JPH07231885A - In-organism gas sensor - Google Patents

Abstract

PURPOSE:To cope with sudden change of the condition of a patient in an early stage by monitoring it by inserting an alimentary canal tube on which a gas sensor is installed into an alimentary canal, and measuring a partial pressure of carbon dioxide. CONSTITUTION:A Pco2 sensor 5 for measuring a partial pressure of carbon dioxide is embedded close to a forward end of a catheter main body 2 on the opposite side of a hole part 4 in a circumferential wall, and an aperture part 2a is formed in the circumferential surface outside the sensor 5. A lead part 6 to introduce a signal of the carbon dioxide gas partial pressure measured by the sensor 5 is also embedded in the circumferential wall of the catheter main body 2 in the axial direction. After calibration of the sensor 5 is performed by specified Pco2 calibration liquid, the sensor 5 is inserted into an alimentary canal of a sick person with the catheter 1 to be set there for measuring Pco2. Only by thus setting the Pco2 sensor 5 installed on the catheter 1 in the stomach, Pco2 can be measured instantaneously. As a result of this, conditions of oxygen metabolism can be known instantaneously, and sudden change of the condition of the patient in an ICU room or the like can be monitored to be coped with in an early stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vivo gas sensor for measuring the partial pressure of carbon dioxide in the alimentary canal of a living body.

[0002]

2. Description of the Related Art For example, in an intensive care unit (ICU) patient, if the circulating blood volume is reduced for some reason, the blood that had been supplied to the abdominal organ until then is redistributed to other important organs. . Therefore, the blood flow in the mucous membrane of the digestive tract is reduced earlier than in other organs, resulting in an ischemic state. As a result, the mucous membrane becomes hypoxic, the tissue becomes acidic, and acidosis occurs, and eventually the mucosal tissue disintegrates and intestinal bacteria and endotoxin, which is a bacterial toxin, move into the body fluid, which causes sepsis and multiple organ failure. It becomes one cause. That is, if it is possible to detect the ischemic state of the digestive tract at an early stage and take measures to improve it, one of the causes of multiple organ failure, which is said to be the main cause of death in ICU, can be prevented. it can.

In order to measure this ischemic state, conventionally, physiological saline is injected into a silicone balloon placed in the digestive tract, and after 30 to 60 minutes, the physiological saline is sampled to obtain a blood gas analyzer. Has been used to measure the partial pressure of carbon dioxide and indirectly calculate the increased tissue pH (pH).

[0004]

However, according to the above-mentioned conventional method, a balloon infused with physiological saline is left in the digestive tract for a predetermined period of time, and then the physiological saline is anaerobically sampled to analyze the blood gas. Since it is necessary to measure the carbon dioxide partial pressure, the procedure is difficult and time-consuming. In addition, continuous monitoring is not possible, and the measured values differ depending on the model of the blood gas analyzer, which is extremely inconvenient for practical use.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an in-vivo gas sensor capable of accurately measuring the partial pressure of carbon dioxide gas in the lumen of the digestive tract immediately by a simple procedure. To do.

[0006]

In order to achieve the above object, the in-vivo gas sensor of the present invention according to claim 1 is provided in the vicinity of the distal end of a digestive tract tube for medical treatment by inserting it into the digestive tract of a living body. It is characterized by being equipped with a sensor for measuring the carbon dioxide partial pressure in the lumen of the digestive tract.

In the in-vivo gas sensor according to the second aspect of the present invention, a lead portion for leading out a signal measured by a sensor mounted near the tip of the digestive tract tube from the sensor is integrally formed with the digestive tract tube. It is characterized by being provided.

[0008]

According to the above-mentioned structure, according to the invention of claim 1, the sensor can be inserted and left in the digestive tract of the living body together with the digestive tract tube to measure the carbon dioxide partial pressure. Is possible. As a result, the state of oxygen metabolism of the tissue can be immediately known, and a rapid change in the patient's condition in, for example, the ICU room can be monitored and an early treatment can be performed. Further, according to the invention of claim 2, by providing the lead portion for guiding the signal measured by the sensor integrally with the digestive tract tube, the lead portion does not become an obstacle when the digestive tract tube is inserted into the digestive tract. , Can be easily inserted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the in-vivo gas sensor of the present invention will be described below with reference to the drawings.

