F2 and chronic obstructive pulmonary disease: The univariate logistics analysis showed that statistically significant risk factors were age, hypertension, diabetes, history of smoking, COPD, duration from admission to surgery, length of surgical incision, duration of operation, P1%, intraoperative infusion of crystalloids, preoperative total cholesterol, preoperative triglyceride, preoperative ALB, preoperative PT, and preoperative fibrinogen (P < 0.05).