JP2554082B2 - Arterial blood oxygen gas partial pressure measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an arterial blood oxygen gas partial pressure measuring device by real-time correction of percutaneous oxygen gas partial pressure.

[Conventional technology]

The oxygen gas partial pressure of the body, particularly arterial blood, contains information on metabolism and respiratory function, and plays an important role in short-term or long-term respiratory management of neonates and critically ill patients. Therefore, the method of non-invasively measuring the gas partial pressure of arterial blood from the body surface has been attracting attention as a powerful means for monitoring the respiratory circulatory dynamics of neonates and critically ill patients. In such a measurement, oxygen and carbon dioxide gas that permeate the skin from the body are measured, and the oxygen gas partial pressure and carbon dioxide gas partial pressure of arterial blood are estimated from this.

2. Description of the Related Art Conventionally, there is a method in which the partial pressure of oxygen or carbon dioxide in arterial blood is continuously measured percutaneously by an electrode method or medical mass spectrometry. this is,
The detection unit has a built-in heater and thermistor, and the temperature control circuit including them holds the set temperature at about 44 degrees Celsius. When the detector is attached to the skin in this manner, the skin below the skin is heated, blood flow increases to the vicinity of the epidermis, the gas permeability of the skin increases, and the arterial blood gas partial pressure can be measured. Here, the arterial blood gas is diffused through the skin tissue and the polymer gas permeable film stretched on the bottom surface of the detection unit, introduced into the detection unit, and guided to the electrode or the gravimetric analyzer for analysis.

FIG. 5 is a diagram showing a gas diffusion model in transcutaneous oxygen gas partial pressure measurement.

In FIG. 5, the vertical axis is the oxygen partial pressure, A is the detection part side, and B and C are the tissue side. In particular, C is a tissue which is supplied with sufficient blood and holds the arterial oxygen gas partial pressure Pa, B
Is a skin tissue with no blood supply, and A is a gas permeable membrane stretched over the detection part. The transcutaneous oxygen gas partial pressure tcPo ₂ is measured by the inflow amount J of oxygen molecules that permeate the membrane and flow into the detection section. The inflow amount of oxygen molecules into the detection part is regulated by the oxygen gas diffusion resistance Rt in the skin and the membrane diffusion resistance Rm. Therefore, the oxygen molecules that enter the detector are
Since the oxygen gas is immediately consumed for measurement, the oxygen gas partial pressure in the detector is always zero. That is, since the inflowing oxygen amount J is proportional to the oxygen gas partial pressure value at the contact surface between the membrane and the skin surface, the transcutaneous oxygen gas partial pressure tcPo ₂ measured by J is the oxygen gas at the contact surface. It becomes partial pressure. Conventional method is intended to be tend to bring said oxygen partial pressure at the contact surfaces as possible to the arterial oxygen partial pressure, transcutaneous oxygen partial pressure TCPO ₂ by performing a predetermined warming to its
From this, the arterial blood oxygen gas partial pressure is estimated.

[Problems to be solved by the invention]

As described above, in the conventional method of percutaneously measuring the partial pressure of oxygen gas in arterial blood, it is indispensable to heat the skin at about 44 degrees Celsius, and the heated detection unit heats the skin.

However, such a device is generally used on a patient as a long-term clinical monitor. However, if you heat the skin to about 44 degrees Celsius and wear it on the same place for a long time, there is a risk of low temperature burns, and there is a problem that eczema appears and inflammation occurs due to sweating during hot weather. . Therefore, it had to be moved frequently, which was extremely inconvenient.

The present invention is to solve the above problems, and percutaneously arterial blood under the condition of slight heating or no heating without fear of low temperature burn while calculating oxygen gas diffusion resistance of skin tissue. It is an object of the present invention to provide an arterial blood oxygen gas partial pressure measuring device capable of accurately measuring oxygen gas partial pressure in real time.

[Means for solving problems]

To this end, the present invention provides a detection unit that integrates two detection units having a membrane system with different oxygen gas diffusion resistances as an arterial oxygen gas partial pressure measuring device, and detects the oxygen gas amount of the arterial blood from the oxygen gas amount detected by the detection unit. A data processing means for determining a partial pressure is provided, and the data processing means is characterized in that the drop value of the partial pressure of oxygen gas caused by the metabolism of each diffusion resistance blood and the skin tissue of the membrane system is inputted in advance. .

[Action]

In the arterial blood oxygen gas partial pressure measuring device of the present invention, the oxygen gas amount is measured by the two detection units having the membrane systems having different oxygen gas diffusion resistances, and the oxygen produced by the diffusion resistance values of the membrane system and the metabolism of the skin tissue. Since the oxygen gas diffusion resistance of the skin tissue is calculated using the drop value of the gas partial pressure to determine the arterial oxygen gas partial pressure, it is possible to determine the arterial oxygen gas partial pressure without estimating it from the percutaneous oxygen gas partial pressure. it can. Therefore, the oxygen gas partial pressure in arterial blood can be measured with high accuracy without particularly heating the skin.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of an arterial blood oxygen gas partial pressure measuring device of the present invention, FIG. 2 is a diagram showing a configuration example of a detection unit, and FIG. 3 is a comparative example of oxygen gas permeation coefficient. FIG. 4 and FIG. 4 are views showing the correlation with the skin temperature due to skin heating.

