US3612281A

US3612281A - Parallel membranous layer type fluid diffusion cell

Info

Publication number: US3612281A
Application number: US6015A
Authority: US
Inventors: Ronald James Leonard
Original assignee: Baxter Laboratories Inc
Current assignee: OMNIS SURGICAL Inc A DE CORP
Priority date: 1968-03-11
Filing date: 1970-01-26
Publication date: 1971-10-12
Anticipated expiration: 1988-10-12

Abstract

A fluid diffusion cell having a diffusion membrane folded to define a first set and a second set of oppositely opening pockets. Each pocket in both sets contains a support member, and a pair of manifolds are provided to provide a fluid inlet and outlet at opposite ends of each of said sets of pockets to permit fluid to pass from each inlet into one end of each of the pockets of one set, to pass through each of the pockets and the outlet.

Description

United States Patent Inventor Ronald James Leonard Elk Grove Village, 111. Appl. No. 6,015 Filed Jan. 26, 1970 Division of Ser. No. 712,066, Mar. 11, 1968, Pat. No. 3,560,340. Patented Oct. 12, 1197 1 Assignee Baxter Laboratories, llnc.

Morton Grove, 1111.

PARALLEL MEMBRANOUS LAYER 'llYlPE lFLUllD DIFFUSION CELL 14 Claims, 9 Drawing Figs.

US. Cl 210/321, 23/2585 Int. Cl A6lm l/03, B01d 13/00 Field of Search 195/18; 210/22, 23; 23/2585 References Cited UNITED STATES PATENTS 3,396,849 8/1968 Lande et a1. 23/2585 X 3,413,095 11/1968 Bramson 23/2585 3,503,850 3/1970 Dibelius 23/2585 X 3,318,747 5/1967 Presser et a1 156/204 OTHER REFERENCES William G. Esmond et al.; Profound Hypothermia With Simplified Equipment: A Disposable Stainless Steel Heat Exchanger of High Efficiency Journal of Thoracic and Cardiovascular Surgery; Vol. 42, No. 5, Nov. 1961; pp. 563- 574 (Copy in 23/2585) Primary Examiner-Morris O. Wolk Assistant Examiner-Barry S. Richman Attorneys walter C. Kehm, Richard J. Reilly and W.

Garrettson Ellis ABSTRACT: A fluid diffusion cell having a diffusion membrane folded to define a first set and a second set of oppositely opening pockets. Each pocket in both sets contains a support member, and a pair of manifolds are provided to provide a fluid inlet and outlet at opposite ends of each of said sets of pockets to permit fluid to pass from each inlet into one end of each of the pockets of one set, to pass through each of the pockets and the outlet.

PATENTEDncnzusn SHEET 3 0F 3 Mayan-ran EON/1L0 J LEO V4190 3,6l2,2bl

lfAllltAlLlLlElL MllilltllhhANUlUS LAifhllt TYPE ll' 'lUUlllllr lllllllilflldlltllhl lClElLlL This application is a division of application, Ser. No. 712,066, filed ll/lar. ll, 1968.

The present invention relates to fluid diffusion devices in which material transfer occurs across a selectively permeable membrane disposed between first and second fluids. Particularly the invention relates to a diffusion cell for oxygenating or dialyzing blood by fluid passage through a laminous structure, such as that which is provided by a continuous folded or pleated selectively permeable membrane.

As heretofore known device of the class with which the present invention is concerned dialyzes blood through an unsupported flexible folded membrane which provides a plurality of parallel flow paths for blood along one face of the membrane and a plurality of countercurrent flow paths for dialyzing fluid along the other face of the membrane. The device is adapted for blood and dialyzing fluid which are moved intermittently and reciprocally by pumping them alternately and countercurrently. in consequence thereof the poclrets formed along one face of the membrane fill while the poclrets formed along the other face of the membrane empty. The device is itself an effective pump and requires valving for fluid flow in a manner intended. As a result of the constantly alternating condition of the membrane thereto incident variation in blood treatment results. Moreover, because of the required lack of rigidity in the membrane, the likelihood of generating short circuits of the regular paths through the device give rise to an inherent hazard of inadequate blood treatment.

