JPH05508567A - Apparatus and method for monitoring cardiac output - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Background of the invention field of invention TECHNICAL FIELD This invention relates generally to devices and methods for measuring the flow rate of fluids, and more particularly to blood flow metering devices and methods. A device that continuously monitors cardiac output by measuring the flow rate of blood flowing through a tube. and on methods.

Description of prior art Cardiac output monitoring devices are used in the health care field to monitor patients along with various medical instructions. It is widely used to monitor blood flow during treatment. these hearts Stroke volume monitoring devices rely on accurate measurement of cardiac output as blood flow for life support. important situations, e.g. during the patient's pre-operative diagnosis, critical care, post-operative care; It is useful in medical treatment, and during the patient's own surgery. This is the heart rate function It not only allows for early warning of possible decline in heart disease but also aids in evaluating the effectiveness of treatments to save or stimulate

There are several commonly used methods for monitoring cardiac output; Each comes with advantages and disadvantages. Fick's method involves administering a predetermined amount of stain to the patient. The dye was injected into an artery in one arm, and the concentration of the dye was later measured in a vein in the other arm. It is. The degree of decrease in intravenous dye concentration is directly proportional to the patient's cardiac output It is assumed that. Although Fick's method has the advantage of being easy to implement, , there are several problems in implementing this method. Typically, something like this Measurement of dye concentration is done outside the body and requires a large number of blood samples for each measurement. shall be. This is troublesome and bothersome for the patient. On top of that , many doctors recommend that dyes be present in the blood, or that large amounts of dyes may be injected into blood vessels. I don't like to let it pass inside. Therefore, by limiting the amount of dye injection, It is necessary to limit the number of measurements in order to keep the amount of . Furthermore, this stain treatment inherently requires a This results in measurement errors due to the ring amount and the time interval between samplings.

Fick's method does not allow for continuous measurements and therefore can lead to serious problems. If this occurs, the response time for this situation may be longer. Finally, this method may be caused by the stain solution or equipment, as frequent injections of stain are required. may cause infection.

The more commonly used method for measuring cardiac output is using thermodilution techniques. be. This method involves pumping a predetermined amount of cooled saline into the heart through the lumen of the catheter. The procedure consists of injecting the catheter into the right atrium of the heart and cooling the blood near the tip of the catheter. stop The temperature of the blood away from the injection site is measured, and the temperature of the cooled blood is measured. Cardiac output can be determined by considering the distance traveled and the time interval between measurement and injection. Can be determined.

Other thermal techniques have been used in methods similar to the thermodilution systems described above. however , the blood is heated by a heated fluid mass instead of a cooled infusion.

The temperature of the blood is then measured and a determination of cardiac output is calculated in a similar manner.

Generally, this thermodilution technique is applied locally in increments of 10 degrees to obtain proper correlation. requires a significant increase in blood temperature. A significant drawback due to increased temperature is that proteins in the blood to the point of potentially damaging white matter and other tissues. Moreover, these thermodilutions This method requires a very long measurement time due to the long time delay between measurements. be done.

Although widely used, thermodilution techniques have a number of drawbacks. and, This technique is expensive because it requires skilled health care professionals and specialized equipment. Become. Due to the nature of the measurements, they are intermittent and not suitable for continuous monitoring. Furthermore, total Active intervention is required to initiate measurements and involves some degree of risk. This danger The risk is compounded by the risk of infection from multiple injections of chilled salt water. will be expanded to. Additionally, measurements tend to fluctuate over a wide range; Three or more cardiac output measurements are required to compare the results.

The third method is to mix oxygen into the veins in a saturated state (hereinafter referred to as 5vO7). It is known as a device that measures the amount of oxygen in venous blood. And consumed Assuming that the amount of oxygen delivered is directly proportional to cardiac output, the blood flow rate can be determined.

