JP3779900B2 - Blood vessel tension measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring the elasticity of blood vessels, and more particularly to an apparatus capable of monitoring useful for diagnosis of peripheral circulation of a human circulatory system.
[0002]
[Technical background]
In the operating room and emergency care, the management of blood circulation affects the prognosis of patients. The peripheral circulation is greatly affected by the degree of blood vessel tension (contraction / dilation). Nevertheless, in the blood pressure measurement method that has been generally performed, it is difficult to grasp whether the blood vessel is constricted or dilated even though the blood pressure value can be known.
For example, blood pressure is grasped as the product of blood flow (cardiac output) and vascular resistance, but blood pressure can be maintained by contraction of blood vessels even when the cardiac output decreases due to bleeding or heart failure. Therefore, it may not be possible to recognize a decrease in cardiac output only by measuring blood pressure. In the case of hypotension observed in patients with shock, different treatments are required depending on whether the cause is a decrease in vascular resistance (vasodilation) or a decrease in cardiac output. Nevertheless, it is impossible to discriminate between the two by measuring blood pressure alone.
[0003]
Therefore, in order to grasp the degree of vascular tension, the propagation time of the pressure wave, which is conventionally shortened with the vascular tension, is measured, or a measurement method using a pulmonary artery catheter is used in combination with blood pressure measurement It has been. This method measures the cardiac output and the like, and determines the degree of tension of each blood vessel in the circulatory system in combination with the blood pressure situation.
To describe the pulmonary artery catheter method more specifically, first, a catheter in which pressure sensors are arranged in a plurality of longitudinal positions is inserted from, for example, a patient's jugular vein, and through the heart while performing X-ray observation, Place in the pulmonary artery. The cardiac output (l / min) is measured by injecting a fixed amount of solution with a temperature difference from the body temperature into the blood vessel from the proximal end of the catheter, and measuring the time at which the tip of the catheter is reached and its temperature change with a temperature sensor. Is required. The degree of vascular tone was judged by comprehensively considering the propagation time of these pressure waves, cardiac output, and blood pressure.
However, the above-mentioned pulmonary artery catheterization has problems such as large invasiveness to the patient, skill in handling the measuring instrument, a long time for a single measurement and a delay in judgment, and the need for a large-scale device. was there.
[0004]
Blood vessel tension is a change in blood vessel elasticity. For example, when the elasticity of the blood vessel is expressed by viscoelasticity (compliance), it is defined by the ratio (ΔV / ΔP) of the increase in the intravascular volume to the pressure increase at a certain part of the blood vessel at a certain time. By continuously measuring the intravascular volume and blood pressure, the elasticity of the blood vessel at a certain time can be calculated, for example, as the ratio of the time derivative of each measured value or the ratio of the difference from the previous value at a minute time interval. .
However, changes in blood pressure and intravascular volume (intravascular volume) form a peak after rising in synchronization with the heartbeat period (several hundred ms to about 1 s), and then gradually attenuate. Therefore, even if both waveforms are observed only with the waveform expressed on the time axis, it is extremely difficult to determine whether or not a change in the elasticity (blood vessel tension) of the blood vessel occurs.
[0005]
[Problems to be solved by the invention]
The present invention solves the above-described problems, and an object of the present invention is to provide a measuring apparatus that can display the degree of tension (elasticity) of blood vessels in an easy-to-understand manner.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a measuring device for measuring the degree of blood vessel tension, and measures a blood pressure measuring unit for measuring blood pressure of a blood vessel in a certain part of the body and a blood vessel capacity of a blood vessel in the vicinity thereof. Display a plurality of Lissajous figures for one heartbeat based on the relationship between the intravascular volume measuring unit, the blood pressure obtained by the blood pressure measuring unit, and the intravascular volume from the intravascular volume measuring unit , and orthogonal to the time axis And a display processing unit for three-dimensional expression with coordinate axes .
The display processing unit can display a plurality of Lissajous figures by rotating coordinates expressed in three dimensions.
The display processing unit may display a plurality of Lissajous figures at a preset display time interval.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings.
An example of the configuration of the embodiment of the present invention is shown in the block diagram of FIG.
In FIG. 1, 1 is a patient's hand (arm), 2 is a blood pressure converter, 3 is a pulse oximeter detector, 4 is a blood pressure measuring device, 5 is a pulse oximeter measuring device, 6 is an electrocardiograph, 10 to 12 are A / D converters, 13 is a digital recorder, 21 is an input interface unit for inputting a digital value of the microcomputer, 22 is the same operation control unit (CPU), 23 is an operation unit such as a switch, 24 Is a storage unit (MEM), 25 is a display unit such as a CRT or liquid crystal, and 26 is an acoustic output unit such as a speaker.
