CS255055B1 - Device with optimized support of membrane intented for substances exchange between two flowing liquids - Google Patents

Abstract

The invention relates to a device for the exchange of substances between two flowing liquids, e.g. blood and dialysate. The device is especially suitable for haemodialysis, but also for dialysis, filtration, ultrafiltration and heat exchange. The invention resides in the creation of an optimised membrane holder. This optimisation resides in the fact that such a geometrical arrangement of the housing and the membrane holder at the given mechanical parameters of the membrane is found that little air is incorporated in the sieve meshes and there are only low pressure drops on the blood and dialysate side, and that optimum leading array of the two functional liquids on the membrane surface and hence maximum efficiency are ensured.

Description

BACKGROUND OF THE INVENTION The present invention relates to a device with optimized diaphragm support for the exchange of substances between two flowing fluids, one of which is, for example, blood and the other a dialysate, useful in particular in hemodialysis, dialysis, filtration, ultrafiltration and heat transfer.

One method of treating acute or chronic renal insufficiency, intoxication or other diseases is hemodialysis. The treatment process consists of removing toxic substances or metabolic products from the patient's blood by dialysis of the blood in a hemodialyser. A hemodialyser is a device consisting of two compartments, blood and dialysate, which are separated from each other by a dialysis membrane through which diffuse transition of uremic substances from the patient's blood to the dialysate occurs. There are several basic designs of hemodialysers.

They are

1. Capillary dialysers

2. Flat diaphragm dialysers

3. Plate dialysers with tubular membrane

In capillary hemodialysers, transport of substances occurs through the capillary membrane wall. The capillary bundle is self-supporting and therefore no diaphragm support is required in this technical arrangement.

The flat diaphragm dialysers are arranged such that two different compartments are formed by suitable folding of the diaphragm restraints and the flat diaphragm, with respect to the surroundings and sealed between them by a sealant or by compression through which both working fluids (in the case of hemodialysis blood and dialysis solution). Such an arrangement is known from U.S. Pat. No. 4,404,100.

The tubular diaphragm dialysers consist of a set of superimposed tubular membranes in which the diaphragm support is inserted and glued together at the end. This dialyser beam is provided and inserted into the dialyser's housing. By sealing, the working spaces of the dialyser are formed, wherein one of the working fluids (eg, dialysate) flows through the inside of the diaphragm hose and the other of the working liquids (eg, blood) flows through the outside. Such an arrangement is known from German Patent 3,045,495. The last two types of dialysers agree that their properties depend substantially on the overall geometrical arrangement and in particular on the geometrical arrangement of the diaphragm support.

The mechanical properties of the diaphragm, together with the diaphragm support geometry and overall geometry of the housing, determine the properties of the dialyser. The currently used plate dialysers have a diaphragm support made of plastic, woven or nonwoven. Those having a diaphragm support made of woven or nonwoven fabric currently have considerably different parameters, many of which, in particular the exclusion of air bubbles in the eyes of the woven or nonwoven material, unfavorable pressure losses, considerable shading of the membrane surface, i.e. ineffective area on its contact with the membrane support, they negatively affect the safe, prompt and effective treatment of the patient.

The purpose of the invention is to design such a device which, by optimum selection of the geometrical arrangement, ensures that at the same time the above mentioned negative effects are minimal. The optimization consists in finding such a geometrical arrangement of the sleeve and the diaphragm support with given mechanical parameters of the diaphragm, that at the same time minimal air settling in the eyes of the woven diaphragm support, minimal pressure losses in the spaces flowing through both working fluids. of functional liquids across the membrane surface and thus maximum efficiency.

