JPH0113374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION A. Technical Field The present invention relates to catheters. For more details,
The partial pressure of liquids, especially gases such as blood and tissue fluids in the body,
This invention relates to a catheter that can continuously measure PH value and PH value at the same time.

B. Prior art and its problems Conventionally, the following methods have been used to measure gas partial pressures and PH values in blood and tissue fluid.

(1) Sample blood and measure gas partial pressure and PH value using an IL meter or radiometer.

(2) Place a micro PH electrode in the blood vessel and measure PH.

(3) Heat the capillary to make it arterial, and measure gas partial pressure transcutaneously.

(4) The catheter is placed in a blood vessel or tissue fluid, and the catheter is inserted through the gas permeable membrane of the catheter.
Only the gas from blood or tissue fluid is collected and the gas partial pressure is measured using a mass spectrometer.

However, with method (1) above, Po ₂ , Pco ₂ , and PH can be measured, but blood must be sampled for each measurement, and O ₂ and CO ₂ from the blood must escape after sampling. A further drawback is that strict care must be taken to avoid contact of the blood with air, and that continuous measurements of these are not possible.

On the other hand, in (2) above, continuous measurement of PH and Pco ₂ is possible, but measurement of Po ₂ is not possible.

In addition, in (3) above, it is possible to continuously measure Po ₂ and Pco ₂ non-invasively, but its reliability is questionable, and in addition, PH cannot be measured.

Furthermore, in all of the above (1) to (3), anesthetic gas, etc.
In order to measure the partial pressure of gases other than O ₂ and CO ₂ , a dedicated measuring means must be added, and such measurement is actually extremely difficult.

On the other hand, in (4) above, it is possible to continuously measure the partial pressure of blood gas and tissue gas, but it is not possible to measure PH.

As described above, conventional means cannot simultaneously and continuously measure the gas partial pressure and PH value of blood or tissue fluid. On the other hand, these above
Although it is possible to simultaneously and continuously measure gas partial pressure and PH value by combining (2) to (4), this would require an extremely large-scale device and procedure, so it cannot be adopted at all.

Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and it is possible to remove gaseous components from liquids such as blood or tissue fluid by simply placing one catheter in a blood vessel or a fluid such as tissue fluid. Pressure and PH value at the same time,
Furthermore, the main objective is to provide a catheter that can perform continuous measurements.

The present invention has been made through various studies to achieve these objectives, and has resulted in the realization of a catheter having a structure that effectively achieves these objectives.

That is, the present invention provides a tubular body made of a gas-impermeable material and having an open end, and a gas-permeable body provided from the side surface of the tubular body to the open end and covering the open end surface in a liquid-tight manner. A temperature sensor and a pH measuring electrode are provided on the outer surface of the gas permeable membrane at the distal end of the catheter body, which has a membrane and allows gas to pass through the gas permeable membrane into the tubular body near the open end. a connecting means for introducing the gas that has permeated into the tubular body into an external gas partial pressure measuring means; a potential output end of the PH measuring electrode; The catheter is characterized in that it is provided with a temperature output end.

Furthermore, the embodiments of the present invention are intended to provide a specific structure that more effectively achieves the above objects, and are as follows.

(i) The gas permeable membrane shall be a membrane made of fluororesin or silicone resin, or a porous membrane made of polyolefin resin.

(ii) A gas permeation hole is formed near the open end of the tubular body so that gas in the liquid can permeate from the gas permeable membrane into the tubular body through the gas permeation hole.

(iii) A gas permeation hole forming member is connected to the tip of the tubular body, so that gas in the liquid can permeate from the gas permeable membrane into the tubular body through the gas permeation hole forming member.

(iv) At the tip of the tubular body, as a gas permeation hole forming member,
Connecting springs or porous bodies.

(v) The electrode for PH measurement must be a Pd/d0 electrode.

(vi) The temperature sensor is a thermocouple or thermistor.

Specific Configuration of the Invention Hereinafter, the specific configuration of the present invention will be described in detail according to examples.

FIG. 1 shows an embodiment of the invention.

In FIG. 1, a catheter 1 of the present invention has a tubular body 2 made of a gas-impermeable material such as a metal such as stainless steel or a gas-impermeable resin such as vinyl acetate resin, in this case stainless steel. .

This tubular body 2 has one open end, and has a gas permeable membrane 3 extending from the side surface to the open end so as to cover the open end in a liquid-tight manner. As the gas-permeable membrane 3, any membrane material that has air permeability and is impermeable to liquids such as blood can be used. Suitable are breathable resin membranes such as, and impermeable porous membranes made of polyolefin resins such as polypropylene.

