Blood cell washing systems and methods

• US 5,053,121 A
• Filed: 11/29/1989
• Issued: 10/01/1991
• Est. Priority Date: 08/11/1986
• Status: Expired due to Term

• Current Assignee: Baxter International Inc.
• Original Assignee: Baxter International Inc.
• Inventors: Williamson, Lee H., Schoendorfer, Donald W.
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US07/443,550
• Time in Patent Office: 671 Days
• Field of Search: 210/639, 210/651, 210/321.64, 210/321.68, 210/321.87, 210/335, 210/90, 210/360.1, 210/382, 210/96.2
• US Class Current: 210/90
• CPC Class Codes: A61M 1/265 inducing Taylor vortices
• CPC Class Codes: A61M 1/34 Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
• CPC Class Codes: A61M 1/3403 Regulation parameters
• CPC Class Codes: A61M 1/3601 Extra-corporeal circuits in which the blood fluid passes more than once through the treatment unit
• CPC Class Codes: A61M 1/3692 Washing or rinsing blood or blood constituents
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/50 with microprocessors or computers

Abstract

A system and method for cleaning contaminants from shed blood to enable reinfusion of a cell concentrate in the patient employs successive rotary membrane filtering stages in which Taylor vortices are generated. Shed blood led into the first rotary membrane stage is filtered to produce a hematocrit in the range of 50-60 with some of the waste matter being removed. The intermediate cell concentrate is passed to the second filter stage where further waste matter is initially extracted. At any intermediate region, however, a major amount of wash solution is fed into the concentrate and effectively mixed therein. In the remaining length of the second filter stage, waste matter is entrained in the wash solution and both waste and wash solution are filtered out to provide a cell concentrate from which the great majority of contaminants have been removed.

Claims

1. A system in which shed blood containing contaminants is processed to a red cell concentrate having reduced contaminants, said system comprising:

first filter means for receiving the shed blood and passing it longitudinally through a gap which extends adjacent a first filtration membrane of less than 1.2 micron pore size, the first filter means providing a filtered waste product and an intermediate cell concentrate product;

fluid flow control means receiving the intermediate cell concentrate product and providing a buffer supply thereof; and

second filter means coupled to the fluid flow control means for receiving the intermediate cell concentrate product and passing it longitudinally through a gap which extends adjacent a second filtration membrane of less than 1.2 micron pore size, wherein the second filter means is for mixing a saline solution with the intermediate cell concentrate within the gap to provide a washed red cell concentrate.

2. The system as set forth in claim 1, wherein the first filter means provides an intermediate cell concentrate product having hematocrit in the range of 50-60 and the second filter means provides a washed red cell concentrate having hematocrit in the range of 60-70.

3. The system as set forth in claim 1, wherein the second filter means has an active length for filtering action and wherein the saline solution is added at an intermediate position along the active length.

4. The system as set forth in claim 3, wherein the first and second filter means each comprise rotating membrane means within a cylindrical shell and having diameters, interior spacing and rotational velocities selected to establish Taylor vortex flows within the gap without causing hemolysis therein, and means for extracting filtrate from the rotating membrane means.

5. The system as set forth in claim 4, wherein the second filter means includes:

spaced apart input and output cell fluid ports coupled to the interior spacing between the rotating membrane; and

a saline solution input port longitudinally disposed between the input and output blood ports.

6. The system as set forth in claim 5 further including:

means providing controllable intermediate cell concentrate flow to the second filter means;

means providing controllable saline solution flow to the second filter means;

means for monitoring transmembrane pressure across the membrane in the second filter means; and

means responsive to increases in the transmembrane pressure of the second filter means for controlling the blood flow and saline solution flow in the second filter means so as to backflush the filter membrane with saline solution.

7. The system as set forth in claim 6, wherein the system further includes:

a cardiotomy reservoir coupled to provide shed blood input to the first filter means;

hemoglobin detector means coupled to indicate the hemoglobin concentration in the filtrate from the first filter means; and

means responsive to the detected hemoglobin indication for varying the flow rate of saline solution to the second filter means relative to an input flow of intermediate cell concentrate.

8. The system as set forth in claim 1, wherein the system further includes:

means for varying the flow rate of the saline solution so as to vary the washed red cell concentrate output flow rate.

9. The system as set forth in claim 1, wherein the system further includes:

means for controllably recirculating washed red cell concentrate through the second filter means.

10. The system as set forth in claim 1 further including:

means for alternatively directing shed blood through the first and second filter means in parallel.

11. The system set forth in claim 1, wherein said second filter means induces Taylor vortices within the gap to accelerate the mixing of said saline solution with said intermediate cell concentrate.

12. A disposable apparatus for use in washing and filtering blood constituents, said apparatus comprising:

a cardiotomy reservoir for temporary storage of input blood constituents;

a first rotatable filter coupled to receive fluid from said cardiotomy reservoir;

a pooling reservoir coupled to receive filtration concentrate from said first rotatable filter; and

a second rotatable filter having an input coupled to receive filtration concentrate from said pooling reservoir, and having a washing solution inlet for receiving a washing solution and coupling the washing solution into mixing relationship with the received filtration concentrate.

13. The disposable apparatus as set forth in claim 12 further comprising:

a first controllable diverter valve disposed to selectably couple fluid between said cardiotomy reservoir and said first filter and between said cardiotomy reservoir and the input of said second filter; and

a second controllable diverter valve disposed to selectably couple fluid between said first filter and said pooling reservoir and between said first filter and an alternate cell concentrate output line.

14. The disposable apparatus as set forth in claim 12 further comprising waste conduit means connected to collect and pass filtrate output from said first and second filters.

15. The system set forth in claim 12, wherein said second rotatable filter induces Taylor vortices within the gap to accelerate the mixing of said saline solution with said intermediate cell concentrate.

16. A disposable apparatus for use in washing and filtering blood constituents, said apparatus comprising:

a first rotatable filter having a fluid input for receiving blood to be washed and filtered, a filtrate output and a cell concentrate output;

a second rotatable filter having a fluid input, a filtrate output, a cell concentrate output and a washing liquid input disposed intermediate said fluid input and said cell concentrate output;

the cell concentrate output of said first filter being in fluid communication with the blood fluid input of the second filter.

17. The disposable apparatus as set forth in claim 16 wherein:

said first and second rotatable filters each comprise a longitudinally extending annular gap area between relatively rotatable generally cylindrical surfaces, at least one of which includes a blood constituent filtering membrane; and

said washing fluid input is disposed relatively closer to the fluid input of the second filter than to the cell concentrate output thereof.

18. The system set forth in claim 16, wherein said second rotatable filter induces Taylor vortices within the gap to accelerate the mixing of said saline solution with said intermediate cell concentrate.

19. A blood constituent washing and filtering apparatus, comprising:

a rotatable, generally cylindrical, blood constituent filtering membrane disposed within a stationary housing and defining a longitudinally extending annular gap therebetween in which Couette fluid flow, having Taylor vortices, can be established;

a fluid inlet port to said gap;

a fluid concentrate outlet port from said gap being longitudinally spaced apart from said fluid inlet port;

a washing solution inlet port to said gap longitudinally disposed intermediate said fluid inlet port and said fluid concentrate port and closer to said fluid inlet port than to said fluid concentrate output port.

20. The system as set forth in claim 19, wherein said rotatable filtering membrane induces Taylor vortices within the gap to accelerate the mixing of said saline solution with said intermediate cell concentrate.