Effect of body mass index on perioperative complications in thoracic surgery.

Obesity is perceived as a risk factor in general thoracic surgery. We conducted a single-center retrospective evaluation of perioperative complications in 822 patients who underwent thoracic surgery between 2000 and 2005. According to body mass index, 82 were underweight (< 18.5 kg m(-2)), 568 were normal (18.5-24.9 kg m(-2)), 155 were overweight (25.0-29.9 kg m(-2)), and 17 were obese (>or=30 kg m(-2)). A significant increase in preoperative comorbidity (hypertension and ischemic heart disease) was observed with increasing body mass index. There was no significant difference in operation time or length of stay in the operating room, but extubation time was significantly different among the 4 groups. Of the intraoperative complications, alveolar-arterial oxygen difference increased significantly with increasing obesity, and hypoxia was least common in the normal group. Postoperatively, there was more pulmonary leakage in the underweight group and less pneumonia in the normal group. Both the underweight and the obese are at increased risk of perioperative complications and need to be carefully observed and managed intraoperatively and postoperatively.