JPS62122634A - Sensor for percutaneous measurement of concentration of oxygen in blood - 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] [Field of Industrial Application] The present invention relates to the structure of a sensor for a device for transcutaneously and continuously measuring the oxygen concentration in arterial blood, and in particular to a sensor whose membrane holder is easy to attach and detach. It is something.

[Conventional technology]

Knowing the oxygen concentration (or partial pressure) in blood, especially in arterial blood, is extremely important for respiratory management of newborns and severely injured patients requiring artificial respiration. Unlike the method of measuring oxygen concentration in arterial blood, which involves drawing blood from the artery and directly measuring it, this method traps oxygen that diffuses from the blood through the subcutaneous tissue on the surface of the skin, causing pain to the patient. A transcutaneous blood oxygen concentration measurement method is already known that allows for continuous measurement over time.

FIGS. 2 and 8 show the structure of a typical sensor for measuring transcutaneous blood oxygen concentration that has been conventionally used.

(1) in Figure 2 is a cathode made of noble metal such as gold or platinum, (
2) is an insulating material such as glass or epoxy, (3) is an anode made of silver/silver chloride, (4) is a heating heater, (5) is a temperature detection element, and (6) is a material made of tetrafluoride resin, polyester, etc. An electrode membrane made of an oxygen gas permeable polymer film, (7) an electrolytic solution made of an electrolyte solution such as KCI, (8) a fixing mechanism such as a ``0'' ring for fixing the electrode membrane, (9) )
is the outer protective skin. Next, the principle of transcutaneous measurement will be explained using the sensor shown in FIG.

A contact liquid mainly composed of water, saline, etc. is interposed between the sensor and the skin as shown in Figure 2, and the sensor is tightly attached to the skin surface using a disc-shaped double-sided adhesive tape with a hole in the center. When the temperature of the fixed-temperature heating section is set at 43 to 44° C., the skin in contact with it is heated and the subcutaneous tissue is arterialized. The oxygen concentration in the tissue is therefore substantially equal to that contained in arterial blood, and this oxygen diffuses through the skin tissue, permeates the membrane, and further diffuses through the electrolyte to reach the cathode. At this time, if a polarization voltage necessary for the oxygen reduction reaction is applied between the cathode and the anode, the oxygen reduction reaction occurs at the cathode, and an electrolytic current proportional to the amount of oxygen flows between the electrodes.

Therefore, by measuring this current, it is possible to approximately measure the oxygen concentration in the subcutaneous tissue and therefore in the arterial blood.

However, the conventionally used sensor shown in FIG. 2 has the following drawbacks. That is, since this type of sensor uses a cathode as a skin heating element, it necessarily requires a large cross section. Therefore, the amount of oxygen reacted at the cathode is large, and the electrolyte is consumed extremely quickly.

Therefore, it is necessary to frequently replace the electrolytic solution, and the electrode membrane must be replaced each time. Furthermore, due to high oxygen consumption, an oxygen concentration gradient occurs within the skin tissue, and the actual measured value is much lower than the oxygen concentration contained in arterial blood. If a membrane with poor oxygen permeability is used to avoid this, the actual measured value will be close to the oxygen concentration in arterial blood, but this will have the disadvantage of slow response speed. Another disadvantage of the sensor shown in Figure 1 is that when replacing the membrane, the film-like electrode membrane is fixed to the end of the electrode using a 11011 ring or an alternative fixing mechanism. It is difficult to install the membrane under constant conditions, and replacing the membrane requires skill, so there is a problem that variations in characteristics occur depending on whether the membrane is properly installed or not.

