What is a pulmonary embolism?
The lungs are a pair of organs in the chest that are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and blood. The lung is composed of clusters of small air sacs (alveoli) divided by thin, elastic walls (membranes). Capillaries, the tiniest of blood vessels, run within these membranes between the alveoli and allow blood and air to come near each other. The distance between the air in the lungs and the blood in the capillaries is very small, and allows molecules of oxygen and carbon dioxide to transfer across the membranes.
Pulmonary edema facts
- Pulmonary edema is typically caused by filling of alveoli in the lungs by fluid leaking out of the blood.
- Pulmonary edema may be caused by a number of cardiac or non-cardiac conditions.
- Breathing difficulty is the main manifestation of pulmonary edema.
- Treatment of the underlying cause of pulmonary edema is an essential step in the management of pulmonary edema.
What is pulmonary edema?
Edema, in general, means swelling. This typically occurs when fluid from inside blood vessels seeps outside the blood vessel into the surrounding tissues, causing swelling. This can happen either because of too much pressure in the blood vessels or not enough proteins in the bloodstream to hold on to the fluid in the plasma (the part of the blood that does not contain any blood cells).
Pulmonary edema is the term used when edema happens in the lungs. The immediate area outside of the small blood vessels in the lungs is occupied by very tiny air sacs called the alveoli. This is where oxygen from the air is picked up by the blood passing by, and carbon dioxide in the blood is passed into the alveoli to be exhaled out. Alveoli normally have a thin wall that allows for this air exchange, and fluids are usually kept out of the alveoli unless these walls lose their integrity.
Picture of the alveoli and lung
Pulmonary edema occurs when the alveoli fill up with excess fluid seeped out of the blood vessels in the lung instead of air. This can cause problems with the exchange of gas (oxygen and carbon dioxide), resulting in breathing difficulty and poor oxygenation of blood. Sometimes, this can be referred to as "water in the lungs" when describing the condition to patients.
Pulmonary edema can be caused by many different factors. It can be related to heart failure, called cardiogenic pulmonary edema, or related to other causes, referred to as non-cardiogenic pulmonary edema.
Medically Reviewed by a Doctor on 5/7/2015