SE434120B - DIALYZER WITH HALIGAN FIBERS - Google Patents

Description

8100863-3 10 15 20 25 30 35 The invention is explained in more detail below with reference to the accompanying drawing, which illustrates an exemplary embodiment.

Fig. 1 shows an axial section through a hollow-shaped dialyzer according to the invention; Figs. 2-4 show different cross-sections taken along lines 2-2, 3-3 resp. 4-4 in Fig. 1; and Fig. 5 shows a section through a lid of the dialyzer according to Fig. 1.

The embodiment to be described below illustrates a suitable dialyzer construction according to the invention, which contains hollow fibers.

Embodiment Figs. 1-5 show a dialyzer 20 according to the invention. This dialyzer has three parallel dialyzer passages, the dialyzate flowing in countercurrent relative to the flow of blood or other liquid to be dialyzed in each passage containing fibers.

The dialyzer 210 has a tubular housing with widened end portions 214, 216 and a partition structure 211 which divides the interior of the housing into separate passages. The bundles of hollow fibers are enclosed in the passages 221, 222 and 223, while the passages 224, 225 are unfilled, so that the dialysate can flow through the later passages without coming into contact with the fibers.

The dialysate flow is controlled by the appropriate design of the partitions of the structure of Fig. 1, so that this flow enters and flows upwards in the passage 221, further downwards through the passage 224, further upwards through the passage 222 and this time in return downwards to the bottom via the passage 225, and finally upwards again, during the completion of the dialysis, through the passage 223 and out via the outlet 238. 10 15 20 25 30 35 8100863-3 No venting is needed because the flow rate of the dialysate is rather large in the very narrow return passages 224, 225. A flow rate of only about 30 cm per second is generally sufficient to bring generated air or gas bubbles. At lower flow rates, which may occur if the dialysate is discarded after a single pass through the dialyzer and is not recirculated from the outlet 238 to the inlet 236, venting means can of course also be provided in this construction.

Venting is also not necessary if the dialysate is treated to reduce gas evolution, for example by boiling under low pressure before supply to the dialyzer. This removes practically all dissolved gases, and maintaining a certain pressure on the dialysate during pumping through the dialyzer can also prevent gas evolution.

The dialyzer of Fig. 1 is substantially triangular in cross-section, especially at the end portions 214, 216. Each of these end portions has a mounting bead 217 formed as an annular bead, which facilitates the fitting of the caps 262 closed at the ends. 217 may be provided with a ridge 219, which only needs to be about 0.4-0.5 mm high and which facilitates the fixing of the lid by, for example, ultrasonic welding of the attached lid to the ridge. In this case, the ridge and the adjacent part of the lid fuse together as a result of the formed frictional heat, whereby these parts are welded together and provide an effective, fluid-tight seal.

For better sealing of the blood or liquid to be dialyzed against unwanted cracks or the like, each lid 262 is provided with an inner sealing lip 263, which is designed to seal against the seal 257 on the outside of the fiber-containing zone. The liquid to be dialyzed is thereby prevented from penetrating the gap 265 between the inside of the lid and the outside of the casing. 10 15 20 25 30 35 8100863-3 To further improve the sealing effect, the seal 257 may project a short distance 267, for example about 0.3 mm, from the end of the housing.

A batch of hollow lamoammonium regenerated cellulose fibers with a wall thickness of about 12 μm É 2 μm and an inside diameter of about 200 μm in 50 μm is rinsed, preferably from a plurality of spools in parallel strands, and cut to a suitable length and thoroughly cleaned. Normally, these fibers are prepared by extruding ammonium-cellulose solution through an annular die into a regeneration bath while supplying water-insoluble liquid into the holes of the hollow strand. A typical liquid-insoluble liquid is isopropyl myristate. After this regeneration, this liquid is removed by thorough washing with isopropanol. The interior of the fibers can then be wetted with a plasticizer, such as glycerin, the plasticizer suitably remaining in an amount of about 5% by weight, based on the pure fiber.

