Safety Study of Positive Airway Pressure Via a Nasal Mask in Obese Patients

Upper airway obstruction (UAO) is a frequently occurring complication during induction of general anesthesia. The American Society of Anesthesiologist (ASA) closed claim analysis of anesthesia complications indicate that a difficult airway is one of the most challenging scenarios continuously facing anesthesia providers. The mechanism of UAO during anesthesia has not been well understood. Posterior displacement of soft palate, tongue and epiglottis are believed to be the primary contributing factors. Obesity is well known to be an essential characteristic which reflects propensity to UAO. The mechanism of 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. Therefore, 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.