The above-mentioned drawbacks are eliminated by a device with optimized diaphragm support designed for the exchange of substances between two flowing liquids, one of which is most often blood and the other dialysate, which consists in that the dialysate half-housing is equipped with an inlet dialysate chamber and outlet dialysate chamber of 10 to 20 mm and the center spacing of these cells is 180 to 210 mm, while the mutual distances and sizes of the inlet blood chamber on the blood half-shell and the inlet dialysate chamber on the dialysate half-shell are the same, the membrane being anisotropic and having the following gg values in the direction of the major axis of elasticity Young's modulus of elasticity 1.6.10 to 1.9.10 Pa 7 7 and shrinkage Young's modulus of elasticity 1.2.10 to 1.6.10 Pa and extensibility of 5 to 6%, while the woven membrane support has warp fibers parallel to the direction perpendicular to main 8 8 an axis having a Young's modulus of elasticity of 1.6.10 to 1.9.10 Pa and a fiber center distance (t ^) of up to 1.9.10 weft in the diameter range (d ^) of 0.001 to 1 mm and satisfies the equation = ^A i ^{d + + B} l ^d u where ^t U ^d U ^and 1 l ^three filaments wherein the distance in mm wefts fiber diameter is wefts mm (2.26 to 2.68) (-0.53 to -0.41) mm ^-1 total area the membranes used are 1.4 to 1.5 m restraints 75 to 85 further characterized in that said selected diameter (d ^) satisfies the relation of the weft threads and number of membrane diameter (d _Q) of warp threads in the range závilosti on average (d ^) weft 0.001 to 1 mm where ^d o ^{d A A} 2 b ₂ ^d = = ^A 2 ^{d + + B} 2 ^d je is the fiber diameter is the fiber diameter (0.45 to 0.69) (-0.074 to 0) , 15) weft warp in mm mm

-1 mm

Furthermore к diameter characterized in that the spacing (t _Q) center warp fibers satisfies the relationship (d ^) of the weft in the range of the diameter (D ^) of the weft from 0.001 to 1 mm, the relationship ^T o - ^A 3 ^D U ^{+ B} 3 ^d p wherein ^fc o d.

for ^A 3 ^B 3, the warp fiber distance in mm is the weft fiber diameter in mm (1.47 to 2.12) (-0.53 to -0.71) mm ^-1 double warp fibers, where the distance where d _Q is warp diameter and for distance mm the relation is characterized in that warp contains O ^{+ d} o 'is valid in the range of weft diameters from 0.001 to 1 ^ť o = ^A 3 ^d ú ^{+ B} 3 ^d ú

Furthermore, even or odd warp threads is T _(where ^T warps on ^d 3 U ^and 3 ^B is the distance the warp fibers in the fiber diameter is mm (1.47 to 2.12) (-0.71 to -0.53) weft in mm

-1 mm

It is further characterized in that it is equal to (3.0 to 3.1).

ratio of the diameter (d _Q ) of the warp fibers to their distance (t ^) in the area of entry or exit of the dialysate or inlet, or the support provided with weft fibers of larger diameter (d ^) than

Further characterized in that the blood outlet is a woven membrane is the diameter (d 6) of the weft fibers of the functional portion.

Further characterized in that in the region of the inlet or outlet of the dialysate or of the inlet or outlet of the blood, the woven membrane support is provided with weft fibers of smaller diameter (d ^) than the diameter (d ^) of the weft fibers of the functional part.

Further characterized in that in the region of the inlet or outlet of the dialysate or the inlet or outlet of the blood, the woven membrane support is provided with weft fibers, wherein the distance (t t) between them is greater than the distance (t t) between the weft fibers of the functional part. Further characterized in that in the region of the inlet or outlet of the dialysate or the inlet or outlet of the blood, the woven membrane support is provided with weft fibers, wherein the distance (t t) between them is less than the distance (t ^) between the weft fibers of the functional part. Further characterized in that in the region of the inlet or outlet of the dialysate or the inlet or outlet of the blood, the woven membrane support comprises pressed weft fibers.

A new and higher effect of the device according to the invention is that the mathematical optimization of the geometric parameters important for the function of the hemodialyser determines the best possible arrangement of the individual elements of the hemodialyser so that the hemodialyser has minimal possible pressure loss on the dialysate side Hemoclear, U.S. Pat. No. 4,404,100. At the same time, the shape of the channels through which the dialysate flows is such that the released gas bubbles cannot be trapped in the eyes of the membrane support. These two improvements allow efficient use of the hemodialyser even on dialysis monitors with a lower degree of deaeration of the dialysate, which is an essential advantage of the geometric arrangement of the invention.

By finding the optimum relationship for the arrangement of the width, allowing the best possible distribution of liquids across the membrane surface, it makes it possible to approach the parameters of a tubular diaphragm dialyser by a technological process suitable for automation (and thus economically advantageous). U.S. Patent No. 3,037,506.

Other variants of the optimized woven membrane backing also make it possible to achieve the shape of blood space channels analogous to capillary dialysers, thereby approaching their advantages while maintaining the economical modality of using a flat membrane which is currently cheaper than the capillary membrane. In some cases, the product is easier to process than the capillary membrane. However, in terms of only functional parameters, the same properties of capillary and plate dialysers cannot be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further elucidated by way of non-limiting examples, which are described with reference to the accompanying drawings, in which: Figure 1 schematically depicts one functional layer of a hemodialyser; Figure 2 illustrates one possible membrane support variant; Fig. 3 is a plan view of the device; Fig. 4 is a sectional view; Fig. 5 is a partial cross-section with the exposed flank; and Fig. 6 is a diaphragm support used in a hemodialyser.

Fig. 1 shows one functional layer of a hemodialyser. The functional layer, i.e. one membrane support on both sides covered by the membrane, is divided into five parts, namely: dialysate entry area 1, blood entry area 2 / functional part 2, dialysate exit area 5, and blood exit area 2 · dialysate enters the dialysate 2 entry area in the direction of arrow 6, is divorced therein so that in the functional portion of the hemodialysate 2 it flows parallel to its longer edge, i.e. in the direction indicated by the arrow 2 ·

The dialysate flowing out of the function part 2 ³ and collecting in the outlet dialysate 5 _t from where it is withdrawn in the direction of arrow 2 · Likewise, the blood enters the inlet region 2 in the direction of arrow 9 and is distributed so that in the functional part 2 moves in parallel with a longer edge a hemodialyser, that is, in the direction of the Arrow 10 and in the opposite orientation to the flow direction of the dialysate; The blood, after passing through the functional part 2 ³ and collection of blood outlet 4, where it flows in direction 21 · Functional area # 2 has a length of width of the inlet of the dialysate and the blood is made.

The device object of the invention is a solution to the following requirements:

1. The pressure loss in the functional area dialysate space is minimal.

2. Pressure loss in the blood space of the functional area is minimal.

3. The pressure drop across the inlet and outlet areas of the dialysate downstream of the incoming liquid is equal to the pressure drop in the functional area for the dialysate, thereby ensuring dialysate distribution.

4. Deflection of the diaphragm under working conditions on the diaphragm support fibers lying perpendicular to the longer dimension of the dialyser is equal to 0.9 to 1.1 of the radius of these fibers. Within this range, the bubbles formed are unstable and at the same time the shading of the membrane on the fibers of the membrane support is minimal.

5. The geometrical arrangement of inputs and outputs on the blood and dialysate side is symmetrical, thus ensuring the optimization of the blood side by simply optimizing the dialysate side.

6. The diaphragm rests are made of a fabric formed by intertwining three fibers. the warp 12, the weft 13 and the binding 14, see Fig. 2.

These requirements are solved by the present invention for a flat anisotropic membrane whose Young's

The modulus of elasticity in the direction of the principal axis of elasticity is 1.6.10 to 1.9.10 Pa and whose Young's

7 the modulus of elasticity in the direction of the minor axis of elasticity is 1.2.10 to 1.6.10 Pa, both measured in the wet state of the diaphragm, which shrinks by 0.9 to 1.1% in the direction of the main elastic axis and in the direction of the minor the axis of elasticity swells by 5 to 6% and shrinks by 1% in a direction parallel to the direction of its drawing.

Further, the width of the entrances to the dialysate space is 10 to 20 mm, the functional area length is 180 to 210 mm, the number of membrane supports used is up to 85 and the total area of the dialyser is 1.4 to 1.5 m. The solution is carried out under operating conditions for the total product: flow rate 200 ml / min., Flow rate dialysate 500 ml / min. and a working pressure of 40 kPa.

FIG. 2 schematically illustrates the geometric configuration of the diaphragm support for which optimization has been performed.

FIG. 3 shows a plan view of a device according to the invention.

The device according to the invention consists of a housing 20, which is two-piece and consists of a dialysate half-shell 21, integral with a dialysate inlet 22 with a dialysate chamber 23 defining a width of the entrance space of the dialysate inlet and outlet of 10 to 20 mm; a dialysate chamber 24 180 to 210 mm from the inlet and defining the outlet space width of the dialysate outlet area to 10 to 20 mm, terminated with an outlet sleeve 25, and a blood semiconductor 26 comprising an integral blood inlet sleeve 27 with an inlet blood chamber 28 and a sleeve 29 for blood outlet and outlet blood chamber 30.

