Effect of Recruitment Maneuver on Postoperative Atelectasis Assessed by Lung Ultrasound in Laparoscopic Cholecystectomy

Laparoscopic cholecystectomy under general anaesthesia with CO₂ pneumoperitoneum predictably reduces lung aeration and promotes atelectasis that global monitoring parameters may fail to detect. This trial compared two intraoperative ventilation strategies differing solely in the application of alveolar recruitment manoeuvres, using serial lung ultrasound to quantify regional aeration.

Adults aged 18-75 years, ASA physical status I-III, scheduled for elective laparoscopic cholecystectomy were eligible. Patients undergoing emergency surgery, with severe pre-existing pulmonary disease (e.g., COPD GOLD stage ≥ III, interstitial lung disease) or previous thoracic surgery, who were pregnant, or who required conversion to open surgery were excluded. Eligible participants were randomized 1:1 using a computer-generated sequence, with allocation concealed by sequentially numbered, sealed, opaque envelopes.

All patients received standardized general anaesthesia and volume-controlled ventilation (tidal volume 6-8 mL/kg predicted body weight, PEEP 5 cmH₂O, FiO₂ titrated to SpO₂ ≥ 95%, EtCO₂ 35-40 mmHg). In the RM group, a standardized stepwise recruitment manoeuvre (driving pressure 15 cmH₂O; PEEP incremented 5 → 10 → 15 cmH₂O in 10-15-second steps) was performed twice: first immediately after establishment of CO₂ pneumoperitoneum and surgical positioning, and second after pneumoperitoneum deflation and before extubation. PEEP was returned to 5 cmH₂O after each manoeuvre, identical to the control group, so that the groups differed only by the recruitment manoeuvres and not by sustained PEEP. The control group received no recruitment manoeuvre, with PEEP maintained at 5 cmH₂O throughout. Intra-abdominal pressure was limited to 12 mmHg.

An 8-zone LUS protocol (each hemithorax divided into anterior-upper, anterior-lower, lateral-upper, and lateral-lower regions) was applied at five predefined time points: T1, preoperative baseline; T2, 5 minutes after induction; T3, after pneumoperitoneum establishment and the first recruitment manoeuvre; T4, immediately after extubation and the second recruitment manoeuvre; and T5, 30 minutes after arrival in the post-anaesthesia care unit. LUS examinations were performed by a dedicated team of blinded anaesthesiology specialists independent of intraoperative ventilation management.

The primary outcome was the perioperative composite LUS score trajectory across the five time points, analysed with a linear mixed-effects model (group, time, and group × time interaction). Safety outcomes were peripheral oxygen saturation, mean arterial pressure, and heart rate at each time point.

Inclusion criteria

• Adult patients scheduled for elective laparoscopic cholecystectomy under general anesthesia
• Age between 18 and 75 years
• Body mass index (BMI) < 30 kg/m²
• American Society of Anesthesiologists (ASA) physical status classification I-III
• Provision of written informed consent

Exclusion criteria

• Refusal to participate in the study
• Emergency surgical procedures
• Body mass index (BMI) ≥ 30 kg/m²
• American Society of Anesthesiologists (ASA) physical status classification IV