JPS61280844A - Blood gas monitor - 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 [1] Technical field The present invention relates to the treatment of gases (
This invention relates to a monitoring device for partial pressure in extracorporeal circulating blood, which is useful for continuously measuring (monitoring) the partial pressure or concentration of oxygen, carbon dioxide, etc.). According to the present invention, since the blood flow path to the monitoring sensor is branched from the circulatory system, sterilization of the sensor can be omitted, and there is no fear of backflow of bacteria.

[2] Prior art and its problems Figure 2 shows a diagram of the extracorporeal circulation system of blood using an artificial heart-lung machine. After absorbing the heat generated by circulation in [28], the heart-lung machine [24] inhales oxygen and releases carbon dioxide gas, and then returns to the human body.Includes sensors such as blood gas partial pressure and pH monitors. The measurement unit [25] is located in the flow path between the heart-lung machine and the human body, and measurement data is recorded on the recorder [26].

In the above-mentioned extracorporeal blood circulation system, since the sensor is located in the flow path, it is necessary to sterilize it each time it is used. In order to omit this operation, as a means for continuous measurement without contacting the sensor (251) with the blood, a hollow system (252) having micropores of several lθ to several tens of OA is inserted between the sensor (251) and the blood. In this figure, another fluid is circulated using a pump (253, 1) to exchange blood gas at the membrane surface of the system, and a sensor (251) is positioned in the flow path of this second circulation system. It is.

When the phase of blood gas is transferred to the second fluid through the membrane wall of a hollow system, there is a disadvantage that it always takes time to reach an equilibrium state and the measurement becomes slow.

A constant temperature fluid (water) is supplied to the heat exchanger (23) from a constant temperature water tank (27), which is designed to keep the temperature of blood during extracorporeal circulation constant and stabilize the measurement. Although the temperature dependence of sensors made of the body (:251) is large, the gap between the temperature of circulating blood, which has a large heat capacity, and the temperature of the sensor, especially the electrode part, becomes large and affects the measurement. There are many. For example, in the measurement of oxygen partial pressure, even if the gas equilibrium state on both sides of the membrane wall in the hollow system (252) ζ is kept constant, the concentration gradient of oxygen reaching the electrode changes, so the reduction current value, i.e. There was a problem in that the oxygen partial pressure value varied even when the same electrode was used.

The present invention provides an improved continuous blood gas concentration measuring device that solves these problems.

[Means for solving 31 problems The configuration of the present invention is shown in FIG.

Blood that branches off from the extracorporeal circulation channel and passes through the sensor (51) is discarded without being returned to the extracorporeal circulation channel. In order to adjust the flow rate and prevent backflow, a liquid pump (2) is inserted into the blood gas monitor channel. This shortens the distance between the extracorporeal circulation flow path and the sensor, so it is better to insert it after the sensor if possible. Branch flow path to blood gas monitor (52
) is discarded, so keep the flow rate low. The material of the tube in the monitor channel is gas-impermeable to prevent gas exchange with the atmosphere. Also, a thin one is used to shorten the time it takes for blood to reach the sensor.

Also, since the sensor is easily affected by ambient temperature and blood temperature, it is kept warm in a constant temperature bath. Furthermore, the circuit just before the sensor also controls the temperature of the blood. Heat retention and temperature control are performed by circulating constant temperature water at a constant temperature.

[4] Effect Since there is no factor that disturbs blood flow for measurement, there is no effect of measurement on the patient. That is, the sensor is located in the branched blood gas monitor flow path (52), and the blood passing through this bus is discarded rather than returned to the extracorporeal circulation system, so there is no risk of bacteria backflowing. Furthermore, since the temperature of the sensor itself is not affected by the atmosphere or blood temperature, stable measurements can always be performed.

[5] Example: The circuit branching from the extracorporeal circulation channel is made of gas-impermeable tubes to prevent gas exchange with the atmosphere.In order to reduce the amount of waste blood, the blood flow rate is kept low, so the internal volume of the tube is must be small. The flow rate was adjusted using a liquid pump installed after the sensor.

Next, using the device of the present invention, a drawing loop from an extracorporeal circulation blood loop to a sensor during open heart surgery was branched, and Fog and PCOz were measured by the sensor. At the same time, blood was collected from the withdrawal loop and analyzed using a gas analyzer.

The results are shown in the table below.

The analysis results by the gas analyzer and the measurement results by the sensor are almost the same for both P(h and PC(h).

The blood flow rate was set to 50 ml/hr using the pump.
The total waste blood volume was approximately 180 ffl/.

The sensor and blood temperatures during the experiment could be kept below ±0.2°C. Retraction loop tube and inner diameter 1
By making the total length of allXJr 1 m, the measurement delay time could be kept to about 1 minute.

[63 Effects] According to the present invention, blood gases/pH etc. can be measured accurately and with good reproducibility using a branch flow path that does not affect extracorporeally circulating blood. Therefore, there is no need to sterilize the sensor, and even if a measurement problem occurs in a branch path, it is possible to continue measurement by resolving it on the spot.

Furthermore, a pump (53) for liquid feeding and flow rate adjustment is connected to a sensor (53).
By placing it after step 1), the amount of blood to be discarded can be kept within the allowable amount.

Since the circuit branch point and the sensor (51) can be connected with a small diameter tube, the shunted blood can quickly reach the sensor (51) and delay in measurement can be minimized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the extracorporeal blood circulation system of the present invention. FIG. 1 is a diagram showing a measuring section in the present invention. FIG. 2 is a diagram illustrating the prior art. 1.21: Human body 2.22: Circulation pump 23: Heat exchanger 3: Main loop 4.24: Artificial lung 5.25: Measuring section 26; Recorder 27: Thermostatic chamber 51.251: Sensor 52: Branch flow path 521: Teflon tube 522 Stainless steel sleeve 53253: Pump 54; Thermostatic chamber 55: Thermostatic water circulator 56: Sub-loop 57: Waste blood receptor A: Flow path branch point observation 1 [A] Fig. 1 [B

Claims (5)

[Claims] (1) To extract a blood sample into the circulation path (3) in a blood gas monitor that continuously measures the concentration of gaseous components such as oxygen and carbon dioxide contained in blood circulating extracorporeally via an artificial heart-lung machine. A branched flow path (52) is provided, a monitoring sensor (51) is positioned in this flow path so as to be in direct contact with blood, and the blood after measurement is passed through the branched flow path (52).
A blood gas monitor characterized in that the blood gas monitor is discarded from the end opposite to the branch point (A) of 2). (2) The monitoring sensor (51) consists of electrodes,
2. The blood gas monitor according to claim 1, further comprising temperature control means for keeping the ambient temperature of the sensor including the flow path immediately in front of the sensor constant. (3) Claims characterized in that at least a portion of the branched flow path (52) for blood sampling is made of a synthetic resin that does not permeate gas components contained in blood such as oxygen and carbon dioxide. Blood gas monitor according to paragraph 1. (4) A liquid feeding pump (53) is provided after the sensor (51) in the measurement unit (5) provided along the branched flow path (52) for blood sampling, and sampling flowing through the branched flow path (52) The blood gas monitor according to claims 1 and 3, wherein the blood gas monitor adjusts the flow rate of blood. (5) Blood gas according to claim 4, characterized in that the blood flow rate by the sample blood pump (53) is within a range of 200 ml/H or less, preferably not exceeding 50 ml/H. monitor.