pulmonary edema
Meaning of pulmonary edema: Breathlessness that worsens on lying flat is the classic clue, because fluid redistributes toward the lungs when a person lies down.
Definition of pulmonary edema
Pulmonary edema is a buildup of fluid in the lungs, first in the tissue between the air sacs and then inside the air sacs themselves, where it takes the place of air and blocks the passage of oxygen into the blood. Breathlessness is the leading symptom, and it can build over days or arrive within an hour.
What drives the fluid out of the vessels?
| Type | What is happening | Typical settings |
|---|---|---|
| Cardiogenic | Pressure backs up from a heart that cannot empty properly | Heart failure, heart attack, valve disease, an abnormal rhythm, a surge in blood pressure |
| Noncardiogenic | Capillary walls become leaky and let fluid through at normal pressure | Severe infection, pneumonia, inhaled toxins, near drowning, some drugs, high altitude |
The two look similar on a chest film and feel similar to the person affected, but they call for different treatment, so distinguishing them is the first task. Heart failure is by far the commoner route. A blood test measuring a hormone released by a stretched heart chamber helps separate the two, as does an ultrasound scan of the heart. Kidney failure belongs to the first group in effect, since fluid the kidneys cannot remove raises pressure throughout the circulation.
Why does it get worse lying down?
Standing keeps a share of the circulating blood pooled in the legs. Lying flat returns that volume to the chest, and a heart already struggling cannot move the extra load onward, so pressure in the lung vessels climbs and more fluid crosses into the tissue. Breathlessness on lying flat is the result, along with a pattern of waking after an hour or two of sleep gasping for air and needing to sit upright. Sleeping propped on extra pillows is such a consistent adaptation that the number of pillows used is a standard question. The alveoli filling with fluid is the final stage; the earlier and often unnoticed stage is fluid gathering in the tissue around them.
How is it recognized?
Breathing is fast and shallow, and blood oxygen readings fall. Listening to the chest reveals fine crackles rising from the bases as the fluid level climbs, and in severe cases frothy pink tinged sputum appears, colored by red cells carried across with the fluid. A chest x-ray shows a characteristic pattern spreading outward from the center of the lungs, and bedside ultrasound shows lines that betray waterlogged lung tissue. Unlike edema in the ankles, which is visible and uncomfortable rather than dangerous, fluid in the lungs interferes directly with the exchange of gas and is treated as urgent.
Also known as
Used in a sentence
Chest imaging showed findings consistent with pulmonary edema.
Good to know
Pulmonary edema caused by heart problems is described as cardiogenic, while pulmonary edema from other causes, such as infection or direct lung injury, is described as noncardiogenic, a distinction that guides evaluation of the underlying cause.
Word origin
Where “pulmonary edema” comes from
Pulmonary derives from Latin pulmo, meaning lung, while edema comes from Greek oidema, meaning swelling.