Effects of Changes in Driving Pressure on Intraoperative Pulmonary Dynamic Compliance and PaO₂/FiO₂ Ratio in Laparoscopic Sleeve Gastrectomy

Effects of Changes in Driving Pressure on Intraoperative Pulmonary Dynamic Compliance and PaO₂/FiO₂ Ratio in Patients Undergoing Laparoscopic Sleeve Gastrectomy

The goal of this prospective intervention study is to determine whether individualized positive end expiratory pressure (PEEP) titration targeting the minimum Driving pressure (ΔP) during LGS operation improves intraoperative pulmonary dynamic compliance (Cdyn), oxygenation, post operative pulmonary complication (PPCS) Participants will be assigned to two group (incremental - fixed )peep group Researchers will compare the two group to see if peep titration improve lung compliance, lung mechanics intraopertive and PPCS

Obesity (BMI \ge 30 kg/m^2) significantly increases the risk of atelectasis and respiratory dysfunction under anesthesia. During Laparoscopic Sleeve Gastrectomy (LSG), the combination of pneumoperitoneum and the Trendelenburg position further impairs lung compliance. Standard lung-protective strategies often use a fixed PEEP, which may be insufficient for obese patients or cause hemodynamic instability if set too high.

Fixed PEEP (usually 5 cmH_2O) does not account for individual variations in chest wall mechanics during laparoscopy.

This prospective, randomized, double-blind study involving 46 patients (20-60 years old, BMI 35-40 kg/m^2).

The Intervention

• Control Group: Receives a fixed PEEP of 5 cmH_ throughout the procedure.
• Intervention Group: Receives individualized PEEP titration. After a recruitment maneuver, PEEP is adjusted (from 3 to 12 cmH_2O) to identify the level that achieves the minimum Driving Pressure . This optimal PEEP is then maintained for the surgery.

Key Outcomes

• Primary: Dynamic pulmonary compliance measured 10 minutes after pneumoperitoneum cessation (T3).
• Secondary: Oxygenation (PaO_2/FiO_2 ratio), driving pressure levels, postoperative pulmonary complications (PPCs) within 48 hours, and length of hospital stay.

Inclusion Criteria:

• BMI 35 -40kg·m-²
• ASA II-III
• Elective primary laparoscopic sleeve gastrectomy

Exclusion Criteria:

• Patient refusing consent
• ASA IV patients.
• Sever pulmonary disease
• Sever obstructive sleep apnea (OSA)
• Hepatic or cardic or renal imparment