Blood fractionating process and apparatus for carrying out same

Abstract

A process for separating blood plasma from whole blood that dispenses with the known centrifugal-separation techniques and involves passing whole blood along a flow path which is shallow and substantially parallel to the upstream side of filtration membrane, recovering plasma from the downstream side of said membrane, and recovering the retained blood components (formed elements) from the upstream side of the membrane. .Iadd.

We claim: .[.1. Apparatus constructed and arranged to carry out a separation of whole blood into a plasma fraction and a cellular fraction, said apparatus comprising 
     
        the piston of said hypodermic syringe..]. 5. A process for separating blood plasma from the other components of blood .Iadd.without substantial hemolysis .Iaddend.comprising the steps of (1) conducting whole blood in a flow path which is substantially parallel to the upstream side of a filtration membrane and has a maximum depth of 20 mils measured vertically from the face of the membrane, said membrane having a pore size from about 0.1 to about 0.8 micron in diameter,   (2) applying sufficient pressure to said whole blood to cause .Iadd.a .Iaddend.pressure differential from 1 to 15 p.s.i. between upstream and downstream sides of said membrane and to provide a flow velocity across the face of the membrane from 2 to 50 feet per minute,   (3) recovering plasma ultrafiltrate from the downstream side of said membrane, and   (4) recovering the retained blood components from the upstream side of the membrane.Iadd., said plasma ultrafiltrate being substantially free of evidence of     
     
     
        hemolysis.Iaddend.. 6. A process as defined in claim 5 wherein said filtration membrane has a pore size from about 0.4 to about 0.7 micron in 
     
     
        diameter. 7. A process as defined in claim 6 wherein the pressure 
     
     
        differential is from 2 to 5 p.s.i. 8. In a process for removing whole blood from a blood donor and returning the blood constituents to the donor while keeping the plasma for medical use, the improvement consisting of (1) transferring said whole blood from said donor into contact with the upstream side of filtration membrane having a pore size from about 0.1 to about 0.8 micron in diameter,   (2) conducting said whole blood across the surface of the membrane in a path which is substantially parallel to the upstream side of said membrane and has a maximum depth of 20 mils measured vertically from the face of the membrane,   (3) applying sufficient pressure to said whole blood to provide a pressure differential of 1 to 15 p.s.i. between upstream and downstream sides of said membrane and to provide a flow velocity across the face of the membrane from 2 to 50 feet per minute, and   (4) recovering the retained blood components from the upstream side of the membrane and transferring them back to the blood donor.Iadd., said plasma being removed from the downstream side of said membrane and being substantially free of evidence of hemolysis.Iaddend..