JPH0226532A - Method for measuring injection heat quantity and device - Google Patents

Abstract

PURPOSE:To correctly obtain an injection heat quantity with an injection liquid by detecting the injection temperature of the injection liquid and the temperature in an organism to which the injection liquid is injected and obtaining the injection heat quantity with the injection liquid based on such detection information. CONSTITUTION:An injection liquid 7 cooled at a prescribed temperature by a cooling device 44 is injected to a constant-quantity constant-speed injector 45, and the injection liquid made into the constant quantity and constant speed is injected through an air trap 59, a catheter 2 and a lumen 17 from an injection hole 14 into the body. An injection liquid temperature measured value by a thermistor 49 and a blood temperature measured value by a thermistor 8 are supplied to an external device 52. The external device 52 includes a CPU, the injection heat quantity is obtained by the measured values, it is displayed on a display 36, and simultaneously, it is outputted by a printer 37.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an injection calorimetry method for measuring the amount of heat injected into a living body by injecting an injection liquid into the living body, and an apparatus used to carry out this method. Furthermore, the present invention relates to a device that uses the measured amount of injected heat to measure blood flow by a thermodilution method that is more accurate than the conventional method.

Conventional techniques Conventionally, methods for measuring blood flow velocity include laser Doppler method, pulse modulation Doppler method, ultrasound Doppler method,
There are pitot tube catheterization methods, hot film methods, etc.
However, these methods do not reveal the cross-sectional shape or velocity distribution of blood vessels, so it is necessary to use other methods in combination to measure cardiac output (total flow rate). Impedance method, electromagnetic flowmeter method, admittance splesmography, etc. are methods that can theoretically measure the total flow rate, but these methods are not sufficient to measure the flow rate in a specific blood vessel by percutaneously inserting a catheter. do not have.

Therefore, as an excellent method for measuring blood flow (particularly cardiac output) without being affected by changes in blood vessel diameter or flow velocity distribution within blood vessels, thermodilution method using Fick's law and dye dilution method are recommended. law is used. These methods are
Measuring the rate at which physical quantities injected from outside the body, such as the low temperature caused by a cold water mass or the coloration caused by pigments, are diluted by blood,
The cardiac output is determined from this measured value.

According to the thermodilution method, as shown in FIG. 6, a catheter 2 is guided through the vena cava 1 to the right atrium 4 of the heart 13, further through the right ventricle 5 to the pulmonary artery 6, and cold water 7 is injected into the right atrium 4. A sensor (usually a thermistor) 8 near the tip measures blood temperature changes. That is, the recovery from the low temperature state caused by the cold water 7 due to the blood flow is measured by the thermistor 8 as a change in resistance. In addition, 9 in the figure is the left atrium, 1
0 is the left ventricle, 11 is the pulmonary vein, and 12 is the aorta. As shown in FIG. 7 and FIG. 8, which is a sectional view taken along the line ■-■ in FIG. A lumen 17 for cold water supply is provided and corresponds to these.
, a lumen 18 for thermistor wiring, a lumen 19 for pressure measurement, and a lumen 20 for feeding air into the balloon.

However, the thermistor indicated by 49 as shown in FIG. 1 is not provided. Then, as shown in Fig. 6, when inserting the catheter 2 (usually percutaneous insertion) and placing it in the bloodstream, the balloon 16 is inflated (as shown by the dashed line in Fig. 7).
Carry catheter 2.

In this way, the blood temperature change obtained by the sensor 8 is generally converted into cardiac output using the following equation (1).

Cardiac output (blood flow (1/akin) Catheter correction factor liters of injected cold water (ml) Temperature of blood before cold water injection ("C) Temperature of injected cold water ("C) Specific heat of blood ( Kcal/g) Specific gravity of blood (g/cIl13) Specific heat of injected water (Kcal/g) Si: Specific gravity of injected water (g/cm3) t: Time (sec) (sec) ΔTb: Blood temperature change] (1 ), where Cb, Sb, Ci and Si are constants and are known if measured in advance. Therefore, Vi
If , is defined, vb can be obtained by measuring Tb and Ti.

However, the derivation of equation (1) includes several assumptions. These assumptions include: (1) The volume of injected fluid is significantly smaller than the volume of blood flowing during the measurement.

