Delirium

Definition of delirium

Acute disturbance in attention and awareness with reduced ability to focus, sustain, or shift attention; develops over a short period and fluctuates.

Key feature distinguishing delirium from dementia

Delirium has acute onset and fluctuating course, impaired attention; dementia is chronic and stable, with better attention.

Why delirium is a medical emergency

High morbidity and mortality (25–33% at 3 months; 40–50% at 1 year); indicates acute brain failure.

Core cognitive deficits in delirium

Impaired attention, disorientation, memory impairment, language disturbance, perceptual disturbances.

Hyperactive vs hypoactive delirium

Hyperactive = agitation, hallucinations; Hypoactive = lethargy, withdrawal; Mixed = fluctuates between both.

Why delirium is often misdiagnosed as depression

Hypoactive delirium resembles depression (withdrawn, slow, quiet).

Why psychosis is NOT delirium

Psychosis preserves orientation; delirium has impaired orientation and fluctuating consciousness.

Most important question when evaluating confusion

“Is this an acute change?”

Most common causes of delirium

I WATCH DEATH mnemonic: Infection, Withdrawal, Acute metabolic, Trauma, CNS pathology, Hypoxia, Deficiencies, Endocrine, Acute vascular, Toxins/drugs, Heavy metals.

Predisposing factors for delirium

Older age, cognitive impairment, severe illness, vision/hearing impairment, high BUN/Cr ratio.

Precipitating factors for delirium

Physical restraints, malnutrition, >3 new meds, bladder catheter, iatrogenic events.

Pathophysiology: key neurotransmitter

Reduced acetylcholine activity → impaired attention, arousal, memory.

Dopamine role in delirium

Excess dopamine contributes to agitation, delusions, psychosis; inverse relationship with acetylcholine.

Medications with anticholinergic effects that cause delirium

Antihistamines (diphenhydramine), TCAs, antipsychotics, digoxin, steroids, opioids, benzodiazepines.

Most important step in delirium management

Identify and treat the underlying cause.

Medications to avoid in delirium

Benzodiazepines (unless alcohol withdrawal), anticholinergics.

Preferred medication for severe agitation in delirium

Haloperidol (high potency antipsychotic).

Environmental interventions for delirium

Frequent reorientation, glasses/hearing aids, minimize nighttime disturbances, avoid restraints, mobilize early.

Delirium vs dementia: attention

Delirium = impaired; dementia = usually normal early.

Delirium vs depression: consciousness

Delirium = reduced consciousness; depression = normal consciousness.

Why elderly are more prone to delirium

Reduced physiologic reserve, impaired homeostasis, multiple comorbidities, polypharmacy.