JPH0519074Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to an ultrafiltration rate measuring cylinder used in a device for measuring the amount of water removed in hemodialysis.

B. Prior art In hemodialysis, knowing the ultrafiltration rate of a dialyzer is extremely important in managing the amount of water removed during dialysis, but the ultrafiltration rate is determined by the membrane area, membrane pressure, and membrane area of the dialyzer. Differences in the characteristics of each dialyzer, differences in the blood composition of each person and changes over time in the blood composition, effects of temperature conditions on dialyzer efficiency, blood flow rate, etc. Therefore, various filtration rate measuring devices are installed in the dialysate side circuit to measure the ultrafiltration rate at any time during dialysis.

C. Problems to be solved by the invention However, since the dialysate side circuit of the above-mentioned hemodialysis circuit, especially the downstream of the dialyzer, contains various metabolic substances dialyzed from the blood, the inner wall of the measuring section contains the metabolic substances. It has been difficult to accurately measure the amount of ultrafiltration due to problems such as fluctuations in the measured capacity due to the adhesion of particles and clogging of the thin tube section.

The total amount of water removed during dialysis is 3 to 5 times the dialysis treatment time.
The amount of water removed is usually 500 ml to 3000 ml per hour, but considering the physiological effects on the patient at that time, it is desirable that the error in the amount of water removed be within 100 ml.

Therefore, the amount of water removed needs to be detected by measuring the increase in the amount of reflux fluid of the dialysate at 500 ml/mm.

In other words, the accuracy of the error of 100 ml for the total volume of refluxed liquid of 90,000 ml to 150,000 ml is 1/900 to 1/1500 (0.1% to
0.07%), and in this method, the ultrafiltration rate is periodically verified in a short period of time during dialysis, and the ultrafiltration pressure is corrected using the signal to obtain the target water removal rate. As can be seen in the structure, there was a need for a material shape and structure that would cause less measurement errors due to the adhesion of metabolites in actual clinical practice and less damage to the space and structure due to chemical disinfection of the body fluid circuit.

The present invention has been made in view of the above problems, and provides an ultrafiltration rate measurement cylinder that makes it possible to easily and highly accurately measure the ultrafiltration rate in a hemodialysis circuit. The purpose of this project is to enable accurate water removal management.

D. Means for solving the problem The ultrafiltration rate measurement cylinder of the present invention has a structure that eliminates measurement errors caused by the adhesion of metabolites, etc. in the dialysate to the inner wall of the meter, and calculates the capacity as a relative value. In addition to having a structure in which detection is performed depending on the variable of , the detection section and the measurement section are mechanically separated to eliminate the influence of the fluid to be measured on the detection section.

That is, in the dialysate circuit of a hemodialysis machine, the ultrafiltration measurement cylinder of the present invention has a dialysate outlet side flow path separated by a flexible compartment material such as a diaphragm on one side of the cylinder. A communicating volume measuring chamber is configured, and a flexible portion of the volume measuring chamber is airtightly connected to a columnar piston inserted from the other side of the cylinder so as to be able to move in and out in an airtight manner via a non-transpiration fluid. This detects a relative change in the capacity of the capacity measuring chamber based on the amount of change in the protruding and retracting position of the piston.

Further, the amount of change in the protruding and retracting position of the piston can be replaced with a rotation angle (number) by an encoder or the like via a drive coupling mechanism as appropriate, and can be electrically detected by various means such as performing calculations.

E. Effect According to the ultrafiltration amount measuring cylinder described above, the piston is moved back from the cylinder in accordance with the increase in the amount of the fluid to be measured introduced into the volume measuring chamber (pressure is detected in measurement), thereby reducing the amount of ultrafiltration. A flexible chamber material such as a diaphragm is deformed via the transpiration fluid to expand the volumetric chamber.

Therefore, from the product of the amount of movement (length) of the piston and the cross-sectional area of the piston, the volume increase in the volume measuring chamber per measurement time is measured, and it depends on the volume increase value and time. The filtration rate (ultrafiltration rate) of the dialyzer can be measured.

Furthermore, since the volume measuring chamber forcibly controls the advance and retreat of the piston in response to the increase in volume, no elastic force is applied by a flexible chamber material such as a diaphragm, so that air bubbles in the fluid to be measured do not expand or contract, causing errors in the detection value.

F. Example Hereinafter, an example of the ultrafiltration rate measuring cylinder of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a cylinder body consisting of an upper member 2 and a lower member 3, with a flexible diaphragm 4 airtightly interposed between the upper member 2 and the lower member 3, and a volume measuring chamber 5 and a sealed fluid chamber. 6, and two ports 7 and 8 are opened in the volume measuring chamber 5 to communicate with the dialysis circuit.

Further, a columnar piston 10 having a constant cross-sectional area over its entire length is inserted airtightly and slidably from the lower end of the lower member 3 through the seal member 9, and the non-transpiration fluid 11 is inserted into the sealed fluid chamber 6. Along with filling the
A spline wheel 1 continuous to the piston 10
2 is mounted on a spline wheel bearing 13 to prevent rotation, and a threaded shaft portion 14 is formed at the end of the spline wheel 12.

A female screw 16 is screwed into the shaft core of the threaded shaft portion 14, and a gear 15 whose sliding in the axial direction is restricted is screwed into the threaded shaft portion 14, and serves as an input/output shaft 18 of a rotation control drive device 17 such as a pulse motor or an encoder. It is formed by meshing with a gear 19 provided on the shaft.

The ultrafiltration measurement cylinder having the above configuration is installed between the discharge side of dialyzer A and valve B2 in the dialysate side circuit of dialyzer A installed in the hemodialysis circuit, as shown in the measurement principle explanatory diagram in Figure 2. Provided via ports 7 and 8,
Dialyzer A and valve B provided upstream of dialyzer A
1, and a hydraulic pressure gauge P2 is interposed between the dialyzer A and the cylinder for measuring the amount of ultrafiltration.