An object of the present invention is the provision of an improved fluid diffusion device of the laminated membrane type for treating blood.

Another object of the invention is to ensure uniform fluid flow through a blood oxygenator or blood dialyzer of the designated class.

An additional object of the invention is to improve the oxygen and carbon dioxide exchange characteristics in a fluid diffusion cell.

To effect the foregoing objects, a fluid diffusion cell with a laminated selectively permeable membrane structure has a plurality of oppositely opening pockets which define a pair of sets of parallel flow paths along corresponding surfaces of the laminae of said structure. A fluid inlet member and a fluid outlet member are associated with each set of parallel paths for introducing therein and removing therefrom blood and other fluid separated each from the other by said laminae. A rigid support member is disposed in each pocket for filming therein therethrough flowing fluid, and maximizing fluid contact with said laminae.

How to further accomplish the foregoing and other objects, features and advantages of the invention will become more apparent upon consideration of the following description and appended claims, when considered in conjunction with the accompanying drawings wherein the same reference character or numeral refers to like or corresponding parts throughout the several views.

On the drawings:

lFlG. l is a perspective view of a diffusion cell embodying the present invention.

FIG. 2 is a view according to the section line 2-2 of FIG. ll.

FIG. 3 is a view according to section line 3-3 of FlG. 2, spacer-screens having been omitted for the purpose of illustration.

FllG. i is an enlarged view of a section according to the line d-d of H6. 2.

FIG. 5 is a perspective view of a folded membrane comprising the diffusion cell.

FIG. ti is a perspective view of one type of spacer-screen comprising the diffusion cell.

F lG. 7 is a perspective view of another type of spacer-screen comprising said diffusion cell.

FIG. fl is a perspective of a manifold for supplying fluid in said diffusion cell viewed from one aspect.

FIG. 9 is a perspective of said manifold viewed from another aspect.

Referring now more particularly to the drawings, a fluid diffusion cell generally designated ll0 (FllG. l) is illustrated herein as a device for treating a body fluid such as blood. For the purpose of orientation, cell llll may be considered as hav ing a top end portion H, a bottom end portion lid, a front face lit, a thereto parallel bacl: face (not shown) and opposed lateral sides, being a blood side lb and a side 26 for another fluid.

Cell 10 comprises a laminated membranous structure having parallel laminae which may be formed by the courses of a preferably flexible and selectively permeable membrane 22 (MG. 5). The latter is folded or pleated to provide a first set 2d of pockets ZdA, 243, 241C, Z illD and ME which open outwardly toward the blood side lb, and a second set 28 of pockets NM, 28B, 28C and 28D which open outwardly toward the other side 20. The pockets of each set define parallel flow paths along corresponding surfaces of the laminae.

Membrane 22 is fabricated preferably of a biologically inert base, such as a mesh of fiber glass or Dacron about 0.005-inch thiclr. Over the latter there is applied a very thin cover of an elastomer, preferably silicone rubber, sufficient only to fill the spaces defined by the mesh; In a preferred process for the cell, membrane 22 is pleated into oppositely directed membranous courses or layers to form uniformly dimensioned pockets about a plurality of rectangular parallel forming plates (not shown). The latter are supported in horizontal array for separating adjacent courses or pleats by about 0.040 inch. Thereafter, the top edge portions 32 of the pleats forming top end portion 112 of cell and the bottom edge portions 34 of the pleats forming bottom end portion M of said cell are sealed together in fixed and spaced-apart relationship with a sealing material 30. In consequence, sealed top and bottom ends of said pockets are formed. An MTV silicone rubber provides a suitable sealing material and imparts reasonable rigidity to top and bottom end portions l2 and lid of the cell. Rubber sealing is preferred to metal ties and preformed sealing components because its use minimizes production costs.

