All subjects will be assessed daily or more frequently for delirium. The institutional CAM and CAM-ICU Delirium screens, which have been validated in the literature, will be utilized (see appendices IV and V). Subjects may remove oneself from the trial or be un-blinded should he/she, pharmacy, and/or clinical staff deem it medically necessary. Medical necessity is determined by inability to treat without knowledge of trial assignment; otherwise treating staff will assume all patients have received ketamine. All adverse events will be recorded and if necessary subjects will be un-blinded in the event of a serious adverse event.