Fig. 8 shows an improved version of the sensor shown in Fig. 1, and the improved points and features are as follows.
The structure of the sensor shown in the figure does not directly heat the electrode, but has a separate heating section 07), so that the cross-sectional area of the cathode αO can be changed as appropriate to obtain an appropriate amount of reaction with oxygen. became possible. Five examples of the cathode α0 shown in FIG. 3 have a ring-shaped cross section, but
This makes it possible to eliminate the drawbacks caused by the large cathode seen in the sensor shown in Figure 2. Moreover, the trouble that occurs when replacing the electrode membrane can be solved by adopting the structure shown in FIG. In other words, the sensor shown in Fig. 3 has an overall structure that includes an upper lid part 03) containing both negative and negative electrodes, a membrane holder α to which an electrode film is pasted in advance, a resale heat body 08), and a heat sensitive body 09) embedded. It is composed of three independent parts of the heating element (17), and a part of the membrane holder can be easily installed between the upper lid part and the heating element, so the membrane does not wrinkle when installed. Furthermore, since the membrane can be replaced without any skill, troubles during membrane replacement are eliminated. Note that arterialization of the skin is caused not by heating from the electrode part, but by
Since heating is performed with high precision over a wide area by a separately provided heating element, there is an advantage that arterialization of the subcutaneous tissue is effectively performed.

As mentioned above, although the sensor shown in FIG. 3 has solved the drawbacks of the sensor shown in FIG. 1, it has been found that it still has the following drawbacks.

[Problem that the invention seeks to solve]

That is, since the upper lid part 03) containing the electrode part and the heating body αη having a heating mechanism are separated as independent parts,
It is necessary to take out the lead wires (20 and (21) from both the upper lid part and the heating element, respectively. Therefore, the upper lid part and the heating element cannot be fixed together using a rotating mechanism such as a screw, and screws are required. A method is used in which the screws are used to secure the two together.In the aforementioned screw fixing method, if the screws are not tightened uniformly, the top cover and the heating element may be fixed in a distorted state. The end surface of the electrode and the surface of the electrode membrane are similarly distorted when mating, resulting in poor electrode stability.In addition, it is troublesome to remove screws, which tends to cause problems such as losing them when attaching and detaching. .

The present invention has been made to solve the problems of the upper part of the conventional sensor and to facilitate the replacement of the polymer membrane.

[Means for solving problems]

The gist of the present invention is to have an electrode section consisting of a cathode made of a noble metal, an anode section arranged concentrically around the outer periphery of the cathode via an insulating material, and an electrode section that is removably provided outside the electrode section. a membrane holder, a heating element provided on the outside of the membrane holder, and a ring-shaped connecting part on the outer periphery that is thermally connected to the outer periphery of the heating element, and a ring-shaped connecting part that is connected inwardly from the end surface of the connecting part. a skin heating body consisting of a flat plate part having an opening in the center and extending to cover the end faces of the membrane holder and the heating element; A blood oxygen concentration measuring sensor comprising a gas-permeable polymer membrane sandwiched between a part and the flat plate part,
having one or more concave defects at the end of the heating element,
The transcutaneous blood oxygen concentration measuring sensor is characterized in that an end portion of the membrane holder protrudes from the bottom surface of the concave defect.

FIG. 1 is a judgment diagram of the transcutaneous blood oxygen concentration measurement sensor of the present invention, in which (26) is the negative and positive polarity (23), (
24), (25), a heating element, etc., and is made of an electrically and thermally insulating material such as plastic rubber. (271 is a heating element made of metal with a screw (31) at the end, and a heating element (28) and a temperature detection element (29) are built in. (32) is a heating element made of metal with a screw (31) at the end. ) is attached to the membrane holder, and the electrolyte is held between this membrane surface and the electrode end surface. (34)
A skin heating part made of metal is fixed to the heating body (a) by screws (3],'), and is composed of a connecting part (34, -1) and a flat plate part (34-2). Flat plate part (34
-2) There is a hole in the center (a fan).In order to prevent the burn area from getting bigger in the event of a burn, there is heat insulating material made of plastic or rubber on the outer periphery of the side and bottom surfaces. (to) may be pasted.

The defect is a concave defect provided at the end of the heating body (a), and the end of the membrane holder (gong) is located on the bottom surface (38) of the concave defect (37).
).

FIG. 4(a) is a side view of the transcutaneous blood oxygen concentration measurement sensor of the present invention with the skin heating element +34) removed, and FIG. 4(b) is a plan view thereof.

[For production]

The sensor according to the present invention comprises a heating element (equipment) and a skin heating part (equipment).
34) are joined by a threaded portion C31) (31'), and the membrane holder (32) is crimped onto the electrode side by the skin heating section.