■The injection solution is completely mixed up to the temperature change measurement site.
■There is no inflow or outflow of heat between the blood vessel wall and the blood. (2) The injectate temperature Ti and the blood flow Tb are constant during the measurement period.

Among these, assumptions ■ and ■ are considered to be fully established. Furthermore, regarding the assumption (2), there are few individual differences among patients, and it does not differ from measurement to measurement, and is generally corrected using a correction coefficient called a catheter coefficient Ct. The blood flow in assumption (■) can be considered constant during the time required for measurement (generally between 10 seconds and 2 minutes), but
The injectate temperature is not constant. That is, the temperature of the injected liquid has conventionally been measured using a temperature sensing means placed between the syringe and the catheter or before it is drawn up into the syringe. However, the injection liquid left in the catheter from the previous measurement is warmed by room temperature in the external part of the body and by body temperature in the internal part. This means that the average temperature of the injectate changes depending on the measurement interval, and furthermore, the cardiac output is calculated based on equation (1) using a temperature of the injectate that is different from this average temperature. As an attempt to provide a means for detecting a partial temperature rise in the temperature of the injected liquid inside the catheter, Japanese Patent Laid-Open No. 621012
There is a proposed invention in Publication No. 25. However, only by using this temperature detection means, it is difficult to accurately determine the amount of injected heat Qi shown in equation (2) below. That is,
The injection liquid temperature T i (t) and the injection liquid flow 1Fi (t) are time functions, and now not only Ti (t) but also Fi (t
) must also be determined accurately. The above Japanese Patent Publication No. 62-10
In the invention described in No. 1225, a means for accurately determining Ti(t) is proposed, but a means for accurately determining flow 1Fi(t) is not proposed. The present invention utilizes the following (
2) At the same time, it is proposed to obtain the value accurately using the formula.

It is.

[However, Qi: amount of heat injected (Kcal) Ti(
t): Difference between temperature near the catheter injectate outlet during injection and body temperature Fi(t): Injectate flow rate (cm3/5ec) C1
: Specific heat of injection liquid CKca 17g, 'C)Si
: Injection liquid specific gravity (g/cm') to : Injection time
(sec)) Conventionally, the injection of cold water has been done manually, so it is extremely difficult to keep the flow rate of cold water Fi(t) constant.
cannot be determined accurately.

That is, in FIG. 9, a syringe 60 is used,
2 is a schematic diagram illustrating how to inject cold water 7 into a pulmonary artery (not shown) via a catheter 2. FIG.

When the cold water 7 is manually injected as shown in FIG. 9, the flow rate of the cold water 7 tends to be large due to force exerted on the fingers at the beginning of the injection, and this tends to decrease as time passes. However, the way this flow 1Fi(t) changes differs each time.

A thermistor 4 is installed adjacent to the cold water inlet 14 of the catheter 2.
Normally, this thermistor 49 is not provided. ), measure the temperature just before injection of cold water 7 and find the injection heat i1
It is possible to correct Qi, but as mentioned above, it is difficult to accurately determine the amount of heat injected by the above correction unless there is a means to measure the flow rate (there is no suitable method for measuring the flow rate). That's right.

FIG. 10 shows the situation when cold water is injected in the manner shown in FIG. As shown in FIG. 10(a), the cold water flow 1Fi(t) is large at the start of injection and becomes small as time passes, as shown in FIG. 10(a) for the reason described above. The cold water temperature Ti(t) measured by the thermistor 49 is shown in the same figure (b
), at the start of injection, the cold water in the catheter 2 is warmed by body temperature, so from the start of injection until this warmed injection liquid passes through the thermistor 49, the temperature is close to body temperature, and after that, the cold water As it passes through, the temperature decreases.

As shown in FIG. 10(c), the instantaneous value of the amount of heat injected by cold water injection at each minute time decreases over time, as shown in FIG. 10(c), which roughly corresponds to FIG. 10(a).

The time from the start to the end of injection shown in Figure 10(b) is ti
If ti is the time during which the cold injection liquid is injected, then ti'>ti, but the correction is made on the assumption that ti'-ti. Therefore, with this method, it is not possible to accurately determine the amount of heat to be injected.

Purpose of the Invention The present invention has been made in view of the above circumstances, and includes:
An object of the present invention is to provide a method for measuring the amount of heat injected by an injection liquid that can accurately determine the amount of heat injected, and an apparatus used to carry out this method, and to use the accurate amount of heat injected thus obtained, The aim is to provide accurate blood flow measurement at the same time.

