This study is a Prospective observational study for factors affecting immediate extubation in the operating room after lower abdominal oncological surgeries.Optic nerve sheath diameter is assessed with ultrasound guidance using a high frequency linear probe. ONSD is is a reliable method as a surrogate parameter of intracranial pressure during the perioperative period.The first measurement is taken 5 minutes after intubation in neutral position. Subsequent measurements will be taken at 30 minutes after placing in Trendelenburg position and after achieving pneumoperitoneum  and just before the termination of pneumoperitoneum. The last measurement is taken 10 minutes after termination of pneumoperitoneum. 

Parameters like the degree of Trendelenburg position will be noted using protractor, peak airway pressure will be noted half hourly starting from baseline, immediately after intubation, total IV fluids used will be noted. Duration of Trendelenburg position and duration of pneumoperitoneum will be noted.Intra abdominal pressure will be noted.

At the end of the surgery the pneumoperitoneum will be terminated and the patients are moved from the Trendelenburg position to neutral position. Immediate extubation is attempted if the standard criteria for extubation are met.  If extubation could not be done within 20 mins, patient will be shifted to ICU for further management.