Ketamine Intolerance In Enhanced Recovery After Surgery Patients Undergoing Colorectal Operations.

Background Ketamine is used in Enhanced Recovery after Surgery (ERAS) protocols because of its beneficial antihyperalgesic and antitolerance effects. However, adverse effects such as hallucinations, sedation, and diplopia could limit ketamine’s utility. The main objective of this study is to identify rates of ketamine side effects in postoperative patients after colorectal surgery, and secondarily, to compare short-term outcomes between patients receiving ketamine analgesia and controls. Methods Retrospective observational cohort study. Subjects were adults who underwent ERAS protocol-guided colorectal surgery at a large, integrated health system. Patients were grouped into ketamine-receiving and pre-ketamine cohorts. Patients receiving ketamine were divided into tolerant and intolerant groups. Propensity score-adjusted models tested multivariate associations of ketamine tolerance/intolerance versus control group. Results A total of 732 patients underwent colorectal surgery within the ERAS program before ketamine’s introduction (Control). After ketamine’s introduction, 467 patients received the medication. Intolerance was seen in 29% of ketamine recipients, and the most common side effect was diplopia. Demographics and surgical variables did not differ between cohorts. Multivariate models revealed no significant differences in hospital stays. Pain scores in the first 24hours after surgery were slightly higher in ketamine patients. Opiate consumption after surgery was lower for both Ketamine Tolerant and Ketamine Intolerant cohorts versus Controls. Conclusion Rates of ketamine intolerance are high, which can limit its use and potential effectiveness. Ketamine analgesia significantly reduced opiate consumption without increasing hospital stays after colorectal surgery, regardless of whether it was tolerated.