JPH0578332B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a catheter for measuring blood flow, and particularly to a catheter for measuring blood flow based on a thermodilution method.

B. Prior Art Conventionally, methods for measuring blood flow velocity include laser Doppler method, pulse modulation Doppler method, ultrasonic Doppler method, Pitot tube catheter method, hot film method, and the like. Further, as methods that can theoretically measure cardiac output (total flow rate), there are impedance method, electromagnetic flowmeter method, admittance splenomography, and the like.

On the other hand, thermodilution and dye dilution using Fick's law are excellent methods for measuring blood flow (particularly cardiac output) without being affected by changes in blood vessel diameter or intravascular flow velocity distribution. 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 4, 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. As shown in FIG. 4, FIG. 6, and FIG. 7, the catheter 2 has a main body 13 provided with a side hole for injecting cold water, a thermistor 8, and a balloon 16. Lumen 17 for cold water supply, lumen 18 for thermistor 8 wiring, 1st
A lumen 19a for pressure measurement, a lumen 20 for feeding air into the balloon 16, and a second pressure measurement lumen 19 for measuring blood pressure on the upstream side.
b are formed respectively. Then, insert catheter 2 as shown in Figure 4 (usually percutaneous insertion).
When placing the catheter 2 into the bloodstream, the balloon 16 is inflated (as indicated by the dashed line in FIG. 6) 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 ΔTb(t)dt×Ci－Si／Cb
・Sb……(1) [However, Vb: Cardiac output (blood flow rate) Vi: Volume of injected cold water (ml) Vb: Temperature of blood before cold water injection (℃) Ti: Injected cold water Temperature (℃) 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) ΔTb: Change in temperature of blood] In this case, in the measurement of blood flow, Figure 8 The signal is processed according to the flow shown in . 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) 45, and the blood flow rate is displayed on a display device 26 and further recorded on a printer 27.

By the way, in the catheter 2 described above, the blood pressure waveform and blood pressure are measured using the pressure measurement lumen at the tip, and after confirming the insertion position of the catheter, the cold water 7 is injected as described above. In particular, it has been found that the pressure measurement lumen has the following drawbacks.

That is, in the catheter 2, in addition to the cold water injection lumen 17, at least two other lumens (19a and 19b described above) are opened on the outer surface of the catheter body 13, so that the backflow of blood to the opening areas of these lumens is prevented. , blood clots are more likely to occur. As clearly shown in FIG. 6, for example, since the lumen 19a for pressure measurement has an opening 29 at its tip, backflow of blood is likely to occur at the opening 29.
In addition, thrombus formation occurs due to flow turbulence. Therefore, management such as injecting a small amount of physiological saline containing heparin is required, and the operation is complicated. Moreover, during such injections, bacteria can easily invade from outside the body, increasing the possibility of infection. This is further facilitated by the fact that many of the lumens of the catheter 2 are structured to provide fluid communication between the inside of the body and the outside of the body.

Furthermore, since the catheter 2 is provided with at least two lumens 19a and 19b for pressure measurement, it is possible to make the lumen 17 sufficiently large for cold water injection in the limited cross section of the catheter (see Fig. 7). Can not. Therefore, injection of cold water inevitably requires a large force (pressure), which not only places a burden on the injection device but also tends to cause errors in blood flow measurement.

C. Purpose of the Invention The purpose of the present invention is to provide a system that prevents blood backflow, etc., is easy to manage, has little invasion of bacteria from the outside, and is easy to inject an injectable solution, so that measurements can be performed reliably. An object of the present invention is to provide a catheter for measuring blood flow.

D. Structure of the Invention That is, in the present invention, a pressure sensor for blood pressure measurement is disposed at the tip of a catheter body, a balloon for catheter delivery is provided on the catheter body at a position rearward from the tip, and A sensor for measuring blood flow is provided in the catheter body at the rear position, and a lumen for supplying and exhausting air to the balloon extends from the balloon position to the tip position as a lumen for the lead wire. A lumen is closed at the tip position without opening to the outer surface of the catheter body, and the pressure sensor is substantially embedded in this closed position, and the air supply and exhaust gas is connected from the conductor lumen to the catheter body. A lead wire for the pressure sensor is led out through the lumen, and a lead wire for the sensor for blood flow measurement is also arranged in the air supply and exhaust lumen, and the blood flow measurement method is conducted separately from the air supply and exhaust lumen. The present invention relates to a blood flow measuring catheter that is provided with a lumen for injecting a medium, and only this lumen for injecting is open to the outer surface of the catheter body.

In the present invention, the above-mentioned "substantially embedded" means that the pressure sensor is in contact with the outer surface of the catheter body or is located at a position close to the outer surface of the catheter body and is installed at a location that does not affect pressure measurement. It means there is.

Example Examples of the present invention will be described below.

