Hepatopulmonary syndrome (HPS) is a lung disease characterized by widening of arteries and veins (dilatation) in the lungs in people who have chronic liver disease. Because of the dilated vases, the workload of the heart increases and the blood pumped to the body does not have enough oxygen, leading to a decreased level of oxygen in the blood (hypoxemia). The normal diameter of the lung vessels ranges between 8 and 15 μm whereas when in HPS rises to between 15 and 500 μm. While many people with HPS don't have any obvious problems, the main reported symptom is shortness of breath (dyspnea) that is worse when standing or sitting up, and is relieved when lying down (platypnea). Symptoms related to chronic liver disease (generally cirrhosis) include small red spots on the skin (spider angiomas) and abnormal vascular dilatations. Some other symptoms that have been described are infections in the brain (brain abscesses), brain bleeding and an increased number of red blood cells in the blood (polycythemia). There is currently no effective medication for HPS. Oxygen therapy may improve the breathing in some cases. Liver transplant is an efficient treatment which improves the symptoms, even in severe cases. The disease is hepatopulmonary syndrome (MONDO_0004694).