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, trauma to the chest wall, and exercising or living at high elevations.
Pulmonary edema that develops suddenly (acute pulmonary edema) 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 over time.
Sudden (acute) pulmonary edema symptoms
- Extreme shortness of breath or difficulty breathing (dyspnea) that worsens when lying down
- A feeling of suffocating or drowning
- Wheezing or gasping for breath
- Anxiety, restlessness or a sense of apprehension
- A cough that produces frothy sputum that may be tinged with blood
- Chest pain if pulmonary edema is caused by heart disease
- A rapid, irregular heartbeat (palpitations)
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
- Having more shortness of breath than normal when you're physically active.
- Difficulty breathing with exertion.
- Difficulty breathing when you're lying flat.
- Awakening at night with a breathless feeling that may be relieved by sitting up.
- Rapid weight gain when pulmonary edema develops as a result of congestive heart failure, a condition in which your heart pumps too little blood to meet your body's needs. The weight gain is from buildup of fluid in your body, especially in your legs.
- Swelling in your lower extremities.
High-altitude pulmonary edema symptoms
- Shortness of breath after exertion, which progresses to shortness of breath at rest
- Difficulty walking uphill, which progresses to difficulty walking on flat surfaces
- A cough that produces frothy sputum that may be tinged with blood
- A rapid, irregular heartbeat (palpitations)
- Chest discomfort
- Headaches, which may be the first symptom
When to see a doctor
Pulmonary edema that comes on suddenly (acute pulmonary edema) is life-threatening. Get emergency assistance if you have any of the following acute signs and symptoms:
- Shortness of breath, especially if it comes on suddenly
- Trouble breathing or a feeling of suffocating (dyspnea)
- A bubbly, wheezing or gasping sound when you breathe
- Pink, frothy sputum when you cough
- Breathing difficulty along with profuse sweating
- A blue or gray tone to your skin
- A significant drop in blood pressure resulting in lightheadedness, dizziness, weakness or sweating
- A sudden worsening of any of the symptoms associated with chronic pulmonary edema or high-altitude pulmonary edema
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 (cardiogenic 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 (cardiogenic) pulmonary edema
Cardiogenic pulmonary edema is a type of pulmonary edema caused by increased pressures in the heart.
This condition usually occurs when the diseased or overworked left ventricle isn't able to pump out enough of the blood it receives from your lungs (congestive heart failure). 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.
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 muscle 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. Or it isn't a clot that brings on the problems, but rather it is a gradual narrowing of the coronary arteries resulting in a weakness of the left ventricular muscle.
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 gradually backs up into your lungs, forcing fluid in your blood to pass through the capillary walls into the air sacs. This is chronic congestive heart failure.
Cardiomyopathy. When your heart muscle is damaged by causes other than blood flow problems, the condition is called cardiomyopathy.
Because cardiomyopathy weakens the ventricles — your heart's main pump — your heart may not be able to respond to conditions that require it to work harder, such as a surge in blood pressure, a faster heartbeat with exertion, or using too much salt that causes water retention or infections. When the left ventricle can't keep up with the demands that are placed on it, fluid backs up into your lungs.
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 (regurgitation).
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 ventricular muscle 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.
- High blood pressure (hypertension). Untreated or uncontrolled high blood pressure can lead to damage to the heart muscle and worsening of coronary artery disease.
Other conditions may lead to cardiogenic pulmonary edema, such as high blood pressure due to narrowed kidney arteries (renal artery stenosis) and fluid buildup due to kidney disease or heart problems.
Non-heart-related (noncardiogenic) pulmonary edema
Pulmonary edema that isn't caused by increased pressures in your heart is called noncardiogenic pulmonary edema.
In this condition, fluid may 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. Some factors that can cause noncardiogenic pulmonary edema include:
- Acute respiratory distress syndrome (ARDS). This serious disorder occurs when your lungs suddenly fill with fluid and inflammatory white blood cells. Many conditions can cause ARDS, including severe injuries (trauma), systemic infection (sepsis), pneumonia and severe bleeding.
