Fluid building up in the lungs is the most common cause of orthopnea. When standing, this excess fluid distributes throughout the body and presents as swelling of the legs and feet. When the person lays flat, though, gravity is no longer helping the fluid move throughout the body, which causes it to build up in the lungs.
Receive updates on the latest news and alerts straight to your inbox.
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.