4. Acute Liver Failure

Quick Recap

GI & Hepatology System, Protocol 4/13. Distinguish from Acute-on-Chronic Liver Failure (next protocol) — ALF occurs WITHOUT pre-existing chronic liver disease.

1. Definition

ALF = severe acute liver injury with coagulopathy (INR >=1.5) and any degree of hepatic encephalopathy in a patient WITHOUT pre-existing cirrhosis, with illness duration <26 weeks. Etiology and timing of onset are the two dominant prognostic threads running through this entire protocol.

2. Etiology-Based Prognosis

Better prognosis (transplant-free survival >50%): acetaminophen toxicity, hepatitis A, ischemic liver injury ("shock liver"), pregnancy-related liver failure.

Worse prognosis (transplant-free survival <25%): idiosyncratic drug reactions, hepatitis B, autoimmune hepatitis, Wilson disease, Budd-Chiari syndrome.

Timing as a prognostic clue: illness <1 week suggests ischemic hepatopathy or acetaminophen overdose (better survival); illness >4 weeks suggests indeterminate or viral etiology (poor transplant-free survival) — though this is confounded by etiology itself.

Hepatitis B (+/- D) accounts for >50% of viral ALF causes. Hepatitis E is more common in endemic regions — consider in returning travelers/recent immigrants. Hepatitis C alone rarely causes ALF. Other reported viral causes: HSV, EBV, adenovirus, parvovirus B19.

3. Etiology-Specific Treatment

Acetaminophen toxicity — N-acetylcysteine (NAC):

• Treat with NAC even after significant delay — a retrospective study of patients starting NAC 10-36h post-overdose still showed improved outcomes vs no antidote
• NAC efficacy is NOT reduced by prior activated charcoal administration
• Route (PO vs IV) has NOT been shown to affect outcomes
• Cochrane analysis of a controlled trial showed REDUCED MORTALITY with NAC in acetaminophen-related ALF (Peto OR 0.29)

Non-acetaminophen ALF — NAC also has a role (recently established, less widely known than the acetaminophen indication):

• RCT (173 patients) showed improved transplant-free survival at 3 weeks AND 1 year with 72 hours of NAC in non-acetaminophen ALF
• Benefit was seen ONLY in patients with grade 1-2 encephalopathy, NOT in more advanced grades — an important limitation; NAC is not a rescue therapy once encephalopathy is severe
• Given its minimal adverse reaction profile, NAC should be CONSIDERED for all ALF patients with grade 1-2 encephalopathy regardless of etiology
• NAC treatment should NEVER delay transfer to a transplant center
• May not be required in ischemic hepatitis specifically

Hepatitis B: nucleotide/nucleoside analogue treatment generally recommended (lamivudine 100mg/day used in most reports), though evidence for clinical outcome impact is mixed.

Hepatitis A and E: supportive care only.

Sepsis-related liver dysfunction: typically recovers with supportive management (shock correction, appropriate antibiotics) — rarely needs transplant.

For most other non-acetaminophen etiologies: etiology-specific interventions are unlikely to be lifesaving in established ALF — the central decision becomes transplant eligibility/timing, not disease-specific pharmacotherapy.

4. Neurologic Complications — Cerebral Edema and Raised ICP

Risk rises sharply with encephalopathy grade: >75% incidence of cerebral edema in Grade 4 encephalopathy. Advanced edema can cause uncal herniation and death — this is a leading cause of ALF mortality.

West Haven Criteria (semiquantitative encephalopathy grading):

Survival by grade: Grade 2 ~65-70%; Grade 3 ~30-50%; Grade 4 ~20% — encephalopathy grade is itself a strong outcome predictor, independent of etiology.

Management:

• Any degree of encephalopathy -> transfer to a liver transplant center — do not wait for progression
• Grade 3-4 encephalopathy -> intubate for airway protection AND to enable hyperventilation to PaCO2 28-30 mmHg
• Frequent neuro exams essential — systemic hypertension, bradycardia, posturing, decreased pupillary reflexes suggest IMPENDING herniation
• ICP monitoring: consider for rapidly progressive encephalopathy and transplant-listed patients; practice varies widely across transplant programs given lack of definitive mortality benefit evidence; modalities: epidural, subdural, parenchymal, or ventricular catheter — epidural has lower complication rate but is LESS RELIABLE; complications include bleeding (coagulopathy-related), infection, volume overload from coagulopathy correction
• Recombinant factor VIIa reduces ICH risk from 10-20% to <5% when used for ICP monitor placement in this coagulopathic population
• Noninvasive ICP monitoring (transcranial Doppler, pupillometry) shows promise but needs further study
• ICP target: <20 mmHg; CPP target: >50 mmHg (note this CPP target is LOWER than the 60-70 mmHg TBI/general Raised ICP target — reflects the different pathophysiology and evidence base in ALF specifically)

