Delirium with its impaired sensorium, fluctuating consciousness, decreased attention, and global cognitive impairment leads to a number of symptoms that mimic a variety of psychiatric disorders (2,3). Common symptoms include inattention, altered arousal, psychomotor abnormalities, sleep-wake disturbance, impaired memory, disorganized thinking, disorientation, and altered perceptions that can develop into delusions, illusions, and hallucinations. All these symptoms may be fleeting, and a hallmark of delirium is the fluctuating mental status exam.

Although agitated hyperactive delirium may be easier to recognize, it is important to remember that delirium just as frequently presents without such overt manifestations and with reduced motor activity and less dramatic psychiatric manifestations (4). Research indicates that this hypoactive set of delirious patients is frequently underrecognized, especially among the elderly (5). Both the hypoactive and the hyperactive presentations are complex in their own right, and a mixed state can occur as well, making the diagnosis of delirium even more challenging.

Delirium is a serious, life-threatening condition, particularly in the elderly (1). It is vital that the delirious patient be diagnosed quickly and, if the patient is initially seen in a dedicated psychiatric emergency service (PES) by the psychiatrist, that he or she be transferred to the medical emergency service where appropriate treatment can be started as soon as possible. The PES psychiatrist should watch for hallmark signs and symptoms of delirium and have a high index of suspicion, especially when a patient with several mental status exam abnormalities has no psychiatric history or a history of only dementia. Psychiatrists may assist in the management of the patient’s agitation, but the primary care of the emergency patient with delirium should be given by the medical team. The issues that confound rapid diagnosis are numerous, and most cases of delirium lack a clear etiology. Specific and timely treatments can also be confounded. Thus, timely diagnosis in delirium is essential, and if no specific etiology is discovered, then basic medical support and monitoring must be provided to the patient.

History, a key element in medical assessment, is difficult to acquire in “out-of-control” patients. Vital signs and some basic screening tests are
equally important yet difficult to obtain. Differentiating delirium from primary psychiatric illness requires a full set of “agitation vital signs” (oxygen saturation, glucometer, blood pressure, heart rate, temperature, and respiratory rate) in addition to a thorough history and physical exam (6). Important historical questions include rapidity of onset, events leading to the crisis, presence and type of hallucinations, suicidal and homicidal ideation, and a detailed past medical history. Questions related to medications and dosages are also key and are often overlooked (7). Because delirium is difficult to diagnose, patients may be triaged to psychiatric emergency services from medical emergency services as being medically cleared. Emergency physicians are notoriously poor at obtaining and documenting key information, especially in areas related to the psychiatric history, mental status exam, and neurologic examination.

All physicians may be more successful obtaining an adequate history from the agitated patient by appearing calm, speaking in a quiet voice, and presenting themselves as patient advocates. Because the agitated patient is often unable to give an adequate history, family, partners, police, social workers, paramedics, old records, and personal physicians are all excellent resources. Direct, clear questions about drug or alcohol use and other risky behavior are invaluable in the agitated patient’s evaluation. Yet, it is always important to avoid the dangers of labeling the patient and narrowing the differential possibilities prematurely (6,8).

The list of causes for delirium is extensive (11), and because the symptoms of delirium include psychosis, patients can be called psychiatric or “functional” and not get the medical evaluation and care they deserve (12). It is important to differentiate the psychiatric from the delirious because patients presenting with agitation secondary to organic causes have significant mortality and morbidity risk (9). Medical agitation or delirium is an acute reversible impairment of cognition characterized by (a) disorientation and poor attention, (b) impaired short-term memory, (c) altered perception of the environment, (d) inappropriate behavior, and (e) fluctuating levels of consciousness. Delirium is often characterized by visual hallucinations, which are in contrast to the auditory hallucinations of schizophrenia. Factors that would point to an organic etiology include abrupt onset of symptoms, new psychiatric symptoms in a patient older than 40 years, impaired cognitive function, visual or tactile hallucinations that are unorganized, and abnormal vital signs (9). Any patient with recent hospitalizations, medication changes, substance abuse, incontinence, nystagmus, or diaphoresis should be considered to have a medical etiology for his or her agitation until proven otherwise (6).