Perioperative Respiratory Function in Sleeve Gastrectomy

Obesity is associated with substantial alterations in respiratory physiology, including reduced functional residual capacity, decreased respiratory compliance, impaired diaphragmatic excursion, and increased susceptibility to perioperative atelectasis and hypoxemia. These physiologic changes become more pronounced during general anesthesia and laparoscopic surgery because of positive-pressure ventilation and carbon dioxide pneumoperitoneum. Consequently, obese patients undergoing bariatric surgery represent a particularly vulnerable population for perioperative respiratory impairment.

Lung-protective ventilation strategies incorporating low tidal volume ventilation, positive end-expiratory pressure (PEEP), and recruitment maneuvers have been increasingly utilized in obese surgical patients to improve oxygenation and reduce atelectatic changes. However, despite improvements in intraoperative respiratory mechanics and oxygenation reported in previous studies, the clinical significance and incremental benefit of intensified ventilation strategies remain uncertain, particularly in contemporary bariatric anesthesia settings where protective ventilation principles are already routinely applied.

This retrospective single-center cohort study evaluates perioperative oxygenation and respiratory outcomes in obese patients undergoing elective laparoscopic sleeve gastrectomy between January 2021 and January 2026. All patients were managed using standardized anesthetic and surgical protocols, including volume-controlled ventilation with tidal volumes of 6-8 mL/kg ideal body weight and fixed inspired oxygen fraction (FiO₂ 45%).

Patients were divided into two groups according to intraoperative ventilation strategy. The first group received conventional ventilation with PEEP 5 cmH₂O without recruitment maneuvers. The second group received a protective ventilation strategy consisting of PEEP 8 cmH₂O combined with repeated recruitment maneuvers performed after pneumoperitoneum establishment and before extubation.

Perioperative oxygenation was assessed using serial PaO₂/FiO₂ measurements obtained immediately after endotracheal intubation (T0), 10 minutes after pneumoperitoneum establishment (T1), and 5 minutes after extubation (T2). Secondary outcomes included arterial blood gas variables, postoperative spirometric parameters, lactate levels, intensive care unit admission, and hospital length of stay.

The primary objective of the study is to determine whether escalation from conventional PEEP 5 cmH₂O ventilation to PEEP 8 cmH₂O combined with recruitment maneuvers provides incremental perioperative respiratory benefit in obese patients undergoing laparoscopic sleeve gastrectomy within a standardized contemporary bariatric anesthesia setting.