudo cardiac output calculated by 0 is displayed on the display 36. For example, a numerical value indicating the change value ΔSS is displayed, or the change value ΔSS is displayed as a graph.

The abnormality display means 76 includes a change value calculation means 70
When it is determined that the change value of the pseudo cardiac output calculated by the above is outside the predetermined judgment reference range, that is, in the blood pressure measurement activation means (change value abnormality judgment means) 72, it is judged that the change value ΔSS is abnormal. When the blood pressure measurement is started by the blood pressure measurement means 60, the pseudo cardiac output change value ΔS
The abnormality of S is displayed. For example, a character or a symbol indicating the abnormal value of the change ΔSS in the pseudo cardiac output is displayed on the display 36, or a sound or a sound indicating the abnormality in the change value ΔSS is output from a speaker (not shown) of the cardiac output monitoring device 8. A warning sound is output.

FIG. 4 is a flowchart for explaining a main part of the control operation of the electronic control unit 28. After an initial process of clearing a counter and a register (not shown) is performed in step SA1 (hereinafter, step is omitted) in the figure, in SA2, whether a photoelectric pulse wave for one beat, that is, one pulse wave is input is determined. Is determined. If the determination of SA2 is denied, SA2 is repeatedly executed. If the determination is affirmed, in SA3 corresponding to the subsequent pulse wave area calculation means 64, one pulse input from the photoelectric pulse wave sensor 40 in SA2 is obtained. pulse wave area S of the photoelectric pulse wave signal by integrating the intensity of the SM ₂ per one heartbeat of Namibun is calculated.

S corresponding to the following heart rate information calculating means 66
In A4, the peak interval of the pulse wave detected by the pulse wave sensor 40 is measured, and the peak interval, that is, the heartbeat period T
The heart rate HR (time / min) is calculated from H (sec), and in SA5 corresponding to the pseudo cardiac output calculating means 68, S5
The product (S × HR) of the pulse wave area S calculated in A3 and the heart rate HR calculated in SA4 is calculated to be 1
A pseudo cardiac output SS representing the blood volume per minute is calculated.

SA6 corresponding to the subsequent change value calculating means 70
Then, of the pseudo cardiac output SS calculated in SA5,
A change rate ΔSS (%) with respect to the average value SS _AV of the pseudo cardiac output calculated in the past minute up to the previous time is calculated. That is, the pseudo cardiac output SS calculated in SA5
The change rate ΔSS (%) of the pseudo cardiac output in the last routine with respect to the average value SS _AV of the past one minute calculated in SA7 to be described later is calculated based on Expression 1.

[0030]

Equation 1 ΔSS = | SS−SS _AV | / SS _AV

Then, in SA7, the average value SS _AV of the pseudo cardiac output calculated in the past minute, including the pseudo cardiac output SS calculated in SA5, is calculated, thereby obtaining the average value SS _{AV. AV} is updated and S in the next routine
This is used for calculating the change value ΔSS in A6.

SA8 corresponding to the subsequent change value display means 74
In, the change rate ΔSS (%) calculated in SA6 is graphically displayed on the display. For example, as shown in FIG. 5, the rate of change ΔSS calculated sequentially is displayed on the display 36 as a trend graph, and as shown in FIG. 6, the inclination of the arrow 78 indicates the magnitude of the rate of change ΔSS. It is.
In the example shown in FIG. 6, the state where the tip of the arrow 78 (not shown) is vertically upward is the state where the change rate ΔSS is 0%, and FIG. 6A shows the case where the change rate ΔSS is 20% or more. It is a graph shown, (b) is a change rate ΔSS is 3
It is an example of a graph displayed when 0% or more.

At SA9 corresponding to the blood pressure measurement activation means, ie, the change value abnormality determination means 72, the change rate ΔSS (%) calculated at SA6 is set in a predetermined reference range.
For example, it is determined whether it exceeds 30%. If this determination is affirmative, there is a possibility that the cardiac output has changed abruptly.
In FIG. 10, a display indicating an abnormal cardiac output is displayed on the display 36, for example, the back-colored portion 80 of the graph in FIG. 6B is red, and a character or a symbol indicating the abnormal cardiac output is displayed. After that, the SA corresponding to the following blood pressure measurement means 60
At 11, blood pressure measurement using the cuff 10 is activated, and the measured blood pressure value is displayed on the display 36. After the execution of SA11, SA2 and subsequent steps are repeatedly executed.

