Psychosocial, Behavioral & Cognitive · Topic 1 of 8
Delirium
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Delirium
Acute, fluctuating inattention from a medical cause. Screen every shift, find and reverse the cause, and don't reach for routine antipsychotics.
Why it happens
Proposed: cholinergic deficiency, impaired brain metabolism and inflammation
Mechanisms are not fully understood. Stress of any kind impairs cholinergic function and older adults are especially vulnerable, so anticholinergic drugs can contribute.
What causes it
A medical condition, a drug or withdrawal — review every medication
Delirium affects about 15–50% of older adults at some point in a hospital stay.
What you'll see
Develops over hours to days and fluctuates through the day
Hypoactive delirium is common in very old patients and is missed without routine screening.
Screen: CAM-ICU
Positive = 1 + 2 + (3 or 4)
The 2014 CAM-ICU revision swapped the numbering of altered consciousness (now 3) and disorganized thinking (now 4); older materials list them the other way round.
Find the cause
Targeted work-up, guided by the history and the drug list
Red flags
First moves, in order
Drugs to avoid in older adults with or at high risk of delirium (AGS Beers 2023): anticholinergics, benzodiazepines, Z-drug hypnotics, H2 blockers and antipsychotics; minimize corticosteroids and opioids.
Treatment
Treat the cause — the antipsychotic quiets it, the work-up cures it
Treat infection, hypoxia, glucose, electrolytes, retention
Review every medication firstShort course only for severe agitation or distressing psychosis threatening safety
Only after nonpharmacologic measures fail; stop when agitation resolvesWhen agitated delirium prevents weaning or extubation
PADIS conditional recommendationDrugs of choice only for alcohol or benzodiazepine withdrawal
Otherwise they worsen confusion and sedationA sitter can often replace restraints
Release regularly; stop as soon as possible2025 PADIS and Wernicke
MIND-USA: neither haloperidol nor ziprasidone shortened delirium, ventilation, stay or mortality. PADIS 2018 suggests against routine antipsychotics; the 2025 focused update re-reviewed them and made no recommendation for or against, so routine use is still avoided.
Prevention
Prevention is nonpharmacologic and multicomponent
PADIS (conditional): do not give haloperidol, an atypical antipsychotic, dexmedetomidine, a statin or ketamine to prevent delirium in all critically ill adults.
Delirium or a primary psychiatric disorder?
| Delirium | Primary psychiatric (e.g., depression) | |
|---|---|---|
| Onset | Hours to days | Nearly always subacute |
| Attention | Impaired — the core feature | Almost never impaired |
| Level of consciousness | Fluctuates over the day | Stable |
| Cause | Medical illness, drug or withdrawal | Psychiatric illness |
| Quiet, withdrawn older patient | Think hypoactive delirium first | Easily mistaken for hypoactive delirium |
Prognosis
Delirium is a symptom, not a diagnosis: the antipsychotic quiets it, the work-up cures it.
Sources · Delirium (Merck Manual Professional) · PADIS Clinical Practice Guidelines (Crit Care Med 2018) · A Focused Update to the PADIS Guidelines (Crit Care Med 2025) · Management of Delirium in the ICU (Vanderbilt CIBS) · The 2014 updated CAM-ICU compared to DSM-5 (Ann Intensive Care 2018) · Monitoring Delirium in the ICU (Vanderbilt CIBS) · 2023 AGS Beers Criteria (J Am Geriatr Soc 2023) · AGS guideline for postoperative delirium in older adults (J Am Geriatr Soc 2015) · Haloperidol and Ziprasidone for Delirium in Critical Illness (MIND-USA, NEJM 2018) · CAM-ICU Flowsheet (SCCM / Vanderbilt) · The Complete CAM-ICU Training Manual (2016) · SCCM PADIS guideline summary (Guideline Central) · Follow your institution's protocols.