Alcohol withdrawal in the ICU

Contents

Pathophysiology

Chronic alcohol use causes neuroadaptation:

  • Alcohol is a GABA-A receptor agonist and NMDA receptor antagonist
  • Chronic exposure → downregulation of GABA-A receptors (fewer, less sensitive) and upregulation of NMDA receptors (more, more sensitive)
  • On alcohol withdrawal: loss of GABAergic inhibition + unopposed NMDA excitation → CNS excitatory state
  • Manifestations: sympathetic overactivation, seizures, hallucinations, delirium

Timeline of Withdrawal

Timeframe Syndrome
6–24 hours Minor withdrawal: tremor, diaphoresis, anxiety, tachycardia, hypertension, nausea
12–48 hours Alcoholic hallucinosis: auditory, visual, or tactile hallucinations in clear consciousness (not delirium); partial insight retained
24–48 hours Withdrawal seizures: generalised tonic-clonic; typically brief, self-limiting; if prolonged → status epilepticus
48–72 hours (peak) Delirium tremens (DT): altered consciousness, hallucinations, agitation, hyperpyrexia, autonomic instability

In ICU patients, the timeline may be shifted: sedation may mask early withdrawal; abrupt awakening after days of sedation may precipitate sudden severe withdrawal.

CIWA-Ar Assessment

The Clinical Institute Withdrawal Assessment for Alcohol — Revised (CIWA-Ar) is the most widely used validated scoring tool for alcohol withdrawal severity. It measures 10 items:

  1. Nausea/vomiting
  2. Tremor
  3. Paroxysmal sweats
  4. Anxiety
  5. Agitation
  6. Tactile disturbances (paraesthesia, formication)
  7. Visual disturbances
  8. Auditory disturbances
  9. Headache/fullness in head
  10. Orientation/clouding of sensorium

Each scored 0–7 (except orientation, 0–4). Total 0–67.

Score Severity Management
<8 Mild Reassurance; monitor
8–15 Moderate PRN benzodiazepine; medication-assisted withdrawal
>15 Severe Scheduled + PRN benzodiazepine; consider ICU

Limitation in ICU: CIWA-Ar requires patient cooperation and verbal assessment — unreliable in intubated, delirious, or encephalopathic patients.

Management

Benzodiazepines (First-Line)

Benzodiazepines are GABA-A agonists — they directly substitute for the lost alcohol-mediated GABAergic inhibition.

Symptom-triggered therapy (CIWA-Ar guided): PRN doses given when CIWA-Ar ≥8; superior to fixed scheduled regimens in reducing total benzodiazepine dose and duration — validated in outpatient and general ward settings.

ICU patients: symptom-triggered CIWA-Ar may not be feasible; use fixed scheduled dosing + PRN top-ups or protocol-based infusion:

  • Chlordiazepoxide (oral/NG): long-acting; traditional UK ward-based withdrawal; inappropriate in liver failure or ICU (variable absorption, active metabolites)
  • Lorazepam (IV): intermediate-acting; no active metabolites; preferred in hepatic impairment; IV suitable for ICU; dose 1–4 mg IV 4-hourly + PRN
  • Diazepam (IV): long-acting (t½ 20–100h); "front-loading" technique — large initial doses to achieve sedation then taper based on prolonged half-life; effective but risk of accumulation and oversedation

Phenobarbital

  • Long-acting barbiturate; GABA-A agonist via a different binding site
  • Effective as monotherapy or adjunct to benzodiazepines for refractory DT
  • Narrow therapeutic window; respiratory depression at high doses; requires level monitoring
  • Emerging evidence for phenobarbital as monotherapy in ICU-level alcohol withdrawal

Alpha-2 Agonists (Adjuncts)

  • Dexmedetomidine: sympatholytic; reduces agitation, autonomic instability; does NOT prevent seizures — never use as monotherapy; adjunct to GABA agonists
  • Clonidine: similar mechanism; useful for autonomic control (hypertension, tachycardia)

Propofol

  • GABA-A agonist at high doses; used for refractory DT requiring mechanical ventilation — propofol infusion controls refractory withdrawal in intubated patients

