Pulmonary complications are the second most common after cardiac surgery with cardiopulmonary bypass (CPB). Atelectasis can result from intraoperative causes such as prolonged operation and anaesthesia time of more than 3-4 hours, use of a thoracic artery, use of cardiopulmonary bypass during surgery and failure to ventilate, and haemotransfusion of 4 or more units of packed red blood cells in the perioperative period. Impact of mechanical ventilation during cardiopulmonary bypass still unknown.
Methods: Prospective, randomised study at one centre. Adult patients undergoing cardiac surgery with a pump by sternotomy for coronary artery disease were included.
Patients were randomised into two groups – one group receiving mechanical ventilation and one group receiving no ventilation during cardiopulmonary bypass. The main endpoint was PaO2/FiO2 as a marker for the quality of ventilation and perfusion measured. Secondary endpoints were postoperative pulmonary complications such as atelectasis and prolonged mechanical ventilation of more than 72 hours.
Results 190 consecutive patients were included, 92 and 98 in each group. No significant difference was found in the PaO2/FiO2 ratio in the groups (p=0.6). A significant difference was found in the number of atelectasis during ultrasound investigation (USI) of the lungs with a p-value of 0.03 in the non-ventilated group.
Conclusion: On-pump cardiac surgery without mechanical ventilation can lead to atelectasis of the lungs.