JPH06175A - Automatic calibration device and automatic calibration method for instrument sensor for percutaneous measurement of oxygen and carbon dioxide patial pressure - Google Patents

Abstract

PURPOSE:To provide the novel automatic calibration method by improving the automatic calibration device for an oxygen partial pressure value and carbon dioxide partial pressure value. CONSTITUTION:The automatic sensor calibration device consisting of a sensor imposing section, a standard gas supply device, a control circuit 10, an arithmetic circuit 11 and a display circuit 13 is used. The sensor 21 is inserted into the sensor imposing section and after the device is started, the oxygen partial pressure value is calibrated by a standard gaseous mixture-1. The carbon dioxide partial pressure is further calibrated by the standard gaseous mixture-2 at need and thereafter, the test and calibration by the standard gaseous mixture-1 are executed in an initial unstable period and the test of the oxygen partial pressure by the air or the gas-1 is executed in a subsequent stable period. The gas-1 is changed over to the air or the gas-1 after the calibration by the gas-1 and the operation is returned to the startup after lapse of the prescribed period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved sensor calibration device for a transcutaneous oxygen / carbon dioxide partial pressure measuring device for transcutaneously measuring blood oxygen partial pressure and carbon dioxide partial pressure.

[0002]

2. Description of the Related Art Measuring the partial pressure of oxygen and the partial pressure of carbon dioxide in blood is a very important measurement item in clinical practice, and is particularly indispensable for respiratory management of premature babies and newborn babies. A method of diagnosing by measuring the transcutaneous oxygen partial pressure and carbon dioxide partial pressure in the peripheral circulation of the blood flow just under the skin by an electrochemical method by applying a sensor to the skin instead of collecting and measuring blood was embodied. Transcutaneous oxygen and carbon dioxide partial pressure measuring devices have been developed and used. In addition, in the heating power system in this measuring device, it is further confirmed that the amount of electric power supplied to keep the temperature of the sensor electrode portion constant, that is, the heating power is proportional to the circulation velocity of blood in the peripheral circulation. It can also be used to measure circulation speed.

In order to keep this device in a usable state at all times and obtain accurate and stable measurement data, a standard mixed gas-1 containing a large amount of oxygen (for example, 21% oxygen, 5 carbon dioxide).
%, The oxygen partial pressure due to the balance inert carrier gas, hereinafter simply referred to as gas-1) is, for example, 157 mmHg and carbon dioxide 25 mmHg, and the standard mixed gas with a high carbon dioxide content-2 (for example, 0% oxygen, 10 carbon dioxide). %, Residual inert carrier gas, hereinafter simply referred to as gas-2), is required to exhibit a carbon dioxide partial pressure of, for example, 50 mmHg. However, the sensor (electrode component part) that touches the skin of this device is minute and the structure is delicate, and each sensor has different characteristics, so not only the unstable period after the start of measurement but also continuous use (during monitoring) Also in (), the characteristics of individual sensors fluctuate, so it is necessary to repeat the calibration with the standard gas and hold it so as to show a sufficiently stable set value.

[0004]

Conventionally, as the calibration method,
The operator manually caused the two kinds of standard gases to flow on the surface of the sensor electrode, and at his own discretion, two-point calibration of the oxygen partial pressure and carbon dioxide partial pressure display values was performed at appropriate time intervals.
However, this calibration requires a great deal of skill and may take a considerable amount of time to stabilize, which has been a great burden on the operator and in terms of manpower for hospital nursing. As a method of improving this, automation of the calibration is attempted. For example, a method has been proposed in which two-point automatic calibration is continuously performed using each standard gas at regular intervals after the calibration at the start. It has the drawback of being time consuming.

