Method of manufacturing a blood oxygenation system

• US 5,753,173 A
• Filed: 10/02/1996
• Issued: 05/19/1998
• Est. Priority Date: 10/25/1993
• Status: Expired due to Fees

• Current Assignee: Terumo Cardiovascular Systems Corporation (Terumo Corporation)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Maurer, David B., Viitala, Daniel W., Lindsay, Erin J., Leonard, Ronald J.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): GRAY, ROBIN SCOTT
• Application Number:
  US08/725,015
• Time in Patent Office: 594 Days
• Field of Search: 264/250, 264/503, 264/270, 264/512, 264/516, 264/138, 264/263, 156/292, 156/308.4, 156/309.9
• US Class Current: 264/503
• CPC Class Codes: A61M 1/1625 Dialyser of the outside perfusion type, i.e. blood flow outside hollow membrane fibres or tubes
• CPC Class Codes: A61M 1/1629 with integral heat exchanger
• CPC Class Codes: A61M 1/1698 Blood oxygenators with or without heat-exchangers intracorporal A61M1/1678; manufacturing of membranes therefor B01D67/00; semi-permeable membranes for separation processes characterised by their properties B01D69/00; semi-permeable membranes characterised by their material B01D71/00
• CPC Class Codes: A61M 1/3621 Extra-corporeal blood circuits single-needle circuits A61M1/30
• CPC Class Codes: A61M 1/3623 Means for actively controlling temperature of blood
• CPC Class Codes: A61M 1/3627 Degassing devices; Buffer reservoirs; Drip chambers; Blood filters
• CPC Class Codes: A61M 1/3632 Combined venous-cardiotomy reservoirs
• CPC Class Codes: A61M 2209/082 Mounting brackets, arm supports for equipment
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/232 Centrifugal pumps
• CPC Class Codes: A61M 60/279 Peristaltic pumps, e.g. roller pumps
• CPC Class Codes: A61M 60/38 Blood oxygenation
• CPC Class Codes: A61M 60/851 Valves
• CPC Class Codes: B01D 2313/221 Heat exchangers
• CPC Class Codes: B01D 2313/50 Specific extra tanks
• CPC Class Codes: B01D 63/02 Hollow fibre modules
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A novel integral cardiotomy/venous blood reservoir, blood oxygenator and heat exchanging device, method of making a blood oxygenating and heat exchanging device and an extracorporeal circulatory support circuit. The reservoir includes a novel blood defoaming and filtering chamber closely receiving filtering and defoaming media. The blood oxygenating and heat exchanging device includes thermal formed housing portions, and a heat exchanging barrier, blood oxygenating medium and/or filtering medium, which are sealed by potting compound at one time. The oxygenating medium comprises a hollow fiber type medium, with its ends left open to be sealingly mounted in a gas path by a novel mounting bracket.

Claims

1. A method of forming an integral blood oxygenating and heat exchanging apparatus, the method comprising the following steps:

(a) providing a separation medium for separating blood and gas while allowing oxygen and carbon dioxide transfer across the separation medium, the separation medium having opposite ends;

(b) providing a heat exchanging barrier for keeping blood and heat exchanging fluid separate while allowing heat transfer therebetween and across the heat exchanging barrier, the heat exchanging barrier having opposite ends;

(c) thermal forming at least one sheet of thermoplastic material to form a housing for receiving the separation medium and the heat exchanging barrier with the opposite ends of the separation medium and the heat exchanging barrier generally adjacent and generally aligned, the step of thermal forming at least one sheet of thermoplastic material including;

(I) forming potting channels in the at least one sheet of thermoplastic material for directing uncured potting compound adjacent the opposite ends of the separation medium and the heat exchanging barrier; and

(ii) forming at least one overflow reservoir having a depth-defining inlet positioned in fluid communication with a corresponding one of said potting channels to define a depth of the potting compound adjacent the opposite ends of the separation medium and the heat exchanging barrier;

(d) placing the separation medium and the heat exchanging barrier between the at least one sheet in side-by-side relationship;

(e) sealing at least one sheet together to form an assembly comprising the housing, the separation medium and the heat exchanging barrier;

(f) placing the assembly in a centrifuge;

(g) spinning the assembly in the centrifuge around a substantially vertical axis of rotation with the opposite ends of the separation medium and the heat exchanging barrier along opposite sides of the axis of rotation;

