Pulmonary oedema means an excess collection of watery fluid in the lungs. The fluid collects in the many air sacs of the lung, making it difficult to breathe. Pulmonary oedema is most often caused by heart failure (then called cardiogenic pulmonary oedema). However, it may be caused by other conditions which do not directly affect the heart (non-cardiogenic pulmonary oedema).
People with sudden onset of pulmonary oedema usually need urgent admission to hospital. Treatment includes oxygen, medicines to remove the excess fluid from the lungs (diuretics) and other medicines to help the heart work more effectively. Further treatment will depend on the cause of the pulmonary oedema. Pulmonary oedema may be life-threatening, especially without urgent medical treatment.
What do the heart and blood vessels do?
The heart's main function is to pump blood around the body. Blood carries both nutrients and waste products and is vital to life. One of the essential nutrients found in blood is oxygen.
The right side of the heart receives deoxygenated blood (lacking oxygen) from the body. After passing through the right atrium and right ventricle this blood is pumped to the lungs. Here blood picks up oxygen and loses another gas called carbon dioxide. Once through the lungs, the blood flows back to the left atrium. It then passes into the left ventricle and gets pumped into the main artery supplying the body (the aorta). Oxygenated blood is then carried though blood vessels to all the body's tissues. Here oxygen and other nutrients pass into the cells where they are used to perform the body's essential functions. See also the separate leaflets called The Heart and Blood Vessels and The Lungs and Respiratory Tract.
How common is pulmonary oedema?
Pulmonary oedema is a common condition in elderly people but very uncommon in young people. About 1 in 15 people aged 75-84 and just over 1 in 7 people aged 85 years and above have heart failure.
What causes pulmonary oedema?
Pulmonary oedema can occur because of the following reasons:
- An increase in pressure in the blood vessels in the lungs. This often occurs with heart failure.
- Damage to the very small blood vessels (capillaries) in the lungs, allowing more fluid to pass into the lungs. This occurs with lung injury - eg, smoke inhalation or pneumonia.
- Failure of the vessels (lymphatics) to clear fluid from the lungs.
Pulmonary oedema is often caused by heart failure. When the heart is not able to pump blood to the body efficiently, the amount of blood staying in the veins that take blood through the lungs to the left side of the heart increases. As the pressure in these blood vessels increases, fluid is pushed into the air spaces (alveoli) in the lungs. This fluid reduces normal oxygen movement through the lungs, which can lead to shortness of breath. See also the separate leaflet called The Heart and Blood Vessels.
Heart failure that leads to pulmonary oedema may be due to a number of different causes. These may include:
- A heart attack.
- Any disease of the heart that weakens or stiffens the heart muscle (hypertrophic cardiomyopathy or dilated cardiomyopathy).
- Leaking or narrowed heart valves (mitral or aortic valves).
- An abnormal rhythm.
- Sudden, severe high blood pressure (hypertension).
Pulmonary oedema may also be caused by conditions other than heart conditions, including:
- High-altitude exposure.
- Acute (adult) respiratory distress syndrome (ARDS).
- Acute kidney injury or chronic kidney disease.
- Lung damage caused by poisonous gas or severe infection.
- Following a major injury.
What are the symptoms of pulmonary oedema?
Symptoms of pulmonary oedema may include coughing up blood or bloody froth, difficulty breathing when lying down and being unable to speak in full sentences because of shortness of breath. You may need to sleep with your head propped up with extra pillows. Other symptoms may include anxiety or restlessness, a reduced level of consciousness and excessive sweating.
How is pulmonary oedema diagnosed?
An examination by a doctor will include:
- Checking the rate and rhythm of your heartbeat (pulse).
- Checking your blood pressure.
- Listening with a stethoscope for abnormal noises in the lungs, indicating that abnormal fluid is present.
- Listening for heart murmurs, indicating a problem with the heart valves.
- Blood tests, which are carried out to look for:
- Kidney function
- Levels of salts in the blood.
- Whether pulmonary oedema has been caused by a heart attack.
- A substance called natriuretic peptide, which tends to be raised in people with heart failure.
- Monitoring blood oxygen levels, using pulse oximetry, which uses a sensor placed over a thin area of skin such as a fingertip.
- Chest X-ray to look for signs of heart failure or any other problem in the lungs, such as pneumonia.
- An ultrasound scan of the heart (an echocardiogram) to see if there are problems with the heart muscle (such as weakness, thickness, failure to relax properly, leaky or narrow heart valves, or fluid surrounding the heart).
- A 'heart tracing' (electrocardiogram, or ECG) to look for signs of a heart attack or problems with the heart rhythm.
How is pulmonary oedema treated?
People with sudden onset of pulmonary oedema usually need urgent admission to hospital. They require treatment with oxygen, medicines to remove the excess fluid from the lungs (diuretics) and other medicines to help the heart work more effectively.
Further treatment will depend on the cause of the pulmonary oedema. See also the separate leaflet called Heart Failure.
Urgent treatment is also needed for the cause of the pulmonary oedema, such as treatment for a heart attack, high-altitude sickness or acute kidney injury.
If oxygen and medicines do not successfully treat the pulmonary oedema, it may be necessary to use a ventilator or other methods to help with breathing until the pulmonary oedema is improving.
Are there any complications?
If pulmonary oedema continues, it can cause increased pressure in the right side of the heart and eventually cause the right ventricle to fail. Failure of the right ventricle can cause fluid swelling of the legs (oedema), fluid swelling of the tummy (abdomen), called ascites, and congestion and swelling of the liver.
What is the outlook (prognosis)?
The outlook depends on the cause of the pulmonary oedema. Pulmonary oedema may get better, either quickly or slowly. However, it can also be life-threatening, especially without urgent medical treatment.
Further reading and references
Chronic heart failure: Management of chronic heart failure in adults in primary and secondary care; NICE Clinical Guideline (August 2010)
Acute and Chronic Heart Failure; European Society of Cardiology (2012)
Murray JF; Pulmonary edema: pathophysiology and diagnosis. Int J Tuberc Lung Dis. 2011 Feb15(2):155-60, i.
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