Orthopnea or orthopnoea is shortness of breath (dyspnea) that occurs when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair. It is commonly seen as a late manifestation of heart failure, resulting from fluid redistribution into the central circulation, causing an increase in pulmonary capillary pressure
It is also seen in cases of abdominal obesity or pulmonary disease. Orthopnea is the opposite of platypnea, shortness of breath that worsens when sitting or standing up.