Objective: To investigate associations between preoperative variables and postoperative pulmonary complications (PPC) in elective upper abdominal surgery. Design: Prospective clinical trial. Setting: A tertiary university hospital. Patients: 408 patients were prospectively analyzed during the preoperative period and followed up postoperatively for pulmonary complications. Measurements: Patient characteristics, with clinical and physical evaluation, related diseases, smoking habits, and duration of surgery. Preoperative pulmonary function tests (PFT) were performed on 247 patients. Results: The postoperative pulmonary complication rate was 14 percent. The significant predictors in univariate analyses of postoperative pulmonary complications were: age >50, smoking habits, presence of chronic pulmonary disease or respiratory symptoms at the time of evaluation, duration of surgery >210 minutes and comorbidity (p <0.04). In a logistic regression analysis, the statistically significant predictors were: presence of chronic pulmonary disease, surgery lasting >210 and comorbidity (p <0.009). Conclusions: There were three major clinical risk factors for pulmonary complications following upper abdominal surgery: chronic pulmonary disease, comorbidity, and surgery lasting more than 210 minutes. Those patients with three risk factors were three times more likely to develop a PPC compared to patients without any of these risk factors (p <0.001). PFT is indicated when there are uncertainties regarding the patient's pulmonary status. Key words: abdominal surgery, risk factor, morbidity Abbreviations: BMI = body mass index; FEV1/FVC = forced expiratory volume in the first second divided by forced vital capacity; PPC = postoperative pulmonary complication. respiratory infections, bronchoconstriction and respiratory failure. 3,11,12 Preoperative spirometric tests have been reported to be reliable predictors of PPCs. However, the risk of PPCs is usually estimated in heterogeneous populations and in various surgical procedures, 1,13,14 making it difficult to ascertain the relationship between PPCs and previous spirometric abnormalities. The aim of this study was to follow prospectively a group of patients undergoing an elective upper abdominal surgery to identify those factors associated with an increased risk of developing PPCs using a standard preoperative evaluation. In addition, a subgroup of these patients was submitted to spirometr y to investigate the importance of this test as a predictor of PPCs in this population. Original Article METHODSThis study was performed on 408 consecutive patients undergoing elective abdominal surgery at the Federal University of São Paulo's teaching hospital. All patients were referred for a preoperative assessment (between January 1992 and December 1992), after having been scheduled for elective upper abdominal surgery. All were operated on and observed at the same hospital.Of the 408 patients, 206 were men and 202 were women and their mean age was 55 + 15 years. Operative procedures are...