GB1589735A

GB1589735A - Dialyzer and a method of dialysis

Info

Publication number: GB1589735A
Application number: GB5354/80A
Authority: GB
Original assignee: Bentley Laboratories Inc
Current assignee: Bentley Laboratories Inc
Priority date: 1976-07-23
Filing date: 1977-07-20
Publication date: 1981-05-20
Also published as: CA1092515A; BR7704847A; JPS5652584B2; DE2733280A1; JPS5331397A; GB1589734A; FR2358910A1; FR2358910B1; IT1114903B

Description

PATENT SPECIFICATION

( 11) f; ( 21) Application No 5354/80 ( 22) Filed 20 July 1977 > 2 ( 62) Divided out of No 1589734 c>^ ( 31) Convention Application Nos.

708 074 ( 32) Filed 23 July 1976 813455 7 July 1977 in ( 33) United States of Americ (US) ( 44) Complete Specification published 20 May 1981 ( 51) INT CL 3 B Ol D 13/00 A 61 M 1/03 ( 52) Index at acceptance Bl X 6 B 1 6 D 1 6 F 6 6 GX 6 J 5 6 L 2 ( 54) A DIALYZER AND A METHOD OF DIALYSIS ( 71) We, BENTLEY LABORATORIES, INC, a Corporation of the State of Delaware, United States of America, of 17502 Armstrong Avenue, Irvine, State of California, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

The present invention relates to a dialyzer and to a method of dialysis.

Kidney dialyzers function to remove toxic substance from the blood of patients suffering from renal failure The dialyzers are fabricated with semipermeable membranes and dialysis is accomplished by flowing blood along one side of the membrane and a dialysate solution along the other side During the dialyzing process, metabolites such as urea, uric acid, creatine, phosphorus and calcium in the blood diffuse from the blood to the dialysate solution through the membrane due to the lower concentration of metabolites in the dialysate solution.

The present invention provides a helical flow dialyzer comprising:

a dialyzer housing disposed about a central core, said core including a tubular dialysate inlet and a tubular dialysate outlet, both said dialysate inlet and outlet being provided with a'plurality of apertures and being joined by a cylindrical section of said central core for preventing dialysate flow through said cylindrical portion and for forcing dialysate radially through said apertures of said dialysate inlet and outlet; an annular blood inlet chamber and an annular blood outlet chamber formed within said dialyzer housing about said tubular dialysate inlet and outlet, respectively, said inlet chamber having a tangential inlet nozzle and said outlet chamber having a tangential outlet nozzle; and a belt made up of similarly helically oriented semipermeable tubules, wrapped about said central core, opposed ends of said tubule belt being secured in a annular ring of potting compound formed about a portion of said dialysate inlet and outlet such that said dialysate inlet and outlet apertures are located within an enclosure formed by said dialyzer housing, said central core and said annular potting rings, said annular rings forming a portion of said blood inlet 55 and blood outlet chambers, said ends of said tubules passing through said annular rings for communication with said blood inlet and outlet chambers.

The helical orientation of the tubules 60 ensures expansion and contraction of the tubules in a substantially uniform manner thereby minimising masking of the gaps between the tubules.

Advantageously, the packing density (as 65 hereinafter defined) of the tubules, is between substantially 20 % and 50 % and is preferably between 25 % and 35 % This reduced packing density allows for more uniform distribution of the fluid passing out 70 side the tubules.

The present invention further provides a method of waste containing blood flow dialysis comprising:

tangentially admitting blood into a dial 75 yzer blood inlet chamber; passing said blood from said blood inlet chamber into and through a plurality of similarly helically oriented semipermeable tubules packed in a cavity between the dial 80 yzer housing and a central dialyzer core; passing blood wastes through the walls of said tubules into a dialysate; passing the treated blood from said tubules into a dialyzer blood outlet 85 chamber; longitudinally restraining said tubules between said dialyzer blood inlet chamber and said blood outlet chamber; tangentially removing said treated blood 90 from a dialyzer blood outlet chamber;' radially distributing the dialysate about the exterior of said tubules at one end of the cavity; passing in a generally helical manner said 95 dialysate along the exterior of said tubules; and radially removing said dialysate and blood wastes from said dialyzer at the other end of the cavity 100 1 589 735 1 589 735 A dialyser constructed in accordance with the invention, and a method dialysis performed in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings in which:Figures 1 and 3 are partial cross-sectional views illustrating the dialyser constructed in accordance with the invention.

Figure 2 is a pictorial view illustrating the method of construction of the dialyser shown in Figure 1.

Figure 4 is a schematic drawing illustrating the tubule configuration of a prior art dialyser.

Figure 5 is a schematic drawing illustrating the tubule configuration of the dialyser shown in Figures 1 to 3.

Figure 6 is an enlarged partial crosssectional view illustrating part of the dialyser shown in Figures 1 to 3 and 5, and Figure 7 is a partial cross-sectional view of a bundle of tubules which serves to illustrate the definition of the term "packing density" as used herein.

