Pulmonary edema occurs when fluid accumulates in the air sacs of the lungs - the alveoli - making it difficult to breathe. This interferes with gas exchange and can cause respiratory failure.
Pulmonary edema can be acute (sudden onset) or chronic (occurring more slowly over time). If it is acute, it is classed as a medical emergency needing immediate attention.
Treatment of pulmonary edema usually focuses on improving respiratory function and dealing with the source of the problem. It generally includes providing additional oxygen and medications to treat the underlying conditions.
Symptoms of pulmonary edema
Pulmonary edema is classed as acute or chronic.
Acute pulmonary edema causes significant breathing difficulties and can appear without warning.
This is an emergency and requires immediate medical attention. Without proper treatment and support, it can be fatal.
Along with breathing difficulties, other signs and symptoms of acute pulmonary edema can include:
- Cough - often with a pink frothy sputum
- Excessive sweating
- Anxiety and restlessness
- Feelings of suffocation
- Pale skin
- Rapid and/or irregular heart rhythm (palpitations)
- Chest pain
If the pulmonary edema is chronic, symptoms are typically less severe until the body's system can no longer compensate. Typical symptoms include:
- Difficulty breathing when lying flat (orthopnea)
- Swelling (edema) of feet or legs
- Rapid weight gain due to the accumulation of excess fluid
- Paroxysmal nocturnal dyspnea - episodes of severe sudden breathlessness at night
- Increased breathlessness with physical activity
Causes of pulmonary edema
During normal breathing, the small air sacs in the lungs, the alveoli, fill up with air. Oxygen is taken in, and carbon dioxide is expelled.
If the alveoli are flooded with liquid, two problems occur: The bloodstream cannot get enough oxygen, and the body is unable to get rid of carbon dioxide properly.
Pulmonary edema that is due to a direct problem with the heart is called cardiogenic.
Congestive heart failure is a common cause of cardiogenic pulmonary edema; in this condition, the left ventricle cannot pump out enough blood to meet the needs of the body. This causes a buildup of pressure in other parts of the circulatory system, forcing fluid into the air sacs of the lungs and other parts of the body.
Other heart problems that can lead to pulmonary edema include:
- Fluid overload: This can result from kidney failure or intravenous fluid therapy
- Hypertensive emergency: This is a severe increase in blood pressure that puts excessive strain on the heart.
- Pericardial effusion with tamponade: This is a build up of fluid around the sac that covers the heart. This can decrease the heart's ability to pump.
- Severe arrhythmias: This may be tachycardia (fast heartbeat) or bradycardia (slow heartbeat). Either one often results in poor heart function.
- Severe heart attack: This can damage the muscle of the heart, making pumping difficult.
- Abnormal heart valve: This can affect the flow of blood out of the heart.
Causes of pulmonary edema that are not due to poor heart function are called noncardiogenic; they are typically caused by ARDS (acute respiratory distress syndrome). This is a severe inflammation of the lungs that leads to pulmonary edema and significant breathing difficulties.
Common causes include:
- Sepsis (blood infection)
- Exposure to some chemicals
- Reaction to certain medications
- Drug overdose
- Brain injuries such as brain bleeding, stroke, head injury, brain surgery, tumor, or seizure
- High altitude
- Blood transfusion
Diagnosis of pulmonary edema
Sometimes, a chest X-ray can assist in the diagnosis of pulmonary edema.
The patient will undergo a physical exam first. The doctor will use a stethoscope and listen to the lungs for crackles and rapid breathing, and the heart for abnormal rhythms.
Blood tests will be carried out to determine blood oxygen levels, and a doctor will often order other blood tests that include kidney and liver function, blood counts, and blood markers of heart failure.
An ultrasound of the heart, an echocardiogram, and an electrocardiogram (EKG) can help determine heart condition and function.
A chest X-ray may be used to see whether there is any fluid in or around the lungs and to check the size of the heart. A CT scan of the chest may also be ordered.
Treatments for pulmonary edema
To raise the patient's blood oxygen levels, oxygen is given either through a face mask or prongs - tiny plastic tubes in the nose. A breathing tube may be placed into the trachea if a ventilator, or breathing machine, is necessary.
If tests show that the pulmonary edema is because of a problem in the circulatory system, the patient will be treated with intravenous medications to help remove fluid volume and control blood pressure.
Prevention of pulmonary edema
Patients with an increased risk of developing pulmonary edema must follow their doctor's advice, to keep their condition under control.
If congestive heart failure is the problem, following a healthy, well-balanced diet and maintaining a healthy body weight can help reduce the risk of future episodes of pulmonary edema. Regular exercise also improves heart health.
Salt intake should be minimized because excess salt can lead to water retention. This increases the work the heart has to do.
High cholesterol levels can lead to fatty deposits in the arteries which, in turn, can increase the risk of heart attack and stroke and therefore pulmonary edema.
Smoking tobacco increases the risk of a number of diseases, including heart disease, lung disease, and circulatory problems.
Altitude-induced pulmonary edema can be minimized by making a gradual ascent, taking medications before traveling and avoiding excess exertion while progressing to higher altitudes.