Pulmonary Edema

Pulmonary edema is caused by the presence of excess fluid in the lungs, which accumulates and leads to breathing difficulties. Depending on the area where it occurs, it may be of two types:

• Pulmonary edema: fluid is stored in the alveoli, the small air sacs where gas exchange takes place in the lungs. This accumulation makes breathing difficult and may cause a dangerous decrease in blood oxygen levels.
• Pleural effusion: fluids become trapped in the space between the different layers of the pleura surrounding the lung (pleural space).

This condition may present in two different forms:

• Acute pulmonary edema: has a sudden onset and requires immediate medical attention due to the severity of symptoms.
• Chronic pulmonary edema: develops gradually, and symptoms—usually milder—occur intermittently. Although medical treatment is essential for control, as there is no definitive cure, it is not considered a medical emergency.

The prognosis of pulmonary edema varies depending on the underlying cause and the form in which it presents. Nevertheless, it is a serious condition that, if not treated promptly, may be life-threatening.

Symptoms

Symptoms vary depending on the type of pulmonary edema:

• Acute pulmonary edema:
  • Dyspnea: difficulty breathing.
  • Shortness of breath that worsens with physical activity or when lying down (orthopnea).
  • Gasping for breath.
  • Cough with frothy sputum.
  • Occasionally, hemoptysis.
  • Palpitations: rapid and irregular heartbeats.
  • Cold, clammy skin.
  • Sweating.
  • Wheezing: whistling sound in the chest.
  • Anxiety.
  • Agitation.

• Chronic pulmonary edema:
  • Difficulty breathing when lying down that improves when sitting up.
  • Nocturnal cough.
  • Greater-than-usual difficulty breathing during physical activity.
  • Swelling of the lower extremities.
  • Wheezing.
  • Rapid weight gain.

Causes

Pulmonary edema may occur due to various causes, which are classified into two main groups:

• Cardiogenic pulmonary edema: the most common type, occurring when the heart is unable to pump blood effectively, leading to increased pressure in the pulmonary vessels and promoting fluid leakage into the alveoli.
  • Heart failure: increases pressure in pulmonary blood vessels, causing watery fluid to leak into the alveoli.
  • Conditions that may lead to heart failure:
    • Myocardial infarction.
    • Cardiac valve dysfunction.
    • Arrhythmias: abnormalities in heart rate, which may be excessively fast (tachycardia) or abnormally slow (bradycardia).

• Non-cardiogenic pulmonary edema: results from a condition unrelated to the heart and is caused by increased permeability of the pulmonary capillaries.
  • Inflammatory lung conditions, such as pneumonia or acute respiratory distress syndrome. In these cases, a denser fluid containing proteins accumulates (inflammatory exudate).
  • Infectious diseases, whether bacterial or viral.
  • Staying at or exercising at high altitude (high-altitude pulmonary edema – HAPE).
  • Chest trauma.
  • Renal failure.
  • Certain medications.

Risk Factors

The risk of pulmonary edema increases in the following situations:

• Hypertension.
• Sleep apnea.
• Congenital heart disease.
• Coronary artery disease.
• Heart valve disease.
• Chronic obