Study on the Use of Low Dose Ketamine After Gastric Bypass and Gastrectomy

Inclusion Criteria: 1. Adults, \>18 years, \<65 years, who will undergo gastric bypass or sleeve gastrectomy. 2. Subject is non-lactating and is either: * Not of childbearing potential; or * Of childbearing potential but is not pregnant at time of baseline as determined by pre-operative pregnancy testing. 3. Subject is ASA physical status 1, 2, or 3. 4. Subject who is deemed medically stable Exclusion Criteria: 1. \<18 years of age; \>65 years of age 2. Pregnant or breastfeeding 3. Does not speak or understand English (the study forms used are copy-righted in English) 4. Cognitively impairment (by history) or clinical signs of altered mental status 5. History of misuse or abuse of ketamine 6. History of chest pain or chest pain in the PACU 7. Use of a medication that interferes with metabolism of ketamine within the last 24 hours 8. A diagnosis of schizophrenia and/ or a history of chronic antipsychotic medication use 9. History of head trauma 10. History of intracranial mass or hemorrhage 11. History of stroke 12. History of cardiac arrhythmia 13. Subject for whom ketamine is contraindicated 14. Unwillingness to give informed consent according to HIC guidelines