By adopting the above structure, signal lines from both negative and negative poles,
Since heater wires, lead wires from the heat-sensitive element, etc. can gather on the electrode side, as seen in the sensor shown in Figure 2, the lead wires can be connected between the electrode side (20) and the heating element side (20). 21) It is no longer necessary to separate the sensor and the sensor can be connected with a single cord (3■).

As a result, it has become possible to eliminate the drawbacks caused by conventionally fixing the upper lid and the heating section with screws (22).

However, in the conventional sensor shown in Fig. 8, the top cover (
When the heating element (1η) was removed from the heating element (13), the membrane holder (14) was exposed, so it was easy to attach and detach the membrane holder circle.
In the present invention, the heating part (equipment) and the skin heating element (34) are separated, so even if the skin heating element (equipment) is removed, the membrane holder (32) remains housed inside the end of the heating part. ing. In the present invention, by providing the concave cutout (A) at the end of the heat generating part, when replacing the electrode membrane attached to the electrode part, the membrane holder can be grasped with fingers or tweezers through one groove. Therefore, the membrane holder can be easily attached and detached, and the membrane holder can be installed so as to be stored inside the heating section, so it is possible to avoid increasing the height of the sensor by using the membrane holder.

As mentioned above, the concave defect part (I) only works effectively in a sensor in which the heating part (A) and the skin heating body are separated.

〔Effect of the invention〕

As described above, according to the present invention, the signal line from both the negative and negative poles, the heater line, the lead wire from the heat-sensitive element, etc. can be gathered on the electrode side, so the sensor and equipment can be connected with a single cord. This makes it extremely easy to handle, and the membrane holder can be easily attached and detached, making it extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 (,) is a transcutaneous blood oxygen concentration sensor of the present invention, (b), (c), and (d) are an electrode support and a membrane holder, respectively, which are disassembled parts of the sensor according to the present invention. and a sectional view of the skin heating body. Figures 2 (a) and (b) are a cross-sectional view and a plan view of a conventional sensor, respectively, and Figures 3 (a), (b), (C) and (d)
) are sectional views of the whole and each part of other conventional sensors, respectively. FIG. 4(a) is a side view of the sensor of the present invention with the skin heating element removed, and FIG. 4(b) is a plan view thereof. (1)...Cathode (2)...Insulating material (
3)...Cathode (4)...Heating heater (
6)... Electrode membrane (7)... Electrolyte (8
)...Fixing mechanism (9)...Outer protective cover 0
0... Cathode (11)... Insulating material (
12...Anode (13)...Top lid circle...Membrane holder 09...Electrode membrane (16)
...“'o”! J Song 7)...Heating part 08)...
・Heating element (1g)...Thermosensitive element (20)...Signal side lead wire (21)...-bmu lead wire (22)...
・Screw (23)...Cathode C4)
... Anode (25) ... Insulating material (2
6)... Electrode support (5)... Heating part (2
8)... Heat generating body (29)... Heat sensitive body (3
0)... Lead wire (31)... Screw (36
)...opening area (mortar...concave defect area (38
)...Bottom of concave defect Fig. 1(a) Fig. 1(b) Fig. 1) Fig. 3(a) + Fig. 3(b) Fig. 3(C) Fig. 3(d) □ )fart. Figure 4 (a) Figure 4 (b) Old

Claims (1)

[Claims] (1) An electrode part consisting of a cathode made of a noble metal, an anode part arranged concentrically around the outer periphery of the cathode via an insulating material, and a membrane holder detachably provided outside the electrode part; It has a heating element provided on the outside of the membrane holder, and a ring-shaped connecting part on the outer periphery that is thermally connected to the outer periphery of the heating element, and extends inward from the end surface of the connecting part and connects to the membrane holder. A skin heating body consisting of a flat plate part having an opening in the center and covering an end face of the heating element, and an outer peripheral part held between the end face of the membrane holder and the flat plate part so as to hold an electrolyte on the end face of the electrode part. A blood oxygen concentration measurement sensor made of a gas-permeable polymer membrane, which has one or more concave defects on the end surface of the heating element, and the end of the membrane holder is attached to the bottom surface of the concave defect. A transcutaneous blood oxygen concentration measurement sensor that is characterized by its protrusion.