Eliminating discard volumes in neonatal and pediatric blood sampling from arterial catheters: A comparison of three simple blood-conserving aspiration techniques.

Abstract

OBJECTIVE: To compare different blood aspiration techniques to eliminate discarding of blood in arterial blood sampling from critically ill neonates and children. DESIGN: Prospective, randomized controlled trial. SETTING: A 19-bed tertiary neonatal and pediatric intensive care unit. PATIENTS: Critically ill neonates and children with existing arterial and central venous access. INTERVENTIONS: Paired blood samples were obtained by using conventional blood discarding techniques and one of the following blood-conserving aspiration techniques: passive extracorporeal arteriovenous backflow, free passive backflow to ambient pressure, and active aspiration backflow to a distance of 10 or 20 cm proximal to the sampling port of the arterial pressure catheter. Repetitive conventional sampling served as a control and as the standard. The order of sampling was randomly allocated. We determined arterial blood gases, electrolytes, blood glucose, and hemoglobin concentration. Measurement and RESULTS: Bland-Altman bias analysis of the variability among the techniques revealed that the passive backflow and the active aspiration backflow technique with a backflow distance of 20 cm yielded identical results to repetitive conventional sampling with a standardized discard volume of 0.6 mL. In contrast, the extracorporal arteriovenous backflow technique carried the risk of overestimating blood glucose levels (mean bias, 0.96 mmol/L.). A backflow distance of 10 cm (active aspiration) proved insufficient to eliminate contamination by the catheters' flushing solution. CONCLUSIONS: At a backflow distance of 20 cm, the passive backflow and the active aspiration backflow techniques produce, with the used monitoring set, reliable and precise results in critically ill newborns and children and eliminate discard volumes.