The gas permeable membrane 3 covers the side surface of the tubular body 2 and seals the distal end of the tubular body 2 by, for example, being thermally melted. Note that the gas permeable membrane 3 may be provided from the middle of the side surface of the tubular body 2 to its tip, but usually, as shown in the figure, the gas permeable membrane 3 is provided on the side surface of the tubular body 2.
It is provided from the entire side surface to the tip.

In this case, the catheter body 15 consisting of the tubular body 2 and the gas-permeable membrane 3 of the catheter 1 is inserted into the tubular body 2 from the gas-permeable membrane 3 when placed in blood, tissue fluid, or other liquid. , configured to allow gas in the solution to pass therethrough.

In this configuration, gas permeation may be performed through the gas permeable membrane 3 that covers the open end of the tubular body 2, but in a preferred embodiment, the gas permeates through the gas permeable membrane 3 that covers the open end of the tubular body 2. In,
One or more gas permeable holes 25, 25 are formed, and the gas permeable holes 2 are formed from the gas permeable membrane 3.
It is preferable to allow gas in the liquid to pass through the tubes 5 and 25 into the tubular body 2.

In this way, the PH measuring electrode 4 and the temperature sensor 5 are provided at the distal end of the catheter body 15 consisting of the tubular body 2 and the gas permeable membrane 3.

In this case, the PH measurement electrode 4 may be provided on the outer surface at or near the tip of the catheter body 15, and the temperature sensor may be provided on or inside the tip of the catheter body 15 on the outer surface near the tip. In terms of arrangement and to improve temperature detection, both are preferably provided on the outer surface of the gas permeable membrane 3 at the distal end of the catheter body 15, as shown in FIG.

The electrode for PH measurement may be of various types, but is usually a metal/metal oxide electrode, especially a metal/metal oxide electrode.
Preferably it is a Pd/PdO electrode. In the case shown, a metal tubular body 2 made of stainless steel or the like is used as a lead, a Pd wire 45 is connected to this tubular body 2, and the tip of the Pd wire 45 penetrates the surface of the gas permeable membrane 3 at the tip of the catheter body 15. An example of a Pd/PdO electrode 4 in which PdO is formed on the surface by electrodeposition, for example, is shown.

Further, a temperature sensor 5, preferably a thermocouple or a thermistor, is attached to the outer surface of the gas-permeable membrane 3 at the tip of the catheter body 15. A lead 55 is connected to the temperature sensor 5 through the gas permeable membrane 3.

On the other hand, the rear end of the catheter body 15 is connected to the tubular body 2.
It has a connection means for introducing the gas in the liquid that has permeated into the inside to an external gas partial pressure measuring means.

In this case, the connecting means may be of any type as long as it can introduce the permeate gas into an external gas partial pressure measuring means, such as a mass spectrometer, through a suitable connecting pipe.
If such a connecting tube can be connected, the rear end of the tubular body 2 or the catheter body 15 may be configured to function as the connecting means as it is.

However, normally, due to the arrangement of the potential output end 49 of the PH measurement electrode 4 and the output end 59 of the temperature sensor 5, which will be described later, a separate connector 6 is connected to the rear end of the catheter body 15. Preferably, it is a connecting means.

In the example shown in FIG.
The connector 6 is caulked and fixedly connected to the rear end by the connecting ring 7 through the rubber 75.
The structure is such that the rear end 63 of the connector can be connected to a connecting pipe, thereby functioning as a connecting means.

In the illustrated example, a breathable, liquid-impermeable filter 8 is disposed near the rear end 63 of the connector 6. In this way, if the filter 8 is provided in the connecting means, that is, in the rear end of the catheter body 15 or in the connector 6, allowing only gas to pass through but not allowing liquid to pass through, in the unlikely event that the gas permeable membrane 3 is damaged, blood etc. Even if liquid enters into the catheter body 15, the filter 8 prevents the liquid from reaching the external gas partial pressure measuring means, resulting in a more preferable structure.

Further, at the rear end of the catheter body 15, a potential output end 49 of the PH measurement electrode 4 and a temperature output end 59 of the temperature sensor 5 are provided.

