Lower limit of adequate oxygen delivery for the maintenance of aerobic metabolism during cardiopulmonary bypass in neonates

Abstract Background The objective of cardiopulmonary bypass (CPB) is to maintain an adequate balance between oxygen delivery (Ḋo2) and consumption. The critical Ḋo2 is that at which consumption becomes supply dependent. This study aimed to identify the critical Ḋo2 in neonates, who have higher metabolic rates than adults. Methods In a retrospective cohort of neonates, Ḋo2 was calculated from CPB parameters recorded during aortic cross-clamping. High lactate concentration measured after aortic unclamping (lactOFF) was used to identify anaerobic metabolism. Data were analysed using mixed linear and proportional odds regression models. The relationship between Ḋo2 and temperature was analysed in a subgroup of patients with lactOFF Results Overall, 22 896 time points were analysed in 180 neonates. In 40 patients with lactOFF Conclusions It was found that 340 ml min−1 m−2 is likely to represent the lowest suitable Ḋo2 required in neonates to maintain aerobic metabolism during normothermic CPB.