Patent ID: 6059979
Filing Date: 2000-05-09
Classification: A61M,B01D,B04B

Abstract:
A blood processing system comprisinga centrifugal separation device rotatable about a rotational axis at a controlled rate of rotation, the separation device having an area A,an inlet path operable to convey whole blood at a determinable rate Q.sub.b into the separation device for separation into red blood cells and a plasma constituent, the whole blood in the inlet path having an actual whole blood hematocrit value, the red blood cells in the separation device having an actual red blood cell hematocrit value,an outlet path operable to remove plasma constituent from the separation device at a determinable rate Q.sub.p at least in part while whole blood is conveyed into the separation device,an outlet path operable to remove red blood cells from the separation device at least in part while whole blood is conveyed into the separation device and plasma is removed from the separation device,a controller including a stage operable to derive a value H.sup.rbc representing an apparent hematocrit of red blood cells within the separation device at least in part while whole blood is conveyed into the separation device and plasma and red blood cells are removed from the separation device, where:H.sub.rbc =f(Q.sub.b,Q.sub.p,A,g,RBC)where:g represents a centrifugal acceleration factor based upon the controlled rate of rotation, andRBC represents at least one red blood cell dependent factor not including the actual red blood cell hematocrit value,the controller including a stage operable to derive a value H.sub.b representing an apparent hematocrit of whole blood entering the separation device at least in part while whole blood is conveyed into the separation device and plasma and red blood cells are removed from the separation device, based upon a relationship among H.sub.rbc, Q.sub.b, Q.sub.p, and not including the actual whole blood hematocrit value, expressed as follows: ##EQU44## and the controller including a stage operable to generate a control command at least in part while whole blood is conveyed into the separation device and plasma and red blood cells are removed from the separation device, based, at least in part, upon H.sub.b.