However, if the determination in SA9 is denied, in SA12, the set period of about 20 minutes, ie, the calibration period, which has been set in advance since the blood pressure measurement was previously performed by the cuff 10, is set. It is determined whether or not it has elapsed. If the determination in SA12 is denied, SA2 and subsequent steps are repeatedly executed. If the determination is affirmed, blood pressure measurement by the cuff 10 in SA11 is executed.

As described above, according to the present embodiment, when the photoelectric pulse wave sensor 40 detects a photoelectric pulse wave in the peripheral part of the living body, the pulse wave area calculating means 64 (SA3) uses the photoelectric pulse wave. A pulse wave area S indicating the peripheral blood flow rate is calculated from the photoelectric pulse wave detected by the sensor 40, and the pulse wave area S and the heart rate information calculating means 66 are calculated in the pseudo cardiac output calculating means 68 (SA5). Heart rate H calculated in (SA4)
R is calculated as a pseudo cardiac output SS that changes in relation to a change in cardiac output, and the change value calculating means 70 (SA
In 6), the change value ΔSS of the pseudo cardiac output is calculated,
The change value ΔS is obtained by the change value display means 74 (SA8).
S is displayed on the display 36. Therefore, the pseudo cardiac output change value ΔSS that changes in association with the cardiac output change is displayed on the display 36, so that the change in the cardiac output of the living body can be easily and continuously monitored. be able to.

According to the present embodiment, the change value display means 74 (SA8) graphically displays the change value ΔSS calculated by the change value calculation means 70 (SA6) on the display 36. The advantage is that the magnitude of the change value ΔSS, that is, the change in the cardiac output can be easily recognized.

Further, according to the present embodiment, the cardiac output monitoring device 8 includes the cuff 10 for changing the compression pressure on a part of the living body.
Blood pressure measuring means 60 for measuring the blood pressure value of the living body using
(SA11), and based on the fact that the change value ΔSS calculated by the change value calculation means 70 (SA6) exceeds a predetermined judgment reference range, the blood pressure measurement means 60 (SA1
Blood pressure measurement starting means 72 for starting the blood pressure measurement according to 1)
(SA9), the change value calculating means 7
If the change value ΔSS calculated at 0 (SA6) exceeds the predetermined reference range, the blood pressure measurement using the cuff 10 by the blood pressure measurement means 60 (SA11) is immediately started, so that reliability is improved. There is an advantage that a blood pressure measurement value with a high cuff is automatically obtained when a change in cardiac output of a living body is determined.

Further, according to the present embodiment, the abnormality display means 7
6 (SA10) displays an abnormal change in the pseudo cardiac output SS when it is determined that the pseudo cardiac output change value ΔSS calculated by the change value calculating means 70 (SA6) exceeds 30%. It is displayed on the device 36. Therefore, the change value ΔSS of the pseudo cardiac output that changes in relation to the change in the cardiac output
Is displayed, so that it is easy to recognize that the cardiac output of the living body has changed abnormally.

FIG. 7 shows an example of a cardiac output monitoring device using a photoelectric pulse wave detecting probe 90 of a pulse oximeter 88 for measuring so-called blood oxygen saturation as a volume pulse wave detecting device. I have. The pulse oximeter 88 includes a photoelectric pulse wave detection probe 9 for measuring blood oxygen saturation.
0 (hereinafter simply referred to as a probe). The probe 90 is attached, for example, in close contact with a body surface 38 such as a patient's forehead by a not-shown attachment band or the like. The probe 90 is provided in a container-like housing 92 that opens in one direction, and a plurality of first light emitting elements 94a and second light emitting elements 94b that are provided on a portion located on the outer peripheral side of the bottom inner surface of the housing 92. (Hereinafter, the light emitting element 94 is simply referred to unless otherwise specified.)
A central portion of the bottom inner surface of the housing 92,
A light receiving element 96 composed of a photodiode, a phototransistor, or the like, and a transparent resin 98 provided integrally in the housing 92 to cover the light emitting element 94 and the light receiving element 96
And a light emitting element 94 provided between the light emitting element 94 and the light receiving element 96 in the housing 92.
Annular shielding member 100 for shielding reflected light from the body surface 38 of the light irradiated toward the light 8 toward the light receiving element 96
It is comprised including.

