Trepopnea is

dyspnea Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...

(shortness of breath) that is sensed while lying on one side but not on the other (lateral recumbent position). It results from disease of one

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

, one major

bronchus A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchu ...

, or chronic

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

that affects only a side of breathing. Patients with trepopnea in most lung diseases prefer to lie and sleep on the opposite side of the diseased lung, as the

gravitation In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stron ...

increases perfusion of the lower lung. Increased

perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is deliver ...

in diseased lung would increase shunting and

hypoxemia Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the bod ...

, resulting in worsening shortness of breath when lying on the affected lung. To maximize function of the healthier lung and to relieve

, the patient is best to lie on the side of the healthier lung, so that it receives adequate perfusion. Patients with chronic heart failure prefer to lie mostly on the right side, to enable a better blood return, whereby cardiac output is augmented. One exception is

pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per k ...

, in which the patients experience less dyspnea when lying on the side of the pleural effusion, instead of the healthy lung.

References

Breathing abnormalities {{symptom-stub

See also

References