5.2 Cirrhosis, Portal Hypertension & Hepatic Encephalopathy

Pathogenesis & Etiological Spectrum of Cirrhosis

Cirrhosis is the final histological pathway of chronic hepatic parenchymal injury, characterized by diffuse architectural distortion, extensive bridging fibrosis, and the conversion of normal hepatic lobules into structurally abnormal regenerative nodules. In the Caribbean basin, chronic liver disease generates significant inpatient morbidity and premature mortality.

Major Etiological Categories

• Chronic Viral Hepatitis: Chronic Hepatitis B virus (HBV) and Hepatitis C virus (HCV) infections. HBV remains an important cause in unimmunized populations and migrant communities, with high propensity for direct oncogenesis (hepatocellular carcinoma, HCC) even in the non-cirrhotic phase.
• Alcohol-Related Liver Disease (ARLD): Driven by chronic excessive ethanol intake, progressing from steatosis to steatohepatitis, progressive pericellular fibrosis, and micronodular cirrhosis.
• Metabolic Dysfunction-Associated Steatohepatitis (MASH, formerly NASH): Strongly linked to the Caribbean epidemic of type 2 diabetes mellitus, metabolic syndrome, and visceral obesity. MASH has rapidly emerged as a leading indication for liver transplantation globally.
• Autoimmune & Cholestatic Liver Diseases: Autoimmune hepatitis (characterized by anti-smooth muscle antibodies [ASMA], anti-nuclear antibodies [ANA], and elevated IgG); Primary Biliary Cholangitis (PBC, marked by chronic destruction of interlobular bile ducts, elevated alkaline phosphatase, and positive anti-mitochondrial antibodies [AMA]); and Primary Sclerosing Cholangitis (PSC, characterized by "beaded" stricturing of intra- and extrahepatic bile ducts, strongly associated with ulcerative colitis).
• Genetic & Metabolic Infiltrative Disorders: Hereditary hemochromatosis (HFE gene mutations causing parenchymal iron accumulation); Wilson's disease (autosomal recessive ATP7B mutation causing impaired biliary copper excretion, low serum ceruloplasmin, Kayser-Fleischer corneal rings, and basal ganglia copper deposition); and alpha-1 antitrypsin deficiency.

Hemodynamic Pathophysiology of Portal Hypertension

Portal hypertension is defined as a pathological elevation in the hepatic venous pressure gradient (HVPG) above 5 mmHg; HVPG >=10 mmHg defines clinically significant portal hypertension (CSPH), with an increased risk of decompensation.

1. Increased Intrahepatic Resistance: Fixed mechanical resistance from collagen deposition in the space of Disse, microvascular thrombosis, and architectural distortion, compounded by dynamic sinusoidal vasoconstriction mediated by activated hepatic stellate cells and deficient endothelial nitric oxide (NO) production.
2. Splanchnic Vasodilation & Hyperdynamic Circulation: Excessive local release of endogenous endothelial vasodilators (primarily nitric oxide, prostacyclin, and carbon monoxide) induces progressive splanchnic arteriolar vasodilation. Splanchnic blood pooling increases portal venous inflow, maintaining elevated portal pressures despite extensive portosystemic collateral formation.
3. Effective Circulatory Arterial Volume Depletion: Splanchnic arterial pooling decreases effective arterial blood volume, triggering intense neurohumoral activation of the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system (SNS), and non-osmotic arginine vasopressin (ADH) secretion. This results in profound renal sodium and water retention.

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Prognostic Staging: Child-Pugh vs MELD Scores

Objective prognostic models stratify disease severity, guide medical intervention, and direct prioritization for liver transplantation.

Child-Turcotte-Pugh (CTP) Classification

• Evaluates five clinical and biochemical parameters, scoring each from 1 to 3 points:
  1. Total Bilirubin: < 34 umol/L (1 pt), 34-50 umol/L (2 pts), > 50 umol/L (3 pts)
  2. Serum Albumin: > 35 g/L (1 pt), 28-35 g/L (2 pts), < 28 g/L (3 pts)
  3. INR / Prothrombin Time: INR < 1.7 (1 pt), 1.7-2.3 (2 pts), > 2.3 (3 pts)
  4. Ascites: Absent (1 pt), Mild/diuretic-controlled (2 pts), Moderate/severe/refractory (3 pts)
  5. Hepatic Encephalopathy: None (1 pt), Grade 1-2 (2 pts), Grade 3-4 (3 pts)
• Child-Pugh Class A (5 to 6 points): Well-compensated cirrhosis; 1-year survival approximately 100%, 2-year survival 85%.
• Child-Pugh Class B (7 to 9 points): Significant functional compromise; 1-year survival approximately 80%, 2-year survival 60%.
• Child-Pugh Class C (10 to 15 points): Decompensated end-stage cirrhosis; 1-year survival approximately 45%, 2-year survival 35%.