In this case, these output ends 49 and 59 can be provided in various arrangements on the rear end side of the catheter body 15, but it is usually preferable to arrange them in the connector 6. In the example shown in FIG. 1, an insulating connector 6 is provided with a branch 65 whose tip is sealed, a potential output end 49 and a temperature output end 59 are provided at this branch sealed end, and a potential output end 49 and a temperature output end 59 are provided. and a conductive tubular body 3 that functions as a lead for the PH measurement electrode 4.
and the temperature output end 59.
and the lead 55 of the temperature sensor 5 are connected.

Then, as described above, the catheter body 15
The gas introduced into the tubular body 2 is introduced into an external gas partial pressure measuring means to detect the gas partial pressure in the liquid, and taking this gas partial pressure into account, the potential output end 49
From the output from the temperature output terminal 59, the pH of the liquid to be tested can be detected.

Another embodiment is shown in FIG.

In the example shown in FIG. 2, a gas permeable hole forming member is connected to the tip of the tubular body 2, and a gas permeable membrane 3 is provided to cover and seal the tubular body 2 and the gas permeable hole forming member. The gas in the liquid is allowed to permeate from the gas permeable membrane 3 into the tubular body 2 through the gas permeable hole forming member, and a spring 27 is used as the gas permeable hole forming member.

As such a gas permeation hole forming member, the second
In addition to the spring 27 in the example shown in the figure,
Although various materials can be used, materials using porous materials are also suitable.

FIG. 3 shows an example in which a porous body 29 is connected to the tip of the tubular body 2 as a gas permeation hole forming member. In this case, a transmission hole is formed in the center of the porous body 29, and the Pd wire 45 and the lead 55 of the temperature sensor 5 are arranged in this hole.

FIG. 4 shows yet another embodiment.

In the example shown in FIG. 4, the tubular body 3 is made of an insulating, gas-impermeable material such as vinyl acetate resin, and within the tubular body 2 is a pH measuring electrode 4.
lead 46 for temperature sensor 5 and lead 56 for temperature sensor 5
is embedded, and one or more gas permeation holes 25 are formed near its tip. The lead 46 is connected to the PH measurement electrode 4 via the lead 45 at one end, and to the potential output end 49 via the lead 47 at the other end.
On the other hand, the lead 56 passes through the leads 55 and 57,
It is connected to the temperature sensor 5 and the temperature output end 59, respectively. Other than this, the configuration is almost the same as the example shown in FIG.

Specific Effects of the Invention In order to simultaneously and continuously measure the pH and gas partial pressure of a liquid, particularly blood or interstitial fluid, using the catheter of the present invention, the following may be performed, for example.

First, the tip of the catheter is placed in a liquid, particularly in a blood vessel or tissue fluid. At this time, the potential output end 49 and the temperature output end 59 are connected to the potentiometer V, and the connection means consisting of the rear end of the catheter body 15 and the connector 6 are connected to the external device such as the mass spectrometer MS through the connecting tube T. Connected to gas partial pressure measuring means. Furthermore, a reference electrode is connected to the potentiometer V as required. Especially when blood or interstitial fluid is used as the test liquid, a reference electrode El such as Ag-AgCl is connected to the body surface or inside the body near the site where the catheter 1 is placed. Detain.

With this configuration, gas contained in liquids such as blood and tissue fluid passes through the gas permeable membrane 3 of the catheter body 15, passes through the gas permeable holes 25, the voids in the spring 27, the porous body 29, etc., and then enters the tubular shape. introduced into the body 2. At this time, the inside of the catheter 1 is under negative pressure, and the dissolved gas in the liquid is introduced into the catheter in proportion to the partial pressure of the dissolved gas in the blood and tissue fluid that contacts the gas permeable membrane 3. Then, by measuring this gas with an external gas partial pressure measuring means, such as a mass spectrometer, the partial pressure of Po ₂ , Pco ₂ or other gases can be measured.

On the other hand, PH measurement is performed as follows.

That is, from the Henderson-Hasselbalch equation, the electrode potential of the PH measurement electrode is expressed by the following equation (1).

E=Eo+(RT/2F)In(a ² _H+ /P _H2 )...(1) (Here, Eo is the electrode standard potential, a _H+ is the hydrogen ion activity in the liquid, and P _H2 is the H in the liquid. ₂ gas partial pressure, F is Faraday's constant, R is gas constant, and T is liquid temperature.) By transforming the above equation (1), the following equation (2) is obtained.

