Frequency and Risk Factors of Postoperative Pulmonary Complications after Major Abdominal Surgery: A Prospective Observational Study at Hayatabad Medical Complex Peshawar

Background: Postoperative pulmonary complications (PPCs) are among the most common and serious adverse events following major abdominal surgery, contributing to increased morbidity, prolonged hospital stay, and higher healthcare costs. Early identification of patients at risk is essential for implementing preventive strategies and improving postoperative outcomes. This study was conducted to determine the frequency of postoperative pulmonary complications and to identify the independent risk factors associated with their occurrence among patients undergoing major abdominal surgery at a tertiary care hospital. Methodology: A total of 384 adult patients undergoing elective or emergency major abdominal surgery under general anesthesia were enrolled consecutively. Demographic characteristics, comorbidities, smoking history, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, and intraoperative variables were recorded using a structured proforma. Patients were followed for the first 30 postoperative days for development of PPCs (atelectasis, pneumonia, acute respiratory failure, pleural effusion, bronchospasm, prolonged mechanical ventilation, reintubation, pulmonary embolism, and ARDS). Data were analyzed using SPSS version 26. Chi-square and independent-samples t-tests assessed univariate associations; multivariable logistic regression identified independent predictors. A p-value <0.05 was considered statistically significant. Results: The mean age was 58.36 ± 14.63 years, and 218 (56.8%) patients were male. At least one PPC developed in 111 patients, giving an overall PPC frequency of 28.9%. Atelectasis was the most common complication (18.0%), followed by pneumonia (6.8%) and prolonged mechanical ventilation (5.5%). On multivariable logistic regression, independent predictors of PPC were advancing age (adjusted OR 1.04, 95% CI 1.01–1.06), higher BMI (OR 1.05, 95% CI 1.01–1.09), current smoking (OR 4.16, 95% CI 2.04–8.49), ex-smoking (OR 2.34, 95% CI 1.16–4.73), COPD (OR 6.48, 95% CI 2.55–16.43), bronchial asthma (OR 2.67, 95% CI 1.01–7.09), emergency surgery (OR 3.05, 95% CI 1.67–5.58), and upper abdominal or midline incisions (OR 5.20 and 4.93, respectively). Preoperative incentive spirometry was independently protective (OR 0.44, 95% CI 0.23–0.81). Patients who developed PPC had significantly longer hospital stay (11.32 ± 3.27 vs 6.32 ± 2.52 days, p<0.001), higher ICU admission (43.2% vs 5.1%, p<0.001), and higher 30-day mortality (6.3% vs 1.1%, p=0.011) than those without PPC. Conclusion: Nearly three in ten patients undergoing major abdominal surgery developed a postoperative pulmonary complication, which was independently associated with substantially higher morbidity and mortality. Advanced age, elevated BMI, smoking, COPD, asthma, emergency surgery, and upper abdominal/midline incisions were independent risk factors, while preoperative incentive spirometry was protective. Targeted preoperative optimization and perioperative pulmonary care protocols in high-risk patients may reduce the burden of PPCs in this population.