Osmotherapy and adjuncts:

• Mannitol: 0.5-1 g/kg bolus (20% solution), can repeat x2, limited by serum osmolality <320 mOsm/kg; consider hemofiltration if concomitant renal failure
• Hyperventilation: only short-term benefit, target PaCO2 ~25 mmHg; an RCT showed NO benefit of PROPHYLACTIC continuous hyperventilation — reserve for acute/symptomatic use, not routine practice
• Hypertonic saline (3%): RCT (30 ICP-monitored patients) targeting Na 145-155 mmol/L showed SIGNIFICANT ICP reduction and fewer ICP episodes, but NO SURVIVAL BENEFIT — useful for ICP control, not demonstrated to change mortality
• Hypothermia (32-34C): beneficial effect in UNCONTROLLED trials only; goal temperature and rewarming protocol are NOT established — NOT currently recommended for routine practice despite the theoretical appeal, an important honest evidence gap; one trial explored it specifically as a bridge to transplant
• Prophylactic phenytoin has NOT proven effective in improving survival despite ALF's seizure risk — treat seizures if they occur (phenytoin/benzodiazepine), do not give prophylactically
• Ammonia >200 mcmol/L is associated with herniation risk, but NO benefit of gut decontamination or lactulose has been demonstrated in ALF specifically (contrast this with hepatic encephalopathy in cirrhosis, where lactulose IS standard — see Hepatic Encephalopathy protocol)
• CRRT/hemofiltration can reduce ammonia levels, though its effect on ICP specifically has not been studied
• Barbiturate coma: option for refractory elevated ICP, requires close MAP monitoring given hypotension association
• Corticosteroids are NOT effective at prolonging survival or improving cerebral edema — no role

5. Coagulopathy Management

Synthesis of factors I, II, V, VII, IX, X is depressed; expect thrombocytopenia, hypofibrinogenemia, abnormal ROTEM/TEG. Bleeding sources: procedure sites, stress ulcers, lungs, oropharynx.

PPI for stress ulcer prophylaxis — standard.

Platelet transfusion: ONLY for counts <10,000/mcL or active bleeding — not for prophylaxis at higher thresholds.

Vitamin K given routinely (low risk, reasonable given uncertain etiology of coagulopathy).

FFP: do NOT transfuse unless active bleeding or a planned procedure — same principle as other critical care bleeding protocols (avoid reflexive correction of lab-only coagulopathy).

PRBCs for symptomatic anemia or hemorrhage-related blood loss.

6. Hemodynamic Complications

Hypotension is MULTIFACTORIAL: volume depletion, third-spacing, infection, GI bleeding, and a hyperkinetic/low-SVR state resembling sepsis physiology — evaluate broadly rather than assuming a single cause.

7. Renal Complications — Hepatorenal Syndrome Distinction

Hepatorenal syndrome (vs ATN): low urinary sodium (<10 mEq/L), progressive hyponatremia, NO improvement with volume expansion — use these features to distinguish from ATN, which changes fluid management approach.

Avoid nephrotoxins (aminoglycosides, NSAIDs). Use NAC before IV contrast studies (renal protective adjunct, separate from its hepatic indication).

CRRT preferred over intermittent hemodialysis when dialysis is needed — improved cardiovascular dynamics/hemodynamic tolerance.

8. Metabolic Complications

Hypoglycemia (diminished glucose synthesis) and lactic acidosis (anaerobic glucose metabolism) are common — monitor glucose closely, treat with dextrose. Repletion of phosphorus, potassium, magnesium as needed. Enteral or parenteral nutrition should be started EARLY; protein should NOT be restricted (contrast with older, now-outdated practice of protein restriction in liver failure). Cochrane review found no convincing evidence for branched-chain amino acids in hepatic encephalopathy treatment.

9. Prognostic Scoring — King's College Criteria

Non-acetaminophen ALF: presence of a SINGLE King's College factor -> 80% mortality; ALL THREE factors -> 95% mortality.