What NOT to Use

  • Antipsychotics (haloperidol, quetiapine) — lower seizure threshold → risk of withdrawal seizures; not first-line; may be cautiously used for hallucinations if adequate sedation already achieved but always with benzodiazepine basis
  • Carbamazepine/valproate: used in some outpatient protocols; limited ICU evidence

Delirium Tremens

Delirium tremens (DT) is the most severe form of alcohol withdrawal:

Features

  • Altered consciousness and confusion (differentiates from alcoholic hallucinosis)
  • Psychomotor agitation: severe restlessness, combativeness
  • Hallucinations: visual (often insects, animals), auditory, tactile
  • Autonomic instability: hyperpyrexia, diaphoresis, tachycardia, hypertension, tachypnoea

Mortality

Untreated DT: ~15–35% mortality (seizures, aspiration, cardiovascular collapse, hyperthermia). With treatment: mortality <5%.

ICU Management of Severe DT

  1. High-dose benzodiazepines titrated to sedation (RASS 0 to −1): diazepam 5–10 mg IV every 5–10 min until sedated (diazepam loading); or lorazepam infusion
  2. Phenobarbital adjunct or transition if benzodiazepines escalating beyond safe levels
  3. Intubation and propofol infusion for refractory DT (last resort but life-saving)
  4. Cooling: active cooling for hyperthermia (paracetamol, cooling blanket)
  5. Fluid resuscitation: dehydration from diaphoresis and agitation
  6. Electrolytes: hypokalaemia, hypomagnesaemia, hypophosphataemia all common — replace
  7. Nutrition: NG feeding if unable to eat; high caloric and protein needs
  8. Seizure management: withdraw seizures initially treated with benzodiazepines; phenytoin is NOT recommended for alcohol withdrawal seizures (no evidence of efficacy)

Wernicke's Encephalopathy

Definition

Acute neurological emergency caused by thiamine (vitamin B₁) deficiency — particularly common in chronic alcohol misuse (poor intake + reduced absorption).

Classic Triad

  1. Confusion / encephalopathy
  2. Ophthalmoplegia (cranial nerve VI palsy — horizontal nystagmus, lateral gaze palsy)
  3. Ataxia (cerebellar gait)

The full triad is present in only ~20% — have a high index of suspicion in any confused alcoholic patient.

Pathophysiology

Thiamine is a cofactor for several key enzymes: pyruvate dehydrogenase (converts pyruvate → acetyl-CoA for TCA cycle), α-ketoglutarate dehydrogenase, and transketolase (pentose phosphate pathway). Deficiency → failure of oxidative glucose metabolism → lactate accumulation → cell death particularly in mammillary bodies, thalamus, periaqueductal grey, and cerebellum.

Korsakoff Syndrome

Untreated or inadequately treated Wernicke's → permanent anterograde (inability to form new memories) and retrograde amnesia + confabulation. This is the chronic sequela — Wernicke-Korsakoff syndrome.

Treatment: Thiamine Before Glucose

  • Pabrinex (parenteral thiamine/Vitamins B and C): Pabrinex 2 pairs IV over 30 minutes TDS × 3 days, then once daily for 5 days minimum
  • CRITICAL: Never give glucose without thiamine first — glucose metabolism requires thiamine; giving IV glucose in a thiamine-deficient patient can precipitate or worsen Wernicke's encephalopathy by consuming the last thiamine reserves
  • All ICU patients with alcohol use disorder should receive IV thiamine on admission

Complications in the ICU

Complication Notes
Aspiration pneumonia From vomiting or impaired consciousness during withdrawal seizures
Subdural haematoma Alcohol-related falls; coagulopathy from liver disease; high index of suspicion
Pancreatitis Alcoholic pancreatitis may co-present
Hepatic decompensation Acute alcoholic hepatitis, decompensated cirrhosis during admission
Hypoglycaemia Alcohol inhibits hepatic gluconeogenesis; monitor glucose
Cardiomyopathy Alcoholic cardiomyopathy — dilated; reduced EF on echo
Rhabdomyolysis From seizures, prolonged agitation, direct alcohol toxicity; check CK
Prolonged QT From electrolyte disturbances; arrhythmia risk

