JPS6315860B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for draining body fluid in an artificial kidney having a limited initial flow rate, such as an ultrafiltration type artificial kidney.

The limited-pass artificial kidney uses so-called hemodiafiltration (HDF).
There are two methods: the Hemofiltration (abbreviated as HF) method and the Hemofiltration (HF) method.
Hollow Fiber for the latter
There are two types: type and screen filter type.
In order to demonstrate its function in the HF method, 60
An excess of ml/min or more is required. Factors that determine excess include blood protein concentration, pressure drop, shear rate (γ), membrane overcapacity, and overlayer thickness, but protein concentration is determined by the type and nature of the fluid being passed through. Further, since the thickness of the overlayer is affected by the structure and pressure loss of the overlayer, it is impossible to make a major change.

For this reason, in the conventional HF method, in order to obtain a predetermined overdose, we focus on pressure drop among the overdose determining factors, and apply high positive pressure to the blood side, but also apply high negative pressure to the liquid side to increase the pressure drop. There is. However, this method applies high pressure as a transmembrane pressure, so if the blood flow rate is low (e.g.
200 to 100 ml/min), the blood is strongly pressed against the membrane surface, leading to more damage to blood cells (hemolysis), and the shear rate (γ〓) is too small to prevent sufficient overflow. For this reason, some HF systems connect two devices in order to obtain a predetermined excess amount, but in this case there is a problem that the device becomes larger.

On the other hand, the screen filter type also has the same problem because the shear rate γ〓) is small. For example, when the blood flow rate Q _B is 200 ml/min,
Even if the membrane area is large, it will only be 60 to 70ml/
min, and if the blood flow rate is low, the required amount cannot be obtained at all.

Moreover, when increasing only the pressure drop and taking a large amount, in addition to the above-mentioned problem of hemolysis, there is a drawback that concentration polarization due to proteins and the like and clogging of the hypermembrane occur quickly. method, it is extremely difficult to obtain a predetermined overdosage.

Therefore, the inventor focused on the shear rate γ〓) among the overload determining factors, and considered increasing the overload by increasing this. In order to increase the shear rate, it is sufficient to increase the blood flow rate, but as a practical matter, it is not possible to increase the blood flow rate from within the body.

The present invention was made in view of the above circumstances, and its purpose is to increase the shearing rate by increasing the blood flow rate flowing to the hypervascular organ even if the blood flow rate from the body is low, thereby achieving a predetermined shear rate. The present invention provides a method for filtrating body fluids such as blood that can obtain an excess amount, and a body fluid filtration device used to carry out the method.

That is, in the present invention, a filtration membrane is connected to a filter having a pore diameter of 10 to 500 Å (1,000 to 1,000,000 in terms of molecular weight cutoff), and a blood inflow pipe, a blood outflow pipe, and a filtrate discharge pipe are connected to each other, and a filtrate discharge pipe is provided in the middle of the blood outflow pipe. A replacement fluid inlet tube is connected to which an amount of replacement fluid corresponding to the amount of filtrate removed from the tube flows in, and a blood inlet of the blood re-inflow tube is connected to a pipe between the filter of the blood outflow tube and the replacement fluid injection tube. The outlet of the re-inflow tube is connected to the blood inflow tube, so that a part of the blood in the blood outflow tube flows into the blood inflow tube, and the flow rate of blood re-inflowing into the filter is set to 150 to 250 ml/mi.
The blood filtration device is characterized in that it has a pump means indicated by n in the middle of the blood re-inflow pipe.

An example in which the present invention is applied to an ultra-pass artificial kidney will be described below.

Here, the ultrafiltration type artificial kidney has a membrane of 10
~500 Å (1000 to 1000000 in molecular weight cutoff), preferably 30 to 100 Å (15000 to 15000 in molecular weight cutoff)
500,000).

