Recently, the investigators demonstrated that nasal route ventilation is superior to the nasal-oral combined ventilation in the absence of jaw thrust and chin up maneuvers. The investigators hypothesize nasal mask ventilation may reduce the incidence of difficult mask ventilation during the induction of general anesthesia by: 1) producing a better seal than full face mask, and 2)establishing a greater airway patency and more effectively ventilate than full face mask ventilation. The investigators intend to test this hypothesis on adult patients during the induction of general anesthesia in the absence of muscle relaxation.

Inclusion Criteria:

• 18-65 years of age
• ASA physical status classification I-II
• general anesthesia
• elective surgery
• who are able to breathe through both their nose and mouth while awake

Exclusion Criteria:

• Patients with major cardiovascular disease, respiratory disease, cerebral vascular disease or American Society of Anesthesiologists physical status class III or greater.
• Abnormal vital signs on the day of admission for surgery [heart rate (HR, >100 bpm or <40 bpm), blood pressure (BP, >180/100 mmHg or <90/60 mmHg), room air transcutaneous oxyhemoglobin saturation (SPO2) <96%] that are not correctable with his or her routine medication or commonly used pre-operative medication.
• Unable to open mouth (<2.5 cm) or unable to breathe through their mouth or nose.
• Any person with an anticipated difficult airway. This will include subjects that require or may require either a fiberoptic intubation or intubation while awake.
• Gastric-esophageal reflex or a full stomach.
• Neurological symptoms associated with neck extension, a neurological deficit from a previous stroke or spinal cord injury, a recent stroke or Transient Ischemic Attack (TIA) within 2 weeks.
• Pregnant women and women less than one month post-partum. Ruling out pregnancy will be conducted by careful history and physical examination as performed routinely prior to surgery. If the history is believed to be unreliable, the patient will be excluded unless a pregnancy test is performed and the result of the test is negative.
• Emergency cases and subjects who have not adhered to the ASA NPO (Nil Per Os - Nothing By Mouth) guidelines.