The first light emitting element 94a is, for example, 660
The second light emitting element 94b emits red light having a wavelength of about
Emit infrared light having a wavelength of about 800 nm, for example. The first light emitting element 94a and the second
The light-emitting elements 94b emit light alternately at a predetermined frequency in accordance with the drive current from the drive circuit 101, and the capillaries in the body of the light emitted from the light-emitting elements 94 toward the body surface 38 are concentrated. Light reflected from the part is received by the common light receiving element 96.

The light receiving element 96 outputs a photoelectric pulse wave signal SM ₃ having a magnitude corresponding to the amount of received light via the low-pass filter 102. Light receiving element 96 and low-pass filter 10
An amplifier and the like are appropriately provided between the first and second circuits. Low pass filter 102 removes noise from the photoelectric pulse-wave signal SM ₃ input has a higher frequency than the frequency of the pulse wave,
And it outputs a signal SM ₃ whose noise is removed in the de-multiplexer 104. The demultiplexer 104 is switched in synchronization with the light emission of the first light emitting element 94a and the second light emitting element 94b in accordance with a signal from the electronic control device 28, and thereby converts the electric signal SM _R of the red light into the sample hold circuit 106 and the A / A Via the D converter 109,
Sampling and holding circuit 1 for electric signal SM _IR by infrared light
08 and the A / D converter 110, and sequentially supplied to an I / O port (not shown) of the electronic controller 112 for measuring oxygen saturation. Sample hold circuit 106, 1
When the input electric signals SM _R and SM _IR are sequentially output to the A / D converters 109 and 110, the A / D converter 10 for the previously output electric signals SM _R and SM _IR is used.
The electric signals SM _R and SM _IR to be output next are held until the conversion operation in steps 9 and 110 is completed. In addition, a display (not shown) is connected to the electronic control unit 112 to display the oxygen saturation in blood.

The electronic control unit 112 includes a CPU 114, R
The microcomputer 114 includes an AM 116, a ROM 118, and the like, and is capable of communicating with the electronic control unit 28. The CPU 114 performs a measurement operation in accordance with a program stored in the ROM 118 while utilizing the storage function of the RAM 116. While calculating and displaying the oxygen saturation in accordance with the signals SM _R and SM _IR , the electric signal SM _R or SM _IR having a waveform as shown in FIG. 3 is sequentially output to the electronic control unit 28 as a volume pulse wave.

The method of calculating the oxygen saturation is, for example,
For example, Japanese Unexamined Patent Publication No.
440 is similar to the determination method described in
｛(V_dR-V_SR) / (V_dR+ V_SR)｝ / ｛(V_dIR-V
_SIR) / (V_dIR+ V_SIR) The ratio indicated by｝ and oxygen
From the pre-determined relationship between saturation and
The oxygen saturation is determined. In the above equation, V
_dR, V_SRIs the upper peak of the photoplethysmographic waveform caused by red light
Value, lower peak value, V_dIR, V_SIRAre infrared
The upper and lower peak values of the photoplethysmographic waveform due to light.
Also, V_dR-V_SRAnd V_dIR-V_SIRIs the waveform of each photoelectric pulse
Represents the amplitude of the AC component of _dR+ V_SRYou
And V_dIR+ V_SIRDoubles the DC component of each photoplethysmographic waveform
Respectively.

While the embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above-described embodiment, the photoelectric pulse wave sensor 40 or the photoelectric pulse wave detecting probe 90 for measuring oxygen saturation is used as the volume pulse wave detecting device, but an impedance pulse wave sensor is used. You may be. This impedance pulse wave sensor includes at least two electrodes that are brought into contact with the epidermis of the living body at a predetermined interval,
It is configured to output an impedance pulse wave corresponding to the blood volume of the living tissue located between the two electrodes.

In the above-described embodiment, the photoelectric pulse wave sensor 40 and the photoelectric pulse wave detection probe 90 functioning as a volume pulse wave detecting device also function as a heartbeat signal detecting device. By supplying pressure to the wound cuff 10 so as to slightly press the upper arm 12, the cuff pulse wave may be continuously detected, and the cuff pulse wave may be used as a heartbeat signal. An electrocardiographic guidance device, a heart sound microphone, or the like may be provided as a heartbeat signal detection device.