1 to 3 show a blood flow measurement catheter 22 based on a thermodilution method according to a first embodiment of the present invention. However, common parts among the parts described in FIGS. 6 and 7 are given common reference numerals, and their explanations may be omitted.

This catheter 22 is fundamentally different from the conventional catheter 2 described above, in particular, a pressure sensor 15 at the tip position for blood pressure measurement and a pressure sensor 5 at the downstream side.
Each of the lumens 5 does not open to the outer surface of the catheter body 13. That is, to explain this regarding the pressure sensor 15 (the same applies to the other sensor 55), as shown in FIG. A sensor 15 is embedded.
The lead wire 28 of the pressure sensor 15 is installed in a lumen 40 for supplying and exhausting air to the balloon 16, and is led out through the lumen. The pressure sensor 15, the balloon 16, and the thermistor 8 are sequentially provided at a predetermined interval from the distal end side to the rear of the catheter body 13, and the pressure sensor 15 is provided through the lumen 39a formed by extending the lumen 40. Conductor 28
has been derived. In addition, 14 in the figure is a side hole for cold water injection, and 31 is a side hole for air supply or exhaust.
Further, as the pressure sensors 15 and 55, semiconductor pressure sensors can be used.

In addition, in the lumen 40, in addition to the above-mentioned conducting wire 28, as shown in FIG. It has been taken out. FIG. 1 shows a connector 33 from which the conductive wires 28, 38, 32 are commonly led out and connected to an external circuit. Also shown are an air line connector 34 for the balloon and a Luer lock connector 35 for cold water injection.

Furthermore, while the conductors of each sensor are installed together in the common lumen 40 as described above, the lumens for each of these conductors (19a, 19b, 1 in Figure 7) are
8) is omitted, and a correspondingly larger lumen 36 as a cold water injection path is provided as shown in FIG.

In addition, in FIG. 4, the blood flow calculation and display device 3 is connected to the catheter 22 inserted into the living body in the same manner as described above through the above-mentioned connectors.
7. A syringe 41 for balloon expansion/deflation and an infusion bottle 42 (includes a syringe barrel 43 and a sterilization filter 44) are connected. Blood flow calculation display device 3
7 is provided with a blood flow meter 47, a condition setting key 46, and the like. The injection liquid 7 used above is cooled to a predetermined temperature and then injected, and it is preferable to use a maintenance liquid used for maintaining body fluids of a patient or an infusion liquid for nutritional supplementation. In other words, by using such maintenance fluids or infusions, it is possible to replenish maintenance fluids, etc. at the same time as measuring blood flow, which is very efficient and allows for the necessary thermodilution method without losing the balance of body fluids. Can supply injection fluid.

As described above, according to the catheter 22 of this embodiment, the pressure sensor is provided without opening the pressure sensor lumens 19a and 19b on the outer surface of the catheter. Since there is no open lumen in the body, the possibility of thrombus formation or other complications due to backflow or stagnation of blood due to the presence of the open lumen as described above is extremely small. Moreover, there is no need for management operations such as pouring a heparin-containing liquid into the lumen for pressure measurement, and since the lumen tip is closed and there is no communication between the inside and outside of the living body, it is possible to eliminate bacteria from outside the living body. The risk of intrusion and infection is greatly reduced.

Moreover, since only two lumens 36 and 40 need be provided in the catheter body, the size of the cold water injection lumen 36 can be considerably increased. Therefore, it becomes easy to inject cold water, and it is possible to facilitate operation and improve blood flow measurement accuracy.

Furthermore, since the lumen 39a through which the conductive wire 28 of the pressure sensor 15 is passed is an extension of the lumen 40 for the balloon 16, there is no need to provide a separate lumen for the conductive wire 28 from the lumen 40, and the structure is simple. At the same time, the distal end of the catheter body is thickened and its mechanical strength is improved.

Furthermore, since the pressure sensor 15 and thermistor 8 are provided at a predetermined distance on both sides of the balloon 16, the pressure sensor can be placed at the tip of the catheter to ensure pressure measurement, and the pressure sensor can be placed at the tip of the catheter to ensure pressure measurement. Even if they make contact, the sensors 15 and 8 on both sides of the balloon 16 will not contact the blood vessel wall or the like at the same time and will not be able to measure, and at least one sensor will always be in a measurable state and measurement can be performed reliably.

FIG. 5 shows a comparative example of the present invention.

According to this example, unlike the above-mentioned example, the lumen 39a of the pressure sensor 15 (also 55) is closed at the distal end position, so that backflow of blood, thrombus, etc. are unlikely to occur as in the above-mentioned case.

