Is it time to draw such a conclusion concerning the use of washed donor blood during paediatric cardiopulmonary bypass?

Abstract

We read with great interest the recent retrospective series by Boks et al. [1]. The authors concluded that cell saver washing of packed red blood cells (RBCs) does not help prevent hyperkalaemia and hyperlactaemia during paediatric cardiopulmonary bypass (CPB) procedure. Consequently, they did not recommend routinely using this technique during paediatric CPB. However, there are some controversial issues concerning the use of washed RBCs during paediatric CPB: Swindell et al. [2] concluded that cell saver washing of packed RBCs helps prevent hyperkalaemia during CPB but does not prevent hyperlactaemia in paediatric patients; Liu et al. [3] concluded that the levels of potassium, blood glucose and lactate were significantly lower than in the unprocessed group at the beginning and end of CPB. Currently, although smaller circuits and oxygenators have been used for small children and neonates, it is difficult to avoid using donor blood during CPB. Moreover, packed RBCs are an essential part of the CPB priming solution to maintain sufficient oxygen supply in small children and neonates. The storage media in packed RBCs may cause significant acid-base, glucose and electrolyte imbalances, which have been implicated in the development of severe complications [4]. For providing better priming for paediatric patients, many measures have been implemented pre-CPB, such as cell saver and ultrafiltration. In the Boks et al. study, they did not find any benefit in using cell saver to process packed RBCs during CPB. They also suggested that an estimated addition of unwashed RBCs might increase the lactate, K and other measurable variables above acceptable levels. If not, however, pre-washing should not be applied under such specific CPB circumstances. We do not agree with Boks’ opinions. First, their conclusion was based on a retrospective study. Furthermore, they did not compare the results between the two groups regarding postoperative pulmonary function since another recent study [5] reported that washed blood transfusions in cardiac surgery reduced inflammatory biomarkers and may have an impact on post-operative pulmonary function. Consequently, it seems too early to draw such a conclusion based solely on this retrospective study. We think this issue is still under debate and requires a larger number of patients for further clinical investigation to prove whether paediatric patients are benefited by this clinical practice during paediatric CPB.