Orthopnoea is breathlessness that occurs specifically when lying flat, and is relieved — sometimes within minutes — by sitting upright or raising the head of the bed. The word itself comes from Greek: orthos (upright) and pnoea (breathing).
Unlike general breathlessness during exertion, orthopnoea is position-dependent. Most patients learn quickly that adding more pillows at night eases their symptoms — and cardiologists use the number of pillows as a simple, practical measure of severity.
Orthopnoea is one of the most specific symptoms of left ventricular failure and elevated filling pressures within the heart. When the left ventricle is struggling, fluid backs up into the pulmonary circulation. Lying flat accelerates this process dramatically — making expert assessment essential to understand why it is happening and to guide treatment before the condition worsens.