Introduction

The acute confusional state known as delirium is the most common cause of altered mental status in surgical patients. 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 mortality, postoperative complication rates, longer lengths of stay and delayed functional recovery.

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. The cardinal feature of delirium is an alteration in the level of consciousness that fluctuates over time. Patients may also display 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 to 4 weeks if sufficient attention is given to correcting the underlying disorder causing the cerebral dysfunction. Nonetheless, the development of delirium serves as a marker for those patients at risk of progressive functional decline.

Multiple signs and symptoms may accompany delirium. Patients may be grossly psychotic with severe perceptual distortions that can include hallucinations (tactile, auditory, visual, olfactory), paranoia, delusions, thought disorganization and language incoherence resembling schizophrenia. Signs of cognitive dysfunction such as disturbances in memory, attention, concentration, and orientation are usually the first to be recognized. Behavioral abnormalities such as agitation, disinhibition, and combativeness may also occur.