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Hepatic Failure — Comprehensive Notes

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1. NORMAL LIVER PHYSIOLOGY (Foundation)

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2. DEFINITION

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3. TYPES / CLASSIFICATION

A. Acute Liver Failure (ALF) / Fulminant Hepatic Failure

• Defined as severe acute liver injury producing hepatic encephalopathy within 6 months of initial diagnosis, with no pre-existing liver disease
• Encephalopathy develops within 8 weeks of symptom onset in fulminant forms (some definitions within 2–4 weeks)
• Encephalopathy is mediated by cerebral edema, not portosystemic shunting
• Mortality without transplant: >70%

B. Chronic Liver Failure (End-Stage Liver Disease / Decompensated Cirrhosis)

• Slow progressive loss of hepatic reserve over months to years
• Encephalopathy results from portosystemic shunting + portal hypertension
• Hallmark: ascites, varices, jaundice, encephalopathy, coagulopathy

C. Acute-on-Chronic Liver Failure (ACLF)

• An acute insult (infection, GI bleed, alcohol binge, drugs) superimposed on compensated chronic liver disease
• Causes rapid decompensation — carries 30-day mortality of 30–50%
• More common precipitant than de novo acute liver failure

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4. ETIOLOGY

Causes of Acute Liver Failure (Mnemonic: A B C D E F)

Causes of Chronic Liver Failure

• Alcoholic liver disease (ALD) — most common in Western countries
• Non-alcoholic fatty liver disease (NAFLD) / NASH
• Chronic viral hepatitis B and C
• Autoimmune hepatitis
• Primary biliary cholangitis / Primary sclerosing cholangitis
• Hemochromatosis, Wilson disease (metabolic)
• Budd-Chiari syndrome (hepatic venous outflow obstruction)
• Cardiac cirrhosis (right heart failure / congestive)

Precipitants of Acute-on-Chronic Failure

• GI hemorrhage (variceal or peptic)
• Bacterial infection / sepsis (especially SBP)
• Alcohol binge
• Hepatotoxic drugs / acetaminophen
• Surgery or anesthesia
• Dehydration / volume depletion
• Electrolyte imbalance (hyponatremia, hypokalemia)

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5. PATHOGENESIS / PATHOPHYSIOLOGY

5.1 Massive Hepatocellular Loss

• In acute failure: massive necrosis (coagulative or apoptotic) from direct toxicity (acetaminophen → toxic NAPQI metabolite → oxidative stress → mitochondrial dysfunction → hepatocyte death) or immune-mediated destruction (viral hepatitis: CD4+/CD8+ T cells attack virus-infected hepatocytes)
• In chronic failure: progressive fibrosis by activated perisinusoidal hepatic stellate cells (converted to fibrogenic myofibroblasts) → fibrous septa → cirrhosis → loss of functional hepatic mass

5.2 Ammonia Metabolism Failure → Hepatic Encephalopathy

• Normal liver converts NH₃ → urea (urea cycle in periportal hepatocytes) and glutamine (in perivenous hepatocytes)
• In liver failure: ammonia accumulates → crosses blood-brain barrier → astrocyte swelling (astrocytes try to detoxify NH₃ → glutamine accumulation → osmotic astrocyte swelling) → cerebral edema
• In acute failure: cerebral edema is the primary mechanism (not portosystemic shunting)
• In chronic failure: portosystemic shunting + reduced hepatic mass both contribute
• Elevated ammonia → impairs neuronal function, alters neurotransmitter systems (GABA-ergic, glutamatergic)

5.3 Coagulopathy

• Loss of hepatocyte synthesis → reduced production of coagulation factors I, II, V, VII, IX, X, XI, XII (all liver-synthesized)
• Factor V has the shortest half-life — most sensitive early marker of coagulopathy trends
• Thrombocytopenia (portal hypertension → splenomegaly → platelet sequestration; also decreased thrombopoietin synthesis)
• DIC may develop in ALF due to massive cytokine release

