Delirium in the ICU -

Delirium in the ICU

1. Definition

ICU delirium is an acute, fluctuating disturbance of consciousness and cognition, characterized by:

Impaired attention
Altered level of awareness
Disorganized thinking ± perceptual disturbances

It develops over hours to days and is a manifestation of acute brain dysfunction.

2. Why ICU Delirium Matters

Incidence: 30–80% of ICU patients (highest in ventilated, septic, elderly)
Associated with:

↑ Mortality (short- and long-term)
↑ Duration of mechanical ventilation
↑ ICU & hospital LOS
↑ Long-term cognitive impairment (ICU-acquired dementia–like syndrome)

# Delirium is NOT benign and NOT just agitation.

3. Pathophysiology

3.1 Neurotransmitter Imbalance

↓ Acetylcholine
↑ Dopamine
Altered GABA, serotonin, glutamate

3.2 Neuroinflammation

Sepsis → cytokines (IL-1, IL-6, TNF-α)
Blood–brain barrier dysfunction

3.3 Cerebral Hypoperfusion & Hypoxia

Shock, anemia, respiratory failure

3.4 Stress Response

↑ Cortisol, catecholamines

3.5 Iatrogenic Factors

Benzodiazepines
Anticholinergics
Opioids (especially meperidine)

4. Subtypes of ICU Delirium

Subtype	Features	Prognosis
Hyperactive	Agitation, restlessness, hallucinations	Easily recognized
Hypoactive	Lethargy, withdrawal, ↓ responsiveness	Most common, most missed, worse prognosis
Mixed	Alternating features	Common

# Hypoactive delirium ≠ depression or fatigue

5. Risk Factors (Mnemonic: “DELIRIUM”)

Predisposing

Advanced age
Dementia, prior cognitive impairment
Alcohol use disorder
Sensory impairment

Precipitating

Sepsis
Mechanical ventilation
Benzodiazepines
Deep sedation
Sleep deprivation
Metabolic derangements
Organ failure (hepatic, renal)

6. Diagnosis: Routine Screening is Mandatory

6.1 CAM-ICU (Gold Standard)

Diagnosis requires Feature 1 + Feature 2 + (Feature 3 or 4)

Acute onset or fluctuating course
Inattention
Disorganized thinking
Altered level of consciousness

✔ Validated in intubated & non-verbal patients
✔ Takes <2 minutes
✔ Recommended by SCCM / PADIS guidelines

6.2 Other Tools

ICDSC (score ≥4 = delirium)
DSM-5 (diagnostic standard, impractical in ICU)

7. Differential Diagnosis

Condition	Key Difference
Dementia	Chronic, non-fluctuating
Depression	Attention usually intact
Psychosis	Consciousness preserved
Sedation	Improves on stopping sedatives
Non-convulsive status epilepticus	EEG required

8. Management: PREVENTION > TREATMENT

8.1 Non-Pharmacological

ABCDEF Bundle

A: Assess & manage pain
B: Both SAT & SBT
C: Choice of analgesia/sedation
D: Delirium assessment & prevention
E: Early mobilization
F: Family engagement

Other Measures:

Reorientation (clocks, calendars)
Sleep promotion (lights off, noise reduction)
Correct vision/hearing
Hydration & nutrition

9. Sedation Strategy

Preferred	Avoid
Dexmedetomidine	Benzodiazepines
Light sedation (RASS −1 to 0)	Deep continuous sedation
Daily sedation interruption	Unnecessary restraints

# Benzodiazepines are an independent risk factor for delirium

10. Pharmacological Treatment

10.1 Antipsychotics

Haloperidol: for severe agitation threatening safety
Atypicals: quetiapine, olanzapine (symptom control)

# Do NOT prevent delirium
# Do NOT reduce mortality
# Monitor QTc, extrapyramidal effects

10.2 Dexmedetomidine

Useful when agitation prevents extubation
Preferred sedative in delirious ventilated patients

11. Delirium in Special ICU Situations

Sepsis

Often first sign of sepsis-associated encephalopathy

Post-operative ICU

Elderly, major surgery → high risk

Alcohol Withdrawal

Delirium tremens ≠ ICU delirium
Benzodiazepines indicated only here

12. Prognosis & Long-Term Outcomes

Delirium duration correlates with:

Long-term cognitive decline
Reduced quality of life

Each additional delirium day → ↑ mortality risk

13. Exam

Hypoactive delirium is most common
Routine screening is mandatory
Prevention is more effective than drugs
Benzodiazepines worsen delirium
Antipsychotics do NOT improve survival