2. Clinical Laboratory, Tokyo Metropolitan Bokutoh Hospital, Tokyo, Japan.
Introduction: Red blood cell (RBC) transfusion places preterm infants with non-oliguria at high risk of cardiac arrest due to hyperkalemia. Potassium adsorption filters (PAFs) can remove potassium from RBCs. The typical protocol for use of PAFs in Japan involves priming the filter with 200 mL of saline and filling the filter with saline However, the resulting dead volume (approximately 80 mL) is unnecessary in preterm infants, because the blood is diluted with saline. As transfusion volumes are generally ~10 mL, small volume-separated packs (30~80 mL each) are prepared for preterm infants. However, we are unable to use PAFs in small volume-separated packs due to the dead volume. In this study, we examined the effects of saline-filled and saline-removed methods of PAFs on the removal of potassium from RBCs.
Methods: The experiments used expired RBCs from our hospital. RBC potassium, lactate dehydrogenase (LD) and free hemoglobin (markers of erythrocyte damage) were measured by Biomedical Laboratories and compared with levels of RBCs passed through a PAF (KPF-1, Kawasumi Laboratories Incorporated). After priming PAFs with 200 mL of saline, saline was filled (method A) or was removed (method B) before use of the PAF. This study was supported by a grant from the Tokyo Metropolitan Government.
Results: The percent removal of potassium from the RBC for method A (89~93%) was similar to that of method B (95~98%). LD and free hemoglobin levels in method A were lower than those in method B. However, the increased LD and free hemoglobin levels were similar to those of transfusion filters. Potassium in the small volume-separated pack was completely removed by method B.
Discussion: The effects of saline-filled and saline-removed methods of PAF usage on the removal of potassium from RBC were similar, with little erythrocyte damage. These data suggest that PAF might be used for small volume-separated packs in the neonatal ward.
Keywords: Donor exposure, neonate transfusion, hyperkalemia