LAUSR

There is interest in the association between partial pressure of carbon dioxide (PCO2) and neurological outcome following cardiac arrest. Extracorporeal life support is increasingly used in the setting of refractory cardiac arrest (ECPR) but there is a lack of standardisation of PCO2 management during ECPR. We prospectively evaluated CO2 values and investigated the importance of blood sampling site in a series of 23 children undergoing ECPR, comparing the patient's arterial PCO2 (PaCO2) with samples taken pre- (Ppre-oxyCO2), and post- (Ppost-oxyCO2) the circuit oxygenator. Large reductions in PaCO2 were seen following initiation of ECPR; median reduction was 3.7 kPa, and 42% experienced a reduction >5 kPa in the first hour. The relationship between Ppre-oxyCO2, Ppost-oxyCO2 and PaCO2 was not consistent or predictable, and the use of Ppre-oxyCO2 values to guide management was frequently associated with low PaCO2 values; 25% of patients experienced a PaCO2 below 3.5 kPa. PCO2 management during ECPR should be based on PaCO2 measurements and caution is needed to avoid rapid reductions in PaCO2.