Hepatopulmonary Syndrome By Mark T Gladwin, MD, University of Pittsburgh School of Medicine; Andrea R Levine, MD, University of Maryland School of Medicine Reviewed / Revised Sep 2022 View Patient Education Diagnosis Treatment Key Points Hepatopulmonary syndrome is hypoxemia caused by pulmonary microvascular vasodilation in patients with portal hypertension; dyspnea and hypoxemia are worse when the patient is upright.