Delirium is an acute fluctuating disturbance of consciousness accompanied by inattention and changes in cognitive function.¹ Although its exact pathophysiology is poorly understood, delirium in the elderly has been associated with lengthy hospital stays, increased mortality, and substantial economic burden.

Unfortunately, emergency departments continue to do a poor job in recognizing this disease state despite its high prevalence in elderly patients who are admitted—close to 16 percent.² Health care costs associated with delirium are well over $38 billion annually and may be as high as $150 billion.³ Despite increasing research in the field, delirium is still missed by emergency physicians up to 83 percent of the time.^4,5 The good news is there are several areas where physicians can improve in not only the diagnosis but also in prevention.

Diagnosing Delirium
Delirium is found in all areas of medicine and must be dealt with in a multicomponent approach. For emergency physicians, this means prompt recognition as well as ensuring that admitting teams are clearly informed of the diagnosis.

Paramount to the diagnosis of delirium is first understanding who is most at risk. There should be a high index of suspicion in the geriatric population, particularly for severely ill patients and patients with a history of dementia, alcoholism, or hypertension.

Workups must begin with a full history focusing on the patient’s baseline mental status and timing of the confusion. Physicians should review all medications and look closely for precipitants such as anticholinergics and opioids. If a history is lacking upon arrival, assume the mental status change to be acute and proceed with a full workup.⁶ Vital signs, including a blood glucose level, as well as a detailed physical exam, especially the neuro exam, are critical starting points.

Look for signs of occult infection, abdominal processes, dry mucous membranes, focal neurological deficits, or any sign of acute illness. Based on history and physical examination, laboratory tests should be ordered along with imaging tests, as indicated (eg, chest X-ray, CT head). Selected patients may need a lumbar puncture to rule out meningitis/encephalitis, an EEG to rule out nonconvulsive status epilepticus, or an arterial blood gasses/venous blood gasses (ABG/VBG) test to rule out acidosis.

It’s important to differentiate delirium from common mimics such as psychotic illness and dementia.^6,7 In contrast to delirium, dementia occurs over a longer period of time, doesn’t fluctuate, and has an insidious onset. Dementia is the leading risk factor for delirium, but the two are distinct entities. Psychotic disorders are differentiated from delirium by their chronic courses with exacerbations as well as normal level of consciousness and otherwise lack of slurred speech.⁷