Comparison of PaCO2 to ETCO2 gradient in volume vs pressure control ventilation in patients undergoing laparoscopic renal surgeries in the lateral decubitus position.

This is a prospective randomised control study that compares the PaCO2 to EtCO2 gradient in volume vs pressure control ventilation in patients undergoing laparoscopic renal surgeries in lateral decubitus position 90 minutes after creation of pneumoperitoneum. Secondary objective includes comparing airway pressure and dynamic compliance ,Arterial alveolar oxygen gradient, hemodynamic changes and PaCO2 to EtCO2 gradient  in different surgical techniques that is intraperitoneal and retroperitoneal approach at 8 different time points. This study includes patients ASA I to III  aged between 18-80 years but excludes patients with BMI more than 30, emergency nephrectomy, moderate to severe COPD and active smokers. In healthy individuals this gradient is less than 5 mm of Hg. Variations can be seen depending on patients underlying condition, position adopted for surgery and surgery itself. ABG will be analysed using arterial blood and EtCO2 value should be obtained 15 seconds prior to this. Samples are collected at 8 different time points that is before during and after pneumoperitoneum. It was seen in most studies Pressure control mode of ventilation was assosciated with lower airway pressure, higher mean pressure and improved dynamic compliance compared to Volume control. Pressure Control Ventilation improves oxygenation without any side effects and generates higher instantaneous flow peak allowing better alveolar recruitment.