The purpose of this study is to determine the pumping performance of Revision 7 of the Ension pediatric cardiopulmonary assist system (pCAS) when used with cannulae for venoarterial (VA) or venovenous (VV) extracorporeal membrane oxygenation (ECMO). It was hypothesized that the pCAS could deliver flow rates within recommended ranges needed to provide adequate cardiopulmonary support for neonates and infants. Rev 7 pCAS pumping performance was evaluated with the pCAS incorporated into an ECMO circuit connected to an instrumented pediatric mock circulation with cannulae combinations commonly used clinically for VA ECMO or dual lumen cannulae for VV ECMO. The pCAS motor speed was operated from 0 to 4500 rpm while the pCAS pumped blood analog solutions representing a clinically relevant range of viscosity. Maximum flow rates were inversely related to viscosity and were directly proportional to cannulae size. At 4500 rpm, maximum pCAS flow for the VA ECMO configuration was 2.14 L/min for the lowest viscosity and largest cannula combination and 0.72 L/ min for the highest viscosity and the smallest cannulae combination. At a flow of 0.5 L/min, the pressure drop across the pCAS ranged from 121 to 323 mmHg depending on viscosity and cannulae combination. For the VV ECMO configuration at 4500 rpm, the maximum pCAS flow was 1.21 L/min for the lowest viscosity and largest cannula and 0.58 L/min for the highest viscosity and smallest cannula. For a flow of 0.5 L/min, the pressure drop across the pCAS ranged from 82 to 407 mmHg depending on the viscosity and cannula. Possible transition to turbulent flow (Re > 2100 at cannula inlet) was found at the higher flow rates achieved with the lower viscosity test fluid for all cannulae tested. In conclusion, across the range of pump speeds and fluid viscosities evaluated, the pCAS can generate the flow rates recommended to provide adequate cardiopulmonary support for neonates and infants with commonly used clinical cannulae combinations, thus confirming the hypotheses.