JPH0520322Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application The present invention relates to a catheter used for blood flow measurement based on thermodilution method.

B. Prior Art Conventionally, methods for measuring blood flow velocity include laser Doppler method, pulse modulation Doppler method, ultrasound Doppler method, Pitot tube catheter method, hot film method, and the like. However, these methods
Since the cross-sectional shape and velocity distribution of blood vessels are not clear, other methods must be used in combination to measure cardiac output (total flow rate). There are impedance methods, electromagnetic flowmeter methods, admittance spherography, and other 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, thermodilution method using Fick's law and dye dilution method are excellent methods for measuring blood flow (particularly cardiac output) without being affected by changes in blood vessel diameter or flow velocity distribution within blood vessels. law is used. These methods measure the rate at which a physical quantity injected from outside the body, such as the low temperature caused by a cold water mass or the coloring caused by a dye, is diluted by blood, and the cardiac output is determined from this measured value.

According to the thermodilution method, as shown in Figure 5, the vena cava 1
The catheter 2 is guided through the right atrium 4 of the heart 3 and further through the right ventricle 5 to the pulmonary artery 6.
Cold water 7 is injected into the blood, and a sensor (usually a thermistor) 8 near the tip measures changes in blood temperature. 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 the figure, 9 is the left atrium, 10 is the left ventricle, 11 is the pulmonary vein, and 12 is the aorta. The catheter 2 has a main body 13 equipped with a side hole 14 for injecting cold water, a thermistor 8 for measuring blood temperature, and a balloon 16, and a lumen for supplying cold water and thermistor wiring (not shown) corresponding to these. A lumen for measuring pulmonary artery pressure or pulmonary artery inlet pressure, and a lumen for feeding air into the balloon are formed, respectively. And the fifth
As shown in the figure, when the catheter 2 is inserted (usually percutaneously inserted) and carried into the bloodstream, the balloon 16 is inflated and the catheter 2 is carried.

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

Vb＝Vi(Tb－Ti)60／∫ ^∞ ／ ₀ △Tb(t)dt×Ci－Si
/Cb・Sb……(1) [However, Vb: Cardiac output (blood flow rate) Vi: Volume of injected cold water (m) Tb: Temperature of blood before cold water injection (°C) Ti: Injected amount Temperature of cold water (°C) Cb: Specific heat of blood Sb: Specific gravity of blood Ci: Specific heat of injected water Si: Specific gravity of injected water t: Time (seconds) △Tb: Change in blood temperature] In this case, in measuring blood flow The signal is processed according to the flow shown in FIG. That is, the measured value of the temperature measurement unit 21 that measures the temperature of the liquid injected into the catheter 2 is input to the A/D converter 22 and digitized, and the thermistor 8 of the catheter 2 detects the blood temperature as a change in electrical resistance. , this is extracted as a current signal by the bridge circuit 23 and sent to the amplification circuit 24.
The signal is input to the A/D converter 22 through an automatic zero adjustment circuit 25 which further compensates for drift over time. The output of the A/D converter 22 is processed by a central processing unit (CPU) 28, and the blood flow rate is displayed on a display device 26 and further recorded on a printer 27.

However, in the blood flow measurement catheter 2 using the thermodilution method described above, the temperature (Ti) of the injected cold water is determined by a different temperature in the cold water introduction path to the catheter 2 (i.e., outside the catheter 2 or outside the body). Measured by a thermistor (not shown).
However, in this case, the temperature of the cold water measured by the thermistor is often different from the temperature of the cold water actually injected into the blood vessel through the catheter 2, resulting in poor measurement accuracy. In fact, if the cold water injection rate is not well controlled, the accuracy of the measurements will vary widely. However, since cold water is generally injected by humans with a syringe, the injection speed is not constant.
Stable injection cannot be performed.

