JPH04215740A - Body interior blood deficiency detecting device - Google Patents

Abstract

PURPOSE:To obtain an interior blood deficiency detecting device detecting the interior blood deficiency continuously with no trouble and properly even under internal hemorrhage. CONSTITUTION:The mutual correlation function Rxy-a(K) indicating the time drift between the swell of the pressure pulse detected at the step S6 and the fluctuation showing the period of the respiration measured by a carbon dioxide concentration measuring device is calculated for each alpha pulse at the step S8, and the correlation function QBA(1) indicating the drift between the mutual correlation function Rxy-a(K) calculated in sequence and the reference mutual correlation function Rxy-a(K) calculated initially is calculated in sequence at the step S10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vivo blood deficiency detection device for detecting a blood deficiency state within a living body.

0002

2. Description of the Related Art When a large amount of bleeding occurs during surgery or the like, blood transfusion is performed while monitoring the patient's internal blood shortage. In order to detect this state of blood deficiency in the body, conventionally, the bleeding blood is usually wiped off with absorbent cotton whose weight has been measured in advance, and the weight of the absorbent cotton etc. in which the blood has been absorbed is measured. The amount of bleeding is measured by subtracting the weight of absorbent cotton or the like.

0003

[Problems to be Solved by the Invention] However, such conventional techniques for detecting the state of blood deficiency in the body have the disadvantage that the state of blood deficiency in the body can only be determined when the blood is wiped away. There is a problem in that detecting a state of blood deficiency in the body requires a relatively large amount of effort because it requires work to measure the weight of absorbent cotton, etc. for wiping blood, and work to measure the weight of absorbent cotton, etc. after wiping blood. Furthermore, since the system detects a state of lack of blood in the body based on bleeding that can be wiped off, there is a drawback that it is difficult to appropriately detect a state of lack of blood in the body when there is internal bleeding.

[0004] The present invention has been developed against the background of the above circumstances, and its purpose is to continuously detect blood deficiency conditions in the body without any effort and to detect internal bleeding even if there is internal bleeding. An object of the present invention is to provide an apparatus for detecting a state of blood shortage in the body that can suitably detect a state of blood shortage in the body.

[0005]

Means for Solving the Problems By the way, it is known that pulse waves generated from arteries in synchronization with the heartbeat of a living body produce undulations in relation to breathing. After conducting various studies, the inventor of the present invention discovered that the time lag between the undulation of the pulse wave and the wave indicating the respiratory cycle changes depending on the state of blood shortage in the body.

The present invention has been made based on such knowledge, and the gist of the in-body blood deficiency detection device of the present invention is as shown in the claim correspondence diagram of FIG.
(a) a pulse wave detection means for detecting a pulse wave generated from an artery of a living body; (b) a pulse wave undulation detection means for detecting an undulation of a pulse wave successively detected by the pulse wave detection means;
c) respiration detection means for detecting respiration of the living body;
) In order to detect the blood shortage state in the living body, the temporal difference between the pulse wave undulation detected by the pulse wave undulation detection means and the wave indicating the respiration period detected by the respiration detection means is determined. and a shift detection means for detecting a shift.

[0007]

[Operations and Effects of the Invention] According to the apparatus for detecting the state of blood deficiency in the body having the above structure, the pulse wave detecting means successively detects pulse waves from the arteries of the living body, and the undulations of the pulse waves are detected by the pulse wave undulation detecting means. At the same time, the breathing of the living body is detected by the breathing detection means. Then, the time lag between the undulations of the pulse wave and the waves indicating the respiration cycle is detected by the lag detection means, and a blood shortage state in the living body is detected based on the lag. As a result, by sequentially detecting the deviations, it is possible to continuously detect the state of blood deficiency in the body, and since there is no need for weight measurement using absorbent cotton, etc., as in the past, the state of blood deficiency in the body can be detected without any effort. Can be detected. Furthermore, since the state of lack of blood in the body is detected based on the time lag between the undulation of the pulse wave and the wave indicating the cycle of breathing, the state of lack of blood in the body can be suitably detected even if there is internal bleeding.

[0008]

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

In FIG. 2, 10 is a pulse wave detection probe. The pulse wave detection probe 10 includes a housing 12 having a container shape, a diaphragm 16 fixed to the inner wall of the housing 12 to form a pressure chamber 14 inside the housing 12, and a side of the diaphragm 16 opposite to the pressure chamber 14. The pulse wave sensor 18 is fixed to the surface of the patient and can be protruded from the open end of the housing 12, and the pulse wave sensor 18 is attached to the patient's wrist by means of a band 22 with the open end of the housing 12 facing the patient's body surface 20. It is designed to be removably attached to 24.