20 Structure of the Invention The first invention of the present invention is that when injecting a predetermined injection liquid into a living body, the flow rate of the injection liquid is kept approximately constant, and the injection temperature of the injection liquid and the injection liquid are adjusted. The present invention relates to a method for measuring the amount of heat injected by detecting the temperature inside the living body and determining the amount of heat injected by the injection liquid based on the detected information.

A second aspect of the present invention is an injection liquid quantitative supply means for making the flow rate of the injection liquid to be injected into a living body substantially constant, a temperature detection means arranged near the injection port for the injection liquid, and The present invention relates to an injection heat amount measuring device having a heat amount measuring means for determining the amount of heat injected by the injection liquid based on information from the temperature detecting means.

E, Example The present invention will be explained in detail below.

FIG. 1 and FIG. 2 show an injection calorific value measuring device according to this embodiment. However, parts common to those described in FIGS. 6 to 9 are given common reference numerals, and their explanations may be omitted.

In this device, the infusion solution 7 is stored in an infusion bottle 40 and sent to an infusion solution cooling device 44 through an infusion line 41, a connector 42, and further a sterilization filter 43. As the cooling device 44, a thermo module or the like can be used, but other cooling means may also be used.

The injection liquid 7 cooled to a predetermined temperature is transferred to a fixed-quantity injection device 45.
, where the supply amount (injection amount) is constant and at a constant rate. For this purpose, the injection device 45 includes an air cylinder 46, electromagnetic valves 47Aa, 47Ab, and the like. The details will be explained later with reference to FIG.

Next, the injected liquid is guided to the catheter 2 through the air trap 59, and then passes through the lumen 17 and enters the body (i.e., the right atrium 4 in the state shown in FIG. 6) from the injection hole 14 at a predetermined site.
injected into. A thermistor 49 is disposed on the upstream side of the injection hole 14 and adjacent thereto, and the temperature of the injection liquid 7 is measured immediately before injection.

Since the catheter 2 is similar to that shown in FIGS. 7 and 8, description of each part thereof will be omitted. however,
As the catheter 2, for example, U.S. Pat. No. 439993
Ordinary ones shown in No. 2 are acceptable.

In addition, both the infusion liquid temperature measurement value by the thermistor 49 and the blood temperature measurement value by the thermistor 8,
It is taken out by each thermistor conductor 50.
A signal amplification circuit and an auto-zero circuit are provided to compensate for drift over time. And each thermistor 49
and 8 are digitized by the A/D converter 32, and this digital signal is processed by the CPU 35.
From the CPU 35, signals indicating the blood flow rate, the temperature of the injected liquid, the amount of injected liquid, etc. are inputted to a display device 36 such as a light emitting diode or liquid crystal, and each predetermined display is automatically made.
On the other hand, the output from the quantitative constant rate injection device 45 and the output from the injection liquid temperature measuring section (thermistor 49) are input to the calorimeter 33, converted to the amount of injected heat according to the above formula (2), and output to the display device 36. , is displayed together with the above display contents. Further, such display contents are simultaneously recorded by the printer 37.

In the above, the A/D converter 32, CPU 35, etc. are built into the external device 52 including the display device 36.

Note that the A/D converter 32 is further attached with an injection condition setting section 53 and an alarm setting device 54 for the injection liquid, and an alarm device 55 is connected to the display device 36 side.

FIG. 3 is a schematic diagram showing the structure of the quantitative constant rate injection device 45. The solenoid valve 41B consists of two solenoid valves 47Ba and 47Bb.
Compressed air (
(or high-pressure gas) G is supplied to the front side of the piston 46a in the air cylinder 46 via one electromagnetic valve 47Ba. A space on the front side of the piston 46a in the air cylinder 46 is opened to the outside via the other electromagnetic valve 47Bb.

First, a predetermined amount of the injection liquid 7 is supplied from the infusion bottle 40 into the syringe 48 via the upstream electromagnetic valve 47Aa.

