Comparison of Stepwise PEEP vs Sustained Inflation Recruitment Maneuvers on Postoperative Oxygenation and Atelectasis in Bariatric Surgery Patients

In the SI group:, the anesthesiologist adjust the ventilator to manual ventilation mode and ad¬just The ventilator will be switched to manual mode, and the airway pressure-limiting valve will be set to 30 cmH₂O. A sustained manual inflation was then applied by gradually squeezing the anesthesia reservoir bag over 3-5 seconds until a peak airway pressure (Ppeak) of 30 cmH₂O was achieved. This pressure was maintained continuously for 30 seconds. Following the maneuver, mechanical ventilation was resumed with positive end-expiratory pressure (PEEP) back to 5 cmho In the IP group:, alveolar recruitment will be performed as follows: ventilation will be set to pressure control mode and the driving pressure maintained at 10 cmH2O with an initial PEEP of 5 cmH2O, respiratory rate 8-10, I:E 1-1PEEP will be then increased by 5 cmH2O ev¬ery 30 s until the Ppeak reached 30 cmH2O (so peep will reach 20), held for 30 s , then PEEP will be gradually reduced at intervals of 5 cmH2O down to 5 cmH2O, when initial volume control ventilation will be resumed. In the incremental PEEP group, PEEP was increased stepwise by 5 cmH₂O every 3-5 breaths until a peak airway pressure of 30 cmH₂O was achieved, after which mechanical ventilation was resumed with maintenance PEEP. The total duration of the recruitment maneuver was approximately 60-90 seconds.