Hyperkalaemia during massive blood transfusion in paediatric craniofacial surgery

Children undergoing major craniofacial surgery (MCFS) often require transfusion in excess of one blood volume. Therefore they were the subject of a retrospective review which looked at the longitudinal trend of plasma potassium concentration [K+] during surgery. Ten of eleven children had a statistically significant increase in plasma potassium concentration during their intraoperative course and in five the potassium concentration exceeded 5.5 mmol.L-1. This was in contrast to the stable intraoperative plasma [K+] observed in a control group which did not receive blood transfusion. All MCFS children received a blood transfusion with red blood cell concentrates (RBCconc). The age of the units of RBCconc which had been transfused was 16.1 +/- 8.4 days. The amount of extracellular potassium in 28 units of RBCconc was determined in order to estimate the amount of free potassium (Kdose) which the MCFS group received. The plasma [K+] in units of RBCconc less than 1 week of age was less than 20 mmol.L-1, whereas in units aged greater than 2 weeks it was greater than 40 mmol.L-1. The estimated Kdose was 0.2-1.6 mmol.kg-1. We concluded that the amount of extracellular potassium in units of RBCconc was clinically important and may give rise to hyperkalaemia during massive blood transfusion.