At this time, the downstream solenoid valve 47Ab is closed.
Next, the upstream solenoid valve 47Aa closes, and then the downstream solenoid valves 47Ab and 47Ba open, and the pressure of the gas G supplied from the positive pressure source 56 to the air cylinder 46 causes the piston 46a to move in the direction of the solid line arrow. By moving the piston 46a, the piston 48a of the syringe 48 connected to the piston 46a moves forward (solid arrow), and a predetermined amount of the injection liquid 7 in the syringe 48 is applied to the catheter 2 via an air trap (not shown). . At this time, solenoid valve 47Bb
The piston 46a in the air cylinder 46 is opened appropriately.
The air in the front side space of the piston 46 is released to the outside.
The forward movement of a is controlled to be at a constant speed. Therefore, the injection liquid 7 sent from the syringe 48 to the catheter 2 is sent at a constant speed. When one injection of injection solution 7 is completed,
The solenoid valve 47Ba is closed, the solenoid valve 47Bb is fully opened, and the piston 46a can move back. Next, the downstream side solenoid valve 47Ab closes and the solenoid valve 47Aa opens, and the injection liquid 7 is sent into the syringe 48, and the piston 48a and the piston 46a connected thereto move back (indicated by the - dotted chain arrow). Prepare for the next injection of infusate.

FIG. 4 is a graph showing the situation over time when the injection liquid is being injected. FIG. 4(a) shows the injection amount of the injection liquid, and shows that the injection amount remains approximately constant during the injection time ti' (1 to 30 seconds) due to the constant forward movement of the piston 46a. . The injection volume of the injection solution for one cycle is 0.5 to 20 cc. FIG. 4(b) shows the temperature immediately before injection of the injection liquid measured by the thermistor 49.
For the reason explained in the figure, the temperature of the injectate is approximately the same as the body temperature, and the temperature of the injectate decreases after the time (ti' ti) has elapsed. However, ti is the injection time of the low-temperature injection liquid.

The amount of heat injected is determined by the injection time ti, as shown in FIG. 4(c).
' indicates a change similar to the temperature change shown in FIG. 3(b).

From Figure 4, by keeping the flow rate of the injection liquid approximately constant,
It will be understood that the amount of heat injected can be determined simply by measuring the injection temperature of the injected liquid. This means that Fi(t) is constant in equation (2) and that equation (2) is transformed as shown in equation (3) below.

In FIG. 5, a ball screw feed mechanism 57 driven by a deceleration motor 58 is used in place of the air cylinder in FIG. An example is shown in which the injection liquid 7 in the syringe 48 is delivered to the catheter 2 at a constant speed.

By having the above-described configuration, the injected heat amount measuring device of this embodiment can automatically and accurately measure the injected heat amount, for example, every 5 minutes, display this, and record it on a printer along with the time. Therefore, the injected heat amount can be automatically measured intermittently, if not continuously, and a clinical effect substantially similar to that of continuous monitoring can be obtained. Moreover, in addition to the injection amount of heat, the above can be achieved by applying a thermodilution method. As a result, measurement results are automatically output intermittently through the use of a display device and a printer, and the operator only needs to review or check such outputs all at once.

Moreover, the use of the above-mentioned fixed-rate constant-rate injection device 45 eliminates variations in the injection speed of the cooled injection liquid (cold water mass), and therefore, it is a great advantage that errors in measurement results can be reduced.

Note that the above-mentioned injection condition setting unit 53 sets the lower and/or upper limit values of the clinically necessary amount of injected heat and blood flow, and sets the limit values when the actual amount of injected heat and blood flow deviates from the limits. Since the alarm device 55 can issue a warning in response to this, clinical value can be further demonstrated.

Further, as the injectable liquid used above, it is desirable to use a maintenance liquid used for maintaining body fluids of a patient or an infusion liquid for nutritional supplementation.

Normally, when oral intake is no longer possible for a patient, it is necessary to replace the water and electrolytes lost from the body surface and other sources through infusions, which are called maintenance fluids. The amount of maintenance fluid used varies from person to person, but the amount of water per unit area of the body surface is usually 150.
0 ml/…”/day, and since the average Japanese person has a body surface of about 1.5 to 2.0 m, the required amount of water is 2250 to 3000 ml/day, for example 2500 vb 1/day. It will be about. Therefore, according to the device of this embodiment, by using the above-mentioned maintenance fluid or infusion fluid as the infusion fluid, it is possible to replenish the maintenance fluid etc. at the same time as measuring blood flow, which is very efficient and maintains the balance of body fluids. It is possible to supply the injection fluid necessary for carrying out the thermodilution method without losing it.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the type, material, etc. of each component or part of the above-mentioned injection calorific value measuring device may be changed in various ways, and among these, the means used for the fixed-rate constant-rate injection device are other than an air cylinder and a ball screw feeding mechanism. (Also, the temperature measuring element is preferably a thermistor, but it may be other than that. The blood flow measurement interval may also be varied. The position for measuring the temperature of the injected liquid is also limited to the above. In addition, the catheter used in the device of the present invention is not only inserted into the heart as described above, but can also be applied to other parts.In addition, if it is sufficient to measure the amount of heat injected, It goes without saying that the portion only for blood flow measurement in Figure 2 can be omitted.

