JPS5931217Y2 - Calibration device for transcutaneous blood oxygen partial pressure measurement sensor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a calibration device for calibrating the measured value of a sensor that continuously measures oxygen concentration in arterial blood transcutaneously.

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 captures oxygen that diffuses from the blood through the subcutaneous tissue on the surface of the skin.
A transcutaneous blood oxygen concentration measurement method that allows continuous measurement over time without causing pain to the patient is already known.

The present invention relates to a calibration device for calibrating the measured value of such a sensor for transcutaneous blood oxygen concentration measurement.

Figure 1 shows the structure of a typical transcutaneous blood oxygen partial pressure measurement sensor to which this calibration method is applied. An electrolytic solution 6 is placed on one end surface of an electrode consisting of an anode 3 made of silver or the like placed on the
The skin heating section 10 has a built-in heater wire 8 and a temperature detection element 9.

2 and 3 show the principle of a conventionally used calibration method, with FIG. 2 showing a calibration container and FIG. 3 showing a calibration curve.

2. 11 is a container made of transparent material such as acrylic resin or glass, 12 is a heater for heating the water in the container to a constant temperature, 13 is a temperature detection element (for example, a thermistor), and 14 is a pressure feeder. 15 is distilled water, 16 is a presser spring for fixing the sensor, 17 is piping from the air pump, 18 is a N2 gas cylinder 19 indicates a three-way stopper for gas cutoff, and 20 indicates a sensor to be calibrated.

Below, the conventional calibration method will be explained step by step.

Adjust the water temperature in the calibration container to the measured temperature of the sensor, e.g. 44°C.
The air pump pumps out a small amount of air.

When the pumped air passes through the porous plate 14 in the calibration container, it becomes fine bubbles and passes through the water 15 heated to 44° C. At this time, the air becomes approximately the same temperature as the water, and
The so-called humid air containing saturated water vapor at that temperature comes into contact with the electrode membrane surface of the sensor 20, and is subsequently discharged to the outside of the calibration container.

Therefore, the electrode membrane surface of the sensor is constantly in contact with a constant oxygen partial pressure, and if the electrolytic current value of the sensor at this time is determined as Pair, the upper limit of the two-point calibration can be achieved. Become.

Next, when the three-way stopcock 19 is switched and N2 gas is fed under pressure from the N2 cylinder, the air in the calibration container is replaced by the N2 gas, and the oxygen partial pressure becomes zero on the surface of the electrode membrane.

Therefore, by setting the electrolytic current value at this time to zero oxygen partial pressure, the lower limit of the two-point calibration method can be calibrated.

FIG. 3 is a calibration curve obtained by the method described above. By using this calibration curve, the oxygen concentration in a gas or liquid can be determined.

The conventional method is extremely accurate in terms of the accuracy of the calibration values, and is an excellent calibration method in this respect, but it is difficult to use N2 in clinical practice.
It is necessary to bring in a cylinder 1 air pump, etc., and there are various complications such as adjusting the N2 gas pressure, air pressure, etc., and finding a place to put the temperature calibration container.

These matters are not a problem in a normal laboratory7, but clinical sites are generally small and equipped with a variety of equipment, so the complexity described above becomes a major drawback, and it is considered an extremely serious problem in clinical settings. be seen.

The present invention improves the above-mentioned drawbacks and provides a calibration instrument for a sensor for transcutaneous blood oxygen partial pressure measurement that can be easily and accurately calibrated in a clinical setting.

FIG. 4 shows the calibration device and calibration method according to the present invention, where 21 is a main body of the calibration device made of a heat insulating material such as rubber, plastic, or foam, and 22 is a material made of sponge, cotton paper, or nonwoven material. Water-absorbing material for retaining moisture consisting of etc., 23
11 shows a sensor attached to a calibration tool, and a magnet for fixing it on a stand or on the surface of a measuring device.

FIG. 4a shows a state in which the sensor 24 is attached to the calibration instrument and calibration is being performed, and b' shows a plan view and a sectional view of the calibration instrument.

Figure 5 shows the zero point calibration method according to this calibration method, where 24 is the sensor with the membrane side facing up, and 26 is an aqueous solution containing a reducing agent such as sodium sulfite, sodium nitrite, pyrogallol, hydrosulfide, etc. A dropper 27 for dropping the reducing agent is an aqueous solution containing the reducing agent dropped onto the membrane surface of the sensor.

Next, a method for calibrating the transcutaneous blood oxygen concentration sensor using the calibration device according to the present invention will be described.

That is, a small amount of distilled water is dropped onto the water-absorbing agent of the calibration device shown in FIG. 4, and then the sensor is attached as shown in FIG. 4a.

This causes the air gap 25 in the calibration device to be at a constant temperature due to the heat from the sensor's heating device, and filled with air containing saturated water vapor at this temperature, and thus having a constant oxygen partial pressure.

Therefore, the electrode surface does not need to come into contact with the known oxygen partial pressure, and the upper limit value of the sensor can be calibrated correctly.

The zero point calibration is performed as shown in Figure 5.
Since this state is formed, it becomes possible to calibrate the zero point of the sensor.

As mentioned above, according to this calibration method, conventional N2 gas cylinders,
Although it was necessary to bring air pumps and the like to the clinical site, these complications are now completely unnecessary, and the sensor for transcutaneous blood oxygen partial pressure measurement can be calibrated extremely easily and quickly.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a sensor for transcutaneous blood oxygen partial pressure measurement.
Figure 2 shows a conventionally used calibrator, and Figure 3 shows a calibration curve. FIG. 4 attzb' is an explanatory diagram of a calibration instrument according to the present invention, and FIG. 5 is an explanatory diagram of a simple zero-point calibration method. 1...Cathode, 2...Insulating material, 3...
...Anode, 4... Electrode membrane, 5... Membrane holder 6... Electrolyte, I... Electrode holder, 8...・Heater wire, 9...
Heat-sensitive element, 10...Skin heating element, 11...
・・・Metal, 12...Heater, 13...
・Temperature detection element, 14...Porous body, 15...
... Distilled water, 16 ... Presser spring, 17 ...
... Air pump piping, 18 ... Piping from N2 gas cylinder, 19 ... Three-way stopcock, 20.
...Sensor, 21 ... Calibration instrument main body, 22 ... Water absorbing agent, 23 ... Magnet, 2
4...Sensor, 25...Gap, 2
6 indicates a dropper, and 27 indicates an aqueous solution containing a reducing agent.

Claims (1)

[Scope of utility model registration request] Heat-insulating materials such as rubber, plastic, and foam
A transcutaneous blood oxygen device characterized by covering the outer circumference of the sensor except for the upper end side, providing a gap on the electrode membrane side, and interposing a water-absorbing material such as a sponge, paper, or nonwoven fabric in the gap. Calibration instrument for sensors for measuring partial pressure.