When using SvO□, severe The problem is that many factors affect oxygen measurements. These factors and In addition to cardiac output, catheter placement, blood tissue diffusion, and HCT Ru. Therefore, this indirect method does not merely imply cardiac output. The accuracy of cardiac output is questionable, as it depends on other factors.

Therefore, it provides continuous and accurate information about cardiac output and blood temperature. There is a need to provide a device and method that can do this. monitor cardiac output, Devices and methods that can reduce the possibility of undetected serious situations occurring There is a need to provide law. Moreover, the risk of infection is eliminated and significantly reduced. There is a need to provide a method for monitoring cardiac output.

Summary of the invention This invention provides a device for accurately and continuously measuring cardiac output as blood flow rate. and a method. The device of this invention provides information based on continuous measurements. Since there is no significant time delay between delivery and measurement, you will not notice any serious situations. This can significantly reduce the possibility of failure. Therefore, medical treatment for serious situations The response time for therapeutic intervention is reduced.

Practice of the invention also requires frequent injections of fluid to measure cardiac output. The risk of infection can be significantly reduced or eliminated.

According to the invention, a fluid flow comprising a support member having a distal end, a proximal end, and an outer wall. A quantity measuring device is supplied. The first temperature sensing means is arranged on the outer wall and is arranged on the outer wall to detect the second temperature. The temperature sensing means is located on the outer wall closer to the base than the first temperature sensing means.

The heating means is arranged on the outer wall and flush with the first temperature sensing means.

The support member used in the device of this invention is a catheter that can be placed within a patient's blood vessel. It is desirable that The catheter further has a distal end portion that is lower than the first temperature sensing means. It is desirable to have an inflatable device mounted on the outer wall near the. Ma Further, according to the present invention, the first and second temperature sensing means may be thermistors. The heating means is preferably a coiled electrical resistance wire.

The fluid flow rate measuring device of the present invention further includes a current control device electrically connected to the heating means. Equipped with control means and power source. Further, according to the present invention, the temperature monitoring means includes the first and a second thermistor.

The device of the invention allows blood at ambient blood temperature to flow through the support member or catheter. It can be used to measure cardiac output by placing it within a blood vessel. Ru. By energizing the heating means, a temperature is generated between the heating means temperature and the ambient blood temperature. to generate a difference and measure the blood temperature by the second temperature sensing means to maintain the temperature difference. By controlling the heating means, cardiac output can be determined as a unit of blood flow.

Advantageously, the device of the invention does not expose the patient to stains or waste blood. Accurate yet accurate measurement of cardiac output and blood charcoal without exposure to the necessary high temperatures Provide continuous information. Moreover, this invention does not require expensive equipment and , can be implemented without requiring constant training of highly skilled engineers.

The fluid flow rate monitoring device of this invention can be manufactured by a known method. These methods are , extrusion of the support means, and using conventional techniques such as gluing and heat welding. and installing a second temperature sensing means and a heating means on the outer wall.

Additionally, further objects and advantages of the fluid flow monitoring device of the present invention, and the like. A better understanding of the Those skilled in the art will easily understand this.

Drawing description FIG. 1 is a schematic diagram of an apparatus for monitoring cardiac output according to the present invention.

FIG. 2 shows the cardiac output according to the present invention, which includes a display device, a monitoring device, and a control device. 1 is a schematic diagram of a device for monitoring amounts; FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides a device that can be miniaturized and inserted into a small space. death Therefore, the present invention is particularly suitable for measuring minute flow rates of fluid. however , those skilled in the art will appreciate that the present invention can be applied to any situation where fluid flow rate measurement is required. It is easy to understand that the application is not limited to a specific field of use. Will. To illustrate the present invention, the devices and methods described below include cardiac output In other words, it was applied to the case of monitoring blood flow rate.

