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Definition: Orthopnea is dyspnea (shortness of breath) that occurs while lying down. Orthopnea is often a sign of heart failure, and this symptom should always be evaluated by a physician.

What Causes Orthopnea?

In any normal person, when lying down to sleep there is a redistribution of the fluid within the body. Due to gravity, some of the fluid in the legs and in the organs of the abdomen moves into the chest area.

This redistribution of fluid is relatively minor, and in most people it has no effect whatsoever on breathing.

However, in people with heart failure, the heart is unable to accommodate to the extra work it must perform to keep this extra fluid from accumulating in the lungs. As a result, pulmonary congestion - and early pulmonary edema - begin to occur, and shortness of breath results. Sitting up or elevating the head relieves some of the pulmonary congestion, and symptoms are improved.

In addition to shortness of breath, some patients will also experience coughing or wheezing when lying down. These kinds of breathing difficulties caused by assuming the recumbent position are referred to as orthopnea.

Heart failure is not the only cause of orthopnea, but it is by far the most common cause. Sometimes people with asthma or chronic bronchitis will also have more breathing problems while lying down.

Related Symptoms

A similar problem, also strongly associated with heart failure, is paroxysmal nocturnal dyspnea, or PND. It is caused by the same thing that causes orthopnea - the redistribution of fluid in the chest while in the recumbent position. However, people with PND generally do not notice dyspnea right after lying down, Instead, they are awakened from sleep with an episode of severe shortness of breath that causes them to immediately sit up for relief.

In addition to dyspnea, patients with PND also often experience palpitations, severe wheezing, and panic.

Clearly, PND is usually a far more dramatic event than orthopnea. It is thought that some additional mechanism (aside from simple fluid redistribution) is present in people with PND, perhaps related to changes in the brain’s respiratory center that may be associated with heart failure.

Another breathing symptom associated with heart failure is “bendopnea” - shortness of breath that occurs when bending over at the waist.

Evaluating Orthopnea

In any patient who has heart failure or who is suspected to have heart failure, the doctor should ask questions aimed at finding out whether orthopnea is occurring.

Many people with orthopnea deal with the symptom subconsciously by adding a pillow or two. They may not even realize that they get short of breath when lying flat - they may just feel more “comfortable” with their heads elevated. This is why doctors will often ask how many pillows a patient with heart failure is using, and will record the answers in the medical record as “two-pillow orthopnea” or “three-pillow orthopnea.”

Because worsening orthopnea is often an early sign of worsening heart failure, anyone with heart failure (and their significant others) should pay attention to worsening symptoms, and even to the number of pillows they are using.

Early intervention when symptoms are relatively mild can avoid a heart failure crisis, and prevent the need for hospitalization.


Ganong WF. Respiratory adjustments in health and disease. In: Review of medical physiology, 12th ed. Los Altos: Lange Medical Publications, 1985;558–71.

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