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 generally 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, 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, but this risk can be minimized.
- Nervous system conditions. A type of pulmonary edema called neurogenic pulmonary edema can occur after some nervous system conditions or procedures — such as after a head injury, seizure or subarachnoid hemorrhage — or after brain surgery.
- Adverse drug reaction. Many drugs — ranging from illegal drugs such as heroin and cocaine to aspirin — are known to cause noncardiogenic pulmonary edema.
- Pulmonary embolism. Pulmonary embolism, a condition that occurs when blood clots travel from blood vessels in your legs to your lungs, can lead to pulmonary edema.
- Viral infections. Pulmonary edema can be caused by viral infections such as the hantavirus and dengue virus.
Lung injury. Pulmonary edema can occur after surgery to remove blood clots from your lungs, but it occurs only in the part of the lung from which the clots were removed. It can also occur after a collapsed lung has been re-expanded or rarely after volumes of fluid have been removed from the lung.
Noncardiogenic pulmonary edema also occurs in the lung directly below blunt trauma to the chest wall with the most common cause being auto accidents.
- Exposure to certain toxins. These include toxins you inhale as well as those that may circulate within your own body, for example, if you inhale (aspirate) some of your stomach contents when you vomit. Inhaling toxins such as ammonia and chlorine, which can occur with train accidents, causes intense irritation of the small airways and alveoli, resulting in fluid accumulation.
- Smoke inhalation. Smoke from a fire contains chemicals that damage the membrane between the air sacs and the capillaries, allowing fluid to enter your lungs.
- Near drowning. Inhaling water causes noncardiogenic pulmonary edema that is reversible with immediate attention.
If pulmonary edema continues, it can raise pressure in the pulmonary artery (pulmonary hypertension), and eventually the right ventricle in your heart becomes weak and begins to fail. The right ventricle has a much thinner wall of muscle than does the left side of your heart 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:
- Lower extremity and abdominal swelling
- Buildup of fluid in the membranes that surround your lungs (pleural effusion)
- Congestion and swelling of the liver
When not treated, acute pulmonary edema can be fatal. In some instances, it may be fatal even if you receive treatment.
If you have pulmonary edema, you will likely first be seen by an emergency room doctor. If you think you have signs or symptoms of pulmonary edema, call 911 or emergency medical help rather than make an outpatient appointment.
Most people with pulmonary edema will be hospitalized for at least a few days, often longer. You may see several specialists while you're in the hospital. After your condition has been stabilized, you may then be referred as an outpatient to a doctor trained in heart conditions (cardiologist) or lung conditions (pulmonologist).
What you can do
- Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down if you have had similar symptoms in the past, even if you didn't see a doctor.
- Write down key personal information, including any major stresses or recent life changes.
- Obtain copies of medical records whenever possible. Discharge summaries from the hospital, results from heart tests, as well as summary letters from any previous specialists you've seen can be helpful for your new doctor.
- Make a list of all medications as well as any vitamins or supplements that you're taking.
- Keep written track of your weight, and take that record with you so that your doctor can look for any trends.
- Make a list of the salty foods you eat regularly. Mention if you have eaten more of these recently.
- Ask a family member or friend to come along, if possible. Sometimes it can be difficult to soak up all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
- Write down questions to ask your doctor.
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:
- What's the most likely cause of the symptoms I'm currently experiencing?
- What kinds of tests do I need? Do these tests require any special preparation?
- What do my chest X-ray and electrocardiogram show?
- What treatments are available, and which do you recommend?
- What types of side effects can I expect from treatment?
- Are there any alternatives to the primary approach that you're suggesting?
- What's my prognosis?
- Are there any dietary or activity restrictions that I need to follow? Would it help to see a dietitian?
- Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?
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:
- When did you first begin experiencing symptoms?
