Ventilation During Cardiopulmonary Bypass

Postoperative pulmonary dysfunction (PPD) is a widely reported complication of cardiopulmonary bypass (CPB) although there is improvement in perioperative management, that leads to increased morbidity and mortality in cardiac surgery. Many surgical-related factors can predispose to postoperative pulmonary complications such as the effects of general anesthesia combined with the effects of a median sternotomy, CPB, and the use of topical cooling for myocardial protection. Main clinical manifestations of PPD include atelectasis, pleural effusion, and postoperative hypoxemia without clinical symptoms in addition to acute respiratory distress syndrome which is rare to happen but leads to high mortality Different strategies including perioperative management of mechanical ventilation (MV), restrictive transfusion, technical modifications of CPB, and medication administration such as steroids and aprotinin have been developed to lessen impairment of pulmonary function. A recent meta-analysis identified improvement in oxygenation after weaning from CPB when low tidal volume (LTV) ventilation was maintained or after lung recruitment maneuvers (LRM), as compared to when there was no ventilation (noV). Also, maintaining mechanical ventilation may reduce the inflammation response and tissue damage. So far, available researches regarding whether ventilation during CPB could improve respiratory outcomes is still controversial especially in pediatric patients undergoing corrective surgeries for congenital heart defects.