JPS6315856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blood flow measuring device that easily measures the blood flow in an extracorporeal blood circulation circuit in an artificial kidney, an artificial lung, or the like.

BACKGROUND ART Currently, in artificial kidneys, artificial lungs, and the like, roller-type straining pumps that squeeze blood tubes are mainly used as means for circulating a patient's blood outside the body. The blood flow rate in this case is determined and displayed by the blood tube used and the rotation speed of the roller, but the blood flow rate displayed in this way depends on the blood circuit pressure, the tightness of the roller, It is unavoidable that errors occur due to factors such as variations in tube inner diameter that occur during manufacturing and changes in blood tube hardness due to changes in room temperature. Therefore, in order to accurately determine the blood flow rate, it is necessary to collect the blood in a measuring cylinder and measure it each time, or to use a means such as an electromagnetic flowmeter. However, it is complicated and practically impossible to pour blood each time and measure it using a graduated cylinder, etc. If physiological saline or the like is used instead of blood, the viscosity, temperature, etc. will differ, so there may be errors. arise. Further, electromagnetic flowmeters require time to set up, are complicated and expensive, and are not commonly used in clinical practice.

Therefore, as a result of extensive research, the inventors have determined that the blood flow rate can be easily determined by connecting and fixing a syringe to the end of the branch circuit of the extracorporeal blood circulation circuit and measuring the amount of movement of the piston of the syringe per unit time. We found that it is possible to measure

Therefore, an object of the present invention is to provide a branch circuit in the middle of a main conduit in an extracorporeal blood circulation circuit, connect and fix a syringe to the end of the branch circuit, and make it possible to switch blood flow between the main conduit and the branch circuit. A blood flow measuring device for an extracorporeal blood circulation circuit is provided with a clamping mechanism, the blood flow in the main tube is made to flow into a branch circuit, and the blood flow is measured by the amount of movement of a piston of a syringe per unit time. It is about providing.

In the blood flow measuring device described above, the piston of the syringe for measuring blood volume is set at least two positions.
It can be configured to include a measuring circuit that detects the blood flow rate at the location and inputs the moving length and required time of the piston into the calculating circuit using electric signals to calculate and display the blood flow rate.

Next, embodiments of the blood flow rate measuring device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a blood flow measurement circuit according to the present invention. FIG. 2 shows a block diagram of the invention.

During normal operation, the branch conduit 2 side is closed by the clamper 5, and the main conduit 4 side is opened, and blood guided outside the body by the blood pump 9 flows through the main conduit 4. When switching to the flow rate measurement mode (FIG. 1 shows this state), the clamper 5 operates to open the branch conduit 2 and close the main conduit 4, and the blood flows from the branch conduit 2 to the sterilization filter 10, It flows into the syringe 3 via the connector 11. When blood flows into the syringe 3, the piston 6
moves at a speed proportional to blood flow. Therefore, by measuring the moving speed of this piston, the blood flow rate can be determined. The moving speed of the piston can be obtained by placing position detectors at positions separated by a certain distance and counting the time from when the first detector 7 operates to when the second detector 8 operates. . In order to convert the moving speed of the piston into a blood flow rate, it is necessary to take the reciprocal of time and multiply it by an appropriate coefficient, but this operation is performed by the calculation circuit 13. The required coefficient value is
It can be determined experimentally using a syringe with the same shape as the syringe being used, and once set, there is no need to adjust it thereafter.

Note that at the time the second detector 8 operates,
A signal from the control circuit 12 causes the calculation circuit 13 to stop the counting operation, and the display circuit 14 displays the flow rate.
At the same time, the clamper 5 closes the branch conduit 2,
The main pipe 4 is opened to return to normal operation. At this time, blood remains in the syringe, but if the power to the clamper 5 is cut off, the clamper 5 becomes neutral and both the main conduit 4 and the branch conduit 2 become open, so by pushing the piston 6, the remaining blood is drained into the main conduit 4. It can be returned.

As described above, according to the present invention, the extracorporeal circulating blood flow rate can be measured very easily.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a blood flow measuring circuit according to the present invention. FIG. 2 shows a block diagram of the invention. DESCRIPTION OF SYMBOLS 1, 4... Main conduit, 2... Branch conduit, 3... Syringe, 5... Clamper, 12... Control circuit, 13... Calculation circuit, 14... Display.

Claims (1)

[Claims] 1. In an extracorporeal blood circulation circuit, a branch circuit is provided in the middle of the main conduit, a syringe is connected and fixed to the end of the branch circuit, and the blood flow can be switched between the main conduit and the branch circuit, and the main conduit and the branch conduit are connected together. A clamp mechanism configured to open the circuit is provided, and the length of movement of the piston of the syringe when the blood flow from the main tube flows into the branch circuit is detected by detectors installed at at least two locations, and the length of movement of the syringe piston is detected by electrical signals. 1. A blood flow measuring device for an extracorporeal blood circulation circuit, comprising a measuring circuit that calculates and displays the blood flow rate by inputting the moving length of the piston and the required time into a calculation circuit.