As described in detail in Section 8 of the invention, the first invention makes the flow rate of the injectate into the living body substantially constant, and detects the injection temperature of the injectate and the temperature in the living body into which the injectate is injected. The second invention is configured to calculate the amount of heat injected by the injection liquid based on the detected information, and the second invention is configured to detect the injection temperature of the injection liquid by disposing it near the injection port of the injection liquid. Since the temperature is detected by the temperature detection means, the amount of heat injected can be directly determined from the injection temperature of the injection liquid. As a result, the amount of heat injected can be accurately measured, the blood flow rate can also be accurately measured, and medical procedures can be performed safely.

[Brief explanation of the drawing]

Fig. 1 to Fig. 8 show examples of the present invention, Fig. 1 is a schematic diagram of an injection heat m measuring device, Fig. 2 is a flow diagram of the same device, and Fig. 3 is a quantitative determination of injection liquid. Figure 4 is a schematic cross-sectional view of the constant-rate injection device and shows the situation of injection liquid injection, where (a) shows the flow rate, (b) shows the detected temperature, and (c) shows the amount of heat injected. Graphs shown over time. Figure 5 is a schematic cross-sectional view of another example of a fixed-rate fixed-rate injection device for injected liquid. Figure 6 is a schematic cross-sectional view showing the catheter insertion state when measuring the amount of heat injected. Figure 7 is a schematic cross-sectional view of the catheter. Main part front view, FIG. 8 is an enlarged sectional view taken along the line ■-■ in FIG. 7. 9 and 10 show conventional examples.
The figure is a schematic cross-sectional view showing the procedure for supplying the injectate to the catheter, and Figure 10 shows the situation of injecting the injectate. c) is a graph showing the amount of heat injected over time. In addition, in the symbols shown in the drawings, ■・－・−・−Aorta 2−・〜・−・・Catheter 4−・−・・−Right atrium 5・−・−・−・−・-Right ventricle 6...--1----Pulmonary artery 7---1-----Infusion fluid 8.49------- Thermistor 1 t--
−−−−−−−・Injection liquid injection hole (side hole) 16−・・−
・-・Balloon 17.18.19.20° Lumen 23-・・・・
---Burifuji circuit 24-----One-width circuit 25-----Automatic zero adjustment circuit 31----
---・~ Injection temperature measuring section 32--・------A
/D converter 33 - - - - Calorimeter 35 - - - CPU 36 - - - - - Display device 37 - - - - ---Printer 44-------Injection liquid cooling device 45--
−・−・−Injected liquid constant rate constant rate injection device 46 −・−・・・
-・Air cylinders 47Aa, 47Ab, 47Ba, 47Bb
--- Solenoid valve 48 --- Syringe 53 --- Injection condition setting section 54 ---
・−・−・Alarm setting device 55 ・Alarm device 56・−・−・−・Positive pressure source 57・・−・−=・・Ball screw feeding mechanism 58−・−・
-It is a motor.

Claims (1)

[Claims] 1. When injecting a predetermined injection liquid into a living body, the flow rate of the injection liquid is kept approximately constant, and the injection temperature of the injection liquid and the temperature of the inside of the living body into which the injection liquid is injected are adjusted. A method for measuring the amount of heat injected by detecting the amount of heat and determining the amount of heat injected by the injected liquid based on this detected information. 2. An injection liquid quantitative supply means that maintains a substantially constant flow rate of the injection liquid to be injected into the living body, a temperature detection means arranged near the injection port of the injection liquid, and a temperature detection means based on information from this temperature detection means. and a calorific value measuring means for determining the amount of heat injected by the injection liquid.