Influence of storage on red blood cell rheological properties.

Growing evidence shows that transfusion of stored red cells may well harm patients. Studies are therefore necessary in order to help establish the reasons for this negative effect. Decrease of deformability of red cells during storage may be one explanation. Reduced perfusion of the capillary bed may be the consequence of reduced deformability of red cells. Berzina et al., by means of micropore filtration technique, have shown a decrease of the deformability index during storage ― this decrease was already significant after 2 weeks. However, what does it really mean when red cells have to be washed three times and suspended in phosphate buffered saline supplemented with dextrose, bovine serum albumin, etc., before filtration? The conclusion may be that RBCs show decreased tolerance against these extensive manipulations. It is doubtful whether the observed changes can be transferred to the in-vivo situation. Additionally, no detailed information is given about which red cell preparations (with or without buffy coat, which additive solution, etc.) were investigated. Finally, 7% hemolysis at the end of storage is far too high. The European guidelines allow 0.8% hemolysis at the end of storage time. Therefore, the paper is of little value in answering an urgent and current question.

– V. Kretschmer.