(h) inserting a sufficient volume of uncured potting compound into each of said potting channels while the assembly is spinning in the centrifuge so that some of the uncured potting compound flows from each of said potting channels into and along overflow reservoir inlets extending radially inward toward said axis of rotation, said uncured potting compound flowing from each of said overflow reservoir inlets into a corresponding one of said at least one overflow reservoir such that the depth of the uncured potting compound adjacent the opposite ends of the separation medium and the heat exchanging barrier forms a parabolic curve defined by the depth-defining inlets;

(I) allowing the uncured potting compound to solidify and cure while continuing said spinning of the assembly in the centrifuge to form a solidified potting compound; and

(j) cutting the at least one sheet of thermoplastic material and the solidified potting compound to expose the opposite ends of the separation medium and the heat exchanging barrier;

the steps of providing the separation medium and the heat exchanging barrier include positioning the opposite ends of the separation medium and the heat exchanging barrier so that the opposite ends of the separation medium and the heat exchanging barrier will be at a sufficiently equal depth within the potting compound relative to the parabolic curve.

2. The method according to claim 1 further comprising providing a kiln surrounding the centrifuge;

and

during the steps (g), (h) and (i), heating the assembly in the kiln during the step of spinning.

3. The method according to claim 2 wherein the step of thermal forming said at least one sheet of thermoplastic material to form the housing further comprises vacuum forming the at least one sheet of thermoplastic material on a vacuum mold.

4. The method according to claim 3 further comprising:

forming a generally tubular metal barrier having a lumen open at said opposite ends to form the heat exchanging barrier having open opposite ends; and

placing an end cap in each of the open opposite ends of the heat exchanging barrier before the step of spinning the assembly in the centrifuge.

5. The method according to claim 4, wherein the step of cutting the at least one sheet of thermoplastic material and the solidified potting compound includes cutting off or removing at least one said end cap from the heat exchanging barrier in one integral operation.

6. The method according to claim 4 wherein the step of cutting comprises cutting off or removing at least one said end cap from the heat exchanging barrier after the uncured potting compound cures and solidifies.

7. A method according to claim 3 wherein the step of sealing the at least one sheet of thermoplastic material together comprises heat sealing the at least one sheet of thermoplastic material together.

8. The method according to claim 2 further comprising the step of providing a filtering medium for filtering blood;

wherein the step of placing the separation medium and the heat exchanging barrier between the at least one sheet of thermoplastic material further including placing the filtering medium between the at least one sheet of thermoplastic material;

wherein the step of sealing the at least one sheet of thermoplastic material together to form an assembly comprising the housing, the separation medium and the heat exchanging barrier further comprising heat sealing the at least one sheet of thermoplastic material together to form an integral assembly comprising the housing, the separation medium, the heat exchanging barrier and the filtering medium.

9. The method according to claim 8 further comprising the step of pleating the filtering medium before the step of placing the filtering medium between the at least one sheet of thermoplastic material.

10. The method according to claim 1 wherein the housing defines an environment outside the housing, the method further comprising the step of leaving the opposite ends of the separation medium and the heat exchanging barrier open to the environment outside the housing after the step of cutting the at least one sheet of thermoplastic material and solidified potting compound.

11. A method of forming a blood oxygenating apparatus comprising the following steps:

(a) providing a hollow fiber bundle comprising hollow fibers having walls for separating blood and gas while allowing oxygen and carbon dioxide transfer across the walls of the hollow fibers, the hollow fiber bundle having opposite ends;

(b) providing a housing for receiving the hollow fiber bundle, the housing having;

(I) potting channels for directing uncured potting compound adjacent the opposite ends of the hollow fiber bundle; and

(ii) at least one overflow reservoir for each of said potting channels, each said at least one overflow reservoir having a depth-defining inlet positioned in fluid communication with one of the potting channels to define a depth of the uncured potting compound adjacent the opposite ends of the hollow fiber bundle;

(c) placing and sealing the hollow fiber bundle within the housing to form an assembly;

(d) placing the assembly in a centrifuge;

(e) spinning the assembly in the centrifuge around an axis of rotation with the opposite ends of the hollow fiber bundle along opposite sides of the axis of rotation;

(f) inserting a sufficient volume of said uncured potting compound into the potting channels during the step of spinning the assembly such that some of the uncured potting compound flows from each of said potting channels into and along overflow reservoir inlets extending radially inward toward said axis of rotation, said uncured potting compound flowing from each of said overflow reservoir inlets into a corresponding one of said at least one overflow reservoir such that the depth of the uncured potting compound adjacent each of the opposite ends of the hollow fiber bundle is defined by the depth-defining inlet;

(g) allowing the uncured potting compound to solidify and cure during the step of spinning the assembly to form a solidified potting compound; and

(h) cutting the housing, the solidified potting compound and the hollow fiber bundle to expose the opposite ends of the hollow fibers.

