[Storage-induced rheologic and biochemical changes in erythrocyte concentrates with added solution and possible correlations].

Rheological integrity is one of the essentials for red blood cells (rbc) in capillary circulation. The influences of metabolical/biochemical changes of rbc on their rheological properties are well known, but (to our knowledge) until now there are no published studies, which cover both quality aspects of packed rbc (prbc) in additive solutions. According to our standard operating procedures (SOP) we prepared prbc in additive solution (SAG-M) and plasma from 16 regular blood donations. The buffy coat was discharged. Following parameters were measured on day 1, 14 and 28: extracellular pH, ATP and 2,3-DPG content of rbc, prbc-viskosity, -filterability, -aggregability and filter clogging rate. For examination of the filterability a 5% rbc-suspension in phoshate buffered solution was prepared, the remaining tests were performed with rbc-samples adjusted to a hematokrit of 40% with fresh frozen autologous plasma. In correlation with the depletion of ATP a decrease of rbc flexibility and changes of shape (for example spherocytosis) are well known from the literature. Our results confirm the assumed time dependent deterioration of rheological patterns of prbc in SAG-M, reflecting in an increase of rbc-viscosity and filter clogging rate and a decrease of rbc-filterability and -aggregability. We also observed the expected decrease of pH, ATP and 2,3-DPG during storage. The influences of biochemical changes on rheological alterations are discussed. Therefore we recommend on demand rheological examinations in addition to metabolical/biochemical analyses for an extended quality assurance program, for instance for testing new additive solutions or major changes of SOP.