The structure thus formed enables separation of blood and another fluid for flow in respective parallel flow paths along corresponding faces of the membranous laminae by which such fluids are completely separated. in consequence of the foregoing, the flow of blood can be confined to the pockets of one set {herein set M) and the flow of the other fluid can be confined to the pockets of the other set (herein set 2%). When cell llti) is an oxygenator, as shown herein, the other fluid will be oxygen. However, the device is not limited to oxygenators and may be employed with equal effect as a dialyzer. In that event the other fluid would be a dialyzing liquid.

After sealing the top and bottom end portions l2 and M, the rectangular forming plates (not seen) are withdrawn from the pockets. Thereafter, a support member as of a first type, and herein comprising a spacer-screen which is substantially the same height and width as a pocket and of rectangular profile, is inserted into each of the oxygen pockets (the pockets of set 28). A support member of a second type, and herein comprising a spacer-screen 3b which is of a rectangular profile and about the seam width as a pocket but shown as being shorter than the same, is inserted into each of the blood pockets (the pockets of set 24).

Spacer-screen 36 has a top section dill, a bottom section d2, a medial section as, opposed lateral side portions M and 46, and a top surface 48. Spacer-screen 3% has a top portion 50, a bottom portion 52, opposed

lateral side portions

54 and 56, and a top surface 5%. The length and width of each last spacerscreen is substantially the same as the corresponding dimensions of a medial section 66. Each pocket has the same height and width as the others; and as illustrated in FIG. 2, which shows the interior of a blood pocket, each pocket is characterized by an upper end portion 60, a thereto opposed lower end portion 62 and a medial portion rid. While each spacerscreen 36 extends substantially the entire length (between top and bottom) of the pocket in which it is disposed, each spacerscreen 338 is proportioned for disposition only in the medial portion 6 3 of its pocket and extends neither into the associated top portion 60 nor into bottom portion 62. In the illustrated embodiment, although the depth of each pocket (distance between adjacent laminae) preferably is 0.040 inch, immediately after setting as aforesaid, the depth of each spacer-screen 38 is 0.020 inch. On the other hand, medial section 66 of each spacer-screen 36 is 0.060 inch while its top and

bottom end sections

40 and 42, which are substantially of the same length are 0.020 inch. By reason of the foregoing spacerscreen 36 can be considered as having an enlarged medial section or reduced end sections.

Each spacer-screen 36 may be a mesh of fiber glass fabrication covered with vinyl of a thickness insufficient to mask its screen character. Each spacer-screen 38, on the other hand, preferably is of plastic fabrication, fashioned from low density polyethylene by extrusion.

In lieu of spacer-screens, a pair of rectangular rigidifying elements 72 and 74 (FIG. 4) may be inserted or disposed in

pockets

24A and 24E. These members preferably are about 0.020 inch thick and of an area for filling their pockets. They are of any suitable construction, such as fiber glass reinforced with phenolic plastic.

A pair of preferably like structured manifolds, only one of which is shown in FIGS. 8 and 9, comprise a blood manifold 75 and an oxygen manifold 76. They respectively are mounted on

cell sides

18 and 20. Each manifold has a pair of spacedapart, top and bottomlike proportioned, inlet and outlet, end receptacles or

wells

80 and 82 which are connected together by an integral medial section 84. Each inlet well 80, together with an inlet duct 88 comprises inlet means whereas each outlet 82 together with an outlet duct 90 comprises outlet means. Moreover, each manifold has, (1) a pair of parallel front and rear walls 78, the opposite top and bottom portions of which define the front and rear faces of said wells, and (2) a pair of parallel top and bottom walls 79 which define the top and bottom, respectively, of

wells

80 and 82. Furthermore, medial section 84 of each manifold has an inwardly ofiset flat surface 81 which together with

walls

78, 78 and

walls

79, 79 define a chamber of trough 83 for reception of an associated side of the folded membrane with therein disposed spacer-screens. The parts are proportioned so that (l) the

walls

78, 78 of each manifold, on its respective side, engage front and rear surfaces of the folded membrane, (2)

walls

79, 79 of each manifold engage the seals 30 at the top and bottom of the membrane, and (3) each flat surface 81 engages against the medial section of its associated side of the pockets, when the cell is assembled. In such condition all adjoining surfaces are secured together, preferably with an RTV material for sealing silicone rubber from which the manifolds preferably are fabricated.

