Inclusion Criteria:  Age 18-65 years Undergo surgery under general anesthesia in UCI Medical Center Agree to sign the consent and HIPAA forms Subjects who are able to receive sevoflurane  Exclusion Criteria:  Subjects under the age of 18 Chronic Obstructive Pulmonary Disease (COPD) Body Mass Index (BMI) > 30 ASA > 2 Pregnant females Procedures less than 2 hours Those with known sensitivity to sevoflurane or other halogenated agents; those with known or suspected susceptibility to malignant hyperthermia Severe Cardiovascular Disease: Left Ventricular Ejection Fraction (LVEF) < 30%