First, to explain the HF type ultraviolet artificial kidney shown in Fig. 1, this one has a blood inflow pipe 2 attached to the upper end of the HF type ultrafilter 1, and this is attached to the artery side of the human body M. , and attach a blood outflow pipe 3 to the lower end and connect it to the venous side of the human body M,
Further, a liquid discharge pipe 4 is connected to the side surface thereof. The blood inflow pipe 2 is provided with a blood pump 5 for causing blood to flow into the filtration vessel 1.
Further, the blood outflow pipe 3 is provided with a pressure regulating valve 6 for regulating the pressure inside the blood vessel, and is further connected to a replacement fluid injection pipe 7. This replacement fluid injection tube 7 allows a replacement fluid amount corresponding to the amount of fluid removed from the fluid discharge tube 4 to flow into the blood outflow tube 3 to return blood into the human body M.

A blood re-inflow pipe 8 is connected between the blood inflow pipe 2 and the blood outflow pipe 3. This blood re-inflow pipe 8 has its inlet end connected between the pressure control valve 6 of the blood outflow pipe 3 and the connecting portion of the replacement fluid injection pipe 7, and its outlet end connected to the blood pump 5 of the blood inflow pipe 2. It is connected between the filter 1 inlet and the filter 1 inlet. This blood re-inflow pipe 8 is provided with closing means 9, 9 for closing the flow path at its inlet end and outlet end, respectively, and further has a blood pump 11 for flowing blood in the direction of the blood inflow pipe 8.
has been established. In addition, 10 in the figure is an air chamber provided in the blood inflow pipe 2 and the blood outflow pipe 3.

In the apparatus thus constructed, blood is evaporated in the following manner. When blood flows into the ultrafilter 1 through the blood inlet tube 2, the liquid is filtered there and discharged through the liquid outlet tube 4.
The blood from which the fluid has been removed passes through the blood outflow pipe 3, a part of which passes through the blood re-inflow pipe 8, and the rest is returned into the body with replacement fluid added. The blood passing through the blood re-inflow tube 8 is re-introduced into the ultrafilter 1 through the blood inflow tube 2 by a blood pump 11 . Here, the limiter 1
The higher the flow rate of blood that re-inflows, the higher the shear rate will be, but if it is too large, the problem of destruction of blood cells by the blood pump 11 will occur, and the excess flow will become saturated, so it is set at 150 to 250 ml/min. In other words, by setting the blood re-inflow volume within the above range, it is ensured that 60ml/
It is possible to obtain a filtration amount of min or more, and also prevent damage to blood cells. This became clear through experiments conducted by the inventor. The experimental method and results will be described below. Using the filtration device shown in Figure 1, adjust the blood flow rate of the blood pump.
Set the blood reflow volume to 200ml, and set the blood reflow volume from the blood reflow tube to the filter to 100, 150, 200, respectively.
Blood was circulated for 30 minutes as 250, 300, and 400 ml. After this, the obtained blood was taken during the 25 c.c. test period, centrifuged at 3000 rpm for 10 minutes, and the color tone of the supernatant liquid was visually examined. If a red color was observed, it was determined that destruction of blood cells had occurred. did. The results are shown in the table below.

Amount of blood re-inflow Destruction of blood cells (ml/min) Book 1 150 No occurrence 2 200 Unknown 3 250 Unparalleled 1 100 Yes 2 300 Yes 3 400 Yes From the above experimental results, the amount of blood that re-enters the filter can be determined. By limiting it to 150-250ml/min,
It is recognized that destruction of blood cell components is less likely to occur in the blood after filtration. This is because if the reflowing blood flow rate is too small, the blood cells are attracted to the filtration membrane excessively, causing destruction of the blood cell components, while if the reflowing blood cell components are large, the shear rate becomes high, but It is thought that destruction of blood cells by the blood pump occurs.

According to this method, the flow rate of blood flowing through the ultrafilter 1 can be increased regardless of the flow rate flowing from the body, thereby increasing the shear rate and improving the overefficiency. Note that the re-inflowing blood has a high viscosity because it is blood that has passed through the blood, and when this blood is put into the ultrafilter 1 together with the blood from the body, the viscosity of the entire blood flowing into the ultrafilter 1 increases. Although this has an adverse effect on overefficiency, the increase in overefficiency due to an increase in flow rate is more remarkable than this, and as a result, the amount of liquid can be increased.

Note that the closing means 9 is designed to open the flow path during normal operation, but is appropriately closed during priming or at the end of operation to suit these operations. Also, the air chamber 10 is not necessarily required depending on its structure.

