Pulmonary oedema is an excess of watery fluid in the lungs.
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 is pulmonary oedema?
Symptoms of pulmonary oedema may include:
- Coughing up blood or bloody froth (haemoptysis).
- 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. You may have a blue tinge colour of your lips or fingers.
Pulmonary oedema is most often caused by heart failure (in which case it is called cardiogenic pulmonary oedema). However, it may be caused by other conditions which do not directly affect the heart (non-cardiogenic 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, where the heart is pumping blood less efficiently.
- 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.
Cardiogenic heart failure: 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 the leaflets called Anatomy of the heart and The respiratory system. These explain the function of the heart and lungs and the interaction between them which normally keeps fluid levels stable.
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).
Non-cardiogenic pulmonary oedema: 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.
- Pulmonary embolism.
- Following a major injury.
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.
- Checking how fast you are breathing.
- 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 (if body oxygen levels are low), medicines to remove the excess fluid from the lungs (diuretics) and other medicines to help the heart work more effectively. These medicines are usually given through the veins (intravenously, or IV).
Further treatment will depend on the cause of the pulmonary oedema. See also the separate leaflet called Congestive 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.
The outlook (prognosis) 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
Diagnosing and managing acute heart failure in adults; NICE Clinical Guidelines (Oct 2014 - updated Nov 2021)
2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure; European Society of Cardiology (ESC)
Purvey M, Allen G; Managing acute pulmonary oedema. Aust Prescr. 2017 Apr40(2):59-63. doi: 10.18773/austprescr.2017.012. Epub 2017 Apr 3.
Chronic heart failure in adults - diagnosis and management; NICE Guidance (Sept 2018)