FIG. 1 shows a schematic diagram of a typical device 10 for measuring cardiac output in accordance with the present invention. The key points are shown representatively. The device 10 includes a support portion 12 having a distal end 14, a proximal end 16 and an outer wall 18. A first temperature sensing means 20 is installed on the outer wall 18. , and the second temperature sensing means 22 is closer to the base than the first temperature sensing means 20. It is provided on the wall 18. At least one heating means 24.26 provides a first temperature It is provided on the outer wall 18 in parallel with the degree detection means 20.

According to this invention, the first and second temperature sensing means 20.22 include thermistors. , a thermocouple, or a known temperature detector or temperature converter can be used.

The temperature detection means is a type that detects minute changes in temperature in units smaller than 10 degrees Celsius. Preferably a thermistor. The selection of temperature detection means depends on the external shape and , in particular depending on the temperature range and temperature difference to be detected. In this invention Alternatively, a plurality of different temperature detection means may be used in combination.

The heating means 24 and 26 utilized in the device of this invention are insulated heating coils indicated by 26 in the figure. It is an electric resistance wire in the shape of a coil or a plate-shaped heat transfer device as shown by 24. Heating means 24 ．． The selection of 26 depends on the range of fluid flow rate, heat capacity of the fluid, and ambient temperature, as well as the required It is determined by the degree of temperature rise. Purpose of measuring the flow rate of blood flowing in blood vessels Therefore, the heating means is a combination of the nickel chromium heating coil 26 and the heat transfer device 24. be combined.

As shown in FIG. 1, when using the heat transfer device heating means 24, this heat transfer device heating means 24 is used. The stage 24 includes a first temperature sensing means that includes a heat transfer device heating means 24 and an electric resistance coil heating means. It is arranged on the outer wall so as to be located between the step 26 and the step 26. Two types like this By combining the heating means 24 and 26, blood can be heated more stably. As a result, even higher precision and accurate measurements can be made. But long However, as mentioned above, even when using only one coil, it is difficult to determine cardiac output. Accurate measurements can be taken for the target.

When measuring cardiac output, the support member 12 can be easily inserted into a blood vessel such as a pulmonary artery. Preferably, the catheter is configured to allow suitable for such use. catheters are already known and are typically made of flexible polyvinyl chloride, for example. Biological materials such as polyurethane, polyethylene, polypropylene, or nylon Made from materials that can coexist with each other. And this material easily forms elongated flexible chains. It is desirable that it can be formed into a tube shape.

Further, the device of the present invention has a temperature sensor on the outer wall 18 closer to the tip than the first temperature sensing means 20. It is desirable to have an inflation device 26 disposed. In this case, the flow to the expansion device and means (not shown) physically connected to inflate the inflation device. Ru.

It is preferable that the inflation device be a balloon as shown in the figure; It is also possible to use equipment that As shown below, the inflation device is placed in the desired position, Typically, it allows for adequate flotation of the catheter within the pulmonary artery.

The cardiac output monitoring device of the present invention provides a means for monitoring temperature and controlling heat. is equipped with the equipment to perform these functions. Figure 2 is for control and measurement. 1 schematically depicts a cardiac output monitoring device of the invention with a device for monitoring; illustrated Device 30 includes a catheter support member 32 that includes a distal tip. portion 34, proximal portion 36, outer wall 38, and at least one lumen 4 integral therewith. I'm growing 0. An inflatable balloon 42 is provided at the distal end 34 and has at least one lumen 40 . The first thermistor 44 is It is provided on the outer wall 38 in a state connected to the men 40. first thermistor 44 is provided at a position closer to the base than the inflation balloon 42. second thermis The thermistor 46 is provided on the outer wall 38 closer to the base than the first thermistor 44, and has a small Connected to at least one lumen 40.

An insulated electrical resistance heating coil 48 is provided axially on the outer wall 38; The first thermistor 44 is provided in line with the first thermistor 44 and the at least one lumen 40 is electrically connected to the first thermistor 44 . physically connected.