- Have your symptoms been continuous?
- Have you eaten more salty foods lately?
- How severe are your symptoms? Have your symptoms affected your work or daily activities?
- Do you have any symptoms of obstructive sleep apnea?
- Have you been diagnosed with obstructive sleep apnea? If so, what are you doing for it?
- Does anything seem to improve your symptoms?
- What, if anything, appears to worsen your symptoms?
- Do you have any family history of lung or heart disease?
- Have you ever been diagnosed with chronic obstructive pulmonary disease (COPD) or asthma?
- Do you smoke or did you smoke in the past? If so, how many packs a day and when did you quit?
- What kind of exercise do you do?
- Do you travel to altitudes higher than 1 mile?
Because pulmonary edema requires prompt treatment, you'll initially be diagnosed on the basis of your symptoms and a physical exam, electrocardiogram and chest X-ray.
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:
- Chest X-ray. A chest X-ray will likely be the first test you have done to confirm the diagnosis of pulmonary edema and exclude other possible causes of your shortness of breath.
- Pulse oximetry. In pulse oximetry, a sensor attached to your finger or ear uses light to determine how much oxygen is in your blood.
Blood tests. You may 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 may 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 a heart condition.
Other blood tests may be done — including tests of your kidney function, thyroid function and blood count — as well as tests to exclude a heart attack as the cause of your pulmonary edema.
- Electrocardiogram (ECG). This noninvasive test can reveal a wide range of information about your heart. During an ECG, patches attached to your skin receive electrical impulses from your heart. These are recorded in the form of waves on graph paper or a monitor. The wave patterns show your heart rate and rhythm and whether areas of your heart show diminished blood flow.
Echocardiogram. An echocardiogram is a noninvasive test that 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 heart valve problems, abnormal motions of the ventricular walls, fluid around the heart (pericardial effusion) and congenital heart defects.
It can also show areas of diminished blood flow in your heart and if your heart pumps blood effectively when it beats. It can also estimate if there's increased pressure in the right side of the heart and increased pressure in the pulmonary arteries.
Transesophageal echocardiography (TEE). In a traditional cardiac ultrasound exam, the transducer remains outside your body on the chest wall. But in TEE, a doctor inserts a soft, flexible tube (catheter) with a transducer attached to the tip through your mouth and guides it into your esophagus — the passage leading to your stomach.
The esophagus lies immediately behind your heart, which allows your doctor to see a closer and more accurate picture of your heart and central pulmonary arteries.
Pulmonary artery catheterization. If other tests don't reveal the reason for your pulmonary edema, your doctor may suggest a procedure to measure the pressure in your lung capillaries (wedge pressure).
During this test, a doctor inserts a small, balloon-tipped catheter through a vein in your leg or arm and guides it into a pulmonary artery. The catheter has two openings connected to pressure transducers. The balloon is inflated and then deflated, giving pressure readings.
Cardiac catheterization. If tests such as an ECG or echocardiography don't uncover the cause of your pulmonary edema, or you also have chest pain, your doctor may suggest cardiac catheterization and coronary angiogram.
During cardiac catheterization, a doctor inserts a long, thin catheter in an artery or vein in your groin, neck or arm and threads it through your blood vessels to your heart using X-ray imaging. Doctors then inject dye into the blood vessels of your heart to make them visible under X-ray imaging (coronary angiogram).
During this procedure, doctors can perform treatments such as opening a blocked artery, which may quickly improve the pumping action of your left ventricle. Cardiac catheterization can also be used to measure the pressure in your heart chambers, assess your heart valves and look for causes of pulmonary edema.
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. Your doctor will monitor your oxygen level closely. Sometimes it may be necessary to assist your breathing with a machine such as a mechanical ventilator.
