Nitrous Oxide Vasodilation Healthy Adult Volunteers

Inclusion Criteria: * Healthy adult volunteers. * 19 years or older (inclusive) * English speaking. Exclusion Criteria: * ASA class III or greater; * History of, or suspected, difficult airway based on physical exam, facial dysmorphism or syndrome * Any condition in which air may be trapped in a body cavity. These include, but are not limited to: Pneumothorax or chest injury, concurrent acute asthma exacerbation, middle ear occlusion, intestinal obstruction, ileus, or abdominal distension, sinusitis or maxillofacial injuries with potential for trapped gas, recent intraocular surgery or penetrating globe injury, air embolus, severe bullous emphysema (consider in patients with cystic fibrosis), history of craniotomy in previous three weeks * Pregnancy (1st and 2nd trimester) * Increased intracranial pressure, impaired level of consciousness, or head injury * Known Vitamin B12 deficiency * Known MTHFR Deficiency (Inborn error of metabolism) * History of bleomycin administration (note that the oxygen component of N2O administration is what interacts with bleomycin to cause pulmonary toxicity) * Intoxication with alcohol or other drugs * Any condition in which patient may be catecholamine-depleted (e.g. septic shock) * Recent history of altered mental status * Pulmonary hypertension * Congestive heart failure. * Trainees, including students, residents, and fellows, working in the pediatric emergency department.