Blood cell washing systems and methods

DETAILED DESCRIPTION Systems and methods in accordance with the invention pass shed blood in successive serial or concurrent parallel stages through different rotary membrane filtration systems, at least one of which introduces a washing solution intermediately for mixture with a concentrate.
The stages employ Couette flow having enhanced Taylor vortices within a gap area disposed between relatively rotating generally cylindrical surfaces at least one of which includes a blood constituent filtering membrane.
The most used mode is a serial one, in which sufficient non-cellular and waste matter is passed through the membrane of a first filtration unit to raise the hematocrit from its input level (e.
g.
30) to the range of 50-60, despite variables that can exist in the blood being processed.
An input of substantially controlled properties, but still containing some waste matter, is thus applied to the second filtration unit.
Here the concentrate is again filtered, but it is also mixed with a larger amount of an isotonic solution that passes through the filter membrane, carrying with it dissolved molecular material and intracellular matter so as to achieve a final hematocrit in the range of 60-70 while having eliminated the great majority of waste material.
The vortices established in the gap constantly sweep the membrane surface throughout its length, while concurrently mixing the isotonic solution with the shed blood in an extremely efficient fashion.
The same filtration units can alternatively be employed in the parallel mode, with or without substantial cell washing, in emergency and other special situations.
A more specific example of a system and method in accordance with the invention provides automatic control during different modes of operation.
A pair of disposable units coupled serially by disposable tubing each utilize rotating spinners having covering filter membranes of less than about 1.
2 micron pore size and internal passageways leading to coaxial waste outlets.
The units are contained within small cylindrical housings that may be inserted readily into holders which rotate the spinners