49 years old male with hypoxemia

Case provided by Simone

History
49 years old male with stress dyspnea and known liver cirrhosis. Blood gas analysis: pO2 62 mmHg.

 Imaging findings
Abdominal computed tomography shows evidence of liver cirrhosis with status post transjugular intrahepatic stent shunt (A). The chest scans shows dilated pulmonary vessels abnormally extending to the subpleural space and being accentuated in comparison to the accompanying bronchi (MIP reconstruction, B and C). There are no signs of lung fibrosis. The pulmonary trunc is dilated (37 mm, D).

Diagnosis
Hepatopulmonary syndrome.

Discussion
Hepatopulmonary syndrome is present in 15-20 % of patients with advanced liver disease. The affected patient suffers from dyspnea because of disease-related dilation of the pulmonary arterial vessels and capillaries and consecutive hypoxemia (pO2 < 70 mm Hg).

The vasodilation is thought to be caused by a decreased hepatic clearance and increased hepatic production of circulating vasoactive mediators.

The dilation of the pulmonary vessels causes an overperfusion resulting in a ventilation-perfusion mismatch. As a consequence an increased part of the blood circulating the lung is not oxygenated (i.e. intrapulmonary arteriovenous shunting) leading to hypoxemia.

Three criteria leading to the diagnosis of hepatopulmonary syndrome:

  • Chronic liver disease
  • Increased alveolar-arterial gradient on room air
  • Evidence of intrapulmonary vascular dilation (such as dilated pulmonary vessels which extend to the subpleural space in computed tomography examination and are not detectable in the periphery in healthy persons).

The functional intrapulmonary arteriovenous shunting can be demonstrated by echocardiography with microbubbles as contrast media.

Extrem version: Acute respiratory failure associated with fulminant hepatic failure. Vasodilation or noncardiogenic pulmonary edema are thought to cause this clinical picture in patients with extensive necrosis of the liver.

Treatment of hepatopulmonary syndrome consists of supplemental oxygen therapy or liver transplantation. Mortality is 15-40 % in non-transplanted patients.

Teaching points

  • Think of hepatopulmonary syndrome in a patient with advanced liver disease and dyspnea.
  • In hepatopulmonary syndrome the computed tomography examination of the chest shows dilated pulmonary vessels abnormally extending to the subpleural space.
  • The only curative treatment is liver transplantation.

Recommended reading

Meyer at al.
Diseases of the Hepatopulmonary Axis.
RadioGraphics 2000; 20:687-698

Grosse et al.
CT Findings in Diseases Associated with Pulmonary Hypertension: A Current Review
RadioGraphics 2010; 30:1753-1777

Rodriguez-Roisin et al.
Hepatopulmonary Syndrome – A Liver-Induced Lung Vascular Disorder.
N Engl J Med 2008; 358:2378-2387

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