As a result of the foregoing, the inner surface 81 of manifolds 75 is secured along side 18 to the

folds defining pockets

28A, 28B, 28C and 28D and closes the medial sections of the openings of the pockets of set 24 toward side 18 while leaving the upper and

lower end portions

60 and 62 of said last pockets arranged in immediate fluid communication with

wells

80 and 82 of said last manifold. Similarly, inner surface 81 of manifold 76 is secured along side 20 to the folds of

pockets

24A, 24B, 24C, 24D and 24E, and closes the medial sections of the openings of the pockets of set 28 toward side 20 while leaving the upper and

lower portions

60 and 62 of said last pockets arranged in immediate fluid communication with

wells

80 and 82 of the last-mentioned manifold.

The illustrated cell is adapted for supplemental and support oxygenation of blood. To that end, the blood inlet and outlet means are adapted for connection to the circulatory system of an individual to be serviced, respectively, for receiving and for returning blood from and to such individual without the assistance of an auxiliary pump. The parts in each blood pocket are arranged for moving blood according to directional arrows (FIG. 2) from blood inlet well 80, at which the upstream end or opening of each blood pocket immediately is disposed, along the upper portion 60 of such pocket and therefrom downstream through a corresponding lower portion 62 for return from blood outlet well 82 at which the downstream end or opening of each pocket immediately is disposed. The oxygen manifold 76 and oxygen pockets (of set 28) may be similarly arranged for flow in its pockets. However, in a dialyzer flow of blood and the other fluid preferably will be in countercurrent paths.

As illustrated in FIG. 4, the opposite surfaces of each spacer-screen is engaged by an adjoining lamina. This arrangement results in the development of a pair of enlarged opposed channels having end openings and defined in each blood pocket at its upper and

lower end portions

60 and 62. These openings are disposed for immediate communication with blood inlet and outlet means of manifold 75; and the channels herein are about 0.060 inch in depth and extend across the top and bottom of the cell from side to side adjacent seals 30. They provide resistance of no practical significance whereby blood entering the cell rapidly flows across the tops of all of the blood pockets and the flow of blood leaving is not needlessly impeded. The depth of the medial portion 64 of each blood pocket is limited to 0.020 inch, the depth of its blood spacer-screen, against which a pair of laminae are held by the medial sections 66 of adjacent spacer-screens 36. This causes the blood to be spread in a very thin film, as a consequence of which, oxygen exchange, which is a function of blood film thickness, is exceedingly rapid.

The cell is constructed so that almost maximum oxygenation can occur with laminae of minimum total surface area in sections 64 of the blood pockets and while maintaining desired output of blood introduced under blood pressure of an individual being treated. Such surface area, however, is inadequate for liberation of all the CO from normal venous blood. Additional surface area required for adequate CO elimination from the blood is provided by the sections of the laminae which define

end portions

60 and 62 of the blood pockets. An efficient cell has an exchange surface area in the

channel portions

60 and 62 of the blood pockets which is not less than about 15 percent of the exchange surface area of the blood-filming portions of the cell.

In the oxygen pockets adjacent the blood channels a plurality of canals 92 (FIG. 4), which extend from side to side parallel to the blood channels, develop at the front and back of

screen sections

40 and 42 because of the depth of said screen sections and the spacing of the lamina whose top and bottom edges are anchored in fixed relationship. Canals 92 form easy entries into and exits from the oxygen pockets and are disposed at respective oxygen inlet and

outlet wells

80 and 82.

