ICD-116D70	DELIRIUM Delirium
ICD-10F05	Delirium, not induced by alcohol and other psychoactive substances
DSM-5-TRF05	Delirium

1. Definition and nosology

Delirium (ICD-11: 6D70; DSM-5-TR: F05) — a neuropsychiatric syndrome characterized by an acute, fluctuating disturbance of attention and consciousness, cognitive deficit (memory, orientation, language, visuospatial) and perceptual disturbances (illusions, hallucinations). Develops in response to a typical medical cause (infection, medication, metabolic, neurological).

This is a medical emergency — hospitalized elderly patients mortality rate is 25–33%.

2. History

• Hippocrates “phrenitis” — classic description of delirium.
• Lipowski Z.J. (1980-90s) — modern conceptualization.
• CAM (Confusion Assessment Method, Inouye S.K. 1990) — gold standard screening.

3. Epidemiology

• Prevalence in hospitalized elderly 15–30%; in ICU 50–80%; post-surgery 15–50%.
• Comorbidity: dementia (delirium superimposed on dementia), infection, polypharmacy.
• Mortality and morbidity high; risk of long-term cognitive decline.

4. Aetiology and pathogenesis

• Multiple factors:
  • Infections — sepsis, pneumonia, UTI;
  • Medication — anticholinergics, opioids, benzodiazepines, steroids;
  • Substance withdrawal (alcohol, benzodiazepine);
  • Metabolic — electrolyte, glucose, ammonia, uremia;
  • Hypoxia, hypoperfusion;
  • Neurological — seizure, stroke, brain tumor, encephalitis;
  • Pain, constipation, urinary retention;
  • Environment — sensory deprivation, sleep disruption (especially in ICU).

5. Clinical features

Three motor subtypes

• Hyperactive — agitation, hallucination — diagnosis easy;
• Hypoactive — sedation, withdrawal — frequently underdiagnosed, resembles depression.
• Mixed — fluctuation.

Clinical signs

• Acute onset (hours-days) and fluctuation.
• Attention impairment.
• Cognitive deficits — memory, orientation (time, place, person).
• Perceptual disturbances – visual hallucinations typical.
• Sleep-wake cycle disruption.
• Sundowning — worsening in evening hours.

6. Diagnosis

6.1 Unified diagnostic criteria

A. Attention impairment (orientation, maintenance, shifting) and consciousness impairment.

B. Disorder develops over short period (hours–days); differs from baseline indicators; fluctuates within day.

C. Additional cognitive impairment (memory, orientation, language, visuospatial, perception).

D. Not fully explained by dementia or another neurocognitive disorder

E. Evidence — history, examination, laboratory indicate that disturbance is directly due to medical condition, substance intoxication/withdrawal, or multiple etiologies.

6.2 Source-specific clarifications

• DSM-5-TR / ICD-11 — same.
• NICE CG103 — Delirium: prevention, diagnosis, management (2010, 2019 update).

6.3 Diagnostic algorithm

1. CAM (Confusion Assessment Method) — gold standard screening.
2. CAM-ICU — for the intensive care unit.
3. Medical cause investigation: complete blood count, electrolytes (Na, K, Ca, Mg, P), glucose, liver, kidney, TSH, B12, troponin, EKG, urine analysis and culture, blood culture, chest X-ray, brain MRI/CT, EEG (seizure suspicion), lumbar puncture (encephalitis/meningitis).
4. Medication list review — anticholinergics, opioids, benzodiazepines (Beers Criteria).
5. Toxicology.
6. Comorbid dementia assessment (initial indicators).

6.4 Differential diagnosis

7. Examination and assessment

• CAM, CAM-ICU.
• MMSE or MoCA (initial indicators of cognitive function).
• From the above medical panel.
• EEG — rule out non-convulsive status.

8. Treatment

8.1 General principles (NICE CG103)

1. Etiological treatment is the first priority — correction of infection, metabolic disturbance, medication, and the hospitalisation context.
2. Environmental modification — sensory (glasses, hearing aid), daylight, nighttime darkness, quiet environment, presence of loved ones.
3. Bedside care — hydration, nutrition, urination and defecation, movement.
4. Antipsychotic (haloperidol 0.25–2 mg, quetiapine, risperidone) — only for severe agitation or when the patient poses a danger to self/others, short-term, low dose. NICE CG103 — antipsychotics not routinely recommended; evidence base is limited (Burry L. Cochrane 2018).
5. Benzodiazepine — only in alcohol or benzodiazepine withdrawal delirium; otherwise is contraindicated (exacerbates delirium).
6. Prevention — ABCDEF bundle in ICU (Awakening, Breathing, Coordination, Delirium monitoring, Early mobility, Family).

8.2 Source-specific clarifications

• NICE CG103 — etiological and environmental approach first-line; antipsychotics limited.
• SCCM PADIS Guidelines (for ICU, 2018).
• Burry L. Cochrane 2018 — antipsychotics do not reduce delirium duration or mortality.

Treatment methods

1. Confusion Assessment Method (CAM — Confusion Assessment Method) — Inouye (Inouye S.K.) — 4 core features: acute onset/fluctuation + inattention + disorganized thinking or altered consciousness.
2. CAM-ICU — Adapted for intensive care; in patients on ventilator.
3. ABCDEF Bundle (SCCM) — Awakening, Breathing trial, Coordination, Delirium monitoring, Early mobility, Family engagement.
4. Hospital Elder Life Program (HELP — Hospital Elder Life Program) — Inouye (Inouye S.K.) — Multicomponent delirium prevention program; evidence base strong.

9. Prognosis

• Hospital mortality 25–33%.
• In survivors — functional decline, long-term cognitive impairment, increased dementia risk.
• Early etiological intervention improves prognosis.

10. Myths and misconceptions

Myth 1: “Delirium is ‘normal for an elderly person’”

Evidence: Delirium is a clinical emergency with high mortality; it requires active intervention.

Myth 2: “Antipsychotics are a treatment for delirium”

Evidence: NICE CG103, Burry Cochrane 2018 — antipsychotics do not reduce delirium duration or mortality; only for severe agitation.

Myth 3: “Benzodiazepine is safe for an elderly agitated patient”

Evidence: benzodiazepine Delirium exacerbates; only in the case of alcohol/BZ withdrawal.

Myth 4: “Hypoactive delirium is ‘good’ and requires no intervention”

Evidence: hypoactive delirium linked to worse mortality; problem of under-detection.

Myth 5: “Sleeping is best for the patient with delirium”

Evidence: Daytime activity, presence of close ones, sensory stimulation are recommended; HELP program is evidence-based.

11. Sources

1. WHO. ICD-11. 6D70 Delirium. 2024.
2. APA. DSM-5-TR. 2022.
3. NICE CG103. Delirium: prevention, diagnosis and management. 2010, 2019 update.
4. Inouye S.K. et al. Clarifying confusion: the confusion assessment method. Ann Intern Med 1990;113(12):941–948.
5. Burry L. et al. Antipsychotics for treatment of delirium in hospitalised non-ICU patients. Cochrane Database Syst Rev 2018;(6):CD005594.
6. Devlin J.W. et al. SCCM PADIS Guidelines. Crit Care Med 2018;46(9):e825–e873.