Background/Case Studies: Red cells develop storage induced damage which results in potassium (K+) leak and accumulation within the extracellular solution of the stored unit. Irradiation exacerbates this effect even further. At our pediatric hospital-based blood bank, a considerable number of irradiated red cell units are returned to the inventory and therefore might increase the risk of hyperkalemia in our patients. The aim of this experiment was to determine levels of K+ in different types of red cell units to help us determine how long to keep irradiated units in the inventory. This would prevent unnecessary waste of red cells and protect our most vulnerable patients from the risk of hyperkalemia.
Study
Design/Methods: Two aliquots were collected from nine fresh red cell units including: AS-1, AS-3, and CPDA. All those units were less than 7 days old. One aliquot from each unit was irradiated, while the other was left unaltered. Samples were collected from the aliquot bags every four hours from 0 to 28 hours. Samples were analyzed on a Radiometer ABL 835 Blood Gas Analyzer for whole blood K+ levels.
Results/Findings: Prior to the irradiation, at 0 hours, mean K+ level was 13.4 mmol/L (9.9 to 19.8 mmol/L) for AS1, 12.4 mmol/L (8.3 to 17.0 mmol/L) for AS3 and 19.7 mmol/L (17.6 to 22.9 mmol/L) for CPDA. Lowest level of K+ among non-irradiated fresh red cells was 8.0 mmol/L (AS3) at 4 hours and the highest level was 24.1 mmol/L (CPDA) at 28 hours. Lowest level of K+ among irradiated fresh red cells was 8.4 mmol/L (AS3) at 0 hours and the highest K+ level was > 25 mmol/L (exceeding the maximum level of instrument detection) reached at 8 hours in the CPDA unit. Conclusions: There is a significant variability in K+ levels between non-irradiated fresh red cells with the lowest K+ levels noted in AS3 and the highest in CPDA fresh red cell units. Irradiated CPDA red cells quickly reached high K+ level. This experiment confirmed what has been known that levels of K+ are higher in irradiated compared to non-irradiated red cell units. Additional studies are needed to determine acceptable levels of K+ in irradiated red cell units to protect against hyperkalemia.
Importance of research: This study is important because it evaluated changes in levels of potassium, over 28 hours period, in different types of fresh (less than 7 days old) RBCs post irradiation. Our policy requires issuing freshly irradiated RBCs. However, a considerable number of irradiated RBCs are returned to the blood bank. This experiment is important because it might help determine a way to prevent waste of irradiated rbc units and at the same time keep the most vulnerable pediatric patients safe.