In addition to providing great efficiency in oxygenating and dialyzing blood, the invention enables construction of a cell at substantially less cost than related heretofore known devices of the same type. This last feature is highly significant in facilitating widespread enjoyment of the invention.

As many substitutions or changes could be made in the above-described construction and process and as many apparently widely different embodiments of the invention within the scope of the claims could be constructed without departing from the scope and spirit thereof, it is intended that all matter contained in the accompanying specification shall be interpreted as being illustrative and not in a limiting sense.

What is claimed is:

l. A fluid difiusion cell, including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, the improvement comprising first fluid inlet means and first fluid outlet means in communication with the first set of pockets and located at the mouths thereof, and second fluid inlet means and second fluid outlet means in communication with the second set of pockets and located at the mouths thereof, each inlet and outlet means having an enlarged external chamber, open to the mouths of each pocket of a set, to provide flow paths to each pocket of approximately equal length, a medial member between each inlet and outlet means pressing against the mouths of said pockets to force fluid to flow into and through said pockets while passing from each inlet to each outlet means, the first and second sets of pockets defining separate parallel flow paths for respective fluids, and a support member disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the length of said flow paths in the pockets being greater than the dimension of said fluid diffusion cell which is perpendicular to said laminae.

2. The diffusion cell of claim 1 in which said support members in the pockets comprise screens made of a mesh of crossing strands.

3. The fluid diffusion cell of claim l in which said diffusion membrane comprises a mesh over which is applied a thin cover of silicone rubber sufficient to fill the spaces of said mesh.

4. The diffusion cell of claim 3 in which said support membars in the pockets comprise screens made of a mesh of crossing strands.

5. The fluid diffusion cell of claim 4 in which end portions of the fluid diffusion cell are sealed with an elastomeric sealant.

6. The fluid diffusion cell of claim 5 in which one of said sets of pockets receives blood while the other of said sets of pockets receives oxygen.

7. A fluid diffusion cell including a selectively permeable diffusion membrane, folded to form laminae defining altemately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, manifold means in communication with the first and second sets of pockets and located at the mouths thereof to feed and withdraw fluid in a flow path through said pockets, and support members disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the support members in the pockets of said first set extending the entire length of said pockets, while the support members in the pockets of the second set terminate short of the ends of said pockets, whereby unobstructed channels are defined in the ends of the pockets of the second set.

8. A combination according to claim 7 in which each support member in the pockets of one set is of substantially uniform thickness and has opposite faces in contact with adjoining laminae, and each support member in the pockets of said other set has an enlarged medial section and opposed smaller end sections, said medial section and smaller end sections having opposite faces in contact with adjoining laminae for forming said channels.

9. A blood oxygenator including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, manifold means in communication with the mouths of each of the first and second sets of pockets to feed and withdraw blood and oxygen in separate flow paths, each through a separate set of pockets, and a support member disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, in which portions of said support members adjacent the ends thereof are of reduced aggregate thickness, to provide a portion of said blood flow path of increased thickness in contact with said membrane and oxygen flow path, whereby blood flowing through said blood flow path portion of increased thickness is conditioned for relatively increased carbon dioxide diffusion through said membrane, while along the portions of said support members remote from the ends thereof, blood is conditioned for relatively increased oxygen diffusion through said membrane.

110. The blood oxygenator of claim 9 in which said diffusion membrane comprises a mesh over which is applied a thin cover of silicone rubber sufficient to fill the spaces of said mesh.

1111. The blood oxygenator of claim 9 in which said support members comprise screens made of a mesh of crossing rand H2. The blood oxygenator of claim 9 in which the exchange surface area of said flow path portions of increased thickness is not less than 15 percent of the exchange surface area of the remaining flow path portions within said pockets.