Viva Questions

1. Explain the pathophysiology of alcohol withdrawal and why it can cause seizures.

Chronic alcohol use causes neuroadaptation through two mechanisms: downregulation of GABA-A receptors (fewer and less sensitive, since alcohol chronically activates these inhibitory receptors) and upregulation of NMDA (excitatory) receptors (more and more sensitive, as a compensatory response to alcohol's inhibitory effect on NMDA). This neuroadaptation allows normal brain function despite chronic alcohol exposure. On abrupt cessation of alcohol, both adaptations are unmasked simultaneously: GABAergic inhibition is severely reduced (fewer, less sensitive GABA receptors), and NMDA-mediated excitation is unopposed (upregulated excitatory receptors). The result is a state of CNS hyperexcitability that manifests as the autonomic features of early withdrawal (tachycardia, hypertension, diaphoresis from sympathetic overactivation) and can progress to seizures when excitatory activity at the NMDA receptor level reaches the threshold for synchronised neuronal discharge. Alcohol withdrawal seizures are typically generalised tonic-clonic, occur at 24–48 hours after the last drink, and are not explained by other structural causes. Benzodiazepines treat withdrawal by providing GABA-A agonism — substituting for the lost alcohol-mediated GABAergic inhibition and reducing the excitatory-inhibitory imbalance.

2. A patient is admitted to the ICU following a cardiac arrest. On day 3, as sedation is lightened, they become severely agitated, tachycardic (HR 130), sweating, and have tactile hallucinations. What is the diagnosis and management?

This is likely delirium tremens (DT) precipitated by abrupt alcohol withdrawal during the ICU admission — the sedation had masked the early withdrawal phases. Management: (1) Establish IV access; draw U&E (electrolytes — K⁺, Mg²⁺, PO₄ common deficiencies) and glucose; (2) Thiamine immediately: Pabrinex 2 pairs IV — Wernicke's encephalopathy must be excluded/treated empirically in any suspected alcohol-dependent patient; NEVER give glucose first; (3) Benzodiazepines: lorazepam 1–4 mg IV (preferred in ICU for reliable absorption and no active metabolites); titrate to effect; high doses may be needed in severe DT — no artificial ceiling; (4) Alpha-2 agonist adjunct: dexmedetomidine infusion to control autonomic instability and reduce benzodiazepine dose; it does NOT prevent seizures and must never be used alone; (5) Active cooling for hyperpyrexia; (6) Fluid resuscitation; correct electrolytes (replace K⁺, Mg²⁺); (7) Monitor for seizures: EEG if unexplained alteration in consciousness — subtle status epilepticus possible; (8) If benzodiazepines escalating without control: add phenobarbital; consider propofol infusion with intubation as last resort; (9) Identify and treat precipitating illness (the cardiac arrest and any other acute pathology).

3. Why must thiamine be given before glucose in patients with suspected Wernicke's encephalopathy, and how do you dose it in the ICU?

Thiamine (vitamin B₁) is an essential cofactor for pyruvate dehydrogenase — the enzyme that converts pyruvate to acetyl-CoA for entry into the Krebs cycle. In thiamine-deficient patients, glucose metabolism proceeds to pyruvate (via glycolysis) but cannot be further oxidised aerobically — pyruvate accumulates and is converted to lactate (anaerobic) and toxic metabolites. Giving IV glucose to a thiamine-deficient patient floods the system with pyruvate faster than the severely limited thiamine reserves can handle, depleting the last remaining thiamine in the attempt to metabolise it — precipitating or dramatically worsening Wernicke's encephalopathy acutely. The lactate accumulation and neuronal energy failure cause rapid cell death in the metabolically active regions most dependent on oxidative glucose metabolism (mammillary bodies, thalamus, periaqueductal grey). For this reason: thiamine always comes first. In the ICU: Pabrinex 2 pairs IV (Pabrinex Nos. 1 and 2 are given together) over 30 minutes, three times daily for 3 days, then once daily for a minimum of 5 days — or longer if Wernicke's is confirmed. Thiamine is a water-soluble vitamin with an excellent safety profile even at high doses; there is no benefit to using low doses in high-risk patients — always use the parenteral formulation (oral absorption is severely impaired in alcohol misuse).