1 to 3 show the configuration of an embodiment of the present invention. In FIG. 1, a gastric catheter 1 serving as a digestive tract tube includes a tubular catheter body 2 made of silicone rubber or the like that is flexible and has a closed tip. The catheter main body 2 has a length of 1 to 8 m and a diameter of about 3 to 26 mm, and a hollow main lumen 3 is provided inside in the axial direction. In addition, a plurality of holes 4 that communicate the main lumen 3 and the outside are formed in the circumferential wall of the catheter body 2 along the axial direction, and the sampling solution in the gastric lumen is sucked through the holes 4. Also, the cleaning liquid is supplied from the outside through the main lumen 3 and the hole 4 into the lumen of the stomach.

A sensor (hereinafter referred to as Pco ₂ sensor) 5 for measuring the partial pressure of carbon dioxide is embedded in the vicinity of the tip of the peripheral wall of the catheter body 2 opposite to the side where the hole 4 is formed. , Pco ₂ sensor 5 has an opening 2a formed on the outer peripheral wall thereof. In addition, the lead portion 6 for leading out the signal of the carbon dioxide partial pressure measured by the Pco ₂ sensor 5 to the outside.
Is also embedded in the circumferential wall of the catheter body 2 in the axial direction.

As the Pco ₂ sensor 5, one having a structure described in, for example, JP-A-61-144562 is known. FIG. 2 shows an example of the configuration of the Pco ₂ sensor 5. In FIG. 2, the ion sensor 11 and the reference electrode 12 each composed of an ion-sensitive field effect transistor, and the three lead wires 14 respectively connected to the three lead wire lead portions 13 of the ion sensor 11 are It is embedded in the body 15 via an insulating resin 16. Ion sensor 11
The ion sensitive part (gate part) 11a and a part of the reference electrode 12 are filled with a hydrophilic polymer material 17 containing an electrode internal liquid, and the polymer material 17 is further covered with a homogeneous gas permeable film 18. ing.

FIG. 3 shows a circuit for measuring the carbon dioxide partial pressure by the Pco ₂ sensor 5. This circuit is a source follower circuit, and the comparison electrode 12 is grounded via a lead wire 21. A lead wire 14a is connected to the drain 22 of the gate portion 11a of the ion sensor 11 via a lead wire lead portion 13a. The source 23 of the gate portion 11a includes a lead wire lead portion 13b and a lead wire 1.
4b through one output side terminal 25 of the temperature compensation circuit 24
The output side terminal 25b of the temperature compensation circuit 24 is connected to the source 23 of the gate 11a via the lead wire 14c and the temperature element (diode) 26. Further, a constant current circuit 27 is connected to the lead wire 14c.

In the circuit constructed as described above, a constant voltage VD is applied to the drain 22,
A constant current flows between the source and the source 23 by the constant current circuit 27. In this state, when carbon dioxide gas is absorbed by the electrode inner liquid through the gas permeable film 18 and the hydrogen ion concentration changes, the interface potential of the gate portion 11a of the ion sensor 11 changes. The potential VS of the source 23 changes with the change of the interface potential.

At this time, since the relationship between the carbon dioxide partial pressure and the potential VS of the source 23 actually changes depending on the temperature,
A temperature element 26 is provided to change the potential Dt in response to the temperature of the electrolytic solution, and the potential VS is compensated by the temperature compensation circuit 24 to obtain the potential Vsa. By measuring the potential difference between the compensated potential Vsa and the reference electrode 12, the carbon dioxide partial pressure can be measured.

When measuring Pco ₂ using the gastric catheter 1 to which the Pco ₂ sensor 5 is attached, first, the Pco ₂ sensor 5 is calibrated with a predetermined Pco ₂ calibration solution, and then the subject's Pco ₂ sensor 5 is calibrated. Pco ₂ with catheter 1 into digestive tract
The sensor 5 is inserted and placed, and Pco ₂ is measured. Henderson Hasselbalha as needed (Henderso
Using the formula of n-Hasselbalch, pH can be obtained from the measured value and arterial blood [HCO3 ⁻ ] to know the state of tissue oxygen metabolism.

