This is a randomized, double-blind, placebo-controlled, two-arm parallel, single-center study. One hundred subjects (50 in each arm) will be enrolled. Subjects, between the ages 18 and 65, undergoing laparoscopic gastric bypass or sleeve gastrectomy will be recruited and consented during the preadmission visit prior to surgery.

This is a randomized, double-blind, placebo-controlled, two-arm parallel, single-center study. One hundred subjects (50 in each arm) will be enrolled. Subjects, between the ages 18 and 65, undergoing laparoscopic gastric bypass or sleeve gastrectomy will be recruited and consented during the preadmission visit prior to surgery. Eligible subjects will be randomized to one of the two treatment group in a 1:1 ratio to receive either IV ketamine (0.4mg/kg) or matching placebo. Both men and women will be recruited, and there is no limitation as to racial and ethnic origin. In the PACU, patients will receive either 0.4mg/kg IV ketamine or placebo. All patients will also receive standard post-anesthetic monitoring and care, as well as routine care after transfer out of the PACU. Patients are followed until the date of discharge, and endpoints (see below) are collected from patient reports as well as from medical charts. During their hospital stay (and once after their discharge from the hospital), patients will fill out five questionnaires which provide estimates of their postoperative pain control, mood and function, and quality of postsurgical recovery. An additional component of the study, which is entirely optional, is to obtain patient serum samples (about two teaspoons) in the operating room and 15 minutes and 4 hours after ketamine infusion. The investigators will use these samples to assess levels of IL-1, IL-6, TNF-α, and BDNF, which are markers for pain. In addition, with patient consent, the investigators will also store serum samples for future research use to measure other cytokines and neurotrophic factors and molecular markers associated with pain and depression.

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

1 Year

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