The mechanism of Upper airway obstruction (UAO) during anesthesia shares many similarities
with the upper airway obstruction observed during obstructive sleep apnea (OSA). Nasal
continuous positive airway pressure (nCPAP) via nasal mask (NM) can maintain the airway
patent with near 100% success in patients with OSA. Obesity is a major risk factors for
obstructive sleep apnea and obese patients have a higher prevalence of UAO during anesthesia.
The investigators hypotheses that nCPAP should eliminate airway obstruction in obese patients
under anesthesia. The investigators propose to test this hypothesis and determine the
efficacy of nCPAP on maintaining airway patency in obese patients who require general
anesthesia compared with CPAP administering face mask.