Low tidal volume lung ventilation during cardiopulmonary bypass decreases the potential of postoperative lung injury

Background Postoperative pulmonary dysfunction is one of the common complications after cardiac surgery that may lead to serious morbidity and mortality. In this study, we investigated the potential benefit of continued lung ventilation while on cardiopulmonary bypass (CPB) to minimize postoperative lung injury whether resulting from CPB alone or from non-CPB causes. Patients and methods It is a prospective study including 60 patients who were randomized into two groups, each of 30 patients. One group underwent modified CPB (the MB group) where the lungs were ventilated with low tidal volume 3 ml/kg and PEEP of 5 cmH2O, whereas the other group underwent the conventional CPB (CB group) with total ventilation arrest and no PEEP. Parameters such as PaO2/FiO2 ratio, alveolar arterial oxygen gradient [D (A-a) O2], extravascular lung water, static and dynamic lung compliance, extubation time, and postoperative chest complications such as pleural effusion, atelectasis, and pulmonary edema were compared in the two groups. Results In the MB group, there were significantly higher post-bypass extravascular lung water, lower static and dynamic lung compliance, higher post-bypass PaO2/FiO2 ratio, lower D (A-a) O2, and shorter extubation time. However, postoperative complications on first and fourth postoperative days were insignificant in both groups. Conclusion Lung ventilation with low tidal volume during CPB can reduce the potential of post-CPB lung injury by improving lung oxygenation, reducing lung ischemia, and decreasing postoperative lung atelectasis, resulting in shorter extubation time and less postoperative pulmonary complications.