Further, the lumen 39a extends inside the catheter body 13 to the outside, and the lead wire 28 of the pressure sensor 15 is led out. Therefore, the catheter 52 of this example exhibits the above-mentioned excellent effects without significantly changing the conventional product shown in FIG. However, since the lead wire 28 of the pressure sensor 15 is led out through a lumen provided separately from the lumen for the balloon, it is necessary to provide at least three lumens through the catheter body, and the effects described in the above embodiments cannot be obtained. I can't.

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

For example, the type, size, structure, material, etc. of each part of the catheter described above can be varied, and the number of pressure sensors used may be one or more. The pressure sensor may be located inside the outer surface of the catheter as described above, but it may also be located at a position where pressure can be measured satisfactorily, such as a position in contact with the outer surface of the catheter or a position in the vicinity thereof. Note that the catheter 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, in the present invention, the pressure sensor is provided without opening the lumen for the pressure sensor on the outer surface of the catheter. Therefore, the existence of the open lumen can cause backflow of blood and the occurrence of blood clots due to stagnation. The chances of complications are greatly reduced. Moreover, there is no need for management operations such as flowing heparin-containing liquid into the pressure measurement lumen, and since the lumen tip is blocked and there is no communication between the inside and outside of the living body, it prevents the invasion of bacteria from outside the living body. The risk of infection is greatly reduced.

In addition, the conductors of the pressure sensor and the sensor for measuring blood flow are arranged in the lumen for the balloon, and a lumen for injecting a medium for measuring blood flow is provided separately from the lumen for the balloon. Since only the lumen opens on the outer surface of the catheter body, the number of lumens provided in the catheter can be reduced, and the size of a specific lumen (especially the lumen for cold water injection) can be considerably expanded, making it easier to inject cold water, etc. It is possible to realize not only ease of operation but also improvement in blood flow measurement accuracy.

In addition, the lumen through which the pressure sensor wire passes is an extension of the balloon lumen, so there is no need to provide a separate lumen for the pressure sensor wire from the balloon lumen, simplifying the structure. At the same time, the distal end of the catheter body is thickened and its mechanical strength is improved.

Furthermore, since a pressure sensor and a sensor for measuring blood flow are placed at a predetermined distance on both sides of the balloon, the pressure sensor can be placed at the tip of the catheter to ensure pressure measurement, and the pressure sensor can be placed at the tip of the catheter to ensure reliable pressure measurement. Even if the balloon contacts the blood vessel wall or the like, the sensors on both sides of the balloon will not contact the blood vessel wall or the like at the same time and become unable to measure, and at least one of the sensors will always be in a measurable state, ensuring reliable measurement.

[Brief explanation of the drawing]

1 to 5 mainly show embodiments of the present invention, in which FIG. 1 is a schematic front view of the catheter, FIG.
1, FIG. 4 is a schematic sectional view showing the state of catheter insertion during blood flow measurement, and FIG. 5 is a sectional view similar to FIG. 2 of a catheter of a comparative example. 6 to 8 show conventional examples, in which FIG. 6 is a sectional view similar to FIG. 2 of the catheter, FIG. 7 is a sectional view similar to FIG. 3 of the same catheter, and FIG. The figure is a flow diagram of blood flow measurement. In addition, in the symbols shown in the drawings, 1... vena cava, 2, 22, 52... catheter, 4... right atrium, 5... right ventricle, 6... pulmonary artery, 7... infusion fluid, 8... thermistor. , 14... Injection liquid injection hole (side hole), 15, 55... Pressure sensor, 16... Balloon, 17, 18, 19a, 19b, 20, 3
9a...Lumen, 28,38,32...Conductor,
29...Opening, 30...Closing part, 31...Side hole for air supply or exhaust, 33...Sensor connector, 3
4... Connector for balloon, 35... Luer lock connector for cold water, 36... Lumen for cold water,
37... Blood flow calculation display device, 40... Lumen for air supply or exhaust, 41... Syringe for balloon expansion or deflation, 42... Infusion bottle, 43... Syringe barrel, 44... Sterilization filter.

Claims (1)

[Claims] 1. A pressure sensor for blood pressure measurement is arranged at the tip of the catheter body, a balloon for transporting the catheter is provided in the catheter body at a position rearward from the tip position, and blood flow is further provided in the catheter body at a position rearward from the balloon. A measurement sensor is provided, and a lumen for supplying and exhausting air to the balloon extends from the balloon position to the distal end position as a conducting wire lumen, and this conducting wire lumen is connected to the catheter at the distal end position. It is closed without opening on the outer surface of the main body, and the pressure sensor is substantially embedded in this closed position, and the lead wire of the pressure sensor is passed from the lead wire lumen to the air supply and exhaust lumen to the outside. The conductor wire of the sensor for blood flow measurement is also arranged in the air supply and exhaust lumen, and a blood flow measurement medium injection lumen is provided separately from the air supply and exhaust lumen. A catheter for measuring blood flow, in which only the injection lumen is open to the outer surface of the catheter body.