To eliminate such variations in measurement accuracy,
For example, in JP-A-62-101225, a thermistor for measuring cold water temperature is installed in the cold water passage, and is installed 0 to 50 cm upstream from the cold water injection hole. However, with this technology, the thermistor and its lead wire are installed upstream in the cold water passage, which impedes the flow of cold water toward the injection hole and makes it difficult for the cold water to flow smoothly, which ultimately disrupts the cold water injection speed and is one of the reasons why blood flow cannot be measured with sufficient accuracy.

In addition, with a catheter for this purpose, it is necessary to inject 5 to 10 m of cold water into a narrow lumen in a short period of 1 to 3 seconds, and approximately A high pressure of 5 to 10 kg/cm ² is applied. Therefore, if a thermistor is fabricated in the lumen upstream of the cold water injection hole, it will be extremely easy to break due to the high pressure and will be unreliable. Moreover, the catheter is bent inside the heart, and at this time, the seal part of the thermistor, especially the lead wire part (the part fixed to the catheter wall), is simultaneously bent and peeled off. This may increase measurement errors, cold water leakage, turbulence, etc. This will impair the safety and reliability of the catheter.

C. Purpose of the invention The purpose of the present invention is to provide a catheter for measuring blood flow that improves measurement accuracy and has excellent safety and reliability.

D. Structure of the invention In other words, the present invention provides an injection method for injecting a low-temperature liquid guided through a passage provided in the wall of the catheter body into a living body from the catheter body in a catheter used for blood flow measurement based on the thermodilution method. a hole is provided in the catheter body wall in communication with the passage, and a sensor for measuring the temperature of the cryogenic liquid via a septum provided in the catheter body;
A blood flow measuring catheter characterized in that the catheter is installed and built into the catheter body near the injection hole (particularly on the downstream side of the injection hole) and separated from the passage by the partition wall. It is.

Example Examples of the present invention will be described below.

1 to 3 show a blood flow measurement catheter 32 according to this embodiment. However, parts common to those described in Fig. 5 are given common symbols.
The explanation may be omitted.

The characteristics of the catheter 32 of this embodiment are as follows:
A thermistor, which is a sensor for measuring the temperature of the coolant 7, is installed near the injection hole 14 for injecting the coolant 7 into the living body, which is guided through the catheter body wall 13, and particularly on the downstream side of the coolant passage 17. 30 is installed and built in, separated from the coolant passage 17 by the partition wall 13a. In addition, 31 in the figure is a lead wire of the thermistor 30, and the thermistor 30
It is also installed within its own lumen 33.
The main body 13 is also provided with a thermistor 8 for blood temperature measurement and a balloon 16 (the one-dot chain line in FIG. 2 is in an inflated state). A lumen 19 for measuring contract pressure and a lumen 20 for feeding air into the balloon are provided, respectively.
In the figure, 34 is a lead wire of the thermistor 8, and 35 is an air outflow or inflow port. Note that the usage and operation of this catheter 32 may be the same as described in FIGS. 5 and 6.

As described above, the thermistor 30 for measuring the temperature of a low-temperature liquid (for example, cold water) is installed in the catheter body 13 near the cold water injection hole 14, and the thermistor 30 measures the temperature of the low-temperature liquid via the partition wall 13a. Therefore, the temperature measured by the thermistor 30 matches the actual cold water injection temperature, and the injection temperature can always be accurately measured without being affected by the cold water injection speed. In this case, the thermistor 30 will eventually measure the temperature inside the lumen 33 and the wall of the catheter body, but the temperature corresponds to the temperature of the cold water 7 transmitted through the partition wall 13a. 7 will be measured by the thermistor 30 via the partition wall 13a.

Importantly, the thermistor 30 for cold water temperature measurement is installed together with the lead wire 31 in a separate lumen 33 separated from the coolant passage 17 by a partition wall 13a. There are no obstructive attachments, the flow of cold water is extremely smooth, and the flow of cold water injected is undisturbed, ensuring a predetermined flow rate. This leads to highly accurate blood flow measurement. Also. As shown in FIG. 5, the catheter 32 is bent at several points inside the heart, but at this time the thermistor 30 and its lead wire 31 are installed in the lumen 33 without a conventional sealing part. Therefore, there is no adverse effect on measurement due to peeling or the like. Therefore, the catheter itself has excellent reliability and safety.