The softening is not absolutely necessary but reduces the risk of the fibers breaking or being damaged during the subsequent treatment, nor is the efficiency with which the fibers are tightly enclosed in the casing 210 affected. Å A bundle of two to three thousand fibers produced in this way is then introduced in one of the passages 221, 222, 223 and similar bundles in each of the two remaining passages.

The insertion can be done by first stepping over a tapered sleeve of polyethylene over the bundle, after which the filled sleeve is inserted, with its narrower end first, in resp. passage, after which the sleeve is removed from the inserted bundle. The fibers protrude slightly from the narrower end of the sleeve, so that they can be held when pulling the sleeve over the opposite ends of the fibers.

After all three passages have been filled with fibers, the sealing and fixing ("potting") can begin. Each fiber bundle protrudes a small distance from both ends of the casing. Each of these protruding ends of the fiber bundles is dipped in molten carnauba wax, which is then allowed to solidify after the wax has penetrated a short distance into all the fibers. The housing is clamped longitudinally between two sealing heads connected to a container containing a sealing compound, as shown in Fig. 19 of U.S. Pat. No. 3,442,002, and centrifuged as also described in said patent, while it has not yet cured liquid, freshly mixed sealing mixture is poured into the container. This blend may be a polyurethane prepolymer resin having a chain extender, an epoxy resin blend as described in the aforementioned U.S. Patent, or a curable polyisioxane liquid or other curable resin material.

When using a curable polysiloxane liquid with a hardener, such as chloroplatinic acid, the centrifugation is carried out at about 350 g while heating the mixture, and after about half an hour at 65 ° C the sealing mixture hardens to a point where it is no longer liquid. The sealing heads are loosened and removed, after which curing is completed by placing the dialyzer in an oven with an air atmosphere at 65 ° C for two hours.

Thereafter, the sealing mixture is completely rigid, and a sharp metal blade is used to cut off the sealing mixture in line with the housing's: open ends 214, 216. By means of lid 262 the ends 214, 216 of the housing are closed by welding or gluing, but the lids can also be screwed on, if as desired. The construction is now complete and only needs to be flushed to remove the water-soluble plasticizer from the inside of the hollow fibers before it can be used. The dialyzer can be stored either before or after the washing off of the plasticizer, without the dialysis properties being significantly affected. When using the dialyzer, the end 216 is held up, and a dialysis source is connected to the inlet 236, while the outlet 238 is connected to a waste container.

The bundles of fibers can be inserted into the passages without the aid of any sleeve, especially if the walls at one end of the casing gradually taper in the direction of the narrower, central portion. Alternatively, the bundles can be inserted into sleeves and these sleeves are left in the inserted position in the dialyzer around resp. bundle. This is especially suitable if the sleeves have relatively thin walls, such as about 7 μm so that they do not take up so much space.

The insertion of the fiber bundles can also be facilitated by heating the casing. Thereby, the casing expands and thus provides a small extra space, so that the bundles can be inserted in position, after which the casing cools and sealingly encloses the fibers, whereby increased efficiency is achieved. Instead of an elongate sleeve as an aid in the insertion of the fiber bundles, a narrow plastic band or a wire can be wound around the fiber bundle near one end and shrunk or tightened and form a tail for the bundle. The bundle can then be pulled through the passage by first pulling the tail through the passage and then pulling on this tail.

Normally, it is convenient to clean the hollow fibers before using the dialyzer by washing or rinsing with a volatile solvent, especially if the cavities of the fibers contain a liquid which should not come into contact with the dialysate or dialysate.

The partitions can also be more in number than shown in the drawing, so that for example four or five parallel dialysis passages are formed, but the use of more partitions means less space for the fibers, so the dimensions of the casing must be increased if the dialysis capacity is to be maintained. .

