Modified Rapid Sequence Induction in Morbidly Obese Patients

100 adult patients with a body mass index \> 40 undergoing elective laparoscopic surgery will be included. Patients with a history of previous bariatric surgery or with an anticipated difficult airway will be excluded. The randomization will be 1:1:1:1 stratified for gastro-esophageal reflux disease. All groups will receive standardized preoperative continuous positive airway pressure (CPAP) therapy. In the operation theater, Group one will receive pre-oxygenation for 3 minutes via a tight fitting face mask without positive end-expiratory pressure (PEEP). Induction agents will be administered as quick boluses (Propofol 2,5mg/kg total body weight, max 350mg, Fentanyl 250mcg, Rocuronium 1,2mg/kg ideal body weight) and tracheal intubation will be performed after 1 minute. No bag mask ventilation will be performed in-between. Group 2 will receive pre-oxygenation via a tight face mask with a PEEP of 10 mbar for 3 minutes. The same induction agents as in group one will be administered. PEEP via facemask will be continued for one minute and tracheal intubation will be performed. Group 3 will receive pre-oxygenation via a tight fitting facemask with a PEEP of 10 mbar with additional pressure support of 8 mbar and a back up ventilation frequency will be set to 10/min. After the same induction agents are given as in group 1, patients will receive non-invasive ventilation via ventilator at the settings described earlier for group 3. Group 4 will receive the same induction as group 3, in addition a cricoid pressure will be applied during the non invasive ventilation.