The sockets 27 and 29 and the inlet chamber 18 and the outlet chamber 30 are disposed symmetrically to the dialysate sockets 25, and 23, thereby automatically fulfilling the optimum arrangement of the blood space with the optimum arrangement of the dialysate space.

FIG. 4 shows a cross-section of a device according to the invention. In the housing 20 there is arranged a dialysate bundle 31 formed by an accordion-folded membrane 32, between which the woven membrane supports 33 are inserted. The entire bundle 31 is provided at both ends with a wedge plate 37i.

Fig. 5 shows a partial cross-section with the exposed flank showing that the bundle 31, together with the wedge plates 37, is inserted into the housing 20 and sealed along its perimeter where it contacts the housing 20 with a sealant polyurethane compound 38 .

Fig. 6 shows the membrane support used in the device. It consists of three interwoven fibers, of which the warp fiber 34 has a diameter of 170 µm and receives 16 double fibers per centimeter, the weft fiber 35 has a diameter of 250 µm and receives 15 double fibers per centimeter, and the binding fiber 36 has a diameter 50 / µm.

The function of the device according to the invention in this example is as follows: by partitioning the inner housing 20 with an accordion-folded permeable membrane 32 with interleaved optimized membrane supports 33, two spaces are formed inside the device separated by a membrane 32 through which blood and dialysate flow.

Blood enters the device through a mouthpiece 27 to which the appropriate set from the dialysis monitor is connected. After entering the dialyser, the blood initially equally fills the inlet blood chamber 28 from which it flows along the entire height of the bundle to the individual areas of the blood inlet 12, where it is distributed to the functional portions. Since the device operates as a dialyser, there is a negative pressure in the dialysis chamber, blood flows through the formed channels into the outlet region 40 from where it is discharged into the outlet blood chamber 30.

It is brought back to the patient's body. The dialysate enters the dialyser through the inlet mouthpiece 22 and exits the dialyser through the outlet mouthpiece 25, which is located at the opposite end of the dialyser opposite the blood mouthpiece 27. The dialysate, after filling the inlet chamber 23, enters each dialyzate inlet region 2 * where * ^2, which flows into the region of the dialysate 5 outlet, and from there to the dialysate outlet chamber 24. In this way, it is ensured that the blood and the dialysate wash the opposite sides of the permeable membrane 32 and that the concentration gradient causes the substances to pass from the blood to the dialysate. By maintaining the dimensions of the fiber spacing 20 and other parameters mentioned in the design description, it is ensured that the function of the dialyser is optimal.

Another possibility is to use the device according to the invention as a heat exchanger. In this case, the arrangement is completely analogous to that of the previous example, except that an impermeable membrane with analogous mechanical properties and high thermal conductivity is used. On the basis of the design, the arrangement is optimal with respect to the above-mentioned parameters, i.e. minimum bubble formation, minimum pressure drop and maximum efficiency.

A further modification of the device according to the invention is a thickening device for enzymes. In this case, the configuration is quite analogous to that of the hemodialyser, except that an ultrafiltration membrane with mechanical properties analogous to the membrane used in the hemodialyser is used, over whose area the water is removed from the working solution due to the pressure gradient, thereby thickening. On the basis of the design, the arrangement is optimal with respect to the above mentioned parameters.

The optimization procedure has been computerized and allows to create other variants for different arrangement of sieve, inlets and outlets and membrane properties.

Claims (10)

