Filed under: Heart & Vascular
Pulmonary edema is a condition caused by excess fluid in the lungs. This fluid collects in the numerous air sacs in the lungs, making it difficult to breathe.
In most cases, heart problems cause pulmonary edema. But fluid can accumulate for other reasons, including pneumonia, exposure to certain toxins and medications, and exercising or living at high elevations.
Pulmonary edema that develops suddenly (acute) is a medical emergency requiring immediate care. Although pulmonary edema can sometimes prove fatal, the outlook improves when you receive prompt treatment for pulmonary edema along with treatment for the underlying problem. Treatment for pulmonary edema varies depending on the cause, but generally includes supplemental oxygen and medications.
Depending on the cause, pulmonary edema symptoms may appear suddenly or develop slowly.
Sudden (acute) pulmonary edema symptoms
If you develop any of these signs or symptoms, call 911 or emergency medical assistance right away. Pulmonary edema can be fatal if not treated.
Long-term (chronic) pulmonary edema symptoms
High-altitude pulmonary edema symptoms
When to see a doctor
Pulmonary edema that comes on suddenly (acute) is life-threatening. Get emergency assistance if you have any of the following acute signs and symptoms:
Don't attempt to drive yourself to the hospital. Instead, call 911 or emergency medical care and wait for help.
Your lungs contain numerous small, elastic air sacs called alveoli. With each breath, these air sacs take in oxygen and release carbon dioxide. Normally, the exchange of gases takes place without problems.
But in certain circumstances, the alveoli fill with fluid instead of air, preventing oxygen from being absorbed into your bloodstream. A number of things can cause fluid to accumulate in your lungs, but most have to do with your heart (cardiac pulmonary edema). Understanding the relationship between your heart and lungs can help explain why.
How your heart works
Your 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.
Heart-related (cardiac) pulmonary edema
Cardiac pulmonary edema — also known as congestive heart failure — occurs when the diseased or overworked left ventricle isn't able to pump out enough of the blood it receives from your lungs. As a result, pressure increases inside the left atrium and then in the veins and capillaries in your lungs, causing fluid to be pushed through the capillary walls into the air sacs.
Congestive heart failure can also occur when the right ventricle is unable to overcome increased pressure in the pulmonary artery, which usually results from left heart failure, chronic lung disease or high blood pressure in the pulmonary artery (pulmonary hypertension).
Medical conditions that can cause the left ventricle to become weak and eventually fail include:
Coronary artery disease. Over time, the arteries that supply blood to your heart can become narrow from fatty deposits (plaques). A heart attack occurs when a blood clot forms in one of these narrowed arteries, blocking blood flow and damaging the portion of your heart muscle supplied by that artery. The result is that the damaged heart muscle can no longer pump as well as it should.
Although the rest of your heart tries to compensate for this loss, either it's unable to do so effectively or it's weakened by the extra workload. When the pumping action of your heart is weakened, blood backs up into your lungs, forcing fluid in your blood to pass through the capillary walls into the air sacs.
Heart valve problems. In mitral valve disease or aortic valve disease, the valves that regulate blood flow in the left side of your heart either don't open wide enough (stenosis) or don't close completely (insufficiency). This allows blood to flow backward through the valve. When the valves are narrowed, blood can't flow freely into your heart and pressure in the left ventricle builds up, causing the left ventricle to work harder and harder with each contraction. The left ventricle also dilates to allow more blood flow, but this makes the left ventricle's pumping action less efficient. Because it's working so much harder, the left ventricle eventually thickens, which puts greater stress on the coronary arteries, further weakening the left ventricular muscle.
The increased pressure extends into the left atrium and then to the pulmonary veins, causing fluid to accumulate in your lungs. On the other hand, if the mitral valve leaks, some blood is backwashed toward your lung each time your heart pumps. If the leakage develops suddenly, you may develop sudden and severe pulmonary edema.
Noncardiac pulmonary edema
Not all pulmonary edema is the result of heart disease. Fluid may also leak from the capillaries in your lungs' air sacs because the capillaries themselves become more permeable or leaky, even without the buildup of back pressure from your heart. In that case, the condition is known as noncardiac pulmonary edema because your heart isn't the cause of the problem. Some factors that can cause noncardiac pulmonary edema are:
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 — which typically occurs at elevations above 8,000 feet (about 2,400 meters) — can also affect hikers or skiers who start exercising at higher altitudes without first becoming acclimated. 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.
If pulmonary edema continues, it can raise pressure in the pulmonary artery and eventually the right ventricle begins to fail. The right ventricle has a much thinner wall of muscle than does the left side because it is under less pressure to pump blood into the lungs. The increased pressure backs up into the right atrium and then into various parts of your body, where it can cause:
When not treated, acute pulmonary edema can be fatal. In some instances it may be fatal even if you receive treatment.