In the configuration of this embodiment, the hand of a patient who has been anesthetized in general is selected as a site to be measured, and the blood vessel tension (elasticity) of the entire body of the patient during surgery is represented by the hand (arm) for continuous monitoring. An example of the case is shown.
[0008]
Next, the operation in the configuration of FIG. 1 will be described.
The blood pressure measurement in FIG. 1 shows an example using a patient's radial artery wave. The blood pressure in the blood vessel is guided outside the body by a tube (not shown) inserted into the radial artery of the patient's arm 1 and converted into an electrical signal by the blood pressure converter 2. The blood pressure measuring device 4 calculates the converted electrical signal and generates a continuous voltage signal proportional to the blood pressure.
The pulse oximeter 5 is a measuring device that can determine the state of oxygenation of arterial blood simply by sandwiching the detector 3 of the pulse oximeter at the fingertip (see Japanese Patent Publication No. Sho 53-26437 for details). The measurement principle of the pulse oximeter is to apply red and infrared light to the nail and measure the amount of light absorption at two wavelengths with a sensor on the fingerprint side. Since the amount of light absorption varies depending on the amount of blood in the portion through which light passes, the color tone of the pulsating component of the amount of absorption (ie, bright red = oxygen-bonded type or dark red = non-oxygen-bonded type) The ratio of oxygen binding to arterial hemoglobin that is not affected by absorption by the tissue portion can be determined.
The final output of the pulse oximeter is a numerical value of the oxygen binding ratio. However, in order to monitor the operating state, a continuous measurement waveform is usually output in the part that calculates the amount of light absorption. The meaning of this waveform corresponds to the calculated value of the portion where the baseline does not fluctuate, and the wave height corresponds to the portion where the amount of light absorption is minimized. This waveform is normally displayed by inverting the magnitude direction (±) of the wave.
When the oxygen binding state is considered to be substantially constant, the continuous measurement waveform of the pulse oximeter represents the blood volume of arterial blood in the portion to be measured. Because the arterial blood vessel is an elastic tube with muscle tissue on the outer periphery, it expands and contracts by internal pressure, and the baseline of the continuous measurement waveform corresponds to the arterial blood volume when there is no arterial pressure (minimum blood pressure state), The crest portion of the waveform corresponds to the increased blood volume in the time zone in which the pulsation changes including the maximum value. That is, the continuous measurement waveform of the pulse oximeter indicates the amount of change as a relative value to the intravascular volume of the artery.
On the other hand, the change in the intravascular pressure measured at the proximal end of the blood vessel at the fingertip, that is, the radial artery, can be regarded as almost equal to the blood pressure change in the blood vessel at the fingertip.
[0009]
In general, a device that measures volume changes in the whole body, organs, and parts of the body is called a plethysmograph. In the configuration of the embodiment shown in FIG. 1 described above, an example is shown in which a change in blood vessel volume at the fingertip is measured using a pulse oximeter as a plethysmograph. This is a preferable example because the measurement with the fingertip of the pulse oximeter is non-invasive and does not burden the patient. In the present invention, any plethysmograph capable of measuring the internal volume of the blood vessel is not limited to the pulse oximeter. Moreover, as long as a value proportional to the intravascular volume can be obtained, it is not necessarily limited to the capacity changing device. It can be arbitrarily selected according to the measurement site and the examination situation. Other plethysmographs that can be applied in the present invention include, for example, measurement of blood vessel volume using ultrasonic waves and measurement of volume change using a cuff.
Since the sphygmomanometer is always used during normal surgery, it can also be used as its signal. The measurement location is not limited to the hand, and the tonometry method can be used in addition to the blood pressure monitor of the blood vessel insertion type.
[0010]
In the configuration of FIG. 1, the blood pressure waveform from the blood pressure measuring device 4 and the intravascular volume waveform from the pulse oximeter 5 are converted into analog signals by the A / D converters 10 to 12 together with the waveform of the electrocardiograph 6. And recorded in the digital recorder 13 for verification when necessary.
The interface unit 21 of the microcomputer takes in a digital value that has been A / D converted in accordance with a command from the calculation control unit 22. The acquired value is temporarily stored in the storage unit 24. At least one heartbeat cycle is stored. The storage unit 24 also stores a series of processing procedures (programs) that are called by operating the operation unit 23 and repeatedly determined and processed by the control unit.