Depending on your condition and the reason for your pulmonary edema, you may also receive one or more of the following medications:
- Preload reducers. Preload reducing medications decrease the pressure caused by fluid going into your heart and lungs. Doctors commonly prescribe nitroglycerin and diuretics such as furosemide (Lasix) to treat pulmonary edema. Diuretics may make you urinate so much initially that you may temporarily need a urinary catheter while you're in the hospital. The drug nifedipine (Procardia) may sometimes be prescribed.
- Morphine (Avinza, MS Contin). This narcotic may be used to relieve shortness of breath and anxiety. But some doctors believe that the risks of morphine may outweigh the benefits and are more apt to use other more-effective drugs.
- Afterload reducers. These medications, such as nitroprusside (Nitropress), dilate your blood vessels and take a pressure load off your heart's left ventricle.
- Blood pressure medications. If you have high blood pressure when you develop pulmonary edema, you'll be given medications to control it. Alternatively, if your blood pressure is too low, you're likely to be given medications to raise it.
If your pulmonary edema is caused by another condition such as a nervous system condition, your doctor will treat the condition that is causing it and the pulmonary edema.
Treating high-altitude pulmonary edema (HAPE)
If you're climbing or traveling at high altitudes and experience mild symptoms of HAPE, descending 2,000 to 3,000 feet (about 600 to 900 meters) as quickly as you can, within reason, should relieve your symptoms. You should also reduce physical activity and keep warm, as physical activity and cold can make your condition worse.
Oxygen is usually the first treatment and can often relieve your symptoms. If supplemental oxygen isn't available, you may use portable hyperbaric chambers, which imitate a descent for several hours until you can descend to a lower elevation.
In addition to oxygen and descending to a lower elevation, the medication nifedipine (Procardia) may help reduce pressure in the pulmonary arteries and improve your condition.
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 prescription medications such as acetazolamide (Diamox Sequels) or nifedipine to help treat or prevent symptoms of HAPE. To prevent HAPE, medication is started at least one day before ascent.
Depending on your condition, your doctor may recommend lifestyle changes, including:
- Controlling your high blood pressure. If you have high blood pressure, take your medications as prescribed and check your blood pressure regularly. Record the results. Ask your doctor for guidelines regarding your optimal blood pressure.
- Controlling other medical conditions. Control any underlying medical conditions, such as controlling your glucose levels if you have diabetes.
- Avoiding the cause of your condition. If your condition is due to drugs, allergens or high altitudes, avoid these to minimize further damage to your lungs.
- Quitting smoking. If you smoke, quit smoking.
- Eating a healthy diet. Your doctor may recommend that you follow a low-salt diet. Ask for a referral to a dietitian if you need help evaluating the salt content in foods. Also eat a healthy diet of fruits, vegetables and whole grains.
- Maintaining a healthy weight and exercising. Maintain a healthy weight and exercise regularly.
Pulmonary edema is not always 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. In many cases, you can lower your blood pressure or maintain a healthy level by getting regular exercise; maintaining a healthy weight; eating a diet rich in fresh fruits, vegetables and low-fat dairy products; and limiting salt and alcohol.
Watch your blood cholesterol. Cholesterol is one of several types of fats essential to good health. But too much cholesterol can be too much of a good thing. Higher than normal cholesterol levels can cause fatty deposits to form in your arteries, impeding blood flow and increasing your risk of vascular disease.
But lifestyle changes can often keep your cholesterol levels low. Lifestyle changes may include limiting fats (especially saturated fats); eating more fiber, fish, and fresh fruits and vegetables; exercising regularly; stopping smoking; and drinking in moderation.
- Don't smoke. If you smoke and can't quit on your own, talk to your doctor about strategies or programs to help you break a smoking habit. Smoking can increase your risk of cardiovascular disease. Also avoid secondhand smoke.
- Eat a heart-healthy diet. Eat a healthy diet that's low in salt, sugars and solid fats and rich in fruits, vegetables and whole grains.
Limit salt. It's especially important to use less salt (sodium) if you have heart disease or high blood pressure. In some people with severely damaged left ventricular function, excess salt may be enough to trigger congestive heart failure.
