G492(P) Arterial vs venous lactate: A measure of sepsis in children

Aims To assess the level of agreement between Arterial and Venous blood gas pH and Lactate levels in children with sepsis. Methods This is a retrospective single centre study involving 60 PICU patients admitted between June 2012 and October 2015. Data was collected either electronically or directly from patient notes. The inclusion criteria Children with Sepsis (≤17 years of age) VBG taken first with an ABG taken within one hour The Lactate and pH values measured by each method were analysed. Premature infants, patients not admitted with sepsis and patients who received a fluid bolus between the two blood gas samples were excluded from this study. Results Th ere is close agreement between venous and arterial lactate up to the value of 2mmol/L. As the lactate level increases this agreement becomes poor and the differences widen. The limits of agreement (LOA) are clinically too large (±1.90 mmol/L) to allow venous and arterial blood lactate to be used interchangeably. The mean difference and the LOA between the two methods would be a lot smaller if they were derived using only lactate values under 2.0 mmol/L. There is very close agreement between arterial and venous pH, regardless of whether the patient was in acidosis or alkalosis. However clinically, due to the wide variation in pH readings during sepsis, pH alone is an inadequate marker of sepsis. Conclusions A venous blood gas with a lactate of 2mmol/L or lower can be used as a surrogate for arterial lactate during early management of sepsis in children. However if this value is above 2mmol/L, an arterial sample must be taken to confirm the venous result.