The result of the determination / processing is sent to the display unit 25 and the sound output unit 26 so that the processing figure can be seen as described later, and the output of the alarm sound can be heard.
[0011]
Signal processing in the configuration of the embodiment shown in FIG. 1 will be described using waveform examples of measurement results shown in FIGS. FIG. 2 is a diagram illustrating an example of continuous waveform output in the blood pressure measuring device 4 and the pulse oximeter measuring device 5. 2 (c) shows a normal state, FIG. 2 (a) shows a decrease in blood pressure due to vasodilation, FIG. 2 (d) shows a increase in blood pressure due to vasoconstriction, and FIG. 2 (b) shows a cardiac output. It shows the state when the blood pressure is decreasing despite the blood vessel contraction due to the decrease. FIG. 3 captures the waveform of FIG. 2 in the storage unit at a sufficiently short time interval compared to the pulse, and displays the blood pressure waveform on the X axis and the intravascular volume waveform as it is on the Y axis (so-called Lissajous figure). It is the state made to do. Each of the Lissajous figures in FIGS. 3A to 3D corresponds to the same time axis waveform in FIGS. 2A to 2D. If a figure is drawn over and over again, minute changes in each cycle are integrated, making it difficult to understand the figure currently being drawn. Therefore, in this embodiment, after drawing one heartbeat, the previous display is erased before entering the next display.
As shown in FIG. 3A, a significant difference is clearly shown by drawing a Lissajous figure by inputting a blood pressure waveform on the X axis and an intravascular volume waveform on the Y axis. Using this figure, it is possible to determine the contraction / expansion of the blood vessel at the end. The determination will be described below.
[0012]
(Example of figure judgment and medical treatment)
The figure in FIG. 3A shows a case where blood pressure is reduced and blood vessels are dilated. Based on such graphic display, it is determined that the blood pressure is reduced due to vasodilation, and a treatment for tensioning the blood vessel is selected.
The figure in FIG. 3D shows a case where the blood pressure is rising and the blood vessel is contracting. Based on the graphic display of FIG. 3D, it is determined that the blood pressure has increased due to blood vessel contraction, and a treatment for dilating the peripheral blood vessel is selected.
The figure in FIG. 3B shows a case where the blood pressure is lowered and the blood vessel is contracted. From the graphic display of FIG. 3 (b), it can be determined that there is an option to reinforce the function of the heart due to a decrease in blood pressure due to a decrease in cardiac output.
In addition, FIG.3 (c) has shown the figure in the case of normal time without abnormality.
[0013]
<Other processing examples>
In the example of FIG. 3, the blood pressure is shown on the horizontal axis. However, the Lissajous figure in the form of blood pressure (Y axis) with respect to the intravascular volume (X axis) is exchanged by replacing the vertical and horizontal axes of the blood vessel volume and blood pressure. It is also possible to display. In this case, when the shape of the figure is close to the vertical axis, the stiffness of the blood vessel is indicated, and the stiffness of the blood vessel is expressed by stiffness.
Further, for example, by setting a threshold value for the volume in the blood vessel or blood pressure in the elasticity measuring device, an alarm sound can be generated when the threshold value is exceeded.
[0014]
<Display on time axis>
FIG. 4 shows a time axis t and an X axis and a Y axis orthogonal to the time axis, and the time axis t, the X axis and the Y axis are displayed in a three-dimensional manner. The screen 100 of the display unit 25 displaying the above-mentioned Lissajous figure on the X axis and the blood pressure on the Y axis is shown. The X axis and Y axis around the time axis can be rotated by + -90 degrees. It is also possible to rotate the time axis itself by + -90 degrees. The rotation angle is set by moving the knobs 120 and 130 on the lower and side surfaces of the screen 100 about the XY axes with a mouse or the like. The time axis itself is rotated by rotating the lower right knob 140. 4A shows a state where the Y axis is rotated by about −30 degrees and the X axis is rotated by +30 degrees, and FIG. 4B shows a state where the Y axis is rotated by about −30 degrees and the X axis is rotated by −30 degrees. Is shown.
[0015]
When the Lissajous figure observed at one heartbeat is thinned out and displayed in the preset display time interval (10 minutes in the case of FIG. 4) on the XY axis plane orthogonal to the time axis, a large number of Lissajous as shown in FIG. The figure is displayed in 3D. In the case of FIG. 4, 90 beats per minute is thinned out to 2 beats per minute, that is, 1/45. By rotating the time axis itself, it is possible to display a three-dimensional figure from an arbitrary angle. FIG. 4 displays a portion of the heart rate measured and recorded in the past. For example, a figure from one minute before to the present time can be displayed in real time.
