Laparoscopic surgery for gastric reduction is frequently associated with high levels of postoperative pain. Postoperative pain is very often treated with opioids. However large doses of opioids can result in respiratory depression with hypoxemia especially in high risk patients with obstructive sleep apnea. since a large group of patients undergoing surgery for gastric reduction surgery also have obstructive sleep apnea, it is expected that these patients are also at high risk for postoperative respiratory depression and hypoxemia.

Intraoperative ketamine has been used as an effective multimodal agent to reduce postoperative pain. However, ketamine alone has not been examined to improve postoperative pain outcomes in patients undergoing gastric reduction surgery. More importantly, it is unknown if the use of intraoperative ketamine can lead to better overall quality of recovery in the same patient population. In addition, ketamine has been shown to improve ventilation but it remains to be determined if the intraoperative use of ketamine will result in less postoperative hypoxemic events.

The main objective of the current investigation is to examine the effect of intraoperative ketamine on postoperative quality of recovery after gastric reduction surgery. The investigators hypothesize that subjects receiving ketamine will have a greater global quality of recovery score than the ones receiving saline.

Inclusion Criteria:

• Age 18-64
• surgery: laparoscopic gastric reduction (gastric sleeve or gastric bypass)
• ASA physical status classification I, II, III
• Body Mass Index >35kg/m2
• Fluent in English

Exclusion Criteria:

• History of allergy to protocol medications
• History of chronic opioid use
• Pregnant patients
• Drop out: Conversion to an open surgical route, patient or surgeon request.

Time period for adverse events were collected was until discharge from hospital which is indefinite but generally up to 2 weeks.