Which condition is characterized by shortness of breath when lying down?

The condition characterized by shortness of breath when lying down is known as orthopnea. This symptom typically occurs in individuals with heart failure or respiratory illnesses, as lying flat can lead to increased venous return to the heart or decreased lung capacity, both of which can exacerbate breathing difficulties. Patients often find relief by propping themselves up with pillows or sleeping in a more upright position.

While nocturnal dyspnea refers to episodes of shortness of breath that may occur during sleep, it encompasses a broader scenario and does not specify the position of the patient. Dyspnea on exertion is related to difficulty breathing during physical activity and is not specifically tied to body position. Paroxysmal nocturnal dyspnea involves sudden episodes of severe breathlessness that wake individuals from sleep, but it is a specific manifestation that occurs intermittently and typically involves a more dramatic onset than what is described in orthopnea. Thus, orthopnea is the most precise term for shortness of breath that specifically occurs when lying down.