Pressure fluid such as pressurized air is supplied into the pressure chamber 14 from a fluid supply source 26 via a pressure regulating valve 28, so that the pulse wave sensor 18 detects the pressure inside the pressure chamber 14. It is pressed against the wrist 24 with a pressing force corresponding to the pressure. A pressure-sensitive element (not shown) such as a pressure-sensitive diode is provided on the pressing surface 30 of the pulse wave sensor 18, and when the pulse wave sensor 18 is pressed against the body surface 20, the pulse wave sensor 18 is activated in synchronization with the heartbeat. A pressure vibration wave, that is, a pressure pulse wave, generated from the radial artery 32 and transmitted to the body surface 20 is detected, and a pulse wave signal SM representing the pressure pulse wave is output to the control device 34. In this embodiment, the pressure pulse wave corresponds to the pulse wave, and the pulse wave detection probe 10, the fluid supply source 26, and the pressure regulating valve 28 constitute the pulse wave detection means.

The control device 34 includes a CPU, ROM, R
It is configured with a so-called microcomputer consisting of AM, input/output interface, etc., and the CPU is
Signal processing is executed using the memory function of the RAM according to a program stored in advance in the ROM, and the pressure regulating valve 28 is controlled to adjust the pressing force of the pulse wave sensor 18 to a pressing force that can obtain a pressure pulse wave of a suitable size. while sequentially detecting a pressure pulse wave based on the pulse wave signal SM collected by the pulse wave sensor 18 at the set pressing force and displaying the detected pressure pulse wave on the display 36, The highest value of the detected pressure pulse wave is determined sequentially.

A carbon dioxide concentration measuring device 38 is further connected to the control device 34 . This carbon dioxide concentration measuring device 38 continuously detects the carbon dioxide concentration in the breathing air that is expelled and inhaled through a mouthpiece 40 connected to the mouth of a patient undergoing surgery, and detects the detected carbon dioxide concentration. A concentration signal SC representing the concentration is output to the control device 34. Therefore, in this embodiment, the carbon dioxide concentration measuring device 38, the mouthpiece 40, etc. constitute the respiration detection means. The carbon dioxide concentration measuring device 38 includes, for example, an infrared gas analyzer. The control device 34 executes signal processing according to a pre-stored program, and calculates the undulation of the pressure pulse wave determined based on the maximum value of the pressure pulse wave and the wave indicating the respiration period determined based on the concentration signal SC. Sequentially find the temporal relationship between
Based on this relationship and a predetermined reference relationship, the patient's internal blood deficiency state is sequentially detected, and the detected internal blood deficiency state is displayed on the display 36.

Next, the operation of the apparatus for detecting a state of blood deficiency in the body constructed as described above will be explained with reference to the flowchart shown in FIG.

[0014] When the power is turned on, step S1 is executed, and it is determined whether a start switch (not shown) is turned on. If the judgment in step S1 is negative, the standby state is entered, but if the judgment is affirmative, step S2 is executed and the pressing force of the pulse wave sensor 18 is set to a pressing force that allows a pressure pulse wave of a suitable size to be obtained. be done.

Next, step S3 is executed to read the pulse wave signal SM, and the following step S4 is executed to determine whether one beat of the pressure pulse wave has been detected. If one beat has not yet been detected, steps S3 and S4 are repeatedly executed, but if one beat has been detected, step S5 is executed and the waveform of the detected pressure pulse wave is displayed on the display 36. At the same time, step S6 is executed, and the highest value (upper peak value) of the detected pressure pulse wave for one beat is determined and stored together with the time when the highest value appears. When the activation switch is turned on, a concentration signal SC representing the concentration of carbon dioxide in the patient's breath is sequentially detected and stored together with the detection time.