As a characteristic of the sensor, the inventors found that the gas partial pressure value was unstable in the initial stage after calibration, but after that, many of them showed a stable state, and gas-1 had carbon dioxide. Gas is also included, and the fluctuation of the carbon dioxide partial pressure value is much slower than that of the oxygen partial pressure value.
If the oxygen partial pressure at the time of calibration is within the specified range, calibration with gas-2 consisting of carbon dioxide and carrier gas may be omitted again, and instead of gas-1 instead of gas-1 at the intermediate stage after stabilization. It has been found that oxygen partial pressure values can be detected by passing air through, which saves expensive standard gas. How to further omit gas-2,
Or in any case of using air as a substitute for gas-1 in the middle, especially in the unstable initial stage,
The present invention has been completed by finding that the time schedule of the switching requires precise stepwise control, and must rely on precise automatic control.

[0006]

According to the present invention, there is provided a transcutaneous oxygen and carbon dioxide partial pressure measuring device having a built-in sensor automatic calibration device; A sensor mounting portion including a sensor mounting chamber provided with a standard gas / air exhaust device and a sensor pressing plate; A standard mixed gas-1 cylinder, a standard mixed gas-2 cylinder, and a standard gas supply device for sending standard gas to the sensor mounting chamber, which comprises a solenoid valve,
C. A control circuit for controlling on / off of the calibration device and opening / closing control of the solenoid valve; An arithmetic circuit for receiving electric signals of the oxygen partial pressure value and the carbon dioxide partial pressure value of the sensor, performing a comparison operation with a standard set value, and instructing a gas supply to the control circuit if it is out of the allowable range, E.
An automatic calibration device for a transcutaneous oxygen / carbon dioxide partial pressure measuring device, characterized by comprising a display circuit for displaying a partial pressure value of each gas by an electric signal from the arithmetic circuit, and an automatic sensor using this device. A calibration method is provided.

The device of the present invention will be described with reference to the drawings. Figure 1
Is a system diagram of this device. Gas-1 cylinder 1, gas-
The second cylinder 2 communicates with the sensor chamber 6 of the sensor mounting portion 5 via the solenoid valve 3 and the solenoid valve 4, respectively. An upper edge portion of the sensor chamber 6 of the sensor mounting portion forms a horizontal frame corresponding to the bottom surface of the sensor, and horizontally mounts and holds the sensor 21. In addition to the standard gas inlet / outlet port, the sensor chamber is provided with an air passage hole 7, and air is introduced into the sensor chamber when the standard gas is not used. The sensor pressing plate 8 is interlocked with the microswitch 9 to rotate about one end edge as an axis, and the sensor is placed and pressed by the pressing plate 8, so that the control circuit 10 closes the electric circuit of the automatic calibration device and the calibration device. Will start.

The control circuit 10 interlocks with the sensor mounting portion to start and end the calibration device, and at the same time, opens and closes the solenoid valves 3 and 4 in response to a command from the arithmetic circuit 11 according to the calibration program to send standard gas to the sensor chamber. Turn on and off. The output electric signals of the oxygen partial pressure value and the carbon dioxide partial pressure value of the sensor 21 sandwiched and held in the sensor mounting portion are sent to the arithmetic circuit 11 via the amplifier 12, and the arithmetic circuit outputs the set value of each gas partial pressure and the set value. When the comparison calculation is performed and the value is out of the allowable range of the set value, the control circuit is instructed to feed the standard gas, and the automatic calibration is performed using the standard gas. The display circuit 13 displays the oxygen partial pressure value and the carbon dioxide partial pressure value over time.

Next, an automatic calibration method using this apparatus will be described. The automatic calibration program built into the device calibrates the oxygen partial pressure value by gas-1 and the two-point calibration of carbon dioxide partial pressure value by gas-2 in the initial period of sensor output instability at the beginning of calibration, and for a short time. Repeating the intervals, the working gas is set to gas-1, and after stabilizing the calibration gas partial pressure value, the working gas is switched to air, and the oxygen gas partial pressure value by air is verified. If it is outside the allowable range, gas-1
After the calibration, the working gas is air, and after the air is switched, a cycle is returned after a predetermined time to return to the calibration start point. The outline of the specific setting program is as follows.