Furthermore, the partitions in accordance with the invention facilitate the mechanical handling during the manufacture of the dialyzer. The reduced width of the individual passages, for example 1-3 cm, compared with a non-divided dialyzer, results in a reduced number of fibers in each passage and thus simplifies the completion of the individual bundles. Thus, it is considerably more cumbersome to complete a bundle of 6000 fibers than three bundles of 2000 fibers each for use in a dialyzer according to Fig. 1. The fibers containing the passages can also taper towards each end, as illustrated at 211 in Fig. 1, so that a certain constriction is formed at their central portions. Such a constriction of about 0.5 - 1 mm provides a better holding of the fibers and prevents deflection when flowing around them, thus counteracting the channeling effect discussed above.

Furthermore, the different compartments in the described embodiment do not need to be used for the same purpose. Thus, one of the compartments can be filled with an absorber, such as activated carbon or the like, instead of fibers, so that impurities or other undesirable substances in the liquid to be dialyzed are absorbed.

Different types of fibers can be used in the different passages to achieve different dialysis effects on the dialysand, as it passes through the dialyzer. Thus, some passages can be filled with an absorber in order to purify the dialysate during its passage through the dialyzer and improve the conditions of the dialysate during its passage through the remaining fiber-filled passages.

The sealing of the ends of the fibers can be achieved in another way than as described above. Thus, the initial dipping of the fibers for plugging the holes can be performed in molten, resin-modified waxes, thermoplastic resins or compositions which cure to form heat-curable resins.

The sealing mixture itself can be used, for example, in the initial dipping to a shallow depth, followed by a deeper sealing. By maintaining a slightly higher pressure in the non-plugged fiber holes compared to the pressure over the sealing mixture in which the unplugged fiber ends are dipped, the sealing mixture can be kept at a low level in these holes, whereby the initial dipping for plugging the holes can be completely eliminated. . The holes can alternatively be sealed by melting the fiber ends, if these are fusible, and in this way an initial dipping is likewise unnecessary.

Ia ... am -___ __. 8100863-3 5 l0 15 20 25 30 35 In the same way that the centrifugal force applied to the sealing mixture ensures that the mixture impregnates all gaps and cavities around and between the fibers and in this way provides effective sealing between the dialysate chamber and the dialysate, a pressure applied to the liquid sealing liquid has a similar effect during the sealing operation. You can thus seal one end of the fiber bundle at a time, without the need for any centrifugation equipment.

Furthermore, the look can be arranged to snap over the sealing ends of the dialyzer. Such lids can be quite flexible and the sealing ends, over which the lids are fastened, can be provided with ridges for locking the bag-fastened looks in place. 1 is that such a dialyzer provides a more uniform and more efficient dia- An advantage of the dialyzer construction according to fig. Lys than corresponding dialyzers without partition construction.

Despite the widened end portions 214, 216, which act as collecting chambers for the dialysate and bring this into direct contact with the outer fiber layers in the fiber bundles, the dialysate has a tendency to pass from one end of the dialyzer to the other via the simplest wall and thus find and form a channel, even if the fibers are fairly well packed. Such channeling significantly reduces the efficiency of dialysis, in particular through the walls of the fibers which are at some distance laterally from the channel. If this occurs with a dialyzer with a single dialyzer passage, its efficiency becomes so poor that it usually has to be discarded.

Such channeling becomes more pronounced if the wall thickness of the hollow fibers decreases and the fiber diameter decreases. This causes the fibers to become more flexible, so that it is easier for the dialysate to create a channel by bending the fibers. Wall thicknesses of about 5-20 μm are suitable for efficient use, and thicknesses of about 10-15 μm are particularly advantageous. Fibers with passages with a width not exceeding 500 μm, preferably about 100-300 μm, are particularly effective. Regenerated, hollow cuproammonium fibers of this type are rather stiff, especially in the dry state, and are therefore easy to handle when assembled into a bundle for insertion into the dialyzer and at the insertion itself.