12. The method according to claim 11 further comprising the following step:

providing a heat exchanging barrier for keeping blood and heat exchanging fluid separate while allowing heat transfer therebetween and across the heat exchanging barrier, the heat exchanging barrier having opposite ends;

wherein the step (c) of placing and sealing the hollow fiber bundle within the housing to form an assembly further comprising placing and sealing the heat exchanging barrier within the housing; and

wherein step (f) further includes sealing between the heat exchanging barrier and the housing with the uncured potting compound inserted through the potting channels.

13. The method according to claim 12 further comprising:

forming a generally tubular metal barrier having a lumen open at said opposite ends to form the heat exchanging barrier having open opposite ends; and

placing an end cap in each of the open opposite ends of the heat exchanging barrier before the step of spinning the assembly in the centrifuge.

14. The method according to claim 13 wherein the step (h) of cutting the housing, the solidified potting compound and the hollow fiber bundle includes cutting off or removing at least one said end cap from the heat exchanging barrier in one integral operation.

15. The method according to claim 13 wherein the step of cutting comprises cutting off or removing at least one said end cap from the heat exchanging barrier after the uncured potting compound cures and solidifies.

16. A method of forming a blood oxygenation apparatus comprising the following steps:

(a) providing a hollow fiber bundle comprising hollow fibers having walls for separating blood and gas while allowing oxygen and carbon dioxide transfer across the walls of the hollow fibers, the hollow fiber bundle having opposite ends;

(b) providing a housing for receiving the hollow fiber bundle, the housing having;

(I) potting channels for directing uncured potting compound adjacent the opposite ends of the hollow fiber bundle; and

(ii) at least one overflow reservoir for each of said potting channels, each said at least one overflow reservoir having a depth-defining inlet positioned in fluid communication with one of the potting channels to define a depth of the uncured potting compound adjacent the opposite ends of the hollow fiber bundle;

(c) placing and sealing the hollow fiber bundle within the housing to form an assembly;

(d) placing the assembly in a centrifuge;

(e) spinning the assembly in the centrifuge around a substantially vertical axis of rotation with the opposite ends of the hollow fiber bundle along opposite sides of the axis of rotation;

(f) inserting a sufficient volume of said uncured potting compound into the potting channels during the step of spinning the assembly such that some of the uncured potting compound flows from each of said potting channels into and along overflow reservoir inlets extending radially inward toward said axis of rotation said uncured potting compound flowing from each of said overflow reservoir inlets into a corresponding one of said at least one overflow reservoir such that the depth of the uncured potting compound adjacent each of the opposite ends of the hollow fiber bundle forms a parabolic curve defined by the depth-defining inlet;

(g) allowing the uncured potting compound to solidify and cure during the step of spinning the assembly to seal the opposite ends of the hollow fiber bundle in the housing to form a solidified potting compound; and

(h) cutting the housing, the solidified potting compound and the hollow fiber bundle to expose the opposite ends of the hollow fibers.

17. The method according to claim 16 further comprising the following step:

providing a heat exchanging barrier for keeping blood and heat exchanging fluid separate while allowing heat transfer therebetween and across the heat exchanging barrier, the heat exchanging barrier having opposite ends;

wherein the step (c) of placing and sealing the hollow fiber bundle within the housing to form an assembly further comprising placing the heat exchanging barrier within the housing side-by-side with the hollow fiber bundle such that the opposite ends of the heat exchanging barrier will be positioned at a substantially equal depth within the uncured potting compound relative to the parabolic curve and to the depth of the opposite ends of the hollow fiber bundle relative to the parabolic curve, and sealing the heat exchanging barrier within the housing; and

the step (f) further includes sealing between the heat exchanging barrier and the housing with the uncured potting compound inserted through the potting channels.

18. The method according to claim 17 further comprising:

forming a generally tubular metal barrier having a lumen open at said opposite ends to form the heat exchanging barrier having open opposite ends; and

placing an end cap in each of the open opposite ends of the heat exchanging barrier before the step of spinning the assembly in the centrifuge.

19. The method according to claim 18 wherein the step (h) of cutting the housing, the solidified potting compound and the hollow fiber bundle includes cutting off or removing at least one said end cap from the heat exchanging barrier in one integral operation.

20. The method according to claim 18 wherein the step of cutting further comprising the step of cutting off or removing at least one said end cap from the heat exchanger barrier after the potting compound cures and solidifies.