Epidemiology

• Incidence
  • Positive echo bubble study (due to intrapulmonary shunt) is seen in 20% of cirrhotics (although not all are hypoxemic)
  • Hepatopulmonary syndrome occurs in 5-30% of patients with liver disease

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Physiology

• Hepatogenic Pulmonary Angiodysplasia: results in intrapulmonary (right-to-left) shunting
  • Intrapulmonary vascular dilatations (more prominent in the bases)
  • Dysfunctional pulmonary vasoconstriction

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Diagnostic

• Echo with Bubble Study
  • Preferred study
  • Bubbles in left heart immediately after injection: suggests intracardiac shunt
  • Bubbles after 3-6 cardiac cycles after injection: suggests intrapulmonary shunt
• V/Q Shunt Study
  • Procedure: scan over brain and kidneys to assess amount of Te99m-MAA that has traversed the pulmonary circulation -> presence in these organs indicates intrapulmonary shunt
  • 20-60 µm Te99m-MAA (macro-aggregated albumin) particles are normally trapped in pulmonary circulation
  • Quantification (by kidney:dose method): shunt = (right kidney counts x 10)/injected dose
  • Quantification (by kidney:lung method): shunt = (right kidney counts x 10)/[total lung counts + (right kidney counts x10)]
• Swan
  • High CO with normal-low PVR
• ABG
  • Increased A-a gradient
• PFT’s
  • Decreased DLCO
• 100% FIO2 Shunt Study
  • pO2 <500-600 -> suggests presence of intrapulmonary shunt
• Chest CT
  • May demonstrate subpleural vessels
• Pulmonary Angiogram
  • May demonstrate spidery-spongy vascular dilatations
• ABG: hypoxemia/ respiratory alkalosis
  • Shunt physiology: hypoxemia may respond somewhat to supplemental O2 (due to a “diffusion perfusion defect”: vascular dilatations prevent oxygen from diffusing to the center of vessel to provide adequate oxygenation)
  • Orthodeoxia (due to increased flow to bases, where vascular dilatations are more prominent, with standing): supine position improves hypoxemia
• CXR/ Chest CT Patterns
  • Bibasilar interstitial changes: most cases
  • Normal CXR: some cases

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Clinical Manifestations

Pulmonary Manifestations

• Exertional Dyspnea (see Dyspnea, [[Dyspnea]]): dyspnea is the first symptom in only 20% of cases (usually liver symptoms precede onset of dyspnea)
• Hypoxemia (see Hypoxemia, [[Hypoxemia]])
• Orthodeoxia (see Platypnea-Orthodeoxia, [[Platypnea-Orthodeoxia]]): characteristic worsened hypoxemia with upright position
• Platypnea (see Platypnea-Orthodeoxia, [[Platypnea-Orthodeoxia]]): dyspnea with upright position (as vascular diltations are basilar-predominant)

Rheumatologic Manifestations

• Clubbing (see Clubbing, [[Clubbing]])

Other Manifestations

• Spider Angiomata
• Hypotension (see Hypotension, [[Hypotension]])
• Acrocyanosis (see xxxx, [[]])

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Prognosis

• Median Survival: 41 mo after diagnosis of hepatopulmonary syndrome
• Hepatopulmonary syndrome is a poor prognostic factor

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Treatment

• Supplemental O2: for patients with small shunts
• Orthotopic Liver Transplant
  • Preferred treatment: effective in most cases
  • Higher operative mortality with shunt fraction >20% or pre-op pO2 <50
• Indomethacin: may be useful but unproven
• Coil Spring Embolization of Vascular Dilatations: may be used but not always effective (due to multiple areas)
• Octreotide: no benefit shown in 2 studies

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References

• xxx