Arriving at a delirium diagnosis
The clinical presentation of delirium is characterized by acute—and reversible—impairment of cognition, attention, orientation, and memory, and disruption of the normal sleep/wake cycle. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) criteria for a delirium diagnosis include all of the following:
- disturbance of consciousness, with a reduced ability to focus, sustain, or shift attention
- change in cognition, or a perceptual disturbance, that is not accounted for by a preexisting or developing dementia
- rapid onset of cognitive impairment, with fluctuation likely during the course of the day
- evidence from the history, physical exam, or laboratory findings that the disturbed consciousness is a direct physiological consequence of a general medical condition.17
There are 3 basic types of delirium, each associated with a different psychomotor disturbance.
- Hyperactive delirium—the least common—is characterized by restlessness and agitation, and is therefore the easiest to diagnose.
- Hypoactive delirium is characterized by psychomotor retardation and hypoalertness. It is often misdiagnosed as depression, and has the poorest prognosis.
- Mixed delirium—the most common—is characterized by symptoms that fluctuate between hyper- and hypoactivity.18
CASE By lunchtime, Mr. D had awakened; however, he needed help with his meal. After eating, he slept for the rest of the day. At night, a nurse paged the resident to report that the patient’s blood pressure was 82/60 mm Hg and his heart rate was 115. The physician ordered an intravenous fluid bolus, which corrected the patient’s hypotension, but only temporarily.
The fluctuating nature of delirium—most notably, in patients’ level of alertness—is helpful in establishing a diagnosis. The history and physical exam are the gold standard tools, both for diagnosing delirium and identifying the underlying cause (TABLE 3).19,20 A review of the patient’s medications should be a key component of the medical history, as drugs—particularly those with anticholinergic properties—are often associated with delirium. Environmental shifts, including hospitalization and a disruption of the normal sleep/wake cycle, endocrine disorders, infection, and nutritional deficiencies are also potential causes of delirium, among others.
If history and physical exam fail to identify the underlying cause, laboratory testing, including complete blood count, complete metabolic profile, and urinalysis, should be done. Brain imaging is usually not needed for individuals with symptoms of delirium, but computed tomography (CT) may be indicated if a patient’s condition continues to deteriorate while the underlying cause remains unidentified.21 Electroencephalography (EEG) may be used to confirm a delirium diagnosis that’s uncertain, in a patient with underlying dementia, for instance. (In more than 16% of cases of delirium, the cause is unknown.22)
The most common structural abnormalities found in patients with delirium are brain atrophy and increased white matter lesions, as well as basal ganglia lesions.23 Single-photon emission CT (SPECT) shows a reduction of regional cerebral perfusion by 50%,24 while EEG shows slowing of the posterior dominant rhythm and increased generalized slow-wave activity.25
TABLE 3
A DELIRIUM mnemonic to get to the heart of the problem19,20
| Cause | Comment |
|---|---|
| Drugs | Drug classes: Anesthesia, anticholinergics, anticonvulsants, antiemetics, antihistamines, antihypertensives, antimicrobials, antipsychotics, benzodiazepines, corticosteroids, hypnotics, H2 blockers, muscle relaxants, NSAIDs, opioids, SSRIs, tricyclic antidepressants Drugs: digoxin, levodopa, lithium, theophylline OTCs: henbane, Jimson weed, mandrake, Atropa belladonna extract |
| Environmental | Change of environment, sensory deprivation, sleep deprivation |
| Endocrine | Hyperparathyroidism, hyper-/hypothyroidism |
| Low perfusion | MI, pulmonary embolism, CVA |
| Infection | Pneumonia, sepsis, systemic infection, UTI |
| Retention | Fecal impaction, urinary retention |
| Intoxication | Alcohol, illegal drugs/drug overdose |
| Undernutrition | Malnutrition, thiamin deficiency, vitamin B12 deficiency |
| Metabolic | Acid-base disturbances, fluid and electrolyte abnormalities, hepatic or uremic encephalopathy, hypercarbia, hyper-/hypoglycemia, hyperosmolality, hypoxia |
| Subdural | History of falls |
| CVA, cerebrovascular accident; MI, myocardial infarction; NSAIDs, nonsteroidal anti-inflammatory drugs; OTCs, over-the-counter agents; SSRIs, selective serotonin reuptake inhibitors; UTI, urinary tract infection. | |
Treating (or preventing) delirium: Start with these steps
Nonpharmacologic interventions are the mainstay of treatment for patients with delirium, and may also help to prevent the development of delirium in patients at risk. One key measure is to correct, or avoid, disruptions in the patient’s normal sleep/wake cycle—eg, restoring circadian rhythm by avoiding,
to the extent possible, awakening the patient at night for medication or vital signs. Preventing sensory deprivation, by ensuring that the patient’s eyeglasses and hearing aid are nearby and that there is a clock and calendar nearby and adequate light, is also helpful. Other key interventions (TABLE 4)26-28 include:
- limiting medications associated with delirium (and eliminating any nonessential medication)
- improving nutrition and ambulation
- correcting electrolyte and fluid disturbances
- treating infection
- involving family members in patient care
- ensuring that patients receive adequate pain management
- avoiding transfers (if the patient is hospitalized) and trying to secure a single room.