“Despite advances in perioperative care in the last few decades, postoperative pulmonary complications (PPCs) are probably the leading cause of morbidity and mortality in adults undergoing chest and abdominal surgery. PPCs and cardiac complications are commonly regarded as the two major causes of perioperative problems in selected groups of patients undergoing these high-risk surgical procedures. However, PPCs are more common than postoperative cardiac complications and play a bigger role in mortality and healthcare costs. Despite these factors, the natural history of PPCs and the necessity of preventive strategies have not been well recognized in studies to date.”