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Hepatopulmonary syndrome
Last reviewed: 05.07.2025
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[ What causes hepatopulmonary syndrome?
Hepatopulmonary syndrome is the development of microscopic intrapulmonary arteriovenous dilations in patients with chronic liver disease. The mechanism is unknown, but it is thought to be due to increased hepatic production or decreased hepatic clearance of vasodilators, possibly including nitric oxide. The vascular dilations cause perfusion to exceed ventilation, leading to hypoxemia. Because lesions are often more numerous at the lung bases, hepatopulmonary syndrome causes platypnea (dyspnea when supine or sitting) and orthodeoxia (hypoxemia) in the elevated or upright position, which resolve in the supine position. Most patients also have stigmata of chronic liver disease, such as spider angiomas. About 20% of patients, however, have isolated pulmonary symptoms.
Symptoms of hepatopulmonary syndrome
Hepatopulmonary syndrome is suspected in any patient with liver disease who presents with dyspnea (especially platypnea). Patients with clinically significant symptoms should undergo pulse oximetry. If the syndrome is significant, blood gas measurements should be performed on air and 100% O2 to determine the shunt fraction.
Diagnosis of hepatopulmonary syndrome
A useful diagnostic test is contrast echocardiography. Microbubbles of foamed saline injected intravenously are normally rapidly captured by the pulmonary capillaries, transit the lung, and appear in the left atrium within seven beats. Similarly, intravenous technetium-99-labeled albumin may transit the lung and appear in the kidney and brain. Pulmonary angiography may show a diffusely fine or patchy vascular configuration. Angiography is generally unnecessary unless thromboembolism is suspected.
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Treatment of hepatopulmonary syndrome
The mainstay of treatment for hepatopulmonary syndrome is supplemental O 2 for symptomatic patients. Other therapies, such as somatostatin to inhibit vasodilation, have modest results in only some patients. Embolization is virtually impossible due to the number and size of lesions. Inhaled nitric oxide synthesis inhibitors may become the treatment of choice in the future. Hepatopulmonary syndrome may regress after liver transplantation or if the underlying liver disease improves.
What is the prognosis for hepatopulmonary syndrome?
Without treatment, hepatopulmonary syndrome has a poor prognosis (survival less than 2 years).