Oxygen Concentration during Reperfusion in Mitral Valve Surgery

Abstract

Background: By lowering the oxygen fraction of the reperfusate, the reactive oxygen-derived free radicals can be reduced thus facilitating myocardial recovery during weaning from cardiopulmonary bypass and after surgery. Materials & Methods: Thirty patients undergoing mitral valve replacement were randomly exposed to an oxygen fraction of 0.7 (hyperoxic, n = 15) or 0.5 (normoxic, n = 15) during reperfusion. Hemodynamic variables, number of patients requiring additional inotropes and who developed new arrhythmia, duration of ventilation and intensive care unit stay, arterial blood gas and renal function were measured. Results: The demographic data, duration of cardiopulmonary bypass, aortic cross clamp time, duration of mechanical ventilation, intensive care unit stay, additional inotropes, arrhythmia after reperfusion and renal function were similar in both groups. Arterial blood gas analysis was not significantly different, except for the low oxygen partial pressure in the normoxic group during reperfusion. With regard to hemodynamic variables, mean arterial pressure of the hyperoxic group was higher one hour after the cross clamp release. Hemodynamic variables were comparable in all other time periods. Conclusion: By reducing the oxygen concentration during reperfusion, the clinical outcomes in terms of inotropes usage, new arrhythmia after reperfusion, renal function, duration of ventilation and intensive care unit stay were not significantly altered.