Introduction

The acute confusional state known as delirium is the most common cause of altered mental status in surgical patients. The cardinal feature of delirium is an alteration in the level of consciousness that fluctuates over time. Despite its common occurrence delirium can often go unrecognized, leading to delays in treatment. This can have significant implications as patients with delirium suffer from higher postoperative complication rates, longer lengths of stay, and delayed functional recovery [1].

Delirium is usually acute in onset but may develop gradually. It can persist for hours to days and can fluctuate throughout the course of a day. A clouding of consciousness is most common but patients can also show hyperalert, irritable, or agitated behavior. The sleep–wake cycle is often markedly disrupted. Sleep is usually fragmented, with restlessness and agitation. Psychomotor abnormalities may range from hyperactivity to lethargy, stupor, obtundation, and catatonia. Most cases of delirium improve or resolve within 1–4 weeks if sufficient attention is given to correcting the underlying disorder causing the cerebral dysfunction. However, the development of delirium, particularly in frail, elderly patients is a marker for progressive decline [2].