Such rotation and display data processing can be performed by applying a normal CAD program.
[0016]
By such a three-dimensional display including the time axis, it becomes possible to easily grasp the state of continuous change of the Lissajous figure. When the knobs are all in the center (0 degree), a normal two-dimensional Lissajous figure is displayed in a superimposed manner. When the X-axis is set to +90 degrees, the temporal change in the maximum / minimum value of the intravascular volume can be displayed. When the Y axis is set to +90 degrees, the time axis is in the vertical direction, but temporal changes in the maximum and minimum values of blood pressure can be displayed.
By moving the knob and observing it from various angles, the characteristics of the graphic change can be examined. For example, when general anesthesia is introduced during surgery, the patient's blood pressure generally decreases gradually, and the vascular tone relaxes and the intravascular volume gradually increases. By examining the Lissajous figure at that time, anesthesia can be achieved. It is expected that a new index for determining the effect can be derived.
[0017]
The display using the two-dimensional Lissajous figure can easily determine the current vascular tone by displaying the blood vessel tone level in one heartbeat and the blood pressure / intravascular volume pattern. However, it is difficult to grasp temporal changes.
Further, when the pulse oximeter waveform is used, a relative value is obtained as the amount of change in the blood vessel volume. This is useful rather than finding an absolute value in clinical practice for patients of various physiques from newborns to adults. However, it is difficult to quantitatively and qualitatively understand the state of change with a two-dimensional Lissajous figure that cannot display temporal changes.
[0018]
【The invention's effect】
The display of the present invention described above is easy to understand because the amount of information is increased and the relationship between the figures is easy to read, compared to the two-dimensional display of only the Lissajous figures of blood pressure and intravascular volume.
For this reason, the following effects can be acquired by using the elasticity measuring apparatus of this invention.
(1) Since it is possible to grasp the degree of vascular tension quantitatively and over time, it becomes easy to determine the degree of tension / severity of the shock state and the determination of the dosage for it.
(2) Since it is possible to qualitatively observe the treatment during the operation as a change in the pattern of the vascular tone, such as the effect of administration of the vasodilator, it becomes easy to determine whether or not an additional treatment is necessary.
(3) By observing the change pattern of the time-series display from various angles, it is possible to introduce a new index such as an anesthetic effect.
(4) Since the threshold value can be determined from the intravascular volume under observation, the intravascular alarm level including the individual differences can be accurately set for the elasticity measuring apparatus.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an apparatus for measuring the elasticity of a blood vessel.
FIG. 2 is a diagram showing an example of continuous waveform output of a blood pressure measuring device 4 and a pulse oximeter measuring device 5 of the present invention.
FIG. 3 is a diagram showing a display with a Lissajous figure.
FIG. 4 is a diagram showing display by a plurality of Lissajous figures on the time axis.
[Explanation of symbols]
1 hand (arm)
2 Blood pressure transducer 3 Detector 4 Blood pressure meter 5 Pulse oximeter 6 ECG 10-12 A / D converter 13 Digital recorder 21 Interface unit 22 Operation control unit 23 Operation unit 24 Storage unit 25 Display unit 26 Sound output Unit 100 display unit screen 110 Lissajous figure display unit on time axis 120 Y axis rotation designation knob 130 X axis rotation designation knob 140 time axis rotation designation knob

Claims (3)

A measuring device for measuring the degree of tension of blood vessels,
A blood pressure measurement unit for measuring blood pressure of blood vessels in a part of the body;
An intravascular volume measuring unit for measuring the intravascular volume of the nearby blood vessel,
A plurality of Lissajous figures for one heartbeat are displayed based on the relationship between the blood pressure obtained by the blood pressure measuring unit and the intravascular volume from the intravascular volume measuring unit , and three-dimensionally expressed by coordinate axes orthogonal to the time axis. A blood vessel tension measuring device comprising: a display processing unit. In the measurement apparatus for measuring the tension of the blood vessel according to claim 1, wherein the display processing unit, vascular tension measuring apparatus characterized by rotating the coordinates three dimensional representation displays the plurality of Lissajous figures . In the measurement apparatus for measuring the tension of the blood vessel according to claim 1 or 2, wherein the display processing unit, vascular tension measuring apparatus characterized by displaying a plurality of Lissajous figure in display interval set in advance .

Images