The dialysis discussed above differs from osmosis in that in dialysis, fibers whose walls are very porous are used, too porous for use in osmosis. This relationship is clear from the fact that a reverse osmosis process, for example for desalination of brackish water, requires membranes of relatively non-porous material, such as polyvinyl chloride, and the use of a driving pressure greater than the osmotic pressure and as large as is practically possible. An attempt to perform such a reverse osmosis with cuproammonium regenerated cellulose as above will only result in the brackish water being rapidly filtered through the regenerated cellulose fibers and flowing out on the outlet side of the cellulose in substantially the same condition as at the inlet side.

The dialyzer structure according to the invention can also be used in such a way that the dialysate passes through the holes of the hollow fibers, while the dialysand flows along the outside of the fibers, although this arrangement is not suitable as the dialysand consists of blood. Using osmotic type fibers, the structure of the invention can be advantageously used for osmotic processes, such as reverse osmosis, and in such use it is convenient to allow the fluid to be treated to flow on the outside of the hollow fibers, so that the high pressure applied to the fluid in reverse osmosis is applied to the outside of the fibers. Any damage to the fibers does not give rise to leakage.

The apparatus of the invention is also suitable for use in gas separation, provided that the appropriate type of fiber is used, or for treating liquids with gas, such as in oxygenating blood, with silicone fibers being preferred.

Of course, a number of modifications and changes can be made 8190863-3 in 1-0 in light of the above description. Thus, the inventive concept can be applied in different ways, compared to the described embodiments within the scope of the appended claims.

Claims (8)

8100863-3 1? P A T E N T K R A V 1. A hollow fiber dialyzer comprising an elongate tubular housing (210) containing a partition structure (211) which divides the interior of the housing into at least three separate, longitudinally extending passages, dialysate flow control means (214,216) for receiving of dialysate from an external source and directing the flow of dialysate from one end of the casing to the other through one of the passages and then back to the first-mentioned end through another of the passages and so on back and forth in the longitudinal direction through the other passages. and finally out of the casing, at least two of the passages each having a bundle of elongate, hollow blood dialysis fibers extending longitudinally therethrough, at least one of the passages not containing dialysis fibers, and means arranged to transfer blood to be dialyzed from an inlet to the fiber ends of each such bundle at the same end of the casing and to receive blood from the other ends of the hollow fibers for emitting to an outlet, characterized in that the passages (221, 222,223) having these bundles of fibers have a relatively larger cross-section than the passages (z24, z25) which do not contain all fibers, and that said at least one passage which does not contain dialysis fibers has a circular cross-section which is also narrow enough to bring .......______ ..> .._- ... .. .I V. the flowing dialysate to entrain gas bubbles which can be formed in the dialysate. Dialyzer according to claim 1, characterized in that the passages having fiber bundles (221, 222,223) have a substantially circular cross-section along their entire length between the inlet and outlet ends (236,238) of the dialysate. Dialyzer according to claim 1 or 2, characterized in that the passages having fiber bundles (221, 222,223) are grouped around a common center line, and that the passages which do not contain dialysis fibers (224,225) are located near the circumference of the elongate the casing. , | r - 12 Dialyzer according to one of Claims 1 to 3, characterized in that there are two passages with fiber bundles and one passage which does not contain dialysis fibers. Dialyzer according to one of Claims 1 to 3, characterized in that there are three passages with bundles of fibers and two passages which do not contain dialysis fibers. Dialyzer according to claim 5, characterized in that the three passages with fiber bundles are arranged in a tightly packed triangular relationship. Dialyzer according to claim 5 or 6, characterized in that the two passages which do not contain dialysis fibers are located close to the circumference of the elongate casing and that the casing is formed of a transparent material. 8. A catalyst according to any one of claims 1-3, characterized in that the number of passages which do not contain dialysis fibers is one less than the number of passages which have fiber bundles.