High Oxygen is Likely to be Beneficial on Cardiac Contractility after Normothermic Regional Perfusion after Circulatory Death in a Porcine Model.

The impact of high versus low oxygenation during normothermic regional perfusion (NRP) after anoxic circulatory death on donor heart contractility in a porcine model. The animals were anaesthetized, pressure-volume catheters were placed in both ventricles and a pulmonary artery catheter was inserted percutaneously. Through a midline sternotomy, the heparinized animals were cannulated for extracorporeal circulation. Baseline data were obtained. Mechanical ventilation was withdrawn. After 15 minutes of warm ischemia, the aortic arch vessels and infrarenal aorta were clamped before NRP was commenced using a standard heart-lung machine. The animals were randomized to receive either FiO2 of 1.0 (HOX) or 0.21 (LOX) with a gradual increase to 0.40 during NRP. The NRP protocol includes early volume loading of the right ventricle and gradual wean over 35 minutes. Dobutamine and norepinephrine infusions were started during NRP for circulatory support. The animals were observed for 180 minutes after weaning from NRP. 15 of 19 animals were successfully weaned from NRP; 8/9 in the HOX and 7/10 in the LOX group, (p = 0.58). All weaned animals displayed acceptable cardiac function during the observation period and sustained a mean arterial pressure >60 mmHg with low filling pressures and cardiac index >2.5 L/min/m2. The preload independent end-systolic pressure volume relationship as an index of contractility was preserved in both groups. The HOX RV contractility was higher than the LOX group (p=0.035); and not significantly in the LV (p=0.37) (Fig. 1). Biochemestry showed lower lactate levels in the HOX group. There was no difference in norepinephrine requirement between groups. There were minimal haemodynamic and biochemical differences between the groups as all weaned animals demonstrated acceptable cardiac function. The high oxygenation group showed marginally better cardiac performance and lower lactate concentrations. [ABSTRACT FROM AUTHOR]