 This study will consider other clinical data of interest from both intra- and post-operative contexts in order to establish a broader understanding of the potential implications of the use of a low dose of ketamine during closed-loop controlled anesthesia. In the OR, the investigators will record other indications of anesthetic quality, such as vital signs and the occurrence of any unwanted intra-operative events. Propofol and remifentanil consumption will be quantified, and the requirement of any other interventions will be recorded. The investigators will also record post-operative patient outcomes that have previously been associated with ketamine administration, such as acute post-operative pain intensity, opioid requirements, the occurrence of PONV, and shivering occurring in the post-anesthesia care unit PACU. 