If you're having a hard time cutting back on salt, it may help to talk to a dietitian. He or she can help point out low-sodium foods as well as offer tips for making a low-salt diet interesting and good tasting.
- Exercise regularly. Exercise is vital for a healthy heart. Regular aerobic exercise, about 30 minutes a day, helps you control blood pressure and cholesterol levels and maintain a healthy weight. If you're not used to exercise, start out slowly and build up gradually. Be sure to get your doctor's OK before starting an exercise program.
- Maintain a healthy weight. Being even slightly overweight increases your risk of cardiovascular disease. On the other hand, even losing small amounts of weight can lower your blood pressure and cholesterol and reduce your risk of diabetes.
- Manage stress. To reduce your risk of heart problems, try to reduce your stress levels. Find healthy ways to minimize or deal with stressful events in your life.
Preventing high-altitude pulmonary edema (HAPE)
If you travel or climb at high altitudes, acclimate yourself slowly. Although recommendations vary, most experts advise ascending no more than 1,000 to 1,200 feet (about 305 to 366 meters) a day once you reach 8,200 feet (about 2,500 meters). Rest an extra day every 600 to 1,200 feet (about 183 to 366 meters) when you're at a high elevation (8,200 feet, or about 2,500 meters).
Some climbers take prescription medications such as acetazolamide (Diamox Sequels) or nifedipine (Procardia) to help prevent symptoms of HAPE. To prevent HAPE, start taking the medication at least one day before ascent. Continue taking the medication for about five days after you've arrived at your high-altitude destination.
July 24, 2014
- Ferri FF. Ferri's Clinical Advisor 2014: 5 Books in 1. Philadelphia, Pa.: Mosby Elsevier; 2014. https://www.clinicalkey.com. Accessed March 13, 2014.
- Pinto DS, et al. Pathophysiology of cardiogenic pulmonary edema. http://www.uptodate.com/home. Accessed Feb. 26, 2014.
- Givertz MM. Noncardiogenic pulmonary edema. http://www.uptodate.com/home. Accessed Feb. 26, 2014.
- Gallagher SA, et al. High altitude pulmonary edema. http://www.uptodate.com/home. Accessed Feb. 26, 2014.
- Givertz MM. Neurogenic pulmonary edema. http://www.uptodate.com/home. Accessed Feb. 26, 2014.
- What is ARDS? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/ards/. Accessed Feb. 26, 2014.
- What is heart failure? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hf/. Accessed Feb. 26, 2014.
- Pennardt A. High-altitude pulmonary edema: Diagnosis, prevention, and treatment. Current Sports Medicine Reports. 2013;12:115.
- What is the heart? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hhw/. Accessed March 10, 2014.
- What is coronary heart disease? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/cad/. Accessed March 12, 2014.
- What is cardiomyopathy? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/cm/. Accessed Feb. 26, 2014.
- What is heart valve disease? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hvd/. Accessed March 10, 2014.
- What is pulmonary hypertension? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/pah/. Accessed March 11, 2014.
- Pinto DS, et al. Evaluation of acute decompensated heart failure. http://www.uptodate.com/home. Accessed March 11, 2014.
- Rubin LJ, et al. Clinical features and diagnosis of pulmonary hypertension in adults. http://www.uptodate.com/home. Accessed March 11, 2014.
- Clark AL, et al. Causes and treatment of oedema in patients with heart failure. Nature Reviews. Cardiology. 2013;10:156.
- What are lung function tests? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/lft/. Accessed Feb. 26, 2014.
- What is echocardiography? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/echo/. Accessed March 11, 2014.
- How is high blood pressure treated? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hbp/treatment.html. Accessed March 12, 2014.
- Grogan M (expert opinion). Mayo Clinic, Rochester, Minn. April 6, 2014.
- Rosenow EC (expert opinion). Mayo Clinic, Rochester, Minn. April 7, 2014.