This analysis differentiates the causes of postoperative respiratory failure. Respiratory failure in thoracic patients is broken down into two distinct groups, aspiration and pneumonia, promoting actions to prevent respiratory failure. The goal is to develop different strategies to avoid postoperative respiratory failure using an active approach (what can be done in the management of patients undergoing lung resection to prevent problems) rather than passive approach (what patient factors caused problems after surgery). Before that analysis, the operative risks after lung resections (lobectomies, pneumonectomies, elderly patients) and esophagectomies are reviewed to understand the data.