5.4 Cytokine Storm and Multi-Organ Failure

• Rapid hepatocyte death → massive release of pro-inflammatory cytokines (TNF-α, IL-1, IL-6)
• Leads to tissue hypoxia, lactic acidosis, systemic inflammatory response
• Progressive multi-organ dysfunction: kidneys (hepatorenal syndrome), lungs (hepatopulmonary syndrome / ARDS), cardiovascular system (hypotension)

5.5 Portal Hypertension (primarily in chronic failure)

• Progressive fibrosis → increased intrahepatic resistance to portal flow → portal hypertension
• Consequences: varices (esophageal, gastric), splenomegaly, caput medusae, ascites

5.6 Hypoglycemia

• Loss of gluconeogenesis and glycogenolysis capacity → hypoglycemia (especially in ALF)

5.7 Bilirubin Retention / Jaundice

• Failure to conjugate and excrete bilirubin → unconjugated and conjugated hyperbilirubinemia → jaundice, cholestasis

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6. MORPHOLOGY (Gross and Microscopic Pathology)

Gross Pathology

• Acute liver failure: Liver is small and shrunken (may weigh as little as 700 g; normal ~1500 g), bile-stained, soft, congested — due to massive loss of parenchyma
• Chronic (cirrhotic): Liver is small, nodular, firm with coarse fibrous scarring

Microscopic Pathology

• Acute failure: Massive hepatic necrosis — large zones of destruction surrounding occasional islands of regenerating hepatocytes
• Scarring is mostly absent in acute cases (no time to form)
• Chronic failure: Fibrous septa encircle regenerating hepatocyte nodules — classic cirrhosis pattern
• Inflammatory infiltrates (mainly cytotoxic T cells in viral hepatitis)

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7. CLINICAL MANIFESTATIONS

7.1 Cardinal Features

7.2 Hepatic Encephalopathy — Grading (West Haven Criteria)

7.3 Systemic Manifestations (by System)

• Hepatic encephalopathy (grades I–IV)
• Cerebral edema (in ALF) → raised intracranial pressure → Cushing's triad
• Asterixis (flapping tremor of hands)

• Hypotension (splanchnic vasodilation; reduced effective circulating volume)
• High-output circulation (early) → cardiovascular collapse (late)

• Hepatopulmonary syndrome (intrapulmonary vascular dilatation → hypoxemia)
• Portopulmonary hypertension
• Ascites → splinting of diaphragm → atelectasis, dyspnea

• Hepatorenal syndrome (HRS): Functional renal failure; intense renal vasoconstriction; no intrinsic renal pathology; kidneys are normal histologically
  • Type 1 HRS: Rapid deterioration (creatinine doubles to >2.5 mg/dL within 2 weeks)
  • Type 2 HRS: Slower, steady decline; associated with refractory ascites

• Nausea, vomiting, anorexia
• Ascites (hypoalbuminemia + portal hypertension + secondary hyperaldosteronism)
• Variceal bleeding (esophageal/gastric — more common in acute-on-chronic failure)
• Spontaneous bacterial peritonitis (SBP)

• Coagulopathy → easy bruising, petechiae, prolonged bleeding
• Thrombocytopenia
• DIC (in ALF)
• Anemia (multifactorial: bleeding, hemolysis, bone marrow suppression)

• Hypoglycemia (lost gluconeogenesis)
• Hyponatremia (dilutional — excess water retention)
• Hypokalemia / alkalosis
• Lactic acidosis (tissue hypoxia + impaired lactate clearance)
• Relative adrenal insufficiency

• Spider angiomata (estrogen excess → dilatation of skin arterioles)
• Palmer erythema
• Leukonychia (white nails)
• Caput medusae (dilated periumbilical veins)
• Pruritus (bile salt deposition in skin)

• Hypogonadism / gynecomastia (impaired estrogen metabolism)
• Testicular atrophy

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8. LABORATORY FINDINGS / INVESTIGATIONS

8.1 Liver Function Tests

8.2 Hematology

8.3 Renal Function

8.4 Serology / Special Tests

8.5 Imaging

8.6 Prognostic Scoring Systems

• pH <7.3 (regardless of grade of encephalopathy), OR
• PT >100 sec (INR >6.5) + creatinine >3.4 mg/dL + Grade III–IV encephalopathy