Referring now to Figure 1, the blood dialyzer, generally referred to as 1, and its method of operation will be discussed The dialyzer 1 includes a dialyzer housing 3 disposed about a central core 5 The core 5 has a dialysate inlet 7 and a dialysate outlet 9.

The dialysate inlet 7 and outlet 9 are provided with a plurality of apertures 11 and 13, respectively, positioned adjacent a point where the dialysate inlet and outlet abut a cylindrical section 15 of the central core 5 which prevents the dialysate flow from passing through the cylindrical portion 15 of the central core 5 and forces the dialysate to flow radially outwards through apertures 11 at the inlet 7 and radially inwards into apertures 13 prior to exiting the dialyzer 1 at the dialysate outlet 9.

The dialyzer 1 is further defined as including a tangential blood inlet 17 and a tangential blood outlet 19 A blood inlet chamber 21 is formed between the dialyzer cap 4, the exterior of the tubular dialysate inlet 7 and a suitable potting compound 23 within which a number of hollow fiber tubules 25 are secured The tubules are formed of semipermeable material such as that sold under the registered trade marks "Cuprophane" or "Cellophane" Similarly, the annular blood outlet chamber 27 is bounded by a dialyser cap 6, the exterior of the tubular portion of the dialysate outlet 9 and potting compound 23 within which the tubules 25 are secured adjacent the blood outlet chamber 27.

The housing, central core, caps and dialysate inlet and outlet means may be formed from a suitable plastics material such as polycarbonate.

As shown in Figure 2, a plurality of similarly curved and spirally oriented semipermeable hollow fiber tubules 25 are wrapped about the central core 5 such that their opposed ends may be secured in an annular ring of potting compound 23 The 70 front and rear ends of the tubules 25 are preferably manufactured such that they have a rounded edge in order to prevent blood trauma upon entrance and exit from the dialyzer 1 75 The thickness of the annular ring of layers of tubules 25 increases as the wrapping continues, and consequently the tubules 25 nearer the central core 5 are spiralled more than those more toward the outside of the 80 wrap This produces a nonparallel tubule relationship which increases flow shear as between adjacent layers of tubule wrap and promotes dialysate distribution and flow about the tubules 25 and transfer across the 85 tubules.

Dialysate outlet apertures 11 are thus positioned between a front face 29 of the cylindrical portion 15 of the central core 5 and the annular ring of potting compound 90 23 Similarly, the dialysate outlet apertures 13 are positioned between a rear face 31 of the cylindrical portion 15 of the central core and the annular ring of potting compound 23 located at the blood outlet of the tubules 95 25.

A compression means such as an inner flange 33 is positioned near the juncture of the dialysate inlet apertures 11 and the central core cylindrical portion 15 in order to 100 increase the packing density of the tubules in the area of the compression means.

The tubules 25 are separated from each other and having a packing density of between 20 % and 50 %, and preferably bet 105 ween 25 % and 35 % The packing density of the tubules at the flange means 33 is greater than that of the packing density of the balance of the tubules' length, and may be, for example, 90 % or as high as 100 % 110 Referring now to Figure 7, the term "packing density" as utilized in this disclosure will be explained Figure 7 shows a plurality of tubules 25 arranged in contiguous relationship such that each tubule is touch 115 ing the other tubules adjacent it Such a configuration produces a number of voids designated as 50 in Figure 7, due to the generally round configuration of the tubules 25.

If the tubules are compressed beyond the 120 configuration of Figure 7, the tubules will be deformed Accordingly, the contiguous relationship illustrated in Figure 7 is defined as illustrating a packing density of 100 % The packing densities referred to in this disclos 125 ure are defined relative to the 100 % packing density configuration shown in Figure 7.

Referring now to Figures 2 and 3, the method of making such a dialyzer will be discussed A plurality of tubules 25 are con 130 1 589 735 figured in a mat or belt 35 wherein the individual tubules 25 have fiber 37 interwoven within the tubules 25 in order to maintain their lateral spacing The belt or mat 35 is then wrapped about the central core 5 and a cylinder 39 having an external diameter approximately equal to that of the cylindrical portion 15 of the core 5 The tubules may be held in place temporarily by means of an adhesive strip 34 Member 39 is held in place about the tubular portion of the dialysate inlet by means of a keyway slot 41 which engages a key 43 along exterior of the tubular dialysate inlet 7 As shown in Figure 3, a cap member (not shown) may then be placed about each end of the dialyzer 1 engaging the ends of the tubules 25 A potting compound is then inserted into and about the area surrounding the tubules 25 between the cap members and the exterior of the tubular dialyzer inlet and outlet 7 and 9, respectively Preferably, the potting compound consists of a liquid resin (for example, polyurethane) which sets upon exposure to air and/or heat The dialyzer assembly 1 is then rotated about its transverse axis in order to urge the potting compound through centrifugal force to each end of the dialyzer assembly 1 After the potting compound has set, the ends of the assembly are partially cut as shown by line 47 in order to produce the outward faces 49 and 51 of the annular rings of potting compound 23 The ends of the tubules may then be heat set or chemically polished to create a smooth surface around their openings and a rounded entry.