Next, step S7 is executed to determine whether pressure pulse waves have been detected for a predetermined constant number of beats α. This constant beat rate α is set in advance such that, for example, the elapsed time from the start of pressure pulse wave detection is longer than at least the time required for one breath. If the determination in step S7 is negative, steps S3 to S7 are repeatedly executed to display the pressure pulse waves sequentially, and the highest value of the pressure pulse waves is sequentially determined to determine each pressure pulse wave. The undulation of the pressure pulse wave is detected based on the maximum value of the wave. Therefore, in this embodiment, step S6 corresponds to the pulse wave undulation detection means. On the other hand, if the determination in step S7 is affirmative, step S8 is executed to calculate and store the cross-correlation function RXY-a(k) immediately before or at the beginning of the surgery. Ru. This cross-correlation function RXY-a(k) temporally calculates the correlation between the undulation of the pressure pulse wave represented by the highest value of the pressure pulse wave and the wave representing the period of respiration represented by the concentration signal SC. It is calculated by shifting it to , and is calculated, for example, as shown in Equation 1.

[Equation 1] That is, for the (M+1) pieces of data in the time period in which the α-beat pressure pulse wave was detected, the highest value of the pressure pulse wave X(
The cross-correlation function RXY-a(k) between a) and the carbon dioxide concentration y(a) is calculated. Figure 4 shows
This figure shows an example of the waveform and undulation of a pressure pulse wave and a wave indicating the period of respiration, and the undulation of the pressure pulse wave is drawn amplified in the vertical axis direction to make its fluctuations easier to understand. .

Next, by executing step S9, the cross-correlation function RX calculated this time in step S8
Y-a(k) is the first cross-correlation function RXY-a(k
) is determined. Since it is initially the first item, the determination in step S9 is negative and the process returns to step S3. Then, when the cross-correlation function RXY-a(k) is calculated in the subsequent step S8, the cross-correlation function RXY-a(k) is not the first one, so the determination in the subsequent step S9 is denied and the step S10 is executed.

FIG. 5 is a diagram showing an example of the cross-correlation function RXY-a(k) calculated as described above.
(a) shows the result at the peak of bleeding during the surgery, (b) shows the result after the peak of bleeding has passed, and (c) shows the result near the end of the surgery when there is less bleeding. In the cross-correlation function RXY-a(k) in (a), (b), and (c) of Fig. 5, the shift amount k corresponding to the maximum correlation value is the delay of the undulation of the pressure pulse wave with respect to the wave indicating the respiratory cycle, respectively. It shows. Therefore, in this embodiment, the above step S8 corresponds to the deviation detection means. In FIG. 5, one division (not shown) of k on the horizontal axis corresponds to, for example, 5 ms. From this figure 5,
It can be seen that as the surgery progresses, the peak of the cross-correlation function RXY-a(k) shifts in the horizontal axis direction, and the delay of the wave of the pressure pulse wave with respect to the respiratory wave shifts. This is the point of focus in this regard. In this way, as the surgery progresses, the cross-correlation function RXY
The reason for the deviation in -a(k) is presumed to be that the total amount of blood flowing in the patient's blood vessels changes due to the relationship between bleeding during surgery and blood transfusion, which changes the blood shortage state in the body. Ru.

Next, by executing step S10, the first cross-correlation function RXY-a(k) calculated in step S8 is converted into a reference cross-correlation function RXY-a(k).
a(k) A as its reference cross-correlation function RXY−
a(k) A and the subsequently calculated cross-correlation function RX
A correlation function QBA(l) between Y-a(k)B is calculated according to Equation 2.

[Formula 2] This correlation function QBA(l) is RXY-a(k) B
RXY-a(k) represents the deviation in the horizontal axis direction with respect to A , and the deviation reflects the blood shortage state in the patient's body before or at the beginning of the surgery.

Next, by executing step S11, the correlation function QBA(l
) is displayed on the display 36. Thereby, by visually observing the deviation in the time axis direction of the graph of the correlation function QBA(l) displayed on the display 36, the state of blood shortage in the body can be determined. In step S11, the amount of deviation may be detected from the correlation function QBA(l), and the amount of deviation or a numerical value corresponding to the amount of deviation may be displayed. In the following step S12, it is determined whether the starting switch is turned off. If it is still in the ON state, step S
3, the pressure pulse wave is sequentially displayed on the display 36, and the correlation function Q displayed on the display 36 is
BA(l) will be updated sequentially. On the other hand, when the starting switch is turned off and the determination in step S12 is affirmative, the process is terminated.

As described above, according to this embodiment, each time α beats of the pressure pulse wave are detected during surgery, the cross-correlation function RXY-a between the undulations of the pressure pulse wave and the wave representing the period of respiration is determined. (
k) B is determined, and its cross-correlation function R
The correlation function QBA(l) between XY-a(k) B and the reference cross-correlation function RXY-a(k) A obtained immediately before or at the beginning of the surgery is calculated, and the correlation function QBA(l) The state of blood deficiency in the body represented by is displayed on the display 36.
Since the information is displayed sequentially, it is possible to continuously monitor the blood deficiency state in the patient's body during surgery, and
A state of blood deficiency in the body can be automatically detected without requiring the labor of measuring the weight of absorbent cotton or the like as in the past.

