Schematic of the ECMO circuit. Shown is a schematic of the rabbit VA-ECMO circuit used in the protamine/heparin cohort (A) and the citrate/calcium cohort (B). Note that the Medos Hilite LT Infant 800 oxygenator used in the protamine/heparin cohort was replaced with 2 Micro-1 oxygenators (C) in the citrate/calcium cohort.