JPS6254510B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a blood processing device configured to use a semipermeable membrane or a porous membrane to move substances in blood through the wall membrane using principles such as osmosis, dialysis, ultrafiltration, and gas diffusion. The present invention relates to a blood processing device having an improved hollow fiber membrane bundle using hollow fiber membranes. Conventionally, this type of blood processing equipment has been used to purify the blood by removing harmful substances from the blood of patients with renal failure, drug addiction, etc., as well as artificial liver equipment and artificial liver equipment that exchange oxygen and carbon dioxide gas. Widely used as lung devices, etc. The present invention provides an improved device for use in these blood processing devices. Generally, many of such blood processing apparatuses are cylindrical. FIG. 1 shows the structure of a cylindrical hemodialysis apparatus as an example of a blood processing apparatus. In FIG. 1, reference numeral 1 denotes an inlet header with a circular cross section, which is provided to guide blood into the internal space of the hollow fiber membrane 5 and to isolate it from the outside. Blood 10 is introduced from the inlet 20. . 1a is an exit side header with a circular cross section that is provided to collect the blood that has passed through the internal space of the hollow fiber membrane and discharge it from the outlet 20a into a tube of a certain size, and to isolate it from the outside. be. 2 is a gasket for the header 1 or 1a to prevent the header 1 or 1a from separating from the outer cylinder 3, and to guide the blood led into the header to the internal space of the hollow fiber membrane 5 without leaking to the outside. 1
This is a fixing cap provided to make the hollow fiber membrane group adhere to the partition wall 6 through which the hollow fiber membrane group is fixed. Outer cylinder 3
is preferably cylindrical and made of transparent, hard synthetic resin so that its interior can be viewed visually, and its internal space 9 is filled with several hundred to ten thousand hollow fiber membranes 5. Further, this outer cylinder 3 is provided with an inlet 4 and an outlet 4a for dialysate. A large number of hollow fiber membranes 5 are filled in the internal space 9 of the outer cylinder 3, and both ends of the hollow fiber membranes 5 are fluid-tightly fixed by partition walls 6 having excellent blood compatibility. It communicates with Furthermore, the partition wall 6 is generally made of polyurethane resin, and the partition wall 6 separates the internal space 8 of the header from the internal space 9 of the outer cylinder 3. contact only through the wall membrane of the hollow fiber membrane 5. That is, the introduced blood 10 enters the inner space of the hollow fiber membrane via the header inner space 8, and harmful substances in the blood are discharged into the inner space 9 of the outer cylinder 3 through the wall membrane of the hollow fiber membrane. The purified blood is returned to the body via the internal space of the outlet header 1a, and conversely, harmful substances discharged into the internal space 9 of the outer cylinder 3 are absorbed by the dialysate 11 introduced from the inlet tube 4. The liquid is transported along the pipe and taken out to the outside via the discharge pipe 4a. However, such conventional cylindrical blood processing apparatuses have the following problems. In other words, in FIG. 1, due to the structure of the header 1 used, the distance from the header entrance point A to the point B where the header bends horizontally is the same as the distance from point B to point C on the cut surface 7 of the hollow fiber membrane group. It is very long compared to the distance, and the length of the flat part of the header that extends in the space above the cut surface 7 of the hollow fiber membrane group is relatively long. Therefore, when blood is introduced into the header, it first collides with the center of the cut surface of the hollow fiber membrane group without dispersing its own flow velocity, and then the blood enters the inner space of the hollow fiber membrane. Most of the blood is dispersed to the hollow fiber membrane group at the outer periphery due to pressure (or resistance) and the partition wall that fixes the hollow fiber membrane group. Therefore, the speed at which blood flows through the inner space of the hollow fiber membrane is faster in the center and slower in the outer periphery. As a result, the performance of the blood processing device deteriorates, and when blood is returned after blood processing, the blood return speed is different between the center and the outer periphery, resulting in blood remaining in the internal space of the hollow fiber membrane near the outer periphery. cause. Particularly when blood treatment is performed for a long period of time, blood clots occur in the internal space of the hollow fiber membrane where the blood velocity is slow, and there are parts where the blood flow stops. The present invention has been made in view of the above circumstances, and its purpose is to improve the structure of the inlet side header, and to improve the structure of the inlet header so that all the hollow fiber membranes on the cut surface of the hollow fiber membrane group to which the blood to be introduced is fixed are fixed. An object of the present invention is to provide a blood processing device having a structure in which blood flows uniformly into the internal space of the blood processing device. The present invention provides a blood processing device that includes a hollow fiber membrane bundle inside a cylindrical outer shell, and a blood inlet and a blood outlet that communicate with the inside of the bundle of hollow fiber membranes at both ends of the outer shell. In this case, the internal shape of the inlet side header having the blood inlet is a mountain shape with the circular end face of the hollow fiber membrane bundle as the bottom and the blood inlet as the top, and the slope shape of the mountain shape is the inner shape of the inlet side header having the blood inlet. The radius of is R (mm), the arbitrary length on the radius R is r (mm),
