Effect of intermittent recruitment manoeuvre combined with PEEP on postoperative atelectasis in obese patients: a randomized controlled trial

Obese patients undergoing metabolic and bariatric surgery are prone to postoperative atelectasis, which impairs oxygenation and increases the risk of pulmonary complications. Positive end-expiratory pressure (PEEP) and recruitment manoeuvre (RM) are commonly applied to reduce alveolar collapse, but the benefit of combining them remains uncertain. This study aimed to evaluate whether PEEP combined with RM is superior to either intervention alone in preventing postoperative atelectasis. This was a single-center, parallel-group randomized controlled trial. Ninety obese patients scheduled for elective laparoscopic sleeve gastrectomy were randomized (1:1:1) into RM (R), PEEP (P), and combined (C) groups (n = 30 each). The primary outcomes were the incidence and proportion of atelectasis within 48 h postoperatively, assessed by chest CT. Secondary outcomes included intraoperative hemodynamics, respiratory mechanics, and oxygenation indices (PaO₂, OI, and RI). The overall incidence of atelectasis was 34.4%. The C group had a significantly lower incidence compared with the R and P groups (13.3% vs. 46.7% vs. 43.3%; χ²=8.956, P = 0.015). Among patients with atelectasis, the proportion of atelectatic area was also lowest in the C group (2.56 ± 0.51% vs. 4.13 ± 0.83% vs. 5.94 ± 1.01%; F = 27.71, P < 0.001). Oxygenation indices were significantly higher in the C group at postoperative assessment compared with the R and P groups (all P < 0.05), while no significant intergroup differences in hemodynamic parameters were observed. The incidence of pleural effusion was lower in the C group than in the R and P groups (P < 0.05), whereas rates of hypoxemia and pneumonia showed no significant differences. In obese patients undergoing laparoscopic sleeve gastrectomy, the combined application of PEEP and RM was associated with a lower incidence and extent of postoperative CT-defined atelectasis and better postoperative oxygenation under the conditions of this trial. However, given the single-center design, fixed ventilatory settings, and limited sample size, these findings should be interpreted as preliminary and hypothesis-generating rather than definitive evidence for broad clinical adoption. Chinese Clinical Trial Registry, ChiCTR2200060906. Registered on June 14, 2022. Prospectively registered.