Means (not shown) for inflating the balloon 42 is provided, the inflation means comprising at least is also fluidly connected to one lumen 40. This connection has at least one a separate lumen 40 or within at least one lumen. This is done via fluid conduit 50.

According to this invention, the electric resistance coil is electrically connected to the electric resistance heating coil 48. A power supply 52 is further provided for supplying current to 48. In addition, the first thermistor - 44 and a temperature sensing means 54 connected to the second thermistor 46, and a power source 52. and current control means 56 electrically connected to the temperature detection means 54. There is.

As further shown in FIG. 2, the device of the invention preferably comprises a catheter support member 3 An expansion boat 58 and an electric wire boat 60 are provided at the proximal end portion 36 of 2. inflatable boat 58 directly or at least one lumen 40. They are fluidly connected via a fluid conduit 50 within the tube 40 . The expansion boat 58 It is used as a port for supplying fluid to the balloon 42.

A wire boat 60 is also connected to at least one lumen 40 and has first and second For connecting multiple wires between the thermistor 44, 46 and temperature detection means 54 constitutes the entry point for Furthermore, the electric wire boat 60 connects an electric resistance coil from the power source 52. provides an entry point for connecting wiring to the cable 48.

As shown in FIG. 2, the catheter 32 includes first and second thermistors, heating means, , and one lumen 40 connected to the balloon. But long Those skilled in the art will appreciate that the catheter includes first and second thermistors, heating means, Alternatively, it may have multiple lumens each connected to one of the balloons. You can probably understand that. For example, one lumen can be connected to a first thermistor and and a transmission line for connecting the first thermistor to the temperature sensing means. Transmission and reception lines can be passed through. Similarly, connect the second lumen to the second thermistor. and a wire boat for connecting the second thermistor to the temperature sensing means. can pass through the transmitting and receiving lines. In addition, the third lumen can be connected to an electrical resistance coil. and to the wire boat, thereby connecting the power source and the electrical resistance coil. You may do so.

visual and/or audible display actuated by temperature sensing means and current control means; Display devices or signal monitoring devices are also contemplated within the scope of this invention. temperature detection The means, current control means, and display are integrated with a microprocessor-control system. Preferably, the system is configured in the body, and this system is configured to monitor cardiac output and/or surrounding blood pressure. Optimally configured to provide continuous and quick display of liquid temperature to professional users. will be accomplished. These display systems and microprocessors are designated by reference numeral 6 in FIG. 2.

According to this invention, a general method for cardiac output monitoring includes proximal end, distal end, and providing a catheter having at least one lumen. Provided by. Next, a suitable location within the blood vessel with blood flow at ambient blood temperature. positioning the catheter at; activating the heating means placed near the tip of the catheter; by causing a temperature difference between the ambient blood temperature and the heating means temperature; monitoring the heating means temperature in a first temperature detection means arranged in parallel with the heating means; monitor the ambient blood temperature at the temperature sensing means of 2; and maintain this temperature difference. By controlling the heating means so that the current or cardiac output is determined from electrical power.

The catheter has an inflatable balloon-like device at its tip. In this case, the step of positioning the catheter is preferably performed by means of a fluid. This will include the step of inflating the balloon to slidably engage the inner wall of the blood vessel. this The fluid, preferably air, is injected from an inflatable boat and placed into the balloon. It will be done. and a selected distance within the blood vessel by the blood flow behind the inflated balloon. When movement of the catheter occurs, the catheter is positioned floating. because , air is a low-density medium, and a balloon inflated with air easily floats in the blood. This is to do so. However, using other fluid media like salt water to inflate the balloon Also good.

The blood vessel in which the catheter is positioned has a certain flow direction and ambient blood temperature. blood is flowing. For catheters, the direction of blood flow is at the proximal end of the catheter. It is placed inside the blood vessel so that it faces from the tip to the tip.

