November 29, 2025
Background: Postoperative pulmonary complications (PPCs) are a major cause of postoperative morbidity, mortality, and increased healthcare utilization. This study evaluated whether a perioperative lung expansion bundle incorporating individualized intraoperative management could reduce PPC severity compared with usual care in patients undergoing major open abdominal surgery.
Methods: The PRIME-AIR trial was a multicenter, randomized, phase III clinical trial conducted at 17 academic hospitals in the United States. Adults undergoing elective open abdominal surgery expected to last at least 2 hours, with an ARISCAT score ≥26 and a body mass index (BMI) <35 kg/m², were randomized 1:1 to receive either usual care or a perioperative lung expansion bundle. The intervention included preoperative education, individualized intraoperative positive end-expiratory pressure (PEEP) titrated to maximize respiratory system compliance, weight-based neuromuscular blockade and reversal guided by neuromuscular monitoring, and postoperative supervised incentive spirometry with early mobilization. The primary outcome was the highest severity (grades 0-4) of a composite of postoperative pulmonary complications within 7 postoperative days.
Results: Between January 2020 and April 2023, 751 patients were included in the modified intention-to-treat analysis, with 379 assigned to the intervention group and 372 to usual care. Adherence to the intervention components was high (72%-98%). Patients in the intervention group received higher mean PEEP (7.5 ± 2.5 cmH₂O vs. 5.6 ± 1.4 cmH₂O) and more guideline-concordant neuromuscular blockade dosing and reversal. By postoperative day 7, grade 2 PPCs were the most common outcome in both groups (56% vs. 60%). Mean PPC severity was similar between the intervention and usual care groups (1.60 ± 0.94 vs. 1.53 ± 0.93; mean difference 0.07; 95% confidence interval -0.03 to 0.18; P = 0.19). Rates of serious adverse events and mortality at 7, 30, and 90 days were also similar between groups.
Conclusions: In patients with BMI <35 kg/m² at moderate to high risk for postoperative pulmonary complications undergoing prolonged major open abdominal surgery, a comprehensive perioperative lung expansion bundle did not reduce the severity of postoperative pulmonary complications compared with contemporary usual care.
Keywords: postoperative pulmonary complications; lung expansion bundle; individualized positive end-expiratory pressure; protective ventilation; abdominal surgery; randomized controlled trial.
©2026 OR. All Rights Reserved