Model for End-Stage Liver Disease (MELD)

• An objective logarithmic mathematical model incorporating Bilirubin, INR, Serum Creatinine, and (in MELD-Na) Serum Sodium.
• Scores range from 6 to 40; used globally to allocate donor organs for liver transplantation based on 90-day waitlist mortality.

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Ascites Evaluation: The Serum-Ascites Albumin Gradient (SAAG)

Ascites is the most common manifestation of decompensated cirrhosis. Diagnostic paracentesis is mandatory for every patient admitted with new-onset ascites or acute clinical deterioration.

Calculating and Interpreting SAAG

• The Serum-Ascites Albumin Gradient (SAAG) correlates directly with sinusoidal portal venous hydrostatic pressure:
  • SAAG Formula: SAAG = Serum Albumin - Ascitic Fluid Albumin (both specimens obtained simultaneously)
• High SAAG (>= 11 g/L or >= 1.1 g/dL): Reflects the presence of portal hypertension (transudative process driven by elevated sinusoidal hydrostatic pressures):
  • Ascitic Fluid Total Protein < 25 g/L: Cirrhosis, late Budd-Chiari syndrome, massive liver metastases.
  • Ascitic Fluid Total Protein >= 25 g/L: Cardiac ascites (congestive heart failure, constrictive pericarditis), early Budd-Chiari syndrome, sinusoidal obstruction syndrome (hepatic veno-occlusive disease).
• Low SAAG (< 11 g/L or < 1.1 g/dL): Excludes portal hypertension (exudative process driven by increased peritoneal capillary permeability or lymphatic obstruction):
  • Peritoneal carcinomatosis (ovarian, gastric, or colonic malignancies)
  • Tuberculous peritonitis
  • Nephrotic syndrome (severe systemic hypoalbuminemia)
  • Pancreatic ascites (pancreatitis or duct disruption, marked by ascitic amylase > 1000 IU/L)
  • Biliary leak / post-surgical ascites

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Medical Management of Ascites & Large-Volume Paracentesis

• Dietary Sodium Restriction: Limit dietary sodium intake to < 2000 mg/day (88 mmol/day). Strict fluid restriction (< 1.0-1.5 L/day) is not indicated unless serum sodium falls below 125 mmol/L.
• Diuretic Therapy: Combination diuretic therapy is significantly more effective than monotherapy:
  • Initiate Spironolactone 100 mg once daily (aldosterone antagonist) plus Furosemide 40 mg once daily (loop diuretic).
  • Maintain the 100:40 ratio when titrating doses (up to a maximum of Spironolactone 400 mg and Furosemide 160 mg daily) to achieve a daily weight loss of 0.5 kg (or 1.0 kg if peripheral edema is present) while preserving normokalemia.
  • Hold or reduce diuretics for AKI, hypovolemia, serum sodium <125 mmol/L, or severe hypokalemia/hyperkalemia; reassess volume status, renal function and electrolytes.
• Large-Volume Paracentesis (LVP): First-line therapy for tense, symptomatic, or refractory ascites.
• Paracentesis-Induced Circulatory Dysfunction (PICD): Removing large volumes of ascitic fluid triggers rapid splanchnic pooling, further lowering systemic vascular resistance and precipitating acute renal failure and early mortality. When > 5 Liters of ascites is removed, administer intravenous salt-poor albumin at a dose of 8 g per liter of fluid removed (e.g., 40 g of 20% albumin for a 5 L paracentesis, or 64 g for an 8 L paracentesis).

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Spontaneous Bacterial Peritonitis (SBP)

Spontaneous bacterial peritonitis is an acute bacterial infection of ascitic fluid without an identifiable surgically treatable intra-abdominal source. It occurs in up to 25% of hospitalized cirrhotic patients with ascites, originating from enteric bacterial translocation across an edematous gut wall.

Clinical Presentation & Diagnostic Criteria

• Symptoms can be subtle: fever, chills, diffuse abdominal tenderness, altered mental status, or sudden worsening of renal function. In 10-20% of cases, patients are completely asymptomatic.
• Diagnostic Gold Standard: Paracentesis demonstrating an ascitic fluid absolute neutrophil count (ANC) >= 250 cells/mm3 (>= 0.25 x 10^9/L):
  • Ascitic ANC Formula: Ascitic ANC = Total WBC count × (% Neutrophils / 100)
• Ascitic fluid must be inoculated directly into blood culture bottles at the bedside prior to initiating antibiotics (common isolates: Escherichia coli, Klebsiella pneumoniae, Streptococcus pneumoniae).

