Comparison of methods to wash liquid-stored red blood cells and red blood cells frozen with high or low concentrations of glycerol.

The efficiency of washing liquid-stored red blood cells and red blood cells frozen with high or low glycerol concentrations was evaluated by measuring the recovery of red blood cells in vitro, supernatant hemoglobin, extracellular potassium and red blood cell potassium levels, supernatant osmolality, residual 125I albumin, glycerol, hypoxanthine, and di-2-ethylhexyl phthalate (DEHP) levels. Four commercial washing systems were studied, three which used sodium chloride solutions with serial or continuous-flow centrifugation and one which used sugar solutions and dilution/agglomeration. Washing was most efficient using sodium chloride solutions in the IBM Blood Processor, an automated serial centrifugation procedure and in the Fenwal Elutramatic, a continuous-flow centrifugation procedure. Less efficient washing was achieved in the Haemonetics Processor 15, a continuous-flow centrifugation procedure and the least efficient washing occurred using the original and modified dilution/agglomeration procedures. To achieve the most efficient washing, three principles must be utilized: concentration of the red blood cells to hematocrit values of 90 per cent, prior to washing or freezing. Liquid-stored red blood cells concentrated to hematocrit values of 90V per cent should be diluted with hypertonic sodium chloride solutions prior to recovery and washing. Red blood cells containing 20 per cent or 40 per cent W/V glycerol should be diluted with hypertonic sodium chloride solutions before recovery and washing. Finally, on-line dilution should be achieved in the washing systems that use continuous-flow centrifugation.