Best ventilatory strategy - A comparative study between three modes of ventilation in prolonged onco-surgery.

This will be a prospective study, observational, randomized study where patients undergoing prolonged surgeries of 6- 10 hrs duration will be enrolled into the study. After taking a written informed consent, 60 patients will be recruited into the study. Recruited patients will be randomly distributed on chit based system in three groups based on ventilatory modes- volume control, pressure control and volume controlled autoflow mode of ventilation. Ventilator settings will be done with a target tidal volume of 7ml/kg and frequency of ventilation will be adjusted to maintain an end tidal carbon dioxide between 35-45 mm of Hg. Intraoperatively recordings will be done for respiratory mechanics (end tidal carbon dioxide, tidal volume, minute ventilation, positive end-expiratory pressure, lung dynamic compliance, airway pressures) and ABG analysis (Fio2, PaO2/Fio2, ph, Paco2, Po2, lactate).

Respiratory parameters will be recorded every 15 minutes whereas ABG analysis will be done twice per case soon after induction and before reversal as per routine protocol in long surgeries. Rest of anesthetic and surgical management will be done as per usual standardized protocols.