Pressure - flow measurements of pumps used in extracorporeal life support

IntroductionThe blood pump is a central component of the extracorporeal life support (ECLS) circuit. Modern centrifugal and diagonal pumps are mainly used in preference to roller pumps. Compared to roller pumps, centrifugal and diagonal pumps offer lower priming volume, less hemolysis and enable miniaturization of circuits. Drawback is the open design promoting internal recirculation, which influences performance and, in few studies at low flow, may increase risk of coagulation activation and hemolysis. The aim of this work was to provide performance data on available pumps.MethodsManufacturers were asked to lend ECLS consoles and donate pump samples for the study. No financial support was accepted. Missing pumps were bought by the investigators. In a mock-loop, measurements of volume flow and pressures were performed. Pumps were assessed over the operating flow range stated by the manufacturer at different preloads and afterload levels.ResultsEight different ECLS pumps were tested, two available for pediatric use and six for adult use. Six pumps were centrifugal and two were of diagonal design. All were magnetically driven and three were magnetically levitated. Five had impellers with shrouded (covered) design. Water or water-glucose were used as a test fluid and choice of medium is herewith also discussed. Flow-pressure maps for each pump were generated over its operating range. As agreed with manufacturers, no direct comparisons between pumps were made.ConclusionsPerformance curves for blood pumps designed for ECLS use in children and adults were reported and important aspects of design features discussed to support clinicians.