Individualized PEEP Titration on Postoperative Pulmonary Complications

This study aims to investigate the effectiveness and safety of implementing a personalized positive end-expiratory pressure (PEEP) management strategy guided by esophageal pressure (Pes), as well as its potential to reduce the occurrence of postoperative pulmonary complications (PPCs) in elderly patients undergoing laparoscopic surgery.

This trial is a single-blind, randomized, controlled, multicenter study. Elderly patients undergoing laparoscopic surgery under general anesthesia will be recruited according the inclusion and exclusion criteria. Participants in this study will be randomly assigned into two groups. The total sample size will be 232, with 116 participants in the experimental group and 116 participants in the control group. A stratified block randomization method will be employed, using the ARISCAT score for PPCs risk assessment and individual study centers as stratification factors. Anesthesia routine will be applied during pre-anesthetic preparation, anesthetic induction, maintenance and emergence except intraoperative respiratory management. In the control group (PEEP Group), fixed PEEP of 3 cmH2O is applied throughout the procedure without lung recruitment maneuvers. While in the experimental group (Pes-Guided PEEP Group), continuous monitoring of end-expiratory esophageal pressure (Pes_ee) is conducted. PEEP is chosen to maintain a positive transpulmonary pressure at end-expiration (Ptp_ee = PEEP - Pes_ee) after lung recruitment. PEEP titration following lung recruitment should be performed after endotracheal intubation or any procedure that may cause lung collapse, such as pneumoperitoneum, deflation or inflation of the endotracheal tube cuff, changes in position, or endotracheal suctioning. PEEP Titration is also required every hour after the establishment of pneumoperitoneum. Patients will be followed up within 7 days after surgery to assess basic vital signs, potential postoperative pulmonary complications (PPCs). Additionally, postoperative non-respiratory complications will be evaluated.Laboratory tests, the 15-item Quality of Recovery-15 (QoR-15) questionnaire, complications within 30 days after surgery, and 90-day survival rates will also be recorded.

Eligibility Criteria:
Inclusion Criteria:

1. Patients aged 65 years or older, of any gender.
2. Laparoscopic surgery under general anesthesia.
3. Anticipated duration of surgery ≥ 2 hours.
4. Willingness to sign informed consent or provide a legally authorized representative.

Exclusion Criteria:

1. Obesity, defined as BMI ≥ 35 kg/m2.
2. History of pulmonary surgery (of any type).
3. History of severe chronic obstructive pulmonary disease (COPD) requiring non-invasive ventilation and/or home oxygen therapy, or systemic corticosteroid treatment for acute COPD exacerbations.
4. Severe pulmonary arterial hypertension, defined as pulmonary artery systolic pressure \> 40 mmHg.
5. Heart failure, ongoing hemodynamic instability, or severe shock (as determined by the attending internist), cardiac index \< 2.5 L/min/m2, or the requirement for positive inotropic drugs to maintain blood pressure.
6. Severe cardiac disease (NYHA class III or IV, acute coronary syndrome, sustained ventricular tachyarrhythmias, unable to achieve \> 4 METs).
7. Severe liver or renal dysfunction (Child-Pugh score 10-15, serum creatinine ≥ 2 mg/dL, or patients requiring peritoneal dialysis or hemodialysis).
8. Neuromuscular disease (of any type).
9. History of bone marrow transplantation or recent use of immunosuppressive drugs (chemotherapy or radiotherapy within 2 months before surgery).
10. Mechanical ventilation duration \> 30 minutes within the past 30 days (e.g., during surgery under general anesthesia).
11. Requirement for one-lung ventilation.
12. History of acute respiratory distress syndrome with potential need for prolonged postoperative mechanical ventilation.
13. Planned re-intubation after surgery.
14. Pregnancy (excluded by medical history and/or laboratory tests).
15. Brain injury or tumor.
16. Requirement for prone or lateral position during surgery.
17. Severe esophagogastric varices.
18. Enrollment in other interventional studies or refusal to sign informed consent.