Effect of Single Dose Ketamine and Magnesium on Postoperative Pain in Patients Undergoing Bariatric Surgery

Effect of Single Dose Ketamine and Magnesium on Postoperative Pain in Patients Undergoing Bariatric Surgery

Effect of Single Dose Ketamine and Magnesium on Postoperative Pain in Patients Undergoing Bariatric Surgery

Opioid sparing analgesia is extremely important in the post-operative obese population. With more and more obese patients entering the operating room a multi-modal approach to analgesia is crucial. Finding effective alternatives to opioid therapy is the rationale of this proposal. Literature involving ketamine and magnesium in bariatric surgical patients is very sparse.

Patient will be identified by surgeon and consented by member of the research team Patient will be randomized to one of three groups on the day of surgery Following securement of the endotracheal tube, the study medication will be administered over 10 minutes via an IV infusion pump. The subject will receive ketamine, ketamine plus magnesium or a placebo. Following surgery, the patient will be taken to the post anesthesia care unit (PACU) and set up with standard ASA monitoring as well as end-tidal CO2 via nasal cannula. A hydromorphone patient controlled analgesia (PCA) pump will be set-up by nursing and given to the patient. Standard dosing of 0.2 mg bolus, every 6 minutes with a maximum 2 mg will be the starting dose as is standard for these patients post-operatively. Primary outcome will be the total amount of hydromorphone used in the first 24 hours post-operatively. .

Pain scores using VAS scale will be recorded pre-operatively, in the PACU, and every 4 hours until 24 hours post-op. The VAS is a 10 point scale, where 0 = no pain and 10 = the worst pain a subject has ever felt. The highest value 10, indicates an extreme self reported level of pain.

The average MAC concentration of desflurane will be recorded during the intraoperative period. The Minimum Alveolar Concentration (MAC) of an inhaled anesthetic is the alveolar (or end-expiratory) concentration at which 50% of patients will not show a motor response to a standardized surgical incision.

Inclusion Criteria: Subjects undergoing laparoscopic sleeve gastrectomy Consenting adults age 18-80 ASA II to ASA III Ability to understand and use a PCA Required to be hospitalized for at least 24 hours post-op Exclusion Criteria: Patient refusal Chronic opiate use (daily opiate use for >3 months) Chronic Kidney disease (Creatinine>2) Known allergy or adverse effect of ketamine, magnesium or hydromorphone Patients with documented psychiatry (Maniac or MDP) history Patient unable to give informed consent Patient with limited or no English fluency