Acetaminophen-associated ALF: single risk factor -> 55% mortality; severe acidosis alone confers 95% mortality.

Performance characteristics (acetaminophen ALF): King's College Criteria sensitivity 0.59, specificity 0.92 for transplant need. APACHE II >15: specificity 0.81, sensitivity 0.92 for transplant need — APACHE II performs comparably/better and can be a useful adjunct decision tool.

10. Liver Transplantation

Proven ALF treatment when prognostic indicators predict high death likelihood, limited by donor availability. Post-transplant survival 80-90%. Considerations: spontaneous recovery potential, transplant feasibility, contraindication screening.

Deceased donor transplant is primary, but living donor transplantation is an option given organ scarcity — controversial given concern for undue donor pressure and the risk of an incomplete donor evaluation under time pressure.

Auxiliary partial orthotopic liver transplantation (resecting part of native liver, replacing with corresponding donor segment) has shown promise, potentially allowing native liver recovery and later immunosuppression withdrawal in select cases.

11. Organ Support

Cerebral edema/ICP-directed therapy (Section 4); coagulopathy management (Section 5); CRRT for renal failure/ammonia reduction (Sections 4/7); glucose/electrolyte management (Section 8); early nutrition without protein restriction; standard ICU supportive care.

12. Consultation Matrix

13. Monitoring Framework

Serial neuro exams and encephalopathy grading, ICP monitoring if placed, coagulation panel trend, glucose monitoring, ammonia trend, renal function, watch for herniation warning signs (Section 4).

14. Complications

Cerebral edema/herniation (leading mortality driver), coagulopathy-related hemorrhage, hepatorenal syndrome, hypoglycemia, sepsis/infection, multiorgan failure. Prevention: early transplant center transfer, appropriate ICP monitoring in high-risk patients, judicious (not reflexive) blood product use, early nutrition. Rescue: full ICP tiered management (Section 4), CRRT, liver transplantation.

15. Escalation & De-escalation

Escalate: progressing encephalopathy grade -> transfer to transplant center, intubate at Grade 3-4, ICP monitoring/management; King's College or APACHE II criteria met -> expedite transplant evaluation.

De-escalate: spontaneous recovery with improving encephalopathy/coagulopathy/liver function -> wean ICP-directed therapy, transition off transplant-urgent pathway while maintaining surveillance.

16. ICU Discharge Criteria

Encephalopathy resolved/stable at low grade, ICP controlled or resolved, coagulopathy stabilizing, liver function trending toward recovery, OR patient transplanted and post-transplant stable, OR transferred to a transplant center for ongoing higher-level management.

17. Documentation & Medicolegal Checklist

18. Key Guidelines

Bernal W, Wendon J. Acute liver failure. N Engl J Med. 2013;369:2525-2534 — primary consensus reference.

19. Landmark Trials

Lee WM et al. NAC RCT in non-acetaminophen ALF (referenced study, 173 patients) — established the grade 1-2 encephalopathy-limited benefit. Cochrane analysis of NAC in acetaminophen ALF (Peto OR 0.29 mortality reduction). Hypertonic saline ICP-monitored RCT (n=30) — ICP reduction without survival benefit.

20. Controversies

ICP monitoring use varies widely across transplant programs given the absence of definitive mortality benefit evidence — a genuinely unresolved practice variation issue. Hypothermia for refractory ICP remains unrecommended for ROUTINE practice despite appealing uncontrolled-trial signals, specifically because goal temperature and rewarming protocols are not established. Living donor liver transplantation in ALF carries real ethical tension (donor pressure, incomplete evaluation under time constraints) without a fully settled consensus approach.

21. References

1. Kumar A, Sultan S. Acute Liver Failure. Washington Manual of Critical Care, 4th ed, 2025 (Ch. 49).
2. Bernal W, Wendon J. Acute liver failure. N Engl J Med. 2013;369:2525-2534.
3. Janjanam A, Kesavan S. Acute Liver Failure. ICU Protocols: A Step-wise Approach, 2nd ed. Springer; 2020 (Ch. 38 region).
4. O'Grady JG, Alexander GJ, Hayllar KM, Williams R. Early indicators of prognosis in fulminant hepatic failure (King's College Criteria original derivation). Gastroenterology. 1989;97(2):439-445.
5. Lee WM, Hynan LS, Rossaro L, et al. Intravenous N-acetylcysteine improves transplant-free survival in early stage non-acetaminophen acute liver failure. Gastroenterology. 2009;137(3):856-864.