Evidence-Based Treatment Protocol

1. Empiric Antimicrobial Therapy: For suitable community-acquired SBP, use an IV third-generation cephalosporin (Cefotaxime 2 g every 8 hours or Ceftriaxone 1–2 g daily) for 5–7 days. Healthcare-associated infection, severe sepsis or resistance risk requires broader empirical coverage according to local protocol, then culture-guided treatment.
2. Intravenous Albumin Infusion: The landmark randomized trial by Sort et al. demonstrated that administering IV albumin reduces the incidence of hepatorenal syndrome from 30% to 10% and reduces hospital mortality from 29% to 10%. Administer 1.5 g/kg IV within 6 hours of diagnosis, followed by 1.0 g/kg IV on day 3.
3. Secondary Prophylaxis: Following recovery from SBP, long-term secondary prophylaxis with oral Norfloxacin 400 mg daily or Ciprofloxacin 500 mg daily (or Trimethoprim-sulfamethoxazole) is mandatory to prevent recurrent infection.

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Hepatic Encephalopathy (HE)

Hepatic encephalopathy is a spectrum of neuropsychiatric abnormalities seen in advanced liver failure and portosystemic shunting, caused by the failure of the liver to detoxify gut-derived neurotoxins (chiefly ammonia, NH3), which cross the blood-brain barrier and induce astrocyte swelling and cerebral edema.

The West Haven Grading System

• Grade 1: Subtle behavioral changes, mild confusion, sleep rhythm inversion (insomnia at night, daytime somnolence), shortened attention span. Asterixis is absent.
• Grade 2: Obvious lethargy, apathy, disorientation to time/day, inappropriate social behavior, slurred speech. Asterixis (flapping tremor) is easily elicited.
• Grade 3: Somnolence to semi-stupor, responsive only to loud voice or shaking, marked confusion, gross disorientation. Asterixis usually present if patient can cooperate.
• Grade 4: Frank coma; unresponsive to verbal commands. Decerebrate or decorticate posturing may be seen.

Precipitating Factors

Hepatic encephalopathy is almost invariably provoked by an identifiable secondary insult. Common triggers include:

• Gastrointestinal bleeding (massive protein load in the gut converted to ammonia)
• Infections (SBP, urinary tract infection, pneumonia)
• Electrolyte disturbances: hypokalemia and metabolic alkalosis (induced by excessive diuretics; alkalosis shifts ionic NH4+ to diffusible NH3, while hypokalemia increases renal ammonia production)
• Constipation (prolonged colonic transit increases bacterial ammonia generation)
• Dehydration and acute kidney injury
• Administration of sedatives, opioids, or benzodiazepines

Management Strategy

1. Identify and Correct Precipitants: Stop sedatives and diuretics, treat infection, manage GI bleeding, and correct hypokalemia.
2. Lactulose (Non-absorbable synthetic disaccharide): First-line therapy. Colonic bacteria ferment lactulose into lactic and acetic acids, lowering intraluminal pH. Acidification converts lipophilic, diffusible ammonia (NH3) into non-diffusible ammonium (NH4+), trapping it within the bowel lumen for excretion ("ammonia trapping"). It also acts as an osmotic laxative. Administer 20 to 30 g (30 to 45 mL) orally 3-4 times daily, titrated to achieve 2 to 3 soft bowel movements per day.
3. Rifaximin: A non-absorbable oral rifamycin antibiotic (550 mg orally twice daily) that targets urease-producing gut microflora. Indicated as add-on therapy to lactulose for secondary prevention of recurrent encephalopathy episodes.

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Hepatorenal Syndrome (HRS-AKI)

HRS-AKI is a phenotype of acute kidney injury in advanced cirrhosis with ascites, driven by circulatory dysfunction and renal vasoconstriction. Tubular injury, proteinuria or pre-existing CKD may coexist; assess whether another process primarily explains the AKI.

Diagnostic Criteria (ICA-ADQI 2024)

• Cirrhosis with ascites.
• Creatinine increase at least 26.5 umol/L within 48 hours, at least 50% above baseline within 7 days, and/or urine output <=0.5 mL/kg/hour for at least 6 hours.
• No improvement within 24 hours after adequate volume resuscitation, when clinically indicated. Assess volume status promptly; do not require albumin for 48 hours in a euvolemic or overloaded patient.
• No strong evidence that another process primarily explains the AKI, such as septic shock requiring vasopressors, drug-induced injury, obstruction or acute glomerular disease.
• Review diuretics/nephrotoxins, urine findings and renal imaging. Infection without shock, proteinuria or CKD does not automatically exclude coexisting HRS-AKI.

Medical Management

• Vasoconstrictor Therapy + Albumin: Splanchnic vasoconstrictors blunt splanchnic arterial pooling, elevating systemic arterial pressure and improving renal perfusion:
  • Terlipressin: IV bolus 1 mg every 4 to 6 hours (or continuous infusion up to 2-12 mg/day) plus IV Albumin 20 to 40 g/day, adjusted daily to volume status and withheld for overload or pulmonary edema.
  • Alternative regimens (if terlipressin unavailable): Norepinephrine continuous infusion plus IV albumin, or oral Midodrine (alpha-1 agonist) plus subcutaneous Octreotide plus IV albumin.
• Definitive Cure: Orthotopic liver transplantation remains the definitive cure for HRS.

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Differential Matrix: SAAG & Ascitic Fluid Characteristics