Effect of intermittent recruitment manoeuvre combined with positive end expiratory pressure on postoperative atelectasis in obese patients: a randomized controlled trial

Citation:

Qiao Y, Zhang H, Yu J, You J, Hou K, Zhao T, Feng H. Effect of intermittent recruitment manoeuvre combined with positive end expiratory pressure on postoperative atelectasis in obese patients: a randomized controlled trial. BMC Anesthesiology. 2026;[Epub ahead of print].

In a single-centre randomized controlled trial of obese adults undergoing elective laparoscopic sleeve gastrectomy, Qiao and colleagues compared three intraoperative ventilation strategies: zero end-expiratory pressure with a single recruitment manoeuvre, low positive end expiratory pressure alone, and the combination of positive end expiratory pressure plus intermittent recruitment manoeuvres. Moderate-certainty evidence suggests that the combined strategy substantially reduces computed tomography-defined postoperative atelectasis and improves intraoperative lung mechanics and oxygenation, but very-low-certainty data mean that any effects on short-term clinical complications such as hypoxemia or pneumonia remain highly uncertain.

Study at a glance

- Design and setting: Single-centre, parallel-group randomized controlled trial in obese adults (body mass index 30–60 kilograms per square metre), American Society of Anesthesiologists class I–III, aged 18–60 years, undergoing elective laparoscopic sleeve gastrectomy under general anaesthesia at a tertiary hospital in China. Ninety-five patients were randomised and ninety (30 per arm) were included in the analysed population; follow-up for outcomes extended to 48 hours postoperatively. Overall risk of bias was judged as having some concerns.

- Interventions: Three intraoperative ventilation strategies were compared: (1) recruitment manoeuvre group: volume-controlled ventilation with zero end-expiratory pressure throughout and a single standardized recruitment manoeuvre at the end of surgery (positive end expiratory pressure ramped up to 30 centimetres of water for 30 seconds, then stepped down); (2) positive end expiratory pressure group: volume-controlled ventilation with 5 centimetres of water positive end expiratory pressure maintained until extubation, without recruitment manoeuvres; (3) combined group: 5 centimetres of water positive end expiratory pressure plus two recruitment manoeuvres (30 minutes after pneumoperitoneum creation and again at the end of surgery), using the same 30 centimetres of water pattern. Anaesthetic drugs, inspired oxygen fraction, and positioning were standardized across groups.

- Primary outcome: postoperative atelectasis: The primary endpoint was incidence of computed tomography-defined postoperative atelectasis within 48 hours, with atelectasis defined as non-ventilated lung areas between −100 and +100 Hounsfield units on chest computed tomography. Atelectasis occurred in 14 of 30 patients (46.7%) in the recruitment manoeuvre group, 13 of 30 (43.3%) in the positive end expiratory pressure group, and 4 of 30 (13.3%) in the combined group, indicating a large relative reduction with the combined strategy. Among patients with atelectasis, the proportion of atelectatic lung volume was also lowest in the combined group (2.56%±0.51%) versus the recruitment manoeuvre group (5.94%±1.01%) and the positive end expiratory pressure group (4.13%±0.83%). Certainty of evidence for both incidence and extent of atelectasis was rated as moderate (downgraded one level for trial-level risk of bias).

- Secondary outcomes: physiology and mechanics: Dynamic lung compliance at the end of surgery (T3) was higher with positive end expiratory pressure and with the combined strategy (22.42±2.88 and 23.37±3.06 millilitres per centimetre of water, respectively) than with recruitment manoeuvre alone (18.16±1.98). Arterial partial pressure of oxygen at 10 minutes after extubation (T4) was highest in the combined group (83.17±14.91 millimetres of mercury) compared with the positive end expiratory pressure group (72.47±12.52) and the recruitment manoeuvre group (68.13±10.00), and respiratory index at T4 was lowest (0.74±0.34 vs 1.22±0.44 and 1.33±0.49). These findings, supported by consistent trends in oxygenation index and pulse oximetry, are judged to be of moderate certainty (one-level downgrade for risk of bias).

- Clinical pulmonary complications and safety: Postoperative hypoxemia, pneumonia, and pleural effusion within 48 hours were recorded as pulmonary complications, but exact per-arm event counts were only available in a supplementary table not fully accessible in the extracted data. Events appeared infrequent across all groups, and no clear between-group differences could be reliably quantified. Because of the small sample, sparse events, and incomplete numerical reporting, certainty for effects on these clinical complications is very low (downgraded one level for risk of bias and two levels for very serious imprecision). Hemodynamic parameters such as mean arterial pressure and heart rate, as well as peak airway pressures, remained broadly similar between groups, and no major safety signal related to recruitment manoeuvres or positive end expiratory pressure was reported.