According to this invention, once the catheter is placed within the blood vessel, the cardiac output monitoring device: It operates as below. The first and second temperature sensing means send a signal to the temperature monitoring device. The temperature monitoring device first detects ambient blood in the first and second temperature sensing means. Displays each liquid temperature. The first temperature detection is performed by activating the heating means. heating means temperature near the means and ambient blood temperature sensed by the second temperature sensing means; create a temperature difference between By activating the heating means, the heating means The temperature is desirably increased to about 1°C to 3°C above ambient blood temperature. So During this period, the ambient blood temperature is continuously sensed by the second temperature sensing means and the heating means The temperature is detected by the first temperature detection means. When the blood flows over the heating means , the heating means is cooled, the rate and amount of cooling being proportional to the blood flow rate. therefore , the higher the blood flow rate, the higher the cooling effect, and the lower the blood flow rate, the higher the cooling effect. low (naru)

The current supplied to the heating means by the power supply is applied to the first temperature sensing means and the second temperature sensing means. the current control means so as to maintain a small temperature difference of about 1°C to 3°C between the current control means and the current control means; controlled by Calculate the amount of current needed to maintain this temperature difference. allows accurate and continuous direct reading of changes in blood flow rate. . The actual flow rate of blood is determined initially by a known calibration value that indicates the flow rate of blood relative to the current. by preparing a calibration value and directly correlating it with the measured value. Ru.

Those skilled in the art will recognize that it is relatively easy to monitor the power supply in all situations. You will understand. Therefore, for example, instead of current, other factors such as resistance or voltage can be used. Similarly, by monitoring the electrical display medium of the You can color it. Measure the amperage supplied to the heating coil and record the measured amperage. In addition to converting amperage readings to blood flow, it also measures voltage or resistance. You may. In all these cases, very accurate blood flow compared to existing techniques Measurement of liquid flow rate can be done by monitoring the signal instantly at any time interval or by An additional important advantage is that the signal can be measured continuously.

As mentioned above, microprocessor-based control of the method of the invention Therefore, minute temperature changes between the first and second temperature sensing means can be directly detected by the current control means. supply to the heating means in order to operate immediately and maintain the desired temperature difference of 1°C to 3°C. change the current. The microprocessor can reduce or reduce this required current. or increase immediately from a predetermined calibration value to a quantitative expression of blood flow rate. can be converted. The microprocessor then determines the flow rate of the blood. Provides an output signal that provides a visual or audible indication of accurate cardiac output.

The more accurate and continuous measurement of cardiac output obtained by the method and apparatus of the present invention is , both temporal changes and instantaneous values of heart rate function can be displayed immediately. because, Respond to any serious situations that may occur through more accurate and quick measurements. is possible, and by using the device of this invention, any required medical intervention can be performed. The new effectiveness of increasing input is obtained. Moreover, the possibility of infection is virtually will be reduced.

This is because the method of the invention involves injection of cooled or heated solutions or dyes. This is because it is not needed.

The device and method for monitoring cardiac output presented here is intended to monitor cardiac output as well as medical in combination with a catheter or other support medium configured to provide an indication Good too. For example, the Swan-Ganz catheter with six lumens is Catheters of this type also have known It can also perform accurate pressure monitoring functions. Therefore, the swan-gun type model The central lumen of the catheter incorporates a transducer for pulmonary artery pressure measurements. Can be done. Preferred vascular locations for placement of cardiac output monitoring device catheters Since this is the pulmonary artery, the pulmonary artery pressure monitoring device is designed so that the catheter tip is inside the ventricle. It gives an indication of whether it is in the artery. Therefore, to provide continuous pressure measurement In addition, this information may be used by medical professionals to administer catheters to monitor cardiac output. This allows for effective placement of the tube into the pulmonary artery.

°The other lumens of the swan-gun type cartels are generally Provides the necessary communication for infusions to monitor major venous pressures in the same manner as the delivery method. provide. The remaining four lumens are passages for fluid, the heartbeat of the invention described above. Each provides a separate passageway for electrically connecting the output monitoring device. That's it Additionally, two of the four lumens are transmission lines to the first and second temperature sensing means. and reception line. These lines are routed from the wire boat mentioned above.

