Lung-protective ventilation during one-lung ventilation: known knowns, and known unknowns

More than 230 million patients undergo major surgical procedures every year worldwide (1), among whom 16% to 18% will develop major postoperative complications (2,3), which negatively affect morbidity, mortality, healthcare cost, and quality of life. Patients undergoing thoracic surgery are at a higher risk of postoperative complications, especially those involving the respiratory system. Potential pathophysiology leading to postoperative pulmonary complications (PPCs) includes depressed central respiratory drive, changes in end-expiratory muscle tone, reduced lung volume (including functional residual capacity), abnormal regional distribution of ventilation, and atelectasis (4).