Throughout the subject's hospital stay, pain levels and medication usage are recorded. The CAM and MDAS (Memorial Delirium Assessment Scale) are used to identify and determine severity of PD. The evaluations are given twice daily, at approximately 6:00 AM and 6:00 PM, for 7 days or until hospital discharge (whichever comes first). The Postoperative Quality of Recovery Scale (PQRS) is used each post-operative day at 6:00 PM until discharge, and completed over the phone on POD 7 if patient discharged. The PQRS is also administered over the phone on POD 30 and POD 90.