ObjectiveTo investigate the clinical characteristics and risk factors of postoperative pulmonary complications (PPCs) in patients undergoing major abdominal surgery. MethodsA secondary analysis was performed using data from three prospective randomized controlled trials conducted at West China Hospital of Sichuan University between 2018 and 2023. Demographic characteristics, perioperative variables, and the occurrence of PPCs within 7 and 30 days after surgery were collected. Multivariable logistic regression analysis was used to identify factors associated with PPCs. ResultsA total of 2 047 patients undergoing elective major abdominal surgery were included. ① PPCs within 7 days: PPCs occurred in 686 patients (33.5%) within 7 days after surgery. The most common types were atelectasis (453, 66.0%) and pulmonary infection (322, 46.9%). Grade 3 PPCs accounted for the largest proportion (353, 51.5%), and the occurrence of a single PPC was most frequent (392, 57.1%). Increased BMI (OR=1.059, P<0.001), current smoking or smoking cessation for less than 1 month (OR=1.426, P=0.007), history of respiratory disease (OR=1.607, P=0.002), upper abdominal surgery (lower abdominalsurgery vs. upper abdominal surgery: OR=0.633, P=0.036), open surgery (OR=1.841, P<0.001), prolonged operativeduration (OR=1.003, P<0.001), and increased total fluid volume (OR=1.051, P<0.001) were identified as risk factors for PPCs within 7 days. ② PPCs within 30 days: PPCs occurred in 340 patients (16.6%) within 30 days after surgery. Atelectasis (213, 62.6%) and pulmonary infection (157, 46.2%) remained the most common complications, and the occurrence of a single PPC was still predominant (166, 48.8%). Multivariable logistic regression analysis demonstrated that female (OR=1.592, P=0.024), smoking cessation for more than 1 month (OR=1.738, P=0.030), history of respiratory disease (OR=1.788, P=0.011), open surgery (OR=11.986, P<0.001), prolonged operative duration (OR=1.002, P=0.016), and increased total fluid volume (OR=1.122, P<0.001) were independent risk factors for PPCs within 30 days after surgery. Patients who developed PPCs within 7 days postoperatively had a markedly increased risk of developing PPCs within 30 days (OR=50.932, P<0.001). ConclusionsThe incidence of PPCs within 7 and 30 days after major abdominal surgery is high, with atelectasis and pulmonary infection being the most common types. Increased BMI, smoking history, history of respiratory disease, upper abdominal surgery, open surgery, prolonged operative duration, and increased total fluid volume are significant risk factors for PPCs within 7 days. PPCs within 7 days are strongly associated with the occurrence of PPCs within 30 days.