You're likely to start by seeing your primary care doctor, or in the case of acute pulmonary edema, an emergency room physician. Most people with pulmonary edema will be hospitalized for at least a few days, often longer. You may see several specialists while you are in the hospital. After your condition has been stabilized, you may then be referred as an outpatient to a doctor who specializes in disorders of the heart (cardiologist) or in treating lung disorders (pulmonologist).
What you can do
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For pulmonary edema, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:
Because pulmonary edema requires prompt treatment, you'll initially be diagnosed on the basis of your symptoms and a physical exam and chest X-ray. You may also have blood drawn — usually from an artery in your wrist — so that it can be checked for the amount of oxygen and carbon dioxide it contains (arterial blood gas concentrations). Your blood will also be checked for levels of a substance called B-type natriuretic peptide (BNP). Increased levels of BNP may indicate that your pulmonary edema is caused by heart problems. Other blood tests will usually be done, including tests of your kidney function, blood count, as well as tests to exclude a heart attack as the cause of your pulmonary edema.
Once your condition is more stable, your doctor will ask about your medical history, especially whether you have ever had cardiovascular or lung disease.
Tests that may be done to diagnose pulmonary edema or to determine why you developed fluid in your lungs include:
Echocardiography (diagnostic cardiac ultrasound exam). Another noninvasive test, echocardiography uses a wand-shaped device called a transducer to generate high-frequency sound waves that are reflected from the tissues of your heart. The sound waves are then sent to a machine that uses them to compose images of your heart on a monitor.
The test can help diagnose a number of heart problems, including valve problems, abnormal motions of the ventricular walls, fluid around the heart (pericardial effusion) and congenital heart defects. It also accurately measures the amount of blood your left ventricle ejects with each heartbeat (ejection fraction, or EF). It can also estimate if there's increased pressure in the right side of the heart. Although a low EF often indicates a cardiac cause for pulmonary edema, it's possible to have cardiac pulmonary edema with a normal EF.
Giving oxygen is the first step in the treatment for pulmonary edema. You usually receive oxygen through a face mask or nasal cannula — a flexible plastic tube with two openings that deliver oxygen to each nostril. This should ease some of your symptoms. Sometimes it may be necessary to assist your breathing with a machine.
Depending on your condition and the reason for your pulmonary edema, you may also receive one or more of the following medications:
Treating high-altitude pulmonary edema (HAPE)
If you're climbing or traveling at high altitudes and experience mild symptoms of HAPE, descending a few thousand feet (about 600 to 900 meters) as quickly as you can, within reason, should relieve your symptoms. Oxygen also is helpful. When symptoms are more severe, you'll likely need help in your descent. A helicopter rescue may be necessary for the most serious cases, because HAPE can be life-threatening.
Some climbers take the prescription medication acetazolamide (Diamox) to help treat or prevent symptoms of HAPE. To prevent HAPE, acetazolamide is started as long as three days before ascent. Acetazolamide can occasionally have side effects — including tingling or burning in the hands and feet, confusion, diarrhea, nausea, loss of appetite, and hearing problems.
The following suggestions may speed your recovery from cardiac pulmonary edema and help prevent a recurrence:
If you've experienced noncardiac pulmonary edema — including some forms of ARDS — take care to minimize any further damage to your lungs, and as much as possible avoid the cause of your condition, such as drugs, allergens or high altitudes.
Pulmonary edema often isn't preventable, but these measures can help reduce your risk.
Preventing cardiovascular disease
Cardiovascular disease is the leading cause of pulmonary edema. You can reduce your risk of many kinds of heart problems by following these suggestions:
Control your blood pressure. High blood pressure (hypertension) can lead to serious conditions such as stroke, cardiovascular disease and kidney failure. Most adults should have their blood pressure checked at least once every two years. This is a noninvasive and painless procedure using an inflatable cuff that wraps around your upper arm. The test takes just a few minutes.
A resting blood pressure reading below 120/80 millimeters of mercury (mm Hg) is considered normal. If your resting blood pressure is consistently 140/90 mm Hg or higher, you have high blood pressure. A reading in between these levels places you in the prehypertensive category.
In many cases, you can lower your blood pressure or maintain a healthy level by getting regular exercise, reaching your ideal weight, eating a diet rich in fresh fruits, vegetables and low-fat dairy products, and limiting salt and alcohol.
If you travel or climb at high altitudes, acclimate yourself slowly. Although recommendations vary, most experts advise ascending no more than 1,000 or 2,000 feet (300 to 600 meters) a day once you reach 8,000 feet (about 2,400 meters). In addition, it's important to drink plenty of water to stay hydrated. The higher you ascend the more rapidly you breathe, which means you lose larger amounts of water in the air you exhale from your lungs.
Finally, although being physically fit won't necessarily prevent HAPE, people in good condition tend to be less stressed at high altitudes. However, just because you have hiked or skied at high altitude before doesn't protect you from HAPE. Taken 12 to 72 hours before you travel to a high altitude, the medication acetazolamide (Diamox) can help prevent HAPE. Consider continuing the medication for an additional few days if any signs of altitude sickness, especially headache or insomnia, occur.
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