FIG. 4 shows another embodiment.

The catheter 32 according to this example is provided with a partition wall 13b (for example, a thin coating layer) at a downstream position preferably separated by l = 0.5 to 10 mm from the downstream side of the cold water lumen 17 (specifically, the injection hole 14), and this partition wall A thermistor 30 is arranged near 13b,
In addition, the lead wire 31 passes through the wall portion 13a and is guided to the lumen 33.

Even in this case, the thermistor 30 is connected to the partition wall 13
Since it is separated from the cold water passage 17 via b, it does not become an obstacle to the flow of the cold water 7. this is,
The presence of the thermistor 30 on the downstream side of the injection hole 14 ensures reliability, and there is no disturbance in the injection of cold water 7 from the injection hole 14, making it possible to inject a predetermined flow rate. Additionally, temperature measurements can be made accurately.

Note that as the injection liquid used above, it is desirable to use cold water, a maintenance liquid used to maintain the patient's body fluids, or a ring fluid for nutritional supplementation.

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, various shapes, structures, materials, etc. may be adopted for each component of the catheter described above. Further, the position and arrangement method of the above-mentioned thermistor (particularly 30) may be varied in various ways. The lumens for guiding the thermistor wires are not limited to those mentioned above, but may include other lumens,
For example, it may be the lumen 20 to the balloon 16. Further, the temperature measuring element is preferably a thermistor, but may be other than that. Furthermore, 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 sites.

F. Effects of the invention As described above, the present invention has a sensor for measuring the temperature of a low-temperature liquid separated by a cooling passage and a partition wall, installed and built in near the low-temperature liquid injection hole, and measures the temperature of the low-temperature liquid through the partition wall. Since the temperature is measured by the sensor, the temperature measured by the sensor matches the actual low temperature liquid injection temperature, and the injection temperature can always be accurately measured without being affected by the low temperature liquid injection rate.
Moreover, since the sensor does not become an obstacle to the flow of the low temperature liquid, the flow of the low temperature liquid becomes extremely smooth, and there is no disturbance in the injection flow of the low temperature liquid, ensuring a predetermined flow rate and further improving measurement accuracy. I can do it. Since the sensor is separated from the cryogenic liquid passage by a partition wall, the flow of the cryogenic liquid will not be affected by bending, etc., and therefore the catheter itself has excellent reliability and safety. .

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a sectional view of the main part of the catheter, and FIG.
The figure is a front view of the main part of the catheter, FIG. 3 is an enlarged sectional view taken along the line -- in FIG. 2, and FIG. 4 is a sectional view of the main part of another catheter. 5 and 6 show a conventional example, in which FIG. 5 is a schematic cross-sectional view showing a state of catheter insertion during blood flow measurement, and FIG. 6 is a flow diagram of the blood flow measuring device. In addition, in the symbols shown in the drawings, 1... vena cava, 2, 32... catheter, 4... right atrium, 5...
... Right ventricle, 6 ... Pulmonary artery, 7 ... Infusion fluid, 8,
30...Thermistor, 13...Main body, 13a, 1
3b...Partition wall, 14...Injection liquid injection hole (side hole),
16... Balloon, 17, 18, 19, 20, 3
3... lumen, 31, 34... lead wire.

Claims (1)

[Claims for Utility Model Registration] A catheter used for blood flow measurement based on thermodilution method, which has an injection hole for injecting a low-temperature liquid guided through a passage provided in the wall of the catheter body into a living body from the catheter body. , a sensor provided on the wall of the catheter body in communication with the passage, for measuring the temperature of the low temperature liquid via a partition wall provided in the catheter body,
A catheter for blood flow measurement, characterized in that the catheter is installed and built into the catheter main body, separated by the passageway and the partition wall, in the vicinity of the injection hole.