Similarly, the third lumen accommodates the line connecting the power source and the heating means, and the fourth lumen - Men provide a passageway for inflating the inflation device and an inflation port. is accessed from the expansion means via.

The device of this invention can be used by those skilled in the art of designing and manufacturing medical catheters. It can be constructed using commonly available assembly techniques. For example, one and multi-lumen catheters are both readily available commercially. , and these catheters are manufactured using common polymer extrusion techniques known in the industry. Formed using techniques. Thermistor is a well-known type such as adhesive adhesive It is conveniently and conveniently mounted on the outer wall of the catheter using a method. in the same way , the electrical resistance wire is wrapped a predetermined length around the catheter and The catheter is attached using adhesive or mechanical methods to secure the wire to the outer wall of the catheter. spot bonded to the exterior wall of the

Next, using other non-limiting examples, we will discuss how the cardiac output monitoring device of the present invention can be provided. Explain the functionality.

(Example 1) The Swan-Ganz type cartel was obtained from Baxter Healthcare. This catheter The tell is a thermistor and a No. 38 nickel with a resistance of approximately 26 ohms/ft. Equipped with chromium resistance wire. Both the resistance wire and thermistor are made of shellac. is insulated by the outer jacket. The thermistor is located outside near the tip of the catheter. Glued to the wall, the resistance wire is wrapped axially around the catheter over the thermistor. has been done. A resistance wire approximately 1 foot long is used. Both ends of the resistance wire are copper. These leads are then connected to the ends of the multimeter. Connected to child. The tip with the thermistor and electrical resistance wire is temperature controlled. It was placed in a water tank. Then, in order to confirm the reaction due to temperature change, we The resistance was measured as a function of heated aquarium temperature. The results are shown below.

Temperature (’C) Resistance value The catheter is then placed in a silastic (s) placed within a controlled fluid system. ilisjic) tube. The copper wire part of the nickel chrome resistance wire is 5-bore. connected to a constant power source. Connect the thermistor wire end to the multimeter did. Then, measure while changing the flow rate of the fluid flowing inside the silastic tube. did. Additionally, the resistance of the nickel-chromium wire was measured according to varying flow rates.

Graph I shows the results of this experiment. The time required to obtain the resistance value is 10 seconds. It was also short.

Next, using other non-limiting examples, the in vivo cardiac output monitoring device of the present invention will be described. We will explain the operation in .

(Example 2) The Swan-Ganz type cartel was obtained from Baxter Healthcare and The following changes were made to the mister and electrical resistance coil. two thermistors are glued to the outer wall of the catheter (near the tip) approximately 5 cIn apart. A 1.5-foot length of No. 40 nickel-chrome wire covered with rhethane is used for the thermium tip. Set around the star. In the surrounding environment, the resistance value at this wire length is It is approximately 100Ω. The two ends of the nickel-chrome wire are placed within one lumen. connected to a copper wire. The copper wire is connected to the power supply. two thermis The resistor is connected to a multimeter to measure these resistance values. sa - The lead wire connected between the mister and the multimeter is connected to the catheter loop. It is housed within the men. The catheter was then placed in normal saline water at 34.5°C. installed in a controlled flow circulation system. The results are shown below.

