What Is Pulmonary Edema?

Pulmonary edema is a serious medical condition in which the air sacs of the lung, called the alveoli, fill with fluid, making it difficult to breathe. Symptoms include shortness of breath, wheezing, coughing, and a frothy discharge. Pulmonary edema is often associated with heart disease, but fluid can collect in the lungs for other reasons.

This article describes the causes and symptoms of pulmonary edema, including how this serious lung complication is diagnosed and treated.

Symptoms of Pulmonary Edema

Pulmonary edema leads to difficulty breathing and other serious symptoms. These symptoms occur when the alveoli situated at the very end of the branches of the airways fill with fluid.

Under normal circumstances, alveoli are where the lungs and blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

As you inhale, oxygen moves into the alveoli and is transferred to the blood, where it is carried to tissues via the circulatory system. As you exhale, carbon dioxide (a waste product of metabolism) transferred to the alveoli is expelled from the body.

With pulmonary edema, this process is interrupted, and you can neither get enough oxygen to the blood nor remove enough oxygen from the blood.

This can lead to potentially serious symptoms like:

• Shortness of breath (dyspnea)
• Wheezing
• Rapid, shallow breath (tachypnea)
• Coughing up a pink, frothy sputum (hemoptysis)
• Difficulty breathing when lying down (orthopnea)
• Crackling sounds in the lungs (rales)
• Waking up from sleep with a drowning feeling (paroxysmal nocturnal dyspnea)
• Heart palpitations or murmurs
• Excessive sweating
• Pale skin (pallor)
• Anxiety or restlessness
• Leg swelling (peripheral edema)

Pulmonary edema can be chronic (meaning persistent or recurrent), particularly with chronic conditions like heart failure.

Causes of Pulmonary Edema

Pulmonary edema may be caused by heart issues or other conditions. Healthcare providers divide pulmonary edema into one of two types: cardiac pulmonary edema and non-cardiac pulmonary edema.

Cardiac Pulmonary Edema

Heart disease is the most common cause of pulmonary edema. Cardiac pulmonary edema, also known as cardiogenic pulmonary edema, occurs when a heart condition increases pressure within the heart that is then transferred to the capillaries of the lungs. This increased pressure causes fluids to leak from the capillaries into the airways, where they can accumulate in the alveoli.

Almost any kind of heart disease can lead to pulmonary edema. The most common cardiogenic causes include:

• Coronary artery disease (CAD)
• Congestive heart failure
• Heart valve disease (including mitral stenosis, mitral regurgitation, aortic stenosis, or aortic regurgitation)
• Severe hypertension (high blood pressure)

With chronic cardiac pulmonary edema, elevated pressure within the capillaries of the lungs can cause changes that led to pulmonary hypertension. High blood pressure in the lungs, in turn, can contribute to the development of heart failure.

Non-Cardiac Pulmonary Edema

With non-cardiac pulmonary edema, also known as non-cardiogenic pulmonary edema, the capillaries in the lungs become damaged for reasons unrelated to the heart.

The most common cause is acute respiratory distress syndrome (ARDS), a condition that causes rapid, widespread inflammation in the lungs. The inflammation damages the walls of the alveoli, allowing fluids to seep in. ARDS is typically seen in critically ill patients.

In addition to ARDS, non-cardiogenic causes of pulmonary edema include:

• Pulmonary embolism
• High-altitude sickness (known as high-altitude pulmonary edema)
• Blood clots in the lungs (pulmonary embolism)
• Drug reactions or drug overdose
• Inhaled toxins (such as heavy smoke, chlorine, or ammonia)
• Near-drowning
• Nervous system conditions (such as brain trauma or multiple sclerosis)

Diagnosis

Rapidly making the correct diagnosis of pulmonary edema is critical, especially if the symptoms are sudden and severe.

Diagnosing pulmonary edema is usually accomplished by performing a physical examination (and listening for lung sounds), measuring blood oxygen levels, and doing a chest X-ray.

Once pulmonary edema is diagnosed, your healthcare provider will aim to identify the underlying cause based on your medical history, family history, and initial findings.

If cardiogenic pulmonary edema is suspected, an electrocardiogram (ECG) and echocardiogram can help identify the underlying heart condition.

Non-cardiogenic pulmonary edema is suspected when pulmonary edema occurs in the absence of elevated heart pressure.

Treatment of Pulmonary Edema

The immediate goals of treatment for pulmonary edema are to reduce the fluid buildup in the lungs and restore blood oxygen levels to normal. Oxygen therapy is almost always needed.

If signs of heart failure are present, diuretics ("water pills") are given to drain excess fluids from the body. Medications that dilate (widen) blood vessels, such as nitrates, can help reduce pressure within the heart.

If blood oxygen levels are critically low, mechanical ventilation may be required. Mechanical ventilation can increase pressure within the alveoli and drive some of the accumulated fluids back into the capillaries.

The ultimate treatment of pulmonary edema—whether cardiogenic or non-cardiogenic—is the identification and treatment of the underlying cause.

Summary

Pulmonary edema is a serious medical condition caused by excess fluid in the alveoli of the lungs. It is most often due to cardiac disease but can also be produced by a range of non-cardiac medical problems. It is treated by rapidly addressing the underlying cause. Treatment may include diuretics or mechanical ventilation to reduce fluid in the lungs.