In-line filtration of autologous whole blood

Experimental data suggest that autologous white blood cells (WBCs) might exert an immunomodulatory effect. Leukodepletion of autologous blood is considered to prevent this unwanted side effect of autologous transfusion. In some cases, however, prolonged filtration or filtration failures occur. Because such autologous units cannot simply be discarded, the interest was in the storage variables of autologous whole blood (AWB) units after prolonged filtration.

AWB of patients undergoing orthopedic surgery was leukodepleted before storage or left unmodified. Filtration times, volume, WBC count, hemoglobin level, hemolysis, potassium, and ATP were determined in all units with filtration times of more than 60 minutes that had not been transfused by the time of expiry and in representative samples of units that had been filtered normally or that had not been filtered.

In AWB filtration, the rate of prolonged filtrations or filter blockades is three to four times higher than in allogeneic whole-blood filtration. Filtration or prolonged filtration leads to a mean loss of red blood cell (RBC) mass of 7.3 or 18.2 percent, respectively. Even in units with filtration times of more than 3 hours, storage variables were not significantly different from normally filtered or unfiltered units. Filtration times showed a high intraindividual correlation.

Leukodepletion of AWB results in a diminished preoperative deposit of RBCs that is pronounced in units with prolonged filtration. The quality of the latter suggests that it is not justified to discard AWB units with prolonged filtration times. Prolonged filtrations are related to patient characteristics that have yet to be defined.