E=Constant−2.303RT/FPH−RT/2FInPP _H2 ...(2) From equation (2), find the temperature T using the temperature sensor 5,
In addition, P _H2 is determined using a gas partial pressure measuring means such as a mass spectrometer, and the output potential of the PH measurement electrode 4 and the reference electrode E1 are
If we calculate the electrode potential E from the potential difference between
PH will be required.

Therefore, the output of the potentiometer V and the mass spectrometer MS
When the outputs _of gas partial _pressure measuring means such as
It outputs P _H2 and the partial pressures of other gases, and at the same time outputs PH from P _H2 , T, and E, and these are recorded on the recorder R at the same time. In this case, the electrode potential E, gas partial pressures Po ₂ , Pco ₂ , P _H2 , and temperature T can be measured continuously, so that the gas partial pressure and PH
will be automatically and continuously measured at the same time.

Specific Effects of the Invention According to the present invention, as detailed above, by using only one catheter, gas partial pressure in a liquid can be adjusted.
PH value can be measured simultaneously and continuously. At this time, especially for the PH value, the output potential of the PH measurement electrode can be automatically calibrated using temperature and _PH2 , so extremely reliable values can be obtained.

Furthermore, since the catheter of the present invention has an extremely simple structure, it can be used for disposable PH, Pco ₂ ,
It can be used as a catheter for monitoring Po ₂ or other gas partial pressures, and is extremely useful medically.

Furthermore, since the PH measurement electrode and temperature sensor are provided on the outer surface of the gas-permeable membrane at the tip of the catheter body, the accuracy of temperature and potential measurement is improved, and in addition, manufacturing is facilitated.

Furthermore, according to the embodiments (i) to (vi), gas permeation into the catheter is improved, and reliability of measured values is improved, resulting in more favorable results.

That is, if the gas permeable membrane is made of a fluorine or silicone resin membrane or a porous polyolefin membrane according to (i) above, gas permeation will still be better.

If the gas permeation holes 25 are provided in the tubular body 2 according to (ii) to (iv) above, or if a gas permeation hole forming member such as the spring 27 or the porous body 29 is connected to the tubular body, gas permeation to the tubular body 2 is possible. will be better.

According to (v) and (vi) above, if the PH measurement electrode is a Pd/Pd0 electrode or the temperature sensor is a thermocouple or thermistor, the PH measurement accuracy and temperature measurement accuracy will be improved.

Furthermore, when measuring blood or tissue fluid, it is possible to automatically and reliably perform highly reliable measurements using extremely simple means.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.
FIG. 2 is a partially omitted end view showing another embodiment of the present invention. FIG. 3 is a partially omitted end view showing still another embodiment of the present invention. FIG. 4 is a sectional view showing still another embodiment of the present invention. Figure 5 shows
FIG. 2 is a schematic diagram for explaining how to use the catheter of the present invention. 1...catheter, 15...catheter body,
2... Tubular body, 25... Gas permeation hole, 27... Spring, 29... Porous body, 3... Gas permeable membrane, 4... PH measurement electrode, 49... Potential output end,
5...Temperature sensor, 59...Temperature output terminal.

Claims (1)

[Scope of Claims] 1. A tubular body made of a gas-impermeable material and having an open end, and a gas provided from a side surface of the tubular body to the open end to liquid-tightly cover the open end surface. a temperature sensor and a pH sensor on the outer surface of the gas permeable membrane at the distal end of the catheter body, the catheter body having a permeable membrane and allowing gas to pass through the gas permeable membrane into the tubular body near the open end. a connecting means for introducing the gas that has permeated into the tubular body into an external gas partial pressure measuring means;
A catheter characterized in that it is provided with a potential output end of a PH measurement electrode and a temperature output end of the temperature sensor. 2. The catheter according to claim 1, wherein the gas permeable membrane is a membrane made of fluororesin or silicone resin, or a porous membrane made of polyolefin resin. 3. The tubular body is provided with a gas permeation hole near the open end thereof, so that gas can permeate from the gas permeable membrane into the tubular body through the gas permeation hole. catheter. 4. The tip of the tubular body is provided with a gas permeation hole forming member, and the gas in the liquid can permeate from the gas permeable membrane into the tubular body through the gas permeation hole forming member. Catheter described in. 5. The catheter according to claim 4, wherein the gas permeation hole forming member is a spring or a porous body. 6. The catheter according to claim 1 or 2, wherein the PH measurement electrode is a Pd/Pd0 electrode. 7. The catheter according to claim 1 or 2, wherein the temperature sensor is a thermocouple or a thermistor.