When the distance from the hollow fiber membrane end face to the mountain slope at the position of radius r is Y (mm), Y = f x R ² - ^{r 2} /2r + a (where f is an arbitrary constant value and a is a constant). The gist of the invention is "a blood processing device characterized by a curved surface obtained by rotating a given Y by 360 degrees around the Y axis when r=0". According to the present invention, as the blood introduced into the internal space from the top of the chevron of the inlet side header flows down the flow path, which increases due to the gently expanding slope of the chevron, the flow velocity decreases rapidly. .
Therefore, since the pressure distribution is uniform on the cut surface of the hollow fiber membrane bundle at the bottom, the flow of blood flowing from each hollow fiber membrane end is also uniform. This increases the overall blood flow rate and improves dialysis efficiency, ultrafiltration efficiency, etc. There is no problem in applying the chevron-shaped header of the present invention to the outlet side header. In that case, there are advantages such as common parts and overall balance. Next, the blood processing apparatus of the present invention will be further explained based on the drawings. FIG. 2 shows an example of the blood processing apparatus of the present invention in which the inlet header 1 of the blood processing apparatus shown in FIG. 1 is modified, and only the upper half is shown. As is clear from FIG. 2, the upper part of the entrance header 1 has a chevron-shaped, downwardly convex shape with a gentle slope given by the formula set forth in the claims. In order to compare the inlet side headers, only the inlet side header portions of FIGS. 1 and 2 are shown enlarged in FIGS. 3 and 4, respectively. As can be seen from FIG. 4, the internal space 8 of the inlet header 1 has a chevron shape with the cut surface 7 of the hollow fiber membrane bundle as the bottom (in this case, since the blood processing device is cylindrical, this chevron shape has the upper and lower central axes as the bottom). (rotationally symmetrical to the original), and a blood inlet 20 is provided at its top. The introduced blood suddenly loses its previous flow velocity and disperses as shown by the arrow.
It is made to spread over the entire cut surface 7 of the hollow fiber membrane bundle. According to a preferred embodiment of the present invention, the height from the bottom of the chevron-shaped internal space to a point on the chevron slope is such that the horizontal projected area of the slope from the outer circumference of the bottom surface to the inner circumference increases. It is made to be the sum of a constant value and a value proportional to the value divided by the circumference at a point. To explain this in more detail, as shown in FIG.
mm ² (shaded area), the height of the circumference on the radius rmm is y
mm (spatial distance from the cut surface of the hollow fiber membrane group to the mountain-shaped slope), the shape of the header of the present invention is defined by the value of y obtained by the following general formula, and the y axis when r = 0. The structure is such that the curved surface obtained when rotated 360 degrees around the center is the connecting surface between the blood inlet and the outer cylinder. y=f×S/2πr+a=f×R ² −r ² /2r+
a Here, f is an arbitrary value, and a is the distance required between the cut surface of the hollow fiber membrane group and the header ceiling closest to the cut surface of the hollow fiber membrane group, and is preferably about 2 mm. As a result of intensive study of the above equation, the inventors of the present invention confirmed that the range of 1/2≦f≦2 is optimal from a practical standpoint. As can be seen from FIG. 4, the thus obtained header of the present invention forms a gentle slope from the blood introduction part to the cut surface of the hollow fiber membrane group, so that the introduced blood is It approaches the cut surface of the hollow fiber membrane group while distributing the flow velocity to the outer periphery. Next, an example will be shown in which ultrafiltration of blood was performed using the improved blood processing apparatus according to the present invention. In the examples, improved type A refers to a blood processing device having a header having a shape when f=1 in the above formula, and improved type B refers to a blood processing device having a shape when f=0.5 in the above formula. 1 shows a blood processing device having a header having the shape of FIG. Further, for comparison, a conventional type as shown in FIG. 1 is shown as a comparative example. Example 1 Comparative example, improved type A and improved type B hollow fiber membrane blood filtration devices (polyacrylonitrile hollow fiber membranes with an inner diameter of 300μ were used, the number of hollow fiber membranes was 2200)
Book, blood filtration effective membrane area 0.23m ² , hollow fiber membrane filling rate
Fresh bovine blood (hematocrit value 35%, total protein concentration 9.2 g/dl) was added to transmembrane pressure (Trans 50%).
Membrane Pressure (hereinafter abbreviated as TMP)
Table 1 shows the results of measuring the amount _of blood passing through and the amount of ultrafiltration after 3 hours. show.

