Blood processing chamber counter-balanced with blood-free liquid

Abstract

Blood processing systems and methods rotate a processing chamber on a rotating element. The processing chamber includes a first compartment and a second compartment. Blood is conveyed into the first compartment for centrifugal separation into components. A liquid free of blood occupies the second compartment to counter-balance the first compartment during rotation on the rotating element. In one embodiment, the second compartment is served by a single fluid flow access. Prior to use, the single access is coupled to tubing, through which a vacuum is drawn to remove air from the second compartment. While the vacuum exists, communication is opened between the tubing and a source of liquid. The vacuum draws the liquid into the second compartment through the single access, thereby priming the second compartment for use.

We claim:  
     
         1 . A blood processing system comprising 
 a rotating element,    a processing chamber on the rotating element for common rotation with the rotating element, the processing chamber including a separation compartment for receiving whole blood for centrifugal separation into components, the separation compartment including an inlet region where whole blood enters for separation into packed red blood cells, a plasma constituent, and an interface carrying platelets between the packed red blood cells and the plasma constituent, and    a controller for the rotating element operable in a control mode to convey whole blood into the separation compartment for centrifugal separation into components, the controller including an interface control unit operative (i) in a first condition to retain platelets in the processing chamber to enable removal of platelet-poor plasma and packed red blood cells from the processing chamber, and (ii) in a second condition to enable removal of platelets from the processing chamber enabling removal of platelet-rich plasma and packed red blood cells from the processing chamber.    
     
     
         2 . A system according to  claim 1   wherein the interface control unit includes a sensing element to locate the interface in the separation compartment and provide a sensed output.    
     
     
         3 . A system according to  claim 2   wherein the sensing element optically locates the interface in the separation compartment.