113. A fluid diffusion cell, including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, the improvement comprising first fluid inlet means and first fluid outlet means in communication with the first set of pockets and located at the mouths thereof, and second fluid inlet means and second fluid outlet means in communication with the second set of pockets and located at the mouth thereof, each inlet and outlet means hav ing an enlarged external chamber, open to the mouths of each pocket of a set, to provide flow paths to each pocket of approximately equal length, a medial member between each inlet and outlet means pressing against the mouths of said pockets to force fluid to flow into and through said pockets while passing from each inlet to each outlet means, the first and second sets of pockets defining separate parallel flow paths for respective fluids, and a support member disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the length of said flow paths in the pockets being greater than the dimension of said fluid diffusion cell which is perpendicular to said laminae, said selectively permeable diffusion membrane comprising a meshlike support element of biologically inert material, in which the interstitial spaces defined by the meshlike support element are filled with a thin film of selectively permeable elastomer material.

141. The fluid diffusion cell of claim 113 in which said support members in the pockets comprise screens made of a mesh of crossing strands.

Claims

1. A fluid diffusion cell, including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, the improvement comprising first fluid inlet means and first fluid outlet means in communication with the first set of pockets and located at the mouths thereof, and second fluid inlet means and second fluid outlet means in communication with the second set of pockets and located at the mouths thereof, each inlet and outlet means having an enlarged external chamber, open to the mouths of each pocket of a set, to provide flow paths to each pocket of approximately equal length, a medial member between each inlet and outlet means pressing against the mouths of said pockets to force fluid to flow into and through said pockets while passing from each inlet to each outlet means, the first and second sets of pockets defining separate parallel flow paths for respective fluids, and a support member disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the length of said flow paths in the pockets being greater than the dimension of said fluid diffusion cell which is perpendicular to said laminae.

3. The fluid diffusion cell of claim 1 in which said diffusion membrane comprises a mesh over which is applied a thin cover of silicone rubber sufficient to fill the spaces of said mesh.

4. The diffusion cell of claim 3 in which said support members in the pockets comprise screens made of a mesh of crossing strands.

7. A fluid diffusion cell including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, manifold means in communication with the first and second sets of pockets and located at the mouths tHereof to feed and withdraw fluid in a flow path through said pockets, and support members disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the support members in the pockets of said first set extending the entire length of said pockets, while the support members in the pockets of the second set terminate short of the ends of said pockets, whereby unobstructed channels are defined in the ends of the pockets of the second set.

10. The blood oxygenator of claim 9 in which said diffusion membrane comprises a mesh over which is applied a thin cover of silicone rubber sufficient to fill the spaces of said mesh.

11. The blood oxygenator of claim 9 in which said support members comprise screens made of a mesh of crossing strands.

12. The blood oxygenator of claim 9 in which the exchange surface area of said flow path portions of increased thickness is not less than 15 percent of the exchange surface area of the remaining flow path portions within said pockets.

13. A fluid diffusion cell, including a selectively permeable diffusion membrane, folded to form laminae defining alternately positioned first and second sets of pockets, the first set of pockets opening at the opposite side of the membrane to the second set of pockets, the improvement comprising first fluid inlet means and first fluid outlet means in communication with the first set of pockets and located at the mouths thereof, and second fluid inlet means and second fluid outlet means in communication with the second set of pockets and located at the mouth thereof, each inlet and outlet means having an enlarged external chamber, open to the mouths of each pocket of a set, to provide flow paths to each pocket of approximately equal length, a medial member between each inlet and outlet means pressing against the mouths of said pockets to force fluid to flow into and through said pockets while passing from each inlet to each outlet means, the first and second sets of pockets defining separate parallel flow paths for respective fluids, and a support member disposed in each of said pockets for holding adjacent laminae apart from each other and for providing flow paths of predetermined thickness, the length of said flow paths in the pockets being greater than the dimension of said fluid diffusion cell which is perpendicular To said laminae, said selectively permeable diffusion membrane comprising a meshlike support element of biologically inert material, in which the interstitial spaces defined by the meshlike support element are filled with a thin film of selectively permeable elastomer material.

14. The fluid diffusion cell of claim 13 in which said support members in the pockets comprise screens made of a mesh of crossing strands.