The apparatus of the present invention is not limited to the one shown in FIG. 1, but may be the one shown in FIG. 2 or 3.

The one shown in FIG. 2 is a screen-type ultrafiltration artificial kidney, in which a blood inflow pipe 2, a blood outflow pipe 3, and a liquid discharge pipe 4 are attached to an ultrafiltration device 21. Blood re-inflow tube 8 between
are connected. The blood pumps 5, 11, pressure control valve 6, etc. are the same as those shown in FIG.

The device shown in FIG. 3 is the same as that shown in FIG. 1, but the blood inflow pipe 2 and the blood outflow pipe 3 are partially overlapped and a double roller pump 22 is provided there. According to some sources, only one pump is needed.

Next, in the screen-type ultra-pass artificial kidney shown in Fig. 2, we investigated the relationship between the amount of blood re-inflowing from the blood re-inflow tube and the blood overflow.
The results are shown in FIG. In this case, curve a has a blood Q _B of 200 ml/min and a hemacritt value (Ht) of 20 20
(Ht approximately 50 was diluted with physiological saline to obtain Ht20), the pressure on the liquid side was -600 mmHg, the material of the artificial kidney filter was aromatic polyamide, the effective membrane area was 0.3 M ² , and the blood layer thickness was Approximately 60μ, molecular weight cutoff 30000
The case is shown below. Also, curve b is the blood
Q _B 150ml/min, Ht20%, liquid side -600mmHg,
The filter is 0.3M ² , the blood layer thickness is approximately 60μ, and the molecular weight cutoff is 30,000.

According to the experimental results shown in the curves in Figure 4, those that re-inflowed blood improved their overflow compared to those that did not re-inflow blood (those in which the amount of blood re-inflowed was 0). If the amount is 150 to 250,
It can be seen that the filtration rate is definitely over 60ml/min.

In addition, using the HF type ultra-passage artificial kidney shown in Figure 1 as an overflow device, the overflow was measured at a Q _B of 200ml/min, a blood re-inflow rate of 200ml/min, and a pressure drop of 300mmHg, and the result was approximately 30ml/min. , it was. In this case, the effective area of the holofiber is 1M ² , the inner diameter
230 μ and a molecular weight cutoff of 30,000 were used.

On the other hand, when blood was not re-introduced under similar experimental conditions, the excess amount was measured at approximately 25%.
ml/min.

From this result, it was confirmed that according to the present invention, even if the pressure drop is approximately the same, by increasing the amount of blood inflow, the excess amount can be improved compared to the conventional method.

As described above, according to the present invention, it is possible to increase the shear rate by the simple method of re-inflowing the blood, so that the blood flow rate collected from the patient can obtain at least the desired excess amount, and furthermore, the excess amount can be increased. Therefore, there is no need to make the area of the membrane excessively large or to make the thickness of the blood layer extremely thin, so the device can be miniaturized and manufacturing is easy, which brings about remarkable effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a blood filtration device showing one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of different blood filtration devices of the present invention, and FIG. 4 is a diagram showing blood re-inflow amount and excess amount. FIG. 1, 21... Ultrafilter, 2... Blood inflow tube, 3...
Blood outflow pipe, 4...Liquid discharge pipe, 5, 11...Blood pump, 7...Fluid injection pipe, 8...Blood re-inflow pipe.

Claims (1)

[Claims] 1 10 to 500 Å (1000 to 1000000 in molecular weight cutoff)
A blood inflow pipe, a blood outflow pipe, and a filtrate discharge pipe are each connected to a filter equipped with a filtration membrane having a pore size of Connecting a replacement fluid injection tube, and connecting the blood inlet of the blood re-inflow tube to the filter and replacement fluid injection tube of the blood outflow tube, and connecting the outlet of the blood re-inflow tube to the blood inflow tube. , a pump means is provided in the middle of the blood re-inflow tube to cause a part of the blood in the blood outflow tube to flow into the blood inflow tube, and further to set the flow rate of the blood flowing back into the filter to 150 to 250 ml/min. A blood filtration device featuring: 2. The blood filtration device according to claim 1, wherein the filtration membrane of the filter has a pore diameter of 30 to 100 Å (1,500 to 500,000 in molecular weight cutoff).