• MELD = 3.78 × ln[bilirubin] + 11.2 × ln[INR] + 9.57 × ln[creatinine] + 6.43
• Higher MELD = worse prognosis; used for organ allocation

• Uses: Bilirubin, albumin, INR, ascites, encephalopathy
• Class A (5–6): Compensated; Class B (7–9): Significant dysfunction; Class C (10–15): Decompensated

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9. DIAGNOSIS

Diagnostic Criteria for Acute Liver Failure

1. Severe acute liver injury (typically transaminases in the thousands)
2. Hepatic encephalopathy (any grade)
3. INR ≥ 1.5
4. No pre-existing liver disease (onset within prior 6 months)

Diagnostic Approach

1. Confirm liver failure: LFTs, INR, bilirubin, albumin, ammonia, blood glucose, lactate, CBC, renal function
2. Grade encephalopathy: West Haven grading; EEG if needed
3. Determine etiology: Viral serology, autoimmune markers, drug history (acetaminophen levels), metabolic workup, imaging
4. Assess severity + prognosis: King's College Criteria (ALF), MELD score (chronic)
5. Identify complications: Cultures (SBP), ascitic tap, CT head (cerebral edema), renal function (HRS)
6. Refer to transplant center if ALF criteria met — liver transplant is definitive treatment

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10. COMPLICATIONS SUMMARY

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11. MANAGEMENT OVERVIEW (Principles)

General Supportive Care

• ICU admission (Grade III–IV encephalopathy or ALF)
• Intubation if respiratory failure (somnolence + aspiration risk; BiPAP generally avoided)
• Blood pressure support: Volume resuscitation (normal saline) → norepinephrine (first-line vasopressor) → add vasopressin if refractory (caution in encephalopathic patients — may worsen cerebral vasodilatation)
• Hydrocortisone: AASLD recommends a trial in persistent hypotension (relative adrenal insufficiency)
• Glucose monitoring: IV dextrose for hypoglycemia

Encephalopathy Management

• Lactulose: Reduces ammonia by acidifying colon → traps NH₄⁺; also acts as a cathartic
• Rifaximin: Non-absorbable antibiotic → reduces urease-producing gut bacteria → reduces NH₃ production
• Low-protein diet (avoid excessive protein restriction; branched-chain amino acids preferred)
• Treat precipitants (infection, GI bleed, electrolyte disturbance)
• Cerebral edema: Mannitol 0.5–1 g/kg IV; hypertonic saline (goal Na 145–155 mEq/L prophylactically in high-risk cases)

Coagulopathy Management

• Vitamin K 10 mg IV/PO (corrects if due to deficiency)
• Fresh frozen plasma (FFP) if active bleeding or pre-procedure
• Platelet transfusion for thrombocytopenia with bleeding

Specific Antidotes

• Acetaminophen toxicity: N-acetylcysteine (NAC) — replenishes glutathione; given IV in ALF regardless of timing
• Wilson disease: D-penicillamine or trientine

Definitive Treatment

• Liver transplantation — only definitive treatment for ALF and end-stage chronic liver failure
• Urgent referral to transplant center is the most critical early disposition
• Living or deceased donor liver transplantation

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Key Concept Summary

"Liver failure results in loss of the liver's ability to synthesize coagulation factors and metabolize ammonia. The rapid loss of hepatocytes results in a massive release of cytokines, leading to tissue hypoxia and lactic acidosis. In acute liver failure, encephalopathy is mediated by cerebral edema — not by the portosystemic shunting and portal hypertension of cirrhosis." — Goldman-Cecil Medicine

"The most severe clinical consequence of liver disease is liver failure. It occurs primarily in three clinical scenarios: acute, chronic, and acute-on-chronic liver failure." — Robbins & Kumar Basic Pathology

"Potentially fatal sequelae of liver failure include coagulopathy, encephalopathy, portal hypertension and ascites, hepatorenal syndrome, and portopulmonary hypertension." — Robbins, Cotran & Kumar Pathologic Basis of Disease

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