OBJECT OF THE INVENTION An apparatus having an optimized diaphragm support, for exchanging substances between two flowing liquids, one of which is blood and the other a dialysate, formed by a housing in which a dialyser beam consisting of wedge plates, accordion-folded membrane and woven plastic membrane supports are enclosed; they consist of warp and weft fibers which are superimposed on one another and are interconnected by a spiral binding fiber and these supports are slid between the individual layers of the membrane and the entire perimeter of the membrane strip is sealed with polyurethane sealant at the point of contact the inner space of the capsule divided into a blood and dialysate part, the capsule consisting of a dialysate part whose integral part is a mouthpiece for dialyzate inlet with an inlet dialysate chamber and a mouthpiece for dialysate outlet with an outlet dialysate chamber and on the other hand an integral part of the housing comprising a blood inlet with an inlet blood chamber and a blood outlet with an outlet blood chamber, characterized in that the dialysate half-shell (21) is provided with an inlet dialysate chamber (23) and an outlet dialysate chamber (24), having a width of 10 to 20 mm and a center distance of the chambers of 180 to 210 mm, while the relative distances and sizes of the inlet blood chamber (27) on the blood half-shell (20) and the inlet dialysate chamber (23) on the dialysate half-shell (21) are the same wherein the membrane (32) is anisotropic and has the following parameter values in the wet state, 8 8 in the direction of the major axis of elasticity Young's modulus of elasticity 1.6.10 to 1.9.10 Pa and shrinkage 0.9 to 1.1% and in the direction perpendicular to the major axis of elasticity Young's modulus of 1.2.10 ⁷ to 1.6.10 Pa and the 5 to 6% stretch, while the woven membrane support (33) has the warp fibers (12) parallel to each other. perpendicular to the major axis, the diaphragms (32) 1.6.10 ⁸ to 1.9.10 ⁸ Pa and the distance (t ^) of the diameter (d,) 0.001 to 1 mm satisfies the relation having the Young's modulus of elasticity of the weft threads (13) in the range where ^ť ú is the distance of the weft fibers in mm ^d ú is the diameter of the weft fibers in mm ^A 1 (2.26 to 2.68) (-0.53 to -0.41) mm ' ¹ wherein the total area of the membrane used is 1.4 to 1.5 m ² and the number of membrane supports (33) used is 75 to 85. Device according to claim 1, characterized in that the diameter (d _Q ) of the warp fibers (12) as a function of the selected diameter (d ^) of the weft fibers (13) satisfies a relation in the weft diameter (d ^) of 0.001 to 1 mm d _o = л ₂ а _й + в ₂ а ² where d _Q is the warp fiber diameter in mm d ^ is the weft fiber diameter in mm A ₂ (0.45 to 0.69) B ₂ (-0.074 to 0.15) mm ' 3. The device according to points 1 and 2 of the warp fulfills in relation to diameter, characterized in that the distance (t _Q ) of the weft fiber centers (12) (d ^) in the range of weft diameters (d ^) is 0.001 to 1 mm where t is distance of warp fibers in mm o d ^ is the diameter of the weft fibers in mm A ₃ (1.47 to 2.12) B ₃ (-0.53 to -0.71) A device according to any one of claims 1 to 3, characterized in that the warp comprises double warp threads (34), wherein the even or odd warp thread distance (34) is t _Q + d _Q where d _Q is the warp diameter and for warp distance t _Q is valid in the range of weft diameters from 0.001 to 1 mm relation where the distance of the warp fibers in mm is the diameter of the weft fibers in mm А ₃ (1.47 to 2.12) В ₃ (-0.71 to -0.53) mm “ ¹ 5. Apparatus according to claim 1, characterized in that the ratio of the diameter (d _Q) of fibers (12) to form a warp of the distance (TL) is equal to (3.0 to 3.1). Device according to claim 3 or 4 or 5, characterized in that in the region of the dialysate inlet (1) or outlet (5) or the blood inlet (2) or outlet (4), the woven membrane support (33) is provided with weft threads (33). 13) having a larger diameter (d ^) than the diameter (d ^) of the weft fibers (13) of the functional part (3). Device according to claim 3 or 4 or 5, characterized in that in the region of the dialysate inlet (1) or outlet (5) or the blood inlet (2) or outlet (4), the woven membrane support (33) is provided with weft fibers (13). ) having a smaller diameter (d ^) than the diameter (d ^) of the weft fibers (13) of the functional part (3). Device according to claim 3 or 4 or 5, characterized in that in the region of the dialysate inlet (1) or outlet (5) or the blood inlet (2) or outlet (4), the woven membrane support (33) is provided with weft fibers (13). ), wherein the distance (t t) between them is greater than the distance (t t) between the weft fibers (13) of the functional part (3). Device according to claim 3 or 4 or 5, characterized in that in the region of the dialysate inlet (1) or outlet (5) or the blood inlet (2) or outlet (4), the woven membrane support (33) is provided with weft fibers (13). ), wherein the distance (t t) between them is less than the distance (t t) between the weft fibers (13) of the functional part (3). Device according to Claim 3 or 4 or 5, characterized in that in the region of the dialysate inlet (1) or outlet (5) or the blood inlet (2) or outlet (4), the woven membrane support (33) comprises pressed weft fibers (33). 13). 6 drawings FIG