Further, according to this embodiment, the cross-correlation function RXY-a obtained for detecting the state of blood shortage in the body
Since (k) changes depending on the total amount of blood flowing through the patient's blood vessels, it is possible to suitably detect a state of lack of blood in the body even if there is internal bleeding.

In the above-mentioned embodiment, the cross-correlation function RXY-a(k) obtained every time α beat of the pressure pulse wave is detected.
Find the correlation function QBA(l) between B and the reference cross-correlation function RXY-a(k)A, and calculate the correlation function QB
Although it is configured to monitor the state of blood deficiency in the body based on A(l), it is not necessary to do so; for example, without determining the correlation function QBA(l), the cross-correlation function RXY-a(k) B and RXY-a(k) A
It is also possible to monitor the state of blood deficiency in the body by displaying the two functions on the same graph and visually observing the deviation between the two functions, or by calculating the deviation between the two functions and displaying it numerically. Furthermore, the reference cross-correlation function RXY−
It is also possible to monitor the state of blood shortage in the body based on the relative change in the deviation between the successively determined cross-correlation functions RXY-a(k) without determining a(k) A .

Furthermore, in the above-mentioned embodiment, the time lag between the undulations of the pressure pulse wave and the wave representing the period of respiration is determined by the cross-correlation function RXY-a(k).
This is not necessarily necessary; for example, it can be determined based on the average value of the amount of deviation between the peak of the wave of the pressure pulse wave and the peak of the wave of respiration.

[0025] Furthermore, in the above embodiment, the undulation of the pressure pulse wave is detected based on the maximum value of the pressure pulse wave, but it may also be detected based on the minimum value or average value of the pressure pulse wave. .

Furthermore, in the above embodiment, the correlation function QBA
(l) is configured to display the state of blood shortage in the body, but in addition to or in place of that, it is determined whether there is an abnormality in the state of blood shortage in the body based on the correlation function QBA(l), When there is an abnormality, it may be configured to display a predetermined abnormality display or emit a sound indicating the abnormality, or it may be configured to control blood transfusion depending on the state of blood shortage in the body.

Furthermore, in the above-described embodiment, respiration is detected by measuring the carbon dioxide concentration in the breath, but respiration may also be detected by measuring intrathoracic pressure or the like.

Further, in the above-described embodiment, the pressure pulse wave detected by the pulse wave detection probe 10 is used only for detecting the state of blood deficiency in the body.
The pressure pulse wave may be used to continuously measure blood pressure values such as a systolic blood pressure value and a diastolic blood pressure value.

Further, in the above embodiment, pressure pulse waves are detected by pressing the radial artery 32, but pressure pulse waves may also be detected from other arteries other than the radial artery, such as the dorsalis pedis artery or the carotid artery. Alternatively, the pulse wave may be detected invasively using a catheter or the like.

[0030] In addition, various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram.

FIG. 2 is a circuit diagram showing the configuration of an in-body blood deficiency state detection device that is an embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the device in FIG. 2;

FIG. 4 is a diagram showing an example of waveforms and undulations of respiratory waves and pressure pulse waves.

[Figure 5] Cross-correlation function RXY that changes with the surgical progress
It is a figure showing an example of -a(k).

[Explanation of symbols]

{10: Pulse wave detection probe, 26: Fluid supply source, 28
: Pressure regulating valve} : Pulse wave detection means 32 : Radial artery (artery) {3
8: Carbon dioxide concentration measuring device, 40: Mouthpiece}:
Breathing detection means Step S6: Pulse wave undulation detection means Step S8: Displacement detection means

Claims (1)

[Claims] 1. A pulse wave detecting means for detecting a pulse wave generated from an artery of a living body, a pulse wave detecting means for detecting a pulse wave undulation successively detected by the pulse wave detecting means, and a pulse wave detecting means for detecting a pulse wave generated from an artery of a living body. and a pulse wave undulation detected by the pulse wave undulation detection means and a wave indicating a respiration cycle detected by the respiration detection means in order to detect a blood shortage state in the living body. A device for detecting a state of blood shortage in the body, comprising: a time difference detecting means for detecting a time difference between the two times.