Multivariate analysis of factors associated with postoperative pulmonary complications following general elective surgery

Objective: To develop a predictive model identifying perioperative conditions associated with postoperative pulmonary complications (PPCs). Design: A prospective survey of patients whose preoperative history and physical examination, spirometric, PaO2 and PaCO2 analysis, and operative results were recorded. These patients underwent postoperative cardiopulmonary examinations until they were discharged from the hospital; their medical records were also reviewed until they were discharged from the hospital. Setting: The Louisville Veterans Administration Medical Center, Louisville, Ky. Patients: A randomly chosen sample of patients aged 40 years or older who required elective, nonthoracic surgery under general or spinal anesthesia and who were hospitalized at least 24 hours postoperatively. Main Outcome Measure: An analysis of risk factors associated with the development of 1 or more of the following conditions: acute bronchitis, bronchospasm, atelectasis, pneumonia, adult respiratory distress syndrome, pleural effusion, pneumothorax, prolonged mechanical ventilation, or death secondary to acute respiratory failure. Results: Postoperative pulmonary complications developed in 16 (11%) of 148 patients. The risk factors found to be higher among those with PPCs compared with those without PPCs were postoperative nasogastric intubation (81% vs 16%, P < .001), preoperative sputum production (56% vs 21%, P = .005), and longer anesthesia duration (480 vs 309 minutes, P < .001). Upper abdominal surgery was performed in 11 (69%) of the 16 patients with PPCs and in 20 (15%) of the 132 patients without PPCs (P < .001); this difference lost significance in multivariate analysis. The final linear logistic model included postoperative nasogastric intubation (odds ratio [OR], 21.8), preoperafive sputum production (OR, 4.6), and longer anesthesia duration (OR exp[0.01x] for an increase in x minutes) (1 minute of additional anesthesia time increases the OR to 1.01), resulting in 92%, accuracy in predicting PPCs. Conclusions: We identified 3 potentially modifiable risk factors for PPCs, If validated, our results may lead to modifications of perioperative care that will further reduce PPCs.