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Key Concepts
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Confusion and delirium are symptoms, not a diagnosis.
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Focal cortical dysfunction, such as from tumor or stroke, typically does not cause confusion.
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Any underlying clinical process that disrupts optimal central nervous system (CNS) functioning can result in confusion.
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Emergent causes of confusion that need immediate detection and treatment include hypoglycemia, hypoxemia, hypotension, sepsis, and toxic ingestions.
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Assessment of attention is fundamental for the assessment of patients with confusion as disturbances in attention are consistent with delirium versus psychiatric illness or dementia.
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Recommended tools for identifying patients with delirium in the emergency department are the Delirium Triage Screen (DTS) and brief Confusion Assessment Method (bCAM), if indicated.
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Delirium often goes unrecognized unless a structured assessment tool is used.
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Sedatives, including antipsychotics, are useful for managing undifferentiated agitation while the diagnostic evaluation is in progress.
Foundations
The term confusion indicates an acute impairment in higher cerebral functions, such as memory, attention, or awareness. The disorder has multiple synonyms, some of which imply causative mechanisms, and always represents a symptom of another underlying disease process. Confusion ranges in severity from mild disturbances of short-term memory to a global inability to relate to the environment and process sensory input. Along this spectrum, the disorder overlaps with the term delirium (see Chapter 90 ), and the two terms are often used interchangeably. The degree of confusion may fluctuate over time, as may the patient’s level of consciousness.
Delirium implicitly develops over a short period of time, typically hours or days, although it may persist for weeks. Although patients with preexisting dementia are at higher risk for developing delirium, the acute changes of delirium are distinct from and cannot be better explained diagnostically by a newly diagnosed or evolving dementia. The same pathophysiologic processes causing confusion and delirium may manifest with altered mentation and diminished alertness along the coma spectrum.
Confusion has many causes, and an orderly approach is helpful to discover the causative diagnosis. The assessment of mental status and cognitive impairment, with a focus on changes from baseline function, is an important part of the evaluation in older emergency department (ED) patients. Altered mental status may be a frequent finding even without a chief complaint of confusion. Collateral history from family or caregivers, a structured physical examination, and the use of a specific assessment tool may be needed to detect the presence of confusion.
Epidemiology
Emergency clinicians underestimate the incidence of confusion in patients. Because confusion is often accepted as an incidental or secondary component of another condition, it may be overshadowed by the primary condition being treated. When confusion exists as an isolated or unexplained finding, it is more likely to receive full and immediate consideration by the emergency clinician. Confusion occurs in a high percentage of hospitalized patients, with highest risk in frail, elderly, and critically ill populations. An estimate of ED prevalence of delirium in elderly patients is 8% to 17%, and delirium in the ED often persists into the hospitalization. Presence of delirium carries important negative prognostic implications for patients. In hospitalized patients, delirium is associated with higher mortality, worse functional and cognitive outcomes, and decreased rates of home discharge.
Pathophysiology
Conceptually, consciousness is divided into elements of alertness, or arousal, and elements constituting the content of consciousness. Although arousal may be abnormal, the characteristic disturbance in confusion is to the content portion of consciousness, resulting in abnormalities of attention and awareness. Any underlying clinical process that disrupts optimal central nervous system (CNS) functioning can result in confusion. Global CNS dysfunction usually results from substrate deficiencies (e.g., hypoglycemia, hypoxemia), neurotransmitter dysfunction, intoxication with or withdrawal from neuroactive drugs, or circulatory dysfunction. Individuals with a preexisting impairment are more sensitive to these factors and may become confused after even minor changes in their normal physiologic state.
Diagnostic Approach
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