This study is a prospective, single-center, single-blind, randomized controlled clinical trial. Patients scheduled for laparoscopic bariatric surgery will be selected and randomly assigned to either the EIT-guided individualized PEEP group (Group P-eit) or the control group (Group P-8). Group P will be ventilated using the PEEP value determined by EIT, while Group C will be ventilated with a fixed PEEP value of 8 cmH2O.The primary outcome is the incidence of postoperative pulmonary complications (PPCs) within 72 hours after surgery.
Age between 18 and 65 years;
Plan to receive laparoscopic bariatric surgery under general anesthesia;
American Society of Anaesthesiologists (ASA) physical status I-III;
BMI between 30 and 55 kg/m2;
History of smoking or previous thoracic surgery;
Invasive mechanical ventilation within 30 days;
Pregnancy;
Allergy to EIT electrodes;
Parallel
Group P-eit
Device"The Recruitment Maneuver - PEEP Titration - Recruitment Maneuver (RM-T-R) Strategy" will be implemented 5 minutes after endotracheal intubation. The patient will receive an RM (peak pressure 50cm H2O, PEEP 25cmH2O, respiratory rate 6 bpm, for 10 cycles) followed by a decremental PEEP titration, during which PEEP is set to 25cm H2O and decreased stepwise by 2cm H2O every 3min until reaching 5 cmH₂O. Meanwhile, the ventilator parameters (tidal volume, respiratory rate, and inspiratory-to-expiratory ratio) will be adjusted back to their pre-recruitment settings. EIT-based optimal PEEP is defined as the crossing point of the overdistension and collapse curves during a decremental PEEP trial.
Group P-8
DeviceIn group p-8, mechanical ventilation will be administered in volume-controlled mode with a tidal volume of 8 ml/kg (based on ideal body weight). Additional settings include a PEEP of 8 cmH₂O, FiO₂ of 0.5, an inspiratory-to-expiratory ratio of 1:2, and a respiratory rate of 12 breaths/min. A recruitment maneuver (RM) will be performed 5 minutes after intubation and again after surgery, using the same protocol as in group P-eit. The respiratory rate will be adjusted as needed to maintain end-tidal CO₂ between 35 and 45 mmHg throughout the procedure.
incidence of postoperative pulmonary complications
Participants who developed at least one complication are considered as meeting the primary outcome. The PPCs are defined as follows : 1. . Pneumonia (using to the US Centres for Disease Control Criteria ; 2. . Respiratory failure 3. . Bronchospasm (newly detected expiratory wheezing treated with bronchodilators); 4. . Pleural effusion 5. . Pneumothorax 6. . Atelectasis 7. . Pulmonary aspiration 8. . Cardiogenic pulmonary oedema (clinical signs of congestion, including dyspnoea, oedema, rales, and jugular venous distention, with chest X-ray demonstrating an increase in vascular markings and diffuse alveolar interstitial infiltrates).
The point-of-care lung ultrasound (LUS) score
The point-of-care lung ultrasound (LUS) score at 30 min after endotracheal extubation, 8:00 AM on postoperative day 1 (POD 1) and postoperative day 2 (POD2).
The severity of PPCs:
(i) None: planned use of supplemental oxygen or mechanical respiratory support as part of routine care, but not in response to a complication or deteriorating physiology. Therapies that are purely preventive or prophylactic, for example, high-flow nasal oxygen or continuous positive airway pressure (CPAP), should be recorded as none;(ii) Mild: therapeutic supplemental oxygen FiO2\< 0.6. (iii) Moderate: therapeutic supplemental oxygen FiO2 ≥ 0.6, requirement for high-flow nasal oxygen, or both. (iv) Severe: unplanned non-invasive mechanical ventilation, CPAP or invasive mechanical ventilation requiring tracheal intubation.
Arterial blood gas analysis
Arterial blood gas analysis will be performed at: 5 minutes post-intubation (before recruitment maneuver), 1 hour after PNP, at surgery conclusion, and 30 minutes post-extubation.
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Jianbo Wu
Lead sponsor
Qianfoshan Hospital
Sponsor institution
