Apheresis red blood cells associated with repeated hemolysis during blood priming of the Cellex Photopheresis System

Extracorporeal photopheresis (ECP) in young pediatric patients has a risk for procedural hypotension and anemia due to extracorporeal fluid shifts. A standard mitigation policy in these patients is to prime the device with packed red blood cells (RBC) or whole blood. We now report multiple episodes of hemolysis while attempting to prime the Therakos Cellex in a pediatric transplant patient undergoing a course of ECP for severe graft-vs-host-disease. Over the course of 40 ECP treatments, hemolysis was observed on five occasions. An extensive investigation found an association between hemolysis and apheresis RBC (A-RBC). Of 46 RBC units dispensed for blood priming, hemolysis occurred with 22% (4 of 18) of A-RBC and accounted for 80% (4 of 5) of all hemolysis episodes. Hemolysis was significantly higher with A-RBC when compared with RBC collected by whole blood donations (WB-RBC: 3.5% [1 of 28]; P = .049). A comparison of RBC attributes, including unit age, showed that hemolyzed A-RBC units tended to be younger than both nonhemolyzed RBC (6.5 vs 10.3 days, P = .018) and WB-RBC (8.5 days, P = .10). We hypothesize that A-RBC may exhibit "sublethal" RBC damage following prior exposure to centrifugal shear and negative forces at the time of collection, leading to a decrease in RBC deformability and increased susceptibility to hemolysis. This is the first report showing an increased susceptibility to hemolysis with A-RBC during priming of the Cellex.