Comparison of Mask Ventilation Techniques in Patients Requiring General Anesthesia

This study will compare the effectiveness of two-handed V-E mask ventilation technique with the C-E technique. The study hypothesis is based on following considerations:

1. Using C-E technique, the operator's fingers pressure mouth closed and push posteriorily the soft tissue of submandibular region.
2. V-E approach maintains mouth open, creates larger oral cavity and allow positive pressure generated during inspiration to push forwards submandibular region.

Anesthesia care team members, residents or CRNAs familiar with bag-valve mask ventilation, will perform mask ventilation. After receiving preoperative medications, subjects will be placed on the operating table, and electrocardiogram, noninvasive blood pressure, and cutaneous oxyhemoglobin saturation monitoring will be applied. The depth of sedation will be assessed and kept by the care team with IV bolus of propofol.

The sizes of masks will be chosen by the care team and only one size will be used for both techniques. The subject's head will be placed in the neutral position on a pillow and elevate 10 cm from the operating room table, but no backward head tilt or jaw thrust will be performed. One hundred percent oxygen will be delivered throughout the study. The subject will be encouraged to hyperventilate by taking deep breaths to facilitate preoxygenation before the induction of anesthesia.

Pre-oxygenation will be carried out with maximal fresh gas flow and FiO2 1.0 until the expired O2 at or greater than 80%. Then anesthesia will be induced by an intravenous bolus injection of propofol (1-2 mg/kg) after an intravenous bolus injection of fentanyl (50-150 ug).