Ventilation During Cardiopulmonary Bypass (CPB) for Cardiac Surgery

During most types of heart surgery cardiopulmonary bypass (CPB) is used. CPB enables blood to be directed away from the heart and the lungs and pumped through the body while the heart is not beating. Surgery on the heart easier when it is not beating and bloodless area. Generally during CPB the lungs do not need to be ventilated, as no blood is flowing through the lungs and the body received oxygen from a machine (oxygenator) attached to the CPB pump. In this study we are investigating the difference in lung collapse after heart surgery in patient who did have their lungs ventilated during CPB, compared to patients who did not have their lungs ventilated during CPB. We will use lung ultrasound scans to determine the degree of lung collapse at various time periods before and after the heart surgery. We will also investigate if ventilation during CPB will affect: a.) the rate of lung infection or pneumonia after the operation b.) the time it takes for a patient to have the breathing tube removed in the intensive care unit after the operation c.) the time for a patient to be discharged home from the hospital d.) the concentration of oxygen in the blood after the operation.

Inclusion Criteria: * Adult elective coronary artery bypass surgery requiring CPB Exclusion Criteria: * Cardiac surgery without CPB * Complex cardiac surgery (valve repairs, combined bypass and valve repairs etc.) * Emergency cardiac surgery * Fibrotic lung disease * Previous lung volume reduction surgery (CXR will be assessed pre-operatively) * Massive blood product transfusion intra- and/or post-operatively will exclude patient * Patients enrolled in other studies eg. SIRS study (steroid use)