The diagnosis of delirium is clinical. No single test is successful. Obtaining a thorough history is essential.

• Because delirious patients often are confused and unable to provide accurate information, getting a detailed history from family, caregivers, and nursing staff is particularly important. Nursing notes can be very helpful for documentation of episodes of disorientation, abnormal behavior, and hallucinations. Learning to record accurate and specific findings in mental status as well as the particular time the finding was observed is imperative for the staff. Staff should not just report ?he was confused.?

• Delirium always should be suspected when an acute or subacute deterioration in behavior, cognition, or function occurs, especially in patients who are elderly, demented, or depressed.

• Patients may have visual hallucinations or persecutory delusions as well as grandiose delusions.

• Some patients with delirium also may become suicidal or homicidal. Therefore, they should not be left unattended or alone.

• Delirium is mistaken for dementia or depression, especially when patients are quiet or withdrawn. However, by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria, dementia cannot be diagnosed with certainty when delirium is present.

Physical:

• A careful and complete physical examination including a mental status examination is necessary. Testing vital signs such as temperature, pulse, blood pressure, and respiration is mandatory.

• Patients have difficulty sustaining attention, problems in orientation and short-term memory, poor insight, and impaired judgment. Key elements here are fluctuating levels of consciousness.

• Impaired attention can be assessed with bedside tests that require sustained attention to a task that has not been memorized, such as reciting the days of the week or months of the year backwards, counting backwards from 20, or doing serial subtraction.

• DSM-IV diagnostic criteria for delirium

• Disturbance of consciousness (ie, reduced clarity of awareness of the environment) occurs, with reduced ability to focus, sustain, or shift attention.

• Change in cognition (eg, memory deficit, disorientation, language disturbance, perceptual disturbance) occurs that is not better accounted for by a preexisting, established, or evolving dementia.

• The disturbance develops over a short period (usually hours to days) and tends to fluctuate during the course of the day.

• Evidence from the history, physical examination, or laboratory findings is present that indicates the disturbance is caused by a direct physiologic consequence of a general medical condition, anintoxicating substance, medication use, or more than one cause.

• Other diagnostic instruments are the Delirium Symptom Interview (DSI) and the Confusion Assessment Method (CAM).

• Delirium symptom severity can be assessed by the Delirium Rating Scale (DRS) and the Memorial Delirium Assessment Scale (MDAS).

• Table 1. Differentiating Features of Delirium and Dementia

   

  Features	Delirium	Dementia
  Onset	Acute	Insidious
  Course	Fluctuating	Progressive
  Duration	Days to weeks	Months to years
  Consciousness	Altered	Clear
  Attention	Impaired	Normal, except for severe dementia
  Psychomotor changes	Increased or decreased	Often normal
  Reversibility	Usually	Rarely

   

• To make an accurate diagnosis, periodic application of diagnostic criteria such as CAM or DSM-IV criteria and knowledge of the patient's baseline mental status is imperative.

• Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) offers the clinician the opportunity to identify delirium in critical care patients, especially patients on mechanical ventilation. The CAM-ICU makes use of nonverbal assessments to evaluate the important features of delirium.

By: M. Mula

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