Step 1. By mounting the sensor 21 horizontally on the sensor mounting portion and pressing it with the sensor pressing plate, calibration with gas-1 is started. Subsequently, the automatic two-point calibration in which the calibration with gas-2 is performed is started. Since the sensor is extremely unstable during this starting stage, this operation is repeated within a short time. Step 2. If the carbon dioxide partial pressure value is out of the allowable range in step 1, after performing calibration with gas-2, the working gas is switched to gas-1 and the check with gas-1 alone is automatically scheduled at short intervals. Repeatedly, if the oxygen partial pressure value is out of the allowable range, after the automatic calibration, the gas-2 is automatically checked, and if necessary, the calibration is performed. Step 3. After a lapse of a predetermined time from step 2 and the sensor output value stabilizes, the oxygen partial pressure value is checked. If the oxygen gas partial pressure value is within the allowable range, the working gas is switched to air and the process proceeds to step 4. Step 4. In step 3, if the oxygen partial pressure value is out of the allowable range, the working gas is switched to air after the calibration with gas-1, and the process proceeds to step 5. If it is within the permissible range, check with air is started. Step 5. After a certain period of time after switching to air, the sensitivity of the sensor stabilizes, and after the time when the sensor can be maintained in a state in which it can be used at any time, it is possible to periodically perform a long time interval (30 to 60 minutes). Oxygen partial pressure value is checked for the purpose of automatic check. This check is performed after switching the air to gas-1 each time, but if the oxygen partial pressure value is within the allowable range, the air is flowed again to replace the oxygen, the sensor is maintained, and the time comes according to the program. Repeat this work with. Step 6. If the oxygen gas partial pressure value is out of the allowable range in step 5, the gas-1 is calibrated, and after the gas-1 is automatically flowed for a while, it is checked and if calibration is necessary, after the calibration, the gas-2 is used. Perform calibration together and return to air operation. If no calibration is required, immediately return to air operation. Note that the sensor output value is often unstable during the initial period after the start of calibration, and the check of the oxygen partial pressure value in step 3 is repeated on a scheduled basis again at short time intervals such as 1 minute and the next 5 minutes. It is preferable.

It should be noted that the working gas in steps 3 to 6 above is not the air but is a standard mixed gas (gas
Of course, 1) may be used. Also in this case, the two-point check with gas-2 is omitted if the check with gas-1 is within the allowable range, and naturally contributes to economical maintenance operation.

[0012]

According to the present invention, the sensor chamber is provided with the air-conducting hole and the standard gas inlet / outlet line, so that the calibration is performed by the standard gas during the initial unstable period after the start of the calibration. Is checked by air, which was not done in the past, and then the standard gas returns to the calibration start process, so calibration is performed again with standard gas, and the sensor accuracy is not affected by the air check, and the sensor is used for a long time. It is possible to keep the state. Furthermore, the consumption of gas-1 and gas-2 can be reduced. In addition, the fact that the carbon dioxide partial pressure value fluctuates much more gently than the fluctuation of the oxygen partial pressure value is used, and if the carbon dioxide partial pressure value at the time of calibration with gas-1 is within the allowable range, The calibration by 2 can be omitted, the calibration process can be simplified, and the consumption of gas-2 can be saved. In a small mobile device such as a transcutaneous oxygen / carbon dioxide partial pressure measuring device, the volume ratio occupied by the gas cylinder cannot be large, and the gas consumption rate is important for nursing work in combination with the replacement frequency. Has a meaning. Since the sensor is held horizontally on the sensor chamber and held between the pressing plates, there is no risk of the sensor falling off the mounting portion and being damaged. Further interposition between the pressure plates initiates the sensor calibration process and requires no further action.

[0013]

According to the present invention, the starting operation of the automatic calibration is very simple, and the expensive standard mixed gas-1, gas-2 is used.
The consumption of the sensor can be greatly saved, and the sensor can be kept ready for immediate use for a long period of time. In fact, using the device of the present invention, the consumption of the standard mixed gas could be reduced to 1/2 to 1/4. Furthermore, there is no risk that the sensor will come off the sensor mounting portion and be damaged.

[Brief description of drawings]

FIG. 1 is a device system diagram of a sensor automatic calibration device according to the present invention.