In FIG. 1, 1 is a detector, 2 is a 2-channel oxygen gas partial pressure meter, 3 is an ADC (analog-digital converter), 4 is a microprocessor, 5 is a CRT, 6 is a recorder, and 7 is a floppy disk. The detection unit 1 is, for example, an integrated unit of two detection units having a membrane system having different oxygen gas diffusion resistances, and is composed of two detection units having two types of membranes as shown in FIG. Wear it on the skin and measure the amounts of oxygen gas J ₁ , J ₂ flowing into the detector. The microprocessor 4 attaches the detection unit 1 to the skin and calculates the oxygen gas permeability coefficient 1 / Rt of the skin tissue from the oxygen gas amounts J ₁ and J ₂ alternately measured by the medical mass spectrometer, and the oxygen gas partial pressure is calculated. The CRT 5, the recorder 6 and the floppy disk 7 output the data.

The arterial blood oxygen gas partial pressure measuring method of the present invention integrates two detecting parts having two types of membrane systems having different oxygen gas diffusion resistances as described above and is attached to the skin to determine the oxygen gas partial pressure values. The arterial oxygen gas partial pressure Pa is measured by measuring the difference, and the principle thereof will be described next.

First, assuming that the diffusion resistance values of the two types of membrane systems are Rm ₁ and Rm ₂ , the oxygen gas amounts J ₁ and J flowing into the respective detection parts.
₂ is Is given. Here, −ΔPt represents a decrease in oxygen gas partial pressure caused by the metabolism of skin tissue. From both equations, the tissue diffusion resistance is And is determined by the ratio of the inflowing gas amount and the diffusion resistance of the membrane system.

When the diffusion resistance Rt of the skin tissue is given in this manner, the arterial oxygen gas partial pressure Pa is calculated by the following equation (1) or equation (2).

Pa = J ₁ (Rm ₁ + Rt) + ΔPt (4) Here, it can be considered that there is generally no large change in the partial pressure drop ΔPt of the oxygen gas, so a fixed value should be set in advance. It is possible. Therefore, the oxygen gas partial pressure drop ΔP
Since t and the diffusion resistance values Rm ₁ and Rm ₂ of the membrane system are known values, these values are set in advance and used for calculation in the microprocessor 4.

The oxygen gas permeation coefficient 1 / Rt of the skin tissue calculated by measuring the oxygen gas amounts J ₁ and J ₂ flowing into the detection portion by the arterial blood oxygen gas partial pressure measurement method of the present invention was compared with the literature reported values. Is FIG. 3. Although there is no suitable measuring method in the past, it is difficult to compare because of large variations, but according to the arterial blood oxygen gas partial pressure measuring method of the present invention, it is clear from the correlation with the skin temperature by the skin heating in FIG. So reliable measurements can be obtained.

The present invention is not limited to the above embodiment, and various modifications can be made.

〔The invention's effect〕

As is clear from the above description, according to the present invention, the transcutaneous oxygen gas partial pressure tcPo ₂ obtained by low skin heating can be accurately corrected by using Rt that can be calculated using two detection units. Since the arterial blood oxygen gas partial pressure Pa is calculated, the high skin heating of about 44 degrees Celsius which is required to bring the conventional transdermal oxygen gas partial pressure tcPo ₂ close to the arterial oxygen gas partial pressure Pa is unnecessary. , There is no danger of low temperature burns.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of an arterial blood oxygen gas partial pressure measuring device of the present invention, FIG. 2 is a diagram showing a configuration example of a detection unit, and FIG. 3 is a comparative example of oxygen gas permeation coefficient. Shown, 4th
FIG. 5 is a diagram showing the correlation of skin temperature due to skin heating, and FIG. 5 is a diagram showing a gas diffusion model in the measurement of transcutaneous oxygen gas partial pressure. 1 ... Detector, 2 ... 2-channel oxygen gas partial pressure meter, 3
...... ADC (analog-digital converter), 4 ...
… Microprocessor, 5 …… CRT, 6 …… Recorder, 7
……floppy disk.

Claims (1)

(57) [Claims] 1. A detection means which integrates two detection parts having membrane systems having different oxygen gas diffusion resistances, and a data processing means for obtaining an arterial oxygen gas partial pressure from the amount of oxygen gas detected by the detection means. The arterial blood oxygen gas partial pressure measuring device is characterized in that the data processing means is preliminarily input with each diffusion resistance value of the membrane system and the decrease value of the oxygen gas partial pressure generated by the metabolism of the skin tissue.