Protective Mechanical Ventilation and Risk of Postoperative Complications in Abdominal Surgery

This randomized controlled trial, was approved by the institutional ethics committee of our hospital. Informed consent was obtained from all the participants before randomization. Investigators included 80 patients (40 in each group), ASA I or II, planned for open abdominal surgery lasting more than 2 hours under general anesthesia.

Patients were not included if they had specially acute respiratory disease, severe asthma or emphysema, sleep apnea syndrome, septic shock and body mass index (BMI) < 16 or > 35 Kg/m2. Participants were excluded in case of serious peroperative anesthetic complications or hemorrhagic shock.

Primary endpoint was postoperative pulmonary complications occurring within the first 7 days after surgery (defined as hypoxemia, Broncho-pneumopathy, pulmonary infiltrate, acute respiratory distress syndrome, atelectasis, pleural effusion).

Secondary endpoints for all participants were intra-operative complications (change in SpO2 when dropped less than 90%, hypotension <90 mmHg lasting more than 3 min, need for vasopressor administration, new arrhythmia), postoperative extrapulmonary complications (septic shock, postoperative surgical complications, heart disease complications). Investigators recorded for all participants length of hospital stay and mortality rate were .

Investigators randomly allocated patients before entering to the operating room to: