Lung Recruitment Maneuvers in Obese Patients Undergoing General Anesthesia

Abstract

Introduction: Obesity alters respiratory mechanics, increasing atelectasis and hypoxemia during anesthesia. This review examines whether alveolar recruitment maneuvers improve intraoperative oxygenation and postoperative pulmonary outcomes in obese patients.

Methods: Systematic review of randomized trials comparing recruitment maneuvers (sustained inflation or stepwise increases in positive end-expiratory pressure) versus no recruitment in obese adults (body mass index ≥30 kg/m²) receiving general anesthesia. Outcomes included PaO₂/FiO₂ ratio at end of surgery, postoperative atelectasis on imaging, and pulmonary complications.

Results: Eleven trials (875 patients) met criteria. Recruitment maneuvers significantly improved PaO₂/FiO₂ ratio by a mean of 65 mmHg immediately after the maneuver, an effect persisting for 60 minutes. Postoperative atelectasis area on computed tomography was reduced by 22%. No difference was observed in postoperative pneumonia or unplanned ICU admission. Hemodynamic compromise requiring vasopressors occurred in 12% of maneuver recipients.

Discussion: Recruitment maneuvers reopen collapsed alveoli, improving ventilation-perfusion matching. The transient hemodynamic effect reflects reduced venous return during positive pressure. Optimal maneuver parameters remain unclear, with some studies using 40 cmH₂O for 10 seconds and others using 30 cmH₂O with stepwise decrements. Long-term pulmonary benefits were not demonstrated, possibly due to insufficient sample sizes.

Conclusions: Recruitment maneuvers transiently improve intraoperative oxygenation in obese patients but do not clearly reduce major postoperative pulmonary complications. Use should be balanced against hemodynamic risks.