What is pulmonary edema?

Pulmonary edema occurs when fluid accumulates in the air sacs of the lungs, making it difficult to breathe. This interferes with gas exchange and can cause respiratory failure.

Pulmonary edema can be acute (occurring suddenly) or chronic (occurring more slowly over time). Acute pulmonary edema is a medical emergency and requires immediate medical attention.

One of the most common causes of pulmonary edema is congestive heart failure, in which the heart cannot keep up with the demands of the body.

Treatment of pulmonary edema usually focuses on improving respiratory function and addressing the source of the problem. It generally includes providing additional oxygen and medications to treat the underlying conditions.

Fast facts on pulmonary edema

• Pulmonary edema is a condition involving fluid buildup in the lungs.
• Sudden-onset (acute) pulmonary edema is a medical emergency.
• Symptoms include shortness of breath, cough, decreased exercise tolerance, and chest pain.

Causes

Pulmonary edema can be acute or chronic. Image credit: Adisorn Chiamchitr/Alamy Stock Photo

During normal breathing, the small air sacs in the lungs, known as alveoli, fill up with air. The lungs take in oxygen and expel carbon dioxide. Pulmonary edema occurs when fluid floods the alveoli.

This flooding causes two problems:

1. The bloodstream cannot get enough oxygen.
2. The body cannot expel carbon dioxide properly.

Common causes of pulmonary edema include:

• pneumonia
• sepsis (blood infection)
• exposure to certain chemicals
• organ failure that causes fluid accumulation, such as congestive heart failure, kidney failure, or liver cirrhosis
• near-drowning
• inflammation
• trauma
• reaction to certain medications
• overdose of certain drugs, including opioids

Pulmonary edema also occurs as part of a condition called acute respiratory distress syndrome (ARDS), a severe inflammation of the lungs that leads to significant breathing difficulties. Direct injury to the lungs or inflammation in other parts of the body can cause this condition.

Other possible causes include:

• brain injuries such as brain bleeding, stroke, head injury, brain surgery, tumor, or seizure
• high altitude
• blood transfusion

Cardiogenic pulmonary edema

Pulmonary edema that results from a direct problem with the heart is called cardiogenic pulmonary edema.

Congestive heart failure is a common cause of cardiogenic pulmonary edema. In this condition, the left ventricle is unable to pump out enough blood to meet the body’s needs.

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.

The following heart-related problems can also lead to pulmonary edema:

• Fluid overload: This can result from kidney failure or intravenous fluid therapy.
• Hypertensive emergency: This is a severe increase in blood pressure that places excessive strain on the heart.
• Pericardial effusion with tamponade: This is a buildup of fluid around the sac that covers the heart, which can decrease the heart’s ability to pump.
• Severe arrhythmia: This can be tachycardia (fast heartbeat) or bradycardia (slow heartbeat), both of which can result 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 and are often the result of ARDS.

Symptoms

Acute pulmonary edema causes significant breathing difficulties and can appear without warning. It is an emergency and requires immediate medical attention. Without proper treatment and support, it can be fatal.

In addition to breathing difficulties, the following symptoms can indicate acute pulmonary edema:

• cough, often with a pink, frothy sputum
• excessive sweating
• anxiety and restlessness
• feelings of suffocation
• pale skin
• wheezing
• rapid or irregular heart rhythm (palpitations)
• chest pain

If the pulmonary edema is chronic, symptoms are usually less severe until the body’s system can no longer compensate. Symptoms may 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, or episodes of severe sudden breathlessness at night
• fatigue
• increased breathlessness with physical activity

Diagnosis

Sometimes a chest X-ray can assist in the diagnosis of pulmonary edema. Image credit: Photographee.eu/Adobe Stock

A person will undergo a physical exam first. A doctor will use a stethoscope to listen to the lungs for crackles and rapid breathing and to the heart for abnormal rhythms.

The doctor will order blood tests to determine blood oxygen levels. They will often order additional blood tests to check the following:

• electrolyte levels
• kidney function
• liver function
• blood counts and blood markers of heart failure

An echocardiogram or an electrocardiogram (EKG) can help determine the condition of the heart.

The doctor may order a chest X-ray or a lung ultrasound to see whether there is any fluid in or around the lungs and to check the size of the heart. They may also order a CT scan.

Pulmonary edema or pleural effusion

Pulmonary edema happens when fluid collects inside the lungs, in the alveoli, making it hard to breathe. Pleural effusion also involves fluid in the lung area and is sometimes called “water on the lungs.”

However, in pleural effusion, fluid collects in the layers of the pleura that are outside the lungs.

Often, pleural effusion results from inflammation or a blockage due to a condition such as pneumonia, tuberculosis, or cancer. This is known as an exudative pleural effusion.

A transudative pleural effusion is another type that can also be due to excess fluid buildup in the body. This can result from heart failure, cirrhosis, or kidney failure.

Pulmonary edema or pneumonia

Pulmonary edema can overlap with pneumonia, but it is a different condition. Pneumonia is an infection that often occurs as a complication of a respiratory infection such as the flu.

Though it can be difficult to distinguish between the two, a doctor will try to make a correct diagnosis and determine the best course of treatment based on a person’s detailed medical history, physical exam, and test results.

Treatment

To raise a person’s blood oxygen levels, a healthcare professional will administer oxygen through either a face mask or nasal cannulas, which are tiny plastic tubes that a healthcare professional places in a person’s nose to provide oxygen.

Healthcare professionals may place a breathing tube in the trachea if a ventilator — a machine that helps a person breathe — is necessary.

If tests show that the pulmonary edema is the result of a problem in the circulatory system, healthcare professionals will administer intravenous medications to help reduce fluid volume and regulate blood pressure.

Diuretics are the most commonly used medication and can help reduce fluid buildup by increasing the production of urine.

Depending on the specific cause and a person’s symptoms, a healthcare professional may use any of the following other medications to treat pulmonary edema:

• Vasodilators: These medications dilate the blood vessels to decrease pulmonary congestion.
• Calcium channel blockers: These help reduce high blood pressure.
• Inotropes: This type of medication can increase the force of heart muscle contractions so that the heart can pump blood throughout the body.
• Morphine: This medication can help reduce anxiety and shortness of breath. However, because of its potential risks, healthcare professionals do not often recommend it.

Prevention

People with an increased risk of developing pulmonary edema should follow a doctor’s advice to manage the condition.

If a person has congestive heart failure, following a healthy, balanced diet and maintaining a moderate body weight can help ease symptoms and reduce the risk of future episodes of pulmonary edema.

Regular exercise also improves heart health, as do other lifestyle habits, including:

• Reducing salt intake: Excess salt can lead to water retention, which requires the heart to work harder.
• Lowering cholesterol levels: High cholesterol can lead to fatty deposits in the arteries, which can increase the risk of heart attack and stroke in addition to pulmonary edema.
• Smoking cessation: Tobacco increases the risk of a number of health conditions, including heart disease, lung disease, and circulatory problems.

It is possible to minimize altitude-induced pulmonary edema by making a gradual ascent, taking medications before traveling, and avoiding excess exertion while progressing to higher altitudes.

Takeaway

Pulmonary edema can be a result of several conditions, including congestive heart failure, pneumonia, and sepsis.

In addition to causing symptoms such as cough, wheezing, chest pain, and excessive sweating, pulmonary edema can result in severe breathing difficulties and may be fatal without proper treatment.

For this reason, if a person experiences any symptoms of pulmonary edema, it’s important to consult a doctor to determine the cause and the best course of treatment.