[Table] Example 2 Comparative Example, Improved Type A, and Improved Type B Hemofiltration devices with built-in hollow fiber membrane bundles (using polyacrylonitrile hollow fiber membranes with an inner diameter of 500μ, number of hollow fiber membranes)
960 tubes, effective membrane area for blood filtration 0.17 m ² , hollow fiber membrane filling rate 50%) and fresh bovine blood (hematocrit value 38)
%, total protein concentration 9.6g/dl) at TMP25mmHg
Table 2 shows the results of introducing the blood under a differential pressure ΔP _B =25 mmHg, and measuring the amount of blood passing through, the amount of ultrafiltration, and the number of blood remaining after blood return after 3 hours.

【table】

[Table] As can be seen from Tables 1 and 2, the blood processing equipment equipped with the header of the present invention has a higher blood flow rate and ultrafiltration weight than blood processing equipment equipped with commonly used headers. It is much better, and the number of remaining blood has been significantly reduced. Therefore, the blood processing device of the present invention is expected to be highly effective when used with a wearable artificial kidney or with a small amount of blood. Additionally, as an observation, when the headers of improved type A and improved type B blood processing apparatuses were used in Examples 1 and 2, the introduced blood was almost uniformly dispersed within the header. In contrast, in the comparative example, the introduced blood first hits the center of the hollow fiber membrane group, then circulates around the outer periphery, and the blood collects near the outer periphery. vortices are observed. Furthermore, even during long-term blood filtration for 6 hours, it was confirmed that the amount of blood clot in the internal space of the improved type A and improved type B hollow fiber membranes was very small compared to the comparative example.

[Brief explanation of the drawing]

FIG. 1 shows a blood processing device using a conventional cylindrical hollow fiber membrane, and FIG. 2 shows a blood processing device using the hollow fiber membrane of the present invention. 3 is an enlarged view of the header of FIG. 1, and FIG. 4 is an enlarged view of the header of FIG. 2. The arrows in FIGS. 3 and 4 represent the flow of blood. FIG. 5 is an explanatory diagram showing an example of the shape of the inner surface of the inlet header according to the present invention. The symbols used in the drawings are 1, 1a is the header, 3 is the outer cylinder,
4 and 4a are inlet pipes or discharge pipes for dialysate or filtrate, 5 is a hollow fiber membrane, and 10 and 10a are for blood.

Claims (1)

[Scope of Claims] 1. Blood in which a hollow fiber membrane bundle is built into a cylindrical outer shell, and a blood inlet and a blood outlet are provided at both ends of the outer shell to communicate with the inside of the bundle of hollow fiber membranes. In the processing device, the internal shape of the inlet side header having the blood inlet is a mountain shape with the circular end surface of the hollow fiber membrane bundle as the bottom and the blood inlet as the top, and the slope shape of the mountain shape is the shape of the slope of the hollow fiber membrane bundle. Let the radius of the end face be R
(mm), arbitrary length on radius R (mm), radius r
When the distance from the hollow fiber membrane end face to the chevron slope at the position is Y (mm), it is given by Y = f x R ² - ^{r 2} /2r + a (where f is an arbitrary constant value and a is a constant) Y, centering on the Y axis when r=0
A blood processing device characterized by a curved surface obtained by rotating 360 degrees.