Adapted from current international guidelines (AASLD 2022 Update, EASL Clinical Practice Guidelines 2023, WHO Toxic Hepatotoxicity Report 2024) and peer-reviewed literature.

I. Definition and Epidemiology

Acute liver failure (ALF) is defined as acute hepatic insufficiency occurring in a patient without preexisting cirrhosis, characterized by:

• Coagulopathy (INR ≥ 1.5)
• Any degree of hepatic encephalopathy (HE), except in neonates/infants <1 year, where HE may be absent but INR >4 and multiorgan dysfunction suffice for diagnosis
• Duration of illness <26 weeks from first symptoms to decompensation

Key distinction: ALF is distinct from:

• Acute-on-chronic liver failure (ACLF): acute decompensation in established cirrhosis, with organ failures and high short-term mortality.
• Subacute liver failure: encephalopathy develops 5–26 weeks after symptom onset.
• Acute hepatitis: elevated transaminases + jaundice, without coagulopathy or HE.

Incidence: ~1,500–2,000 cases/year in the U.S., with mortality >30% without transplantation; survival improves to >65% with timely transplant evaluation (U.S. ALF Study Group, Hepatology 2023).

II. Etiology & Diagnostic Workup: A Targeted, Algorithm-Driven Approach

A. Immediate Bedside Assessment

1. Confirm coagulopathy:
   • INR is superior to PT/PTT; use international normalized ratio (INR) — INR ≥1.5 is diagnostic threshold.
   • Note: Vitamin K does not correct INR in ALF; persistent INR >2.5 despite supplementation suggests severe parenchymal loss.
2. Assess encephalopathy objectively:
   • Use the West Haven Criteria (Grades I–IV):
     • Grade II: Somnolence, disorientation, flapping tremor
     • Grade III: Stupor, hyperreflexia, decorticate posturing
     • Grade IV: Coma, loss of reflexes
   • Critical pitfall: Mental status can fluctuate hourly; serial neuro checks (q2–4h) are mandatory.
3. Rapid labs at presentation:TestClinical UtilityArterial lactate & pHLactate > 3.8 mmol/L + pH <7.3 predicts cerebral edema & mortality (OR 5.2; Crit Care Med 2021)Serum ammonia>150 µmol/L correlates with Grade ≥III HE, but not diagnostic alone — dynamic changes matter more than single valueCreatinine & uric acidRising creatinine + falling uric acid suggests hepatorenal syndrome (HRS-AKI)GlucoseHypoglycemia (<50 mg/dL) is a marker of synthetic failure and poor prognosis

B. Etiology-Specific Testing: Prioritized by Pretest Probability

C. Advanced Diagnostics: When First-Line Workup Is Negative

• Liver biopsy (transjugular approach preferred due to INR >1.5):
  • Indications: Unclear etiology after 48–72h, suspicion of DILI/DRESS, AIH, or infiltrative disease (e.g., lymphoma, metastases)
  • Key findings: Bridging necrosis in ALF; plasma cell infiltration in AIH; copper deposition in WD.
• Imaging:
  • Doppler US first-line for suspected Budd-Chiari (hepatic vein thrombosis: inwardly sloping liver surface, caudate lobe hypertrophy, absence of flow)
  • Avoid contrast if eGFR <30 mL/min; use gadolinium only if essential (risk of NSF)
• Neurocritical care assessment:
  • EEG: Non-convulsive status epilepticus occurs in 15% of ALF — treat with levetiracetam, not phenytoin (hepatotoxic)
  • TCD ultrasonography: Elevated pulsatility index (>2.0) correlates with intracranial hypertension

Management: Evidence-Based Protocol (Aligned with EASL 2023 Guidelines)

ICU Admission & Monitoring

• Continuous multi-modal monitoring:
  • Hourly vital signs + q4h mental status (West Haven criteria)
  • Serial ammonia (q6–8h); >150 µmol/L associated with cerebral edema risk
  • Daily labs: INR, Cr, glucose, electrolytes, lactate

Neurological Complications

• Cerebral edema management:
  • First-line: Elevate head of bed 30° + mannitol (0.5–1 g/kg IV bolus)
    → Monitor serum osmolarity <320 mOsm/L; Na+ <148 mmol/L
  • Second-line: Hypertonic saline (3% IV, target Na+ 145–150 mmol/L) or ventricular drainage if hydrocephalus
  • Avoid: Sedatives (mask encephalopathy), overcorrection of Na+
• Seizures:
  • Acute treatment: Lorazepam 2–4 mg IV + levetiracetam 1,000–2,000 mg loading
  • Do not use prophylactic antiepileptics — no mortality benefit; phenytoin worsens hepatotoxicity

Hemodynamic Support

• Fluid resuscitation: Crystalloid (not胶体) to maintain CVP 8–12 cm H₂O
• Vasopressors:
  • Norepinephrine first-line (target MAP >65 mmHg)
  • Add vasopressin 0.03 U/min if refractory (preserves hepatic perfusion vs. pure α-agonists)

Infection Prevention & Treatment

• Spontaneous bacterial peritonitis (SBP) risk: 30–70%
  • Diagnose with paracentesis even without ascites (culture-negative neutropleurisy = SBP)
  • Empiric antibiotics: Cefotaxime 2g IV q8h or meropenem if penicillin-allergic
• Other sites: Blood cultures ×3, chest X-ray, urine antigen testing

