Residency · Residency · Internal Medicine
Delirium: Prevention, Recognition, and Management
Introduction
Delirium is an acute, fluctuating disturbance in attention and awareness that is common among hospitalized patients, particularly the elderly. It is associated with increased mortality, prolonged hospital stays, long-term cognitive decline, and higher rates of institutionalization. Despite its clinical significance, delirium remains under-recognized by medical teams. Prevention is the most effective strategy, and every internist must be skilled in identifying and managing this condition.
Epidemiology
- Affects 20-30% of hospitalized medical patients and up to 80% of ICU patients
- Prevalence increases with age, surgical interventions, and critical illness
- Associated with increased in-hospital mortality (up to 3-fold)
- Independently predicts prolonged hospitalization, functional decline, and nursing home placement
- Estimated to contribute to over $150 billion in annual healthcare costs in the United States
Pathophysiology
- Multifactorial: interaction between predisposing (baseline vulnerability) and precipitating factors
- Neurotransmitter imbalance: acetylcholine deficiency and dopamine excess
- Neuroinflammation, blood-brain barrier disruption, oxidative stress
- Medications with anticholinergic properties are the most common iatrogenic cause
Risk Factors
Predisposing Factors (Baseline Vulnerability)
- Age >= 65 years
- Pre-existing dementia or cognitive impairment (single strongest predisposing factor)
- Functional impairment, immobility
- Sensory impairment (vision, hearing)
- History of alcohol use disorder
- Multiple comorbidities, frailty
Precipitating Factors (Acute Triggers)
- Medications: benzodiazepines, opioids, anticholinergics, corticosteroids, fluoroquinolones
- Infections: urinary tract infection, pneumonia, sepsis
- Metabolic derangements: electrolyte abnormalities, hypoglycemia, uremia, hepatic encephalopathy
- Pain: both undertreated and overtreated
- Sleep deprivation and ICU environment
- Urinary retention, fecal impaction, dehydration
- Surgery, anesthesia, restraint use, indwelling catheters
Clinical Subtypes
| Subtype | Frequency | Features | Prognosis |
|---|---|---|---|
| Hyperactive | ~25% | Agitation, hallucinations, psychomotor activation | Easily recognized; better outcomes |
| Hypoactive | ~50% | Lethargy, withdrawal, reduced alertness | Most frequently missed; worst prognosis |
| Mixed | ~25% | Fluctuates between hyperactive and hypoactive | Intermediate |
- Hyperactive delirium: agitation, psychomotor activation, hallucinations; easy to recognize but accounts for only ~25%
- Hypoactive delirium: lethargy, reduced alertness, withdrawal; most common (~50%) and most frequently missed
- Mixed delirium: fluctuates between hyperactive and hypoactive features (~25%)
- Hypoactive delirium carries the worst prognosis because it is often undetected
Diagnosis
Confusion Assessment Method (CAM)
The most widely validated bedside screening tool. Requires both 1 and 2, plus either 3 or 4:
- Acute onset and fluctuating course: is there an acute change from baseline that waxes and wanes?
- Inattention: does the patient have difficulty focusing? (spell WORLD backward, months of the year backward)
- Disorganized thinking: incoherent or illogical thought process
- Altered level of consciousness: anything other than fully alert
CAM-ICU
- Adapted for intubated and critically ill patients
- Uses the Richmond Agitation-Sedation Scale (RASS) to assess level of consciousness
- Validated and widely used in ICU settings
Workup for Underlying Cause
- Always search for reversible causes: medication review (the most important step), infection screen, metabolic panel, urinalysis
- CBC, BMP, calcium, magnesium, liver function tests, TSH
- Blood cultures, chest X-ray, urinalysis if infection suspected
- Consider head CT only if focal neurologic findings, head trauma, or anticoagulation
- EEG if seizures suspected (nonconvulsive status epilepticus)
Prevention
HELP (Hospital Elder Life Program)
The most evidence-based multicomponent delirium prevention program. Reduces delirium incidence by approximately 30-40%. Components include:
- Orientation: reorientation protocols, clocks, calendars, familiar objects
- Sleep promotion: noise reduction, nighttime medication bundling, warm beverages, avoid nighttime vitals if stable
- Early mobilization: get patients out of bed and ambulating as early as possible
- Sensory optimization: ensure glasses and hearing aids are available and in use
- Hydration and nutrition: encourage oral intake, avoid unnecessary NPO status
- Cognitive stimulation: conversation, word games, reminiscence activities
Medication-Based Prevention
- Avoid deliriogenic medications: benzodiazepines, anticholinergics, meperidine, diphenhydramine
- Review the Beers Criteria for potentially inappropriate medications in older adults
- Use the lowest effective dose of necessary medications
- No pharmacologic agent has been proven to prevent delirium (including antipsychotics and melatonin)
Management
Non-Pharmacologic Interventions (First-Line)
- Identify and treat the underlying cause (this is the definitive treatment)
- Reorientation and reassurance; consistent caregivers
- Family presence at bedside
- Minimize tethers: remove unnecessary lines, catheters, and restraints
- Normalize sleep-wake cycle; daytime light exposure, minimize nighttime disruptions
- Early mobilization and physical therapy
- Optimize pain management (prefer acetaminophen, avoid opioids when possible)
Pharmacologic Management
- Reserved for patients who are a danger to themselves or others despite non-pharmacologic measures
- Haloperidol: most studied agent; start 0.5-1 mg PO/IV; titrate cautiously
- Atypical antipsychotics: quetiapine (12.5-25 mg), olanzapine (2.5-5 mg); may be better tolerated
- Monitor QTc before and during antipsychotic use
- Avoid benzodiazepines except in alcohol/benzodiazepine withdrawal or Parkinson disease-related psychosis (use quetiapine instead)
- No evidence that antipsychotics shorten delirium duration or reduce mortality
- Discontinue antipsychotics as soon as delirium resolves; do not discharge patients on new antipsychotics started for delirium
Key Clinical Pearls
- Delirium is a medical emergency; always search for and treat the underlying cause
- Hypoactive delirium is the most common subtype and the most frequently missed
- Prevention with multicomponent interventions (HELP program) is more effective than any pharmacologic treatment
- The single most important step in delirium workup is a thorough medication review
- Antipsychotics are symptom management only; use the lowest dose for the shortest time and always discontinue before discharge
References
- Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. 2014;383(9920):911-922.
- Hshieh TT, Yue J, Oh E, et al. Effectiveness of multicomponent nonpharmacological delirium interventions: a meta-analysis. JAMA Intern Med. 2015;175(4):512-520.
- Ely EW, Shintani A, Truman B, et al. Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit. JAMA. 2004;291(14):1753-1762.
- American Geriatrics Society Expert Panel on Postoperative Delirium in Older Adults. Postoperative delirium in older adults: best practice statement. J Am Coll Surg. 2015;220(2):136-148.