Laparoscopic surgery often requires the Trendelenburg position, which, along with pneumoperitoneum, increases intra-abdominal pressure and CO2 absorption. This can lead to hypercapnia, acidosis, and impaired ventilation. The upward shift of the diaphragm further reduces pulmonary compliance, functional residual capacity, and worsens ventilation/perfusion mismatch. These challenges call for tailored ventilation strategies to ensure optimal oxygenation and carbon dioxide elimination while minimizing ventilator- induced lung injury. 

Volume Controlled Ventilation (VCV), Pressure Controlled Ventilation (PCV) and Pressure Controlled Ventilation-Volume Guaranteed (PCV-VG) are three commonly used modes in such settings. VCV delivers a set tidal volume regardless of airway pressures, potentially leading to high peak pressures in patients with reduced compliance. PCV delivers breaths at a preset pressure with decelerating flow decreasing the risk of barotrauma whilst compromising on minute ventilation in non-compliant lungs. On the other hand, PCV-VG is a hybrid mode designed to combine the benefits of both pressure and volume-controlled ventilation, aiming to deliver consistent tidal volume with lower airway pressures by adjusting inspiratory pressure as compliance changes.

This study aims to compare VCV and PCV-VG ventilation modes in laparoscopic surgeries under Trendelenburg position, assessing their impact on respiratory mechanics, gas exchange, and pulmonary compliance. The findings could help refine anaesthesia practices, ensuring better perioperative outcomes and minimizing ventilatory complications.

Primary objective: To compare peak airway pressures (P peak) in VCV and PCV-VG mode of ventilation in patients undergoing laproscopy surgery in Trendelenburg position. The parameters with respect to respiratory mechanics (mean airway pressure, dynamic compliance) and hemodynamic changes will also be taken into account.