Split red blood cell units contain defined extracellular K levels, which are improved by a washing procedure.

Background And Objectives: We should control free K during massive transfusion (>80 mL/kg) of red blood cells (RBCs) in small children. To manage this, several national and international guidelines recommend using RBCs stored only up to 7 days. We tested a washing step for RBCs in saline-adenine-glucose-mannitol (SAGM) with or without irradiation to reduce supernatant K levels, improve quality and potentially extend the shelf life of stored RBCs.