Current resistance (kΩ) Flow rate Volt Ampere Tip Base end (L 7 minutes) (mmV) (mmA) Thermistor Thermistor 3.10 0 0 2.55 14.56 balls 10 5 50 11.87 14.554 ．． 60 5 50 11.90 14.494.60 5 52 11.87 14.486.95 5 55 11.87 14.48g, 50 5 60 11.87 14.509.80 5 63 11.87 14.50 Graph 2 shows these results in terms of the logarithm of current versus flow rate. There, – Niche to maintain a temperature difference of 1°C to 3°C further away from the mister. A good correlation is found between the current supplied to the Kerchrome wire and the flow rate.

a catheter support member having temperature sensing means and one or more heating means; It is considered to be prepared. The temperature sensing means is provided alongside the heating means. mentioned above A cardiac output monitoring device that does not include a second heat detection means, unlike the embodiment described above, can be easily understood by those skilled in the art. It's easy to understand if you have it. This device includes inflatable devices, electric and inflatable boats, and all other components mentioned above, such as equipment for monitoring and controlling the operation of the equipment. may be provided.

Furthermore, using the general heating means, temperature sensing means, and catheter materials described above, can be done.

In operation, the method of the present invention for utilizing the embodiments described above comprises temperature sensing means. This includes the step of measuring ambient blood temperature. After the measurement, the heating means is activated and the current measurement is performed. A temperature difference is created between the ambient blood temperature and the heating means temperature. This temperature difference The energy required to obtain it is measured by a connected control instrument. this Energy is proportional to blood flow rate and serves as an indicator of blood flow rate. Following this measurement The heating means is then stopped and the temperature of the heating means returns to ambient blood temperature. And Zhou The ambient blood temperature is measured again and the cycle is repeated. By such a method, Cardiac output measurements can be made semi-continuously.

Although typical embodiments of the present invention have been described above, the embodiments described above are merely typical embodiments. This is by way of example only, and various substitutions, modifications, and changes may be made within the scope of the invention. Those skilled in the art will easily notice this. Therefore, this invention covers the specific The invention is not limited by the examples, but only by the claims set forth below.

Summary 1 A device for measuring fluid flow rate and cardiac output includes a distal end (14, 34), a base a support member (12, 32) having an end (16, 36) and an outer wall (18, 38); ). The first temperature detection means (20, 44) is connected to the outer wall (18, 38). ), and the second temperature detection means (22, 46) is provided on the second temperature detection means (22, 46). installed on the outer wall (18, 38) closer to the base than the temperature detection means (20, 44) of No. 1; I'm being kicked. The heating means (24, 26, 48) is connected to the first temperature sensing means (2 0, 44) on the outer wall (18, 38). therefore, First and second temperature sensing by energizing the heating means (24, 26, 48) A temperature difference occurs between the means (20, 22, 44, 46). To maintain temperature difference The energy required for can be controlled and monitored, and fluid flow and cardiac output can be controlled and monitored. are associated with.

Submission of translation of written amendment (Article 184-8 of the Patent Law) November 19, 1992

Claims (24)