The caps 4 and 6 are then positioned at the ends of the housing.

Referring now to Figures 4 and 5, the advantages of the curved configuration of the tubules 25 will be discussed in detail.

Figure 4 shows a number of tubules secured at each end in a configuration typical of a prior dialyzer construction The dotted lines indicate possible movement of the tubules upon expansion In contrast, Figure 5 illustrates movement due to expansion, again shown as dotted lines, of tubules which are arranged in a curved configuration As may be seen in Figure 5, each of the tubules expands in the same direction due to the fact that the tubules are predisposed to move in such a direction by means of the initial curvature of the tubules While Figures 4 and 5 illustrate movement in two planes, it is to be understood that the spiral or helix configuration of the tubules 25 as shown in Figures 1 and 2 produce a three-dimensional predetermined configuration and allow for the tubules to move in expansion or contraction in a predetermined spaced apart relationship.

In operation, blood enters the inlet chamber 21 via the tangential inlet 17, passes into and along the tubules 25, and out of the tangential outlet 19 via the chamber 27.

The tangential inlet 17 and outlet 19 ensure that a gentle and uniform swirling movement is imparted to the blood in the chambers 21 and 27 respectively thereby prevent 70 ing the formation of clots which can be caused by turbulence The openings 11 and 13 ensure that the dialysate solution is introduced radially into the spaces between the tubules 25 and exit radially from those 75 spaces As the dialysate solution passes through the restricted opening produced by the increased packing density of the tubules in the region of the flange 33 it is evenly distributed around the tubules, this even dis 80 tribution being maintained as it flows along the remaining length of the tubules The helical orientation of the tubules causes a gentle mixing or churning action of the blood in the tubules and the dialysate solution out 85 side the tubules and facilitates transfer of metabolites from the blood to that solution.

As described above both the blood and dialysate solution flow along the length of the tubules in the same direction (that is to 90 say, from left to right) It is also possible, in a counter-flow dialyser for the dialysate solution and blood to flow in opposite directions, for example if the dialysate solution enters via the openings 13 and exits via the 95 openings 11, and, in that case, the flange 33 would be provided at the right-hand end of the tubules.

Claims

No protection is claimed herein for any

method or process of treating a human 100 being to cure or prevent disease.

The dialyser described and illustrated above is also described and illustrated in the Complete Specification of our co-pending British Patent Application No 18230/77 105 (Serial No 1589734) to which attention is directed.

Subject to the foregoing disclaimer, WHAT WE CLAIM IS:1 A helical flow dialyzer comprising: 110 a dialyzer housing disposed about a central core, said core including a tubular dialysate inlet and a tubular dialysate outlet, both said dialysate inlet and outlet being provided with a plurality of apertures and being 115 joined by a cylindrical section of said central core for preventing dialysate flow through said cylindrical portion and for forcing dialysate radially through said apertures of said dialysate inlet and outlet; 120 an annular blood inlet chamber and an annular blood outlet chamber formed within said dialyzer housing about said tubular dialysate inlet and outlet, respectively, said inlet chamber having atangential inlet noz 125 zle and said outlet chamber having a tangential outlet nozzle; and a belt made up of similarly helically oriented semipermeable tubules, wrapped about said central core, opposed ends of 130 1 589 735 said tubule belt being secured in a annular ring of potting compound formed about a portion of said dialysate inlet and outlet such that said dialysate inlet and outlet apertures are located within an enclosure formed by said dialyzer housing, said central core and said annular potting rings, said annular rings forming a portion of said blood inlet and blood outlet chambers, said ends of said tubules passing through said annular rings for communication with said blood inlet and outlet chambers.
2 A helical flow dialyzer as claimed in claim 1, wherein said tubules have a packing density (as hereinbefore defined) of between 20 % and 50 %.
3 A helical flow dialyzer as claimed in claim 2, wherein the packing density is between 25 % and 35 %.
4 A method of waste containing blood flow dialysis comprising:

tangentially admitting blood into a dialyzer blood inlet chamber; passing said blood from said blood inlet chamber into and through a plurality of similarly helically oriented semipermeable tubules packed in a cavity between the dialyzer housing and a central dialyzer core; passing blood wastes through the walls of said tubules into a dialysate; passing the treated blood from said tubules into a dialyzer blood outlet chamber; longitudinally restraining said tubules between said dialyzer blood inlet chamber and said blood outlet chamber; tangentially removing said treated blood from a dialyzer blood outlet chamber; radially distributing the dialysate about the exterior of said tubules at one end of the cavity; passing in a generally helical manner said dialysate along the exterior of said tubules; and radially removing said dialysate and blood wastes from said dialyzer at the other end of the cavity.

ABEL & IMRAY, Chartered Patent Agents, Northumberland House, 303-306 High Holborn, London WC 1 V 7 LH.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1981 Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A 1 AY, from which copies may be obtained.