Comparison of the Efficiency of Mouth-to-nose Breathing With Mouth-to-mouth Breathing

Inclusion Criteria: * Healthy subjects between 18 to 59 years of age * meeting ASA I-II criteria * Undergoing elective surgery and requiring general anesthesia * Being able to breathe through both the nose and the mouth while awake Exclusion Criteria: 1. Patients with known infectious diseases, bacteria infections such as Neisseria meningitidis, upper respiratory tract infection (URI), bacterial pneumonia, etc. and patients with known HIV, HBV, HCV, or TB infection. Patients with broken oral mucosa or obvious sores. 2. Patients with immunosuppression from radiotherapy, chemotherapy, etc. 3. Patients with cardiovascular disease, respiratory disease, cerebral vascular disease and ASA class III or greater risk for anesthesia as defined by the American Society of Anesthesiologists. 4. Abnormal vital signs on the day of admission for surgery (HR, BP, room air oxygen saturation, EKG) that are not correctable with his or her routine medication or commonly used pre-operative medication. 5. Ischemic heart disease with chest pain or arrhythmias, patients with a pacemaker or AICD device and patients with heart failure. 6. Respiratory diseases, including subjects with COPD, asthma, pulmonary hypertension, restrictive lung disease, pleural effusion, tracheal stenosis and tracheal malacia, respiratory tract infection within the preceding week and those with previous pneumonectomy, lobectomy, tracheostomy, laryngectomy, tongue resection, and pharyngeal laryngeal plasity. 7. Unable to open mouth (\<2.5 cm) or unable to breathe through mouth or nose. 8. Anticipated difficult airway: Mallampati score of III or greater, decreased neck movement, decreased mandibular movement, history of therapeutic radiation to the larynx or neck, prominent incisors. Subjects require or may require fiberoptic intubation 9. Important nasal septum deviation or other conditions impairing nasal breathing. The patient's nasal patency will be confirmed by inspiring with the mouth shut and open. 10. Gastric-esophageal reflex or a full stomach. 11. Obese with BMI greater than 35. 12. Neurological symptoms associated with neck extension, neurological deficit from previous stroke or spinal cord injury, recent stroke or TIA within 2 weeks. 13. Pregnant women and women less than one month post-partum. Ruling out pregnancy will be conducted by careful history and physical examination as done routinely prior to a 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. 14. Emergency cases, and subjects who have not adhered to the ASA NPO guidelines. 15. Prisoners.