When both valves B1 and B2 are closed during dialysis, the hydraulic pressure values of both hydraulic pressure gauges P1 and P2 increase due to an increase in the amount of water removed from the blood side by the dialysis membrane a of dialyzer A. The fluctuation is detected by the central control mechanism 20, and the rotation control drive device 17 is driven to rotate so that the change becomes the same as the initial value.

That is, when the rotation control drive device 17 is rotated, 2
The shaft part 1 stop and the female screw 1 are connected through the gears 19 and 15.
Due to the screwing action of 6, the piston 10 closes in the sealed fluid chamber 6.
The diaphragm 4 is deformed via the non-transpiration fluid 11, and the volume measuring chamber 5 is expanded or contracted.

Therefore, when the piston 10 is driven so as to maintain the initial values of the hydraulic pressure gauges P1 and P2, the variable of the volume measuring chamber 5 per time, that is, the ultrafiltration amount, is the product of the cross-sectional area of the piston 10 and the moving length. The amount of movement of the piston 10 can be measured depending on the rotation angle (number) of the rotation control drive device 17.

Further, according to the above configuration, even if metabolic substances or the like adhere to the inner wall of the volume measuring chamber 5 or the diaphragm 4, the measured value is not affected at all, and the diaphragm 4 is forcibly deformed. Since the fluid pressure value is controlled constant, it is possible to measure the contained air bubbles without changing their volume. Therefore, measurement errors caused by these external factors can be eliminated and ultrafiltration amount can be measured with high accuracy. It is something that can be done.

Next, the ultrafiltration amount measurement cylinder 5 configured as described above is
Regarding a specific usage example of 0, its dialysis circuit will be explained with reference to FIG.

Reference numeral 51 denotes a dialyzer in which a blood side circuit and a dialysate side circuit 53 are separated via a dialysis membrane 51a, and the blood side circuit 52 includes a blood pump 55 on the upstream side of an artery side flow path 54 and a blood pump 55 on the downstream side of the artery side flow path 54. Air bubble separation trap 5
6 is disposed, and an arterial blood fluid pressure sensor P3 is provided for the bubble separation trap 56, and a filtration pressure regulating throttle valve 58 is provided in the venous flow path 57.

Further, the dialysate side circuit 53 is provided with shutoff valves V1 and V2 at each end of the inlet passage 59 and the outlet passage 60, and a bypass flow having one shutoff valve V3 is provided outside the shutoff valves V1 and V2. The shutoff valve V3 of the bypass flow path 61 is operated in the opposite direction to the other shutoff valves V1 and V2 to perform flow path switching, and the outlet path 60 side and the inlet path of the dialyzer 51 are communicated with each other through the passage 61. Hydraulic pressure sensors P1 and P2 are provided on the 59 side, respectively, and the ultrafiltration rate measuring cylinder 50 of the present invention is further interposed downstream of the hydraulic pressure sensor P2, and a venous pressure interlocking element is provided at the outlet 60 end. 71.

G. Effects of the invention As stated above, the ultrafiltration rate measurement cylinder of the present invention can accurately measure the relative amount of liquid, making it possible to control the amount of water removed in hemodialysis with high precision. Therefore, the practical effects of this invention are extremely large.

[Brief explanation of the drawing]

The drawings show an embodiment of the ultrafiltration measurement cylinder of the present invention, and FIG.
FIG. 2 is a circuit diagram showing a measurement principle in a dialysis circuit, and FIG. 3 is a circuit diagram showing an example of use in a dialysis circuit. 1...Cylinder body, 4...Diaphragm, 5
... Capacity measuring chamber, 6 ... Sealed fluid chamber, 7, 8 ...
Port, 10... Piston, 11... Non-transpiration fluid, 17... Rotation control drive device, 20... Central control mechanism, A... Dialyzer.

Claims (1)

[Scope of utility model registration request] The actual filtration rate at the low ultrafiltration pressure of the dialyzer is measured, a virtual ultrafiltration characteristic straight line passing through the base point is calculated using the actual filtration rate as a base point, and the desired filtration rate is calculated using the virtual ultrafiltration characteristic straight line. Start initial dialysis by determining the ultrafiltration pressure to be applied to the dialyzer corresponding to , while controlling and driving the ultrafiltration measurement cylinder provided downstream of the dialyzer to maintain the average dialysate pressure immediately before measurement, at the measurement time specified by the ultrafiltration measurement cylinder. Weigh the amount of ultrafiltration
A modified ultrafiltration characteristic straight line passing through the base point is calculated from the ultrafiltration amount, and an ultrafiltration pressure corresponding to a desired filtration rate is determined from the modified ultrafiltration characteristic straight line. By integrating the filtration rate and the elapsed time, the amount of water removed in the measurement section is obtained, and after the elapse of time in the measurement section, the ultrafiltration characteristic straight line is corrected again by the same means as the above-mentioned means to calculate the amount of water removed in the measurement section in sequence. In a hemodialysis circuit that obtains the amount of water removed and obtains a predetermined total amount of water removed depending on the sum of the amounts of water removed in each measurement section, one side of the cylinder is isolated via a flexible compartment material such as a diaphragm. A volume measuring chamber is configured which communicates with the dialysate outlet side flow path, and a columnar piston inserted into the flexible part of the volume measuring chamber and the other side of the cylinder airtightly and retractably is inserted through a non-transpiration fluid. A cylinder for ultrafiltration measurement, characterized in that the cylinder is airtightly connected to the piston, and detects a relative change in the volume of the capacity measuring chamber based on a change in the protrusion/retraction position of the piston.