Pulmonary edema can be broadly divided into cardiogenic and
non-cardiogenic causes. Some of the common causes are listed below.
heart is composed of two upper and two lower chambers. The upper chambers
(the right and left atria) receive incoming blood and pump it into the lower
chambers. The lower chambers (the more muscular right and left ventricles) pump
blood out of your heart. The heart valves — which keep blood flowing in the
correct direction — are gates at the chamber openings.
Normally, deoxygenated blood from all over your body enters the right
atrium and flows into the right ventricle, where it's pumped through large
blood vessels (pulmonary arteries) to your lungs. There, the blood releases
carbon dioxide and picks up oxygen.
The oxygen-rich blood then returns to the left atrium through the
pulmonary veins, flows through the mitral valve into the left ventricle and
finally leaves your heart through another large artery, the aorta.
The aortic valve at the base of the aorta keeps the blood from flowing
backward into your heart. From the aorta, the blood travels to the rest of your
body.
Cardiogenic (Heart related) causes of pulmonary edema
Cardiogenic pulmonary edema is a type of pulmonary edema caused by
increased pressures in the heart.
Cardiogenic causes of pulmonary edema results from high pressure in the
blood vessels of the lung due to poor heart function. Congestive heart failure
due to poor heart pumping function (arising from various causes such as
arrhythmias and diseases or weakness of the heart muscle), heart attacks, or
abnormal heart valves can lead to accumulation of more than the usual amount of
blood in the blood vessels of the lungs. This can, in turn, cause the fluid
from the blood vessels to be pushed out to the alveoli as the pressure builds
up.
Non-Cardiogenic (Non-heart related) causes of pulmonary edema
Pulmonary edema that isn't caused by increased pressures in your heart is
called noncardiogenic pulmonary edema. Non-cardiogenic pulmonary edema can be
commonly caused by the following:
Acute respiratory distress syndrome
A potentially serious condition caused by severe infections, trauma, lung
injury, inhalation of toxins, lung infections, cocaine smoking, or radiation to
the lungs. In ARDS, the integrity of the alveoli become compromised as a result
of underlying inflammatory response, and this leads to leaky alveoli that can
fill up with fluid from the blood vessels.
Kidney failure
Kidney failure and inability to excrete fluid from the body can cause
fluid build-up in the blood vessels, resulting in pulmonary edema. In people
with advanced kidney disease, dialysis may be necessary to remove the excess
body fluid.
High altitudes
Mountain climbers and people who live in or travel to high-altitude
locations run the risk of developing high-altitude pulmonary edema (HAPE).
This condition generally occurs at elevations above 8,000 feet (about
2,400 meters). It can also affect hikers or skiers who start exercising at
higher altitudes without first becoming acclimated, which can take from a few
days to a few weeks. But even people who have hiked or skied at high altitudes
in the past aren't immune.
Although the exact cause isn't completely understood, HAPE seems to
develop as a result of increased pressure from constriction of the pulmonary
capillaries. Without appropriate care, HAPE can be fatal.
Nervous system conditions.
Brain trauma, bleeding in the brain (intracranial hemorrhage), severe
seizures, or brain surgery can sometimes result in fluid accumulation in the
lungs, causing neurogenic pulmonary edema.
Lungs
A rapidly expanding lung can sometimes cause re-expansion pulmonary edema.
This may happen in cases when the lung collapses (pneumothorax) or a large
amount of fluid around the lung (pleural effusion) is removed, resulting in
rapid expansion of the lung. This can result in pulmonary edema on the affected
side only (unilateral pulmonary edema).
Toxins and medications
Rarely, an overdose on heroin or methadone can lead to pulmonary edema.
Aspirin overdose or chronic high dose use of aspirin can lead to aspirin
intoxication, especially in the elderly, which may cause pulmonary edema.
Other
Other more rare causes of non-cardiogenic pulmonary edema may include
pulmonary embolism (blood clot which has traveled to the lungs),
transfusion-related acute lung injury (TRALI), some viral infections, or
eclampsia in pregnant women.