According to this embodiment, it is possible to measure Pco ₂ immediately by merely placing the Pco ₂ sensor 5 attached to the catheter 1 in the stomach. As a result, the state of oxygen metabolism in the tissue can be immediately known, and sudden changes in the patient's condition in the ICU room or the like can be monitored and early treatment can be performed.

4 to 11 show a modification of the catheter 1, a Pco ₂ sensor 5 and a lead portion 6 for the catheter 1.
A modified example of the mounting structure of FIG. FIG. 4 shows a double-lumen type in which the lumen 3 has the partition wall 1a in the axial direction at the center.
The co ₂ sensor 5 and the lead portion 6 are embedded. In FIG. 5, the Pco ₂ sensor 5 and the lead portion 6 are embedded in an intestinal catheter 32 having a plurality of metal balls 31 embedded at its tip. FIG. 6 shows the catheter 1 shown in FIG.
The Pco ₂ sensor 5 and the lead portion 6 are integrally molded on the outer peripheral surface of the.

FIG. 7 shows the double lumen 3 shown in FIG. 4 with the Pco ₂ sensor 5 and the lead portion 6 mounted on the inner circumference thereof. In FIG. 8, the Pco ₂ sensor 5 is attached to the outside of the tip of the lead portion 6 of the catheter 1 shown in FIG. 1, and the Pco ₂ sensor 5 is projected into the opening 2 a formed in the catheter body 2.

9 to 11 show that a hole 41 for flowing a calibration gas in the axial direction is provided separately from the lumen 3 in the catheter body 2, and the Pco ₂ sensor 5 and the lead portion 6 are mounted in the hole 41. Of these, FIG. 9 shows that the hole 41 is opened in the opening 2a on the outer peripheral side surface of the catheter body 2, and the Pco ₂ sensor 5 and the lead portion 6 are arranged substantially at the center of the hole 41. In FIG. 10, the hole 41 is opened through a plurality of openings 2b formed in the tip end surface of the catheter body 2, and Pco
_{2 The} sensor 5 and the lead portion 6 are mounted on the inner peripheral surface of the hole 41. Further, in FIG. 11, the holes 41 shown in FIG. 10 are linearly arranged and opened at the end surface of the catheter body 2.

[0021]

As described above, according to the in-vivo gas sensor of claim 1, the gas sensor is attached to the digestive tract tube, and the digestive tract tube is inserted into the digestive tract to measure the carbon dioxide partial pressure. Thus, gas in the gastrointestinal tract can be measured immediately and easily, and sudden changes in the patient's condition can be monitored and early treatment can be performed.

According to the in-vivo gas sensor of the second aspect, since the lead portion for guiding the signal measured by the sensor is integrally provided in the digestive tract tube, the lead portion is inserted when the digestive tract tube is inserted into the digestive tract. Does not become a resistance and can be easily inserted.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of an in-vivo gas sensor of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of an example of the Pco ₂ sensor shown in FIG.

FIG. 3 is a circuit block diagram of the Pco ₂ sensor of FIG.

FIG. 4 is a sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 5 is a cross-sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 6 is a sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 7 is a cross-sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 8 is a sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 9 is a sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 10 is a sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

FIG. 11 is a cross-sectional view showing the configuration of another embodiment of the in-vivo gas sensor of the present invention.

[Explanation of symbols]

1 Catheter (gastrointestinal tube) 5 Pco ₂ sensor 6 Lead part

Claims (2)

[Claims] 1. An in-vivo gas sensor, characterized in that a sensor for measuring the partial pressure of carbon dioxide in the lumen of the digestive tract is mounted near the tip of the digestive tract tube which is inserted into the digestive tract of a living body for medical treatment. . 2. The in-vivo gas sensor according to claim 1, wherein a lead portion for leading out a signal measured by the sensor is provided integrally with the digestive tract tube.