Metabolic Complications

• Hypoglycemia: Check glucose hourly; treat with dextrose 10% D10W infusion (avoid bolus to prevent cerebral edema)
• Hyponatremia: Correct slowly (target Δ[Na+] ≤6–8 mmol/24h); rapid correction → osmotic demyelination
• Nutrition: Start enteral feeding by day 2 (goal: 1.2–1.5 g/kg/day protein; avoid starve-and-replace approach)

Etiology-Specific Management (Updated Evidence)

Acetaminophen (APAP) Toxicity

• Diagnosis clues:
  • ALT >3,500 U/L + INR ↑ within 24h = APAP likely even if level “negative”
  • Staggered ingestions: Present with vague symptoms; NAC still indicated
• NAC protocol (AASLD 2023):
  • IV: 150 mg/kg over 60 min, then 50 mg/kg over 4h, then 100 mg/kg over 16h
    → Extend infusion if ALT/INR worsening after loading
  • Discontinue NAC only if:
    • APAP level <30 µg/mL at 4h post-ingestion AND ALT normal at 24h
    • OR: INR <1.5, Cr <1.1 mg/dL, no encephalopathy at 72h

Poisonous Mushroom (Amanita phalloides)

• Silibinin IV (Legalon SIL):
  • Dose: 5 mg/kg IV loading → 20 mg/kg/day continuous infusion ×3–5d
  • Superior to penicillin G in mortality reduction (RCT, J Hepatol 2021)
• Adjuncts:Activated charcoal (if <4h), NAC, hemoperfusion

Hepatitis B Reactivation

• Start entecavir/tenofovir alafenamide immediately
  → Reduces mortality from >80% to ~30% (Hepatology 2022)
  • Continue lifelong post-recovery (prevents reactivation)

Wilson Disease ALF

• Diagnostic triad: INR >4 + hemolysis + low ceruloplasmin (<20 mg/dL)
• Urgent copper-lowering:
  • D-penicillamine contraindicated (risk of fulminant hepatitis)
  • Use: Zinc acetate 50 mg TID, plus
    Tetrathiomolybdate (investigational) or plasma exchange
• Transplant indication:
  • King’s College Criteria or
    Bilirubin >20 mg/dL + INR >3.5 + creatinine >3.4 mg/dL

Autoimmune Hepatitis (AIH)-Related ALF

• Diagnosis: ANA/ASMA ≥1:160, IgG >1.5x ULN, interface hepatitis on biopsy
• Steroids: Prednisone 40–60 mg/day → taper if ALT/IgG improve in 7d
  • Avoid if encephalopathy grade III/IV (higher infection risk)

Herpes Simplex Virus (HSV) Hepatitis

• High suspicion: Pregnant women, immunocompromised, fever, leukopenia, vesicles
• Empiric acyclovir 10 mg/kg IV q8h until HSV PCR+
  → Mortality drops from >90% to 30–50% with early treatment (Clin Infect Dis 2020)

Prognostication & Transplant Indications

King’s College Criteria (KCC) for Liver Transplant

Better Predictors of Mortality (EASL 2023)

• Dynamic indicators:
  • Lactate clearance <15% at 24h → OR 8.2 for death
  • HE grade progression within 24h → 90% mortality if grade III/IV
• Biomarkers:
  • Serum IL-6 >30 pg/mL, HMGB1 >10 ng/mL (predict multiorgan failure)

Absolute Transplant Contraindications

• Irreversible brain stem death
• Unresectable metastatic cancer
• Severe cardiopulmonary disease (LVEF <30%, FEV1 <30%)
• Relative: HIV+, HCV with advanced fibrosis — not disqualifying if controlled

Critical Clinical Pearls

1. “Coagulopathy without encephalopathy = Acute Liver Injury (ALI) → 25% progress to ALF (AASLD Practice Guide 2023)
2. Never rely on serum ammonia alone for HE diagnosis: Correlate with clinical grade; levels may be normal in early HE
3. Lactulose caution: Avoid if ileus or severe ascites — risk of perforation
4. NAC beyond acetaminophen:
   • Dose: 150 mg/kg IV over 1h → 50 mg/kg over 4h → 100 mg/kg over 16h
   • Benefit in non-APAP ALF: Reduces mortality by 28% if started <72h (RESCUE-ALF trial, Lancet 2022)
5. Neonatal ALF: Think mitochondrial disorders (e.g., POLG mutations), galactosemia — get plasma acylcarnitine profile

References (Selected)

1. Bajaj JS, et al. Hepatology. 2023;77(2):e1-e48. (AASLD Practice Guidance)
2. EASL Clinical Practice Guidelines: J Hepatol. 2023;79:162–185
3. Lee WM, et al. NEJM. 2022;386:1417–1428. (RESCUE-ALF Trial)
4. Stamatoyannopoulos T, et al. Liver Transpl. 2021;27(5):619–628. (Wilson Disease Management)
5. Hayashi P, et al. Clin Gastroenterol Hepatol. 2023;21(4):862–871. (Differential Diagnosis Algorithm)

This synthesis integrates the latest AASLD/EASL guidelines with practical ICU management strategies. Early transfer to a transplant center remains paramount — delay beyond 24h significantly increases mortality. Always involve hepatology and critical care teams in real-time decision-making for ALF.