A prospective randomized, double blinded clinical trial of ketamine use in adult colorectal surgery patients will be conducted. The experimental arm of the trial will receive ketamine infusion therapy while the control arm of the trial receives saline placebo infusions at an equivalent rate. All patients enrolled into the trial will be enrolled in a standardized Enhanced Recovery after Surgery (ERAS) pathway which includes intravenous opioid medications for breakthrough pain, scheduled acetaminophen, and NSAIDs as indicated. All patients will be managed in accordance with the appropriate Division of Trauma and Acute Care Surgery and Division of Colorectal Surgery policies.