Further, the blood pressure measuring means 60 of the above-described embodiment is used.
In (SA11), the blood pressure measurement is executed at each preset blood pressure measurement cycle and when the blood pressure measurement activation means 72 (SA9) determines that the blood pressure measurement is activated. Is not performed, and the blood pressure measurement may be performed only when the blood pressure measurement activation unit 72 (SA9) determines that the blood pressure measurement has been activated.

Further, the blood pressure measuring means 60 of the above-described embodiment is used.
(SA11) is configured to determine the blood pressure value based on the change state of the magnitude of the pressure pulse wave that changes according to the compression pressure of the cuff 10 according to the so-called oscillometric method. , The blood pressure value may be determined based on the Korotkoff sound that is generated and disappears according to the compression pressure of the cuff 10.

The above-mentioned pseudo cardiac output calculating means 68
(SA5) is the product (S × H) of the heart rate HR and the pulse wave area S.
R) was calculated as the pseudo cardiac output SS, but the product (S / TH) of the reciprocal (1 / TH) of the cardiac cycle TH (sec) and the pulse wave area S was calculated as the pseudo cardiac output. May be used.

In the above-described embodiment, the abnormality of the change value ΔSS is determined for each pulse wave. However, the abnormality may be determined for each predetermined number of two or more beats.

In the above-described embodiment, the gradient of the arrow 78 indicating the change rate ΔSS is changed stepwise in the change value display means 74 (SA8) for each change rate ΔSS in the predetermined range. The change may be made continuously corresponding to the change rate ΔSS.

The change value calculating means 70 (SA
The change value ΔSS calculated in 6) is the direction of change, that is, the average value SS _{AV of the} pseudo cardiac output SS calculated sequentially.
The magnitude of the pseudo cardiac output SS and the average value SS _AV which are sequentially calculated may be calculated, but the change value ΔSS may also be calculated.

In addition, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a cardiac output monitoring device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram illustrating a main part of a control function of the electronic control device of the embodiment of FIG. 1;

FIG. 3 is a diagram illustrating a photoelectric pulse wave detected by the photoelectric pulse wave sensor of the embodiment of FIG.

FIG. 4 is a flowchart illustrating a main part of a control operation of the electronic control device according to the embodiment of FIG. 1;

FIG. 5 is a diagram showing a trend graph of a change value displayed on a display device of the cardiac output monitoring device of FIG. 1;

FIG. 6 is a diagram showing an example of a graph of a change value displayed on a display device of the cardiac output monitoring device of FIG. 1;

FIG. 7 is a view showing a main part of a cardiac output monitoring device including a photoelectric pulse wave detection probe of an oximeter as a volume pulse wave detecting device according to another embodiment of the present invention.

[Description of sign]

8: cardiac output monitoring device 36: display device 40: photoelectric pulse wave sensor (volumetric pulse wave detecting device, heartbeat signal detecting device) 64: pulse wave area calculating means 66: heart rate information calculating means 68: pulse wave area normal Conversion means 70: change value calculation means 72: blood pressure measurement activation means (change value abnormality determination means) 74: change value display means 76: abnormality display means

Continued on the front page (72) Inventor Hidekatsu Inukai 2007-1 Kobayashi, Komaki-shi, Aichi Japan F-term in Korin Co., Ltd. (Reference) 4C017 AA02 AA03 AA09 AB01 AB03 AC03 AC27 AD01 BC11 BD01 CC03 FF05

Claims (2)

[Claims] 1. A cardiac output monitoring device for monitoring a cardiac output of a living body, wherein the cardiac pulse wave detecting device detects a volume pulse wave at a peripheral portion of the living body, Pulse wave area calculation means for calculating the area of the volume pulse wave detected by the device; heart rate information calculation means for calculating heart rate information related to the heart rate of the living body; Pseudo cardiac output calculating means for sequentially calculating a pseudo cardiac output which is a product of the plethysmographic area and the heart rate information calculated by the heart rate information calculating means, and the pseudo cardiac output calculating means And a change value display means for displaying a change value calculated by the change value calculation means on a display device. Cardiac output monitoring device. 2. The cardiac output monitoring device according to claim 1, wherein the change value display means displays the change value calculated by the change value calculation means on a display device in a graph.