Psychological Effect of Explicit Recall After Sedation (PEERS)

Awareness, or explicit recall, under sedation is often intended and expected by anesthesiologists and is assumed that does not associate with any sequelae. Thus, awareness under sedation is a common event and is estimated to occur in around one-quarter of patients in our population. However, two recent studies suggested some patients with awareness under sedation have comparable psychological sequelae to those patients with awareness during general anesthesia. As such, we plan to conduct a a single center, prospective cohort study to determine the incidence of explicit recall under sedation/regional anaesthesia in adults, and to identify whether explicit recall experiences - or specific elements of those experiences (e.g. feeling pain and paralysis) - were associated with psychiatric sequelae. In this study, we will prospectively include 2500 patients who will be scheduled to have total hip and knee joint replacement surgery under regional anesthesia and sedation at University Hospital, London Health Sciences Center. All participants will be assessed at four separate time points including: 1. Enrollment/Surgical Preparatory Area (\~ 2 hours before surgery) 2. Post Anesthesia Care Unit (assessment will be conducted in PACU prior to discharge, within a maximum window of 6 hours from PACU admission) 3. Postoperative day one (in hospital) 4. Postoperative 6 weeks (expected to be after discharge via telephone or in-person in clinic)