[Explanation of symbols]

 1 Gas-1 cylinder 2 Gas-2 cylinder 3 Solenoid valve 4 Solenoid valve 6 Sensor chamber 7 Air passage hole 8 Sensor pressing plate 9 Micro switch 10 Control circuit 11 Arithmetic circuit 13 Display circuit 21 Sensor

Claims (5)

[Claims] 1. A transcutaneous oxygen and carbon dioxide partial pressure measuring device having a built-in sensor automatic calibration device; A sensor mounting portion including a sensor mounting chamber having a standard gas inlet / outlet port and a sensor pressing plate, B. A standard mixed gas-1 cylinder, a standard mixed gas-2 cylinder, and a standard mixed gas supply device for sending each standard mixed gas to the sensor mounting chamber, which includes a solenoid valve; A control circuit for controlling on / off of the calibration device and opening / closing control of the solenoid valve; An arithmetic circuit for receiving electric signals of the oxygen partial pressure value and the carbon dioxide partial pressure value of the sensor, performing a comparison operation with a standard set value, and instructing a gas supply to the control circuit if it is out of the allowable range, E. An automatic calibration device for a transcutaneous oxygen / carbon dioxide partial pressure measuring device sensor, comprising a display circuit for displaying a partial pressure value of each gas by an electric signal from the arithmetic circuit. 2. A transcutaneous oxygen and carbon dioxide partial pressure measuring device having a built-in sensor automatic calibration device; A sensor mounting portion including a sensor mounting chamber having a standard gas inlet / outlet port and an air communication hole and a sensor pressing plate; A standard mixed gas-1 cylinder, a standard mixed gas-2 cylinder, and a standard mixed gas supply device for sending each standard mixed gas to the sensor mounting chamber, which includes a solenoid valve; A control circuit for turning on and off the calibration device and for controlling the opening and closing of the solenoid valve;
D. An arithmetic circuit for receiving electric signals of the oxygen partial pressure value and the carbon dioxide partial pressure value of the sensor, performing a comparison operation with a standard set value, and instructing a gas supply to the control circuit if it is out of the allowable range, E. An automatic calibration device for a transcutaneous oxygen / carbon dioxide partial pressure measuring device sensor, comprising a display circuit for displaying a partial pressure value of each gas by an electric signal from the arithmetic circuit. 3. The sensor mounting portion is provided with a sensor mounting horizontal frame at an upper edge of the sensor chamber, the pressing plate is interlocked with a switch, and the sensor is sandwiched between the sensor chamber and the sensor pressing plate. The automatic calibration device for a transcutaneous oxygen / carbon dioxide partial pressure measuring device according to claim 1 or 2, wherein an electric circuit of the automatic calibration device is closed and operated. 4. The sensor automatic calibration device is used to calibrate the sensor partial pressure value with a standard mixed gas-1 and, if necessary, a standard mixed gas-2 during the unstable sensor output period at the beginning of calibration, and the working gas is then standardized. After calibrating as mixed gas-1 and stabilizing the oxygen partial pressure value, the working gas is switched to air, and the oxygen partial pressure value by air is tested.
A method for automatically calibrating a sensor for measuring a partial pressure of transcutaneous oxygen and carbon dioxide partial pressure, which is automatically controlled to return to the start time of calibration after a lapse of a predetermined time by using working gas as air after calibration with standard mixed gas-1. 5. The sensor automatic calibration device is used to calibrate the gas partial pressure value with a standard mixed gas-1 and, if necessary, a standard mixed gas-2 during the period when the sensor output is unstable at the beginning of calibration, and the working gas is then standardized. The mixed gas-1 is used, and after the oxygen partial pressure value is stabilized, the oxygen partial pressure value is verified. If the oxygen partial pressure value is out of the allowable range, the standard mixed gas-1 is calibrated to obtain the standard mixed gas-1.
A method for automatically calibrating a sensor of a transcutaneous oxygen / carbon dioxide partial pressure measuring device, characterized in that it is automatically controlled to return to the start of calibration after a predetermined time has passed.