[Claims] 1. a support member having a distal end, a proximal end, and an outer wall; a first temperature sensing means provided on the outer wall; and a base end of the first temperature sensing means. a second temperature sensing means provided on the outer wall on the side; and a temperature sensing means provided on the outer wall. heating means, said heating means being in parallel with said first temperature sensing means. A device for measuring the flow rate of fluid installed in 2. Claim 1 characterized by a power source electrically connected to said heating means. The device described. 3. characterized by said first and second temperature sensing means and followed by temperature monitoring means; 3. A device according to claim 1 or claim 2. 4. characterized by current control means electrically connected to said power supply and temperature monitoring means; 4. A device according to any one of claims 1 to 3. 5. The temperature sensing means is a thermistor, a thermocouple, or a combination thereof. The device according to any one of claims 1 to 4, characterized in that: 6. The heating means may be an electrical resistance heating wire, a heat transfer device, or a combination thereof. The device according to any one of claims 1 to 5, characterized in that: 7. Claims 1 to 3, wherein the support means is a flexible, elongated tube. 6. The device according to any one of 6. 8. an inflatable device disposed on the outer wall distal to the first temperature sensing means; means connected to the inflatable device for inflating the inflatable device; 8. Device according to claim 7, characterized in that it is provided. 9. a distal end, a proximal end, an outer wall accompanying them, and a distal end provided on the outer wall. a flexible catheter with an inflatable balloon; a first thermistor disposed on a surface of the outer wall proximal to the inflatable balloon; connected to at least one lumen and connected to a second thermistor. a thermistor is provided on the outer wall closer to the base than the first thermistor; an insulated electrical resistance heating coil connected to the at least one lumen; a thermistor is provided on the outer wall along the axial direction and in line with the first thermistor. , the electrical resistance heating wire is connected to the at least one lumen and the inflatable means for inflating a capable balloon and connected to said at least one lumen; is provided, and is electrically connected to the electrical resistance coil to allow blood flow to the poisonous air resistance coil. A power source is provided for supplying a temperature, and is connected to the first and second thermistors. Monitoring means and current control means electrically connected to the electrical resistance heating coil are provided. A device for measuring cardiac output, which is characterized by a sharp curve. 10. The catheter further includes an inflation port at the proximal end, the inflation port is fluidly connected to the at least one lumen. Apparatus according to claim 9. 11. The catheter further includes a wire port at the proximal end, and the wire port is connected to the at least one lumen. or the device according to claim 10. 12. The catheter is made of polyvinyl chloride, polyethylene, polyurethane. made of polymers selected from the group consisting of , polypropylene, and nylon. The device according to any one of claims 9 to 11, characterized in that: 13. Claim 9, wherein the electrical resistance heating wire is made of nickel chromium. The apparatus according to any one of claims 1 to 12. 14. A heat transfer device is configured to locate the first thermistor and the insulated electrical resistance heating wire. According to any one of claims 9 to 13, the Device. 15. the at least one lumen is a plurality of lumens, and the at least one lumen is a plurality of lumens; the second thermistor, the electrical resistance heating coil, and the inflatable each capable balloon is connected to one lumen of the plurality of lumens. 15. The device according to any one of claims 9 to 14, characterized in that: 16. A catheter having a proximal end, a distal end, and at least one lumen is used. the process of Blood flowing in a blood flow direction from the proximal end to the distal end and with an ambient blood temperature. positioning the catheter to a predetermined location within a blood vessel having flow; , actuating the heating means provided near the tip to provide the heating means temperature; With mode, creating a temperature difference between the ambient blood temperature and the heating means temperature; Monitoring the temperature of the heating means with a first temperature detection means provided in parallel with the heating means At the same time, a second temperature detection means is provided closer to the base than the first temperature detection means. monitoring the ambient blood temperature with means; controlling the heating means to maintain the temperature difference; By relating the energy required to maintain said temperature difference to blood flow. and a step of determining cardiac output. How to do it. 17. The catheter further includes an inflatable device disposed near the tip. Eh, the method includes, after providing the catheter, inflating the inflatable device. slidably disposing the catheter within the blood vessel; , floating the catheter to the pre-positioned location within the blood vessel; The claim further comprises the step of deflating the inflatable device. The method according to claim 16. 18. The temperature difference is about 1°C to 3°C higher than the ambient blood temperature. 18. The method according to claim 16 or claim 17. 19. Claims 16 to 18, wherein the blood vessel is a pulmonary artery. Any method described. 20. Inflation of the inflatable device may be performed through the at least one lumen. Claim 17, characterized in that it is accomplished by injecting air into the inflatable device. 20. The method according to any one of claims 19 to 20. 21. a catheter support member having a distal end, a proximal end, and an outer wall; a temperature detection means provided above, and a heating hand provided in line with the temperature detection means; A device for monitoring cardiac output characterized by stages. 22. Claim 2, characterized in that a power source is electrically connected to the heating means. 1. The device according to 1. 23. A claim characterized in that temperature monitoring means is connected to the temperature sensing means. The device according to item 22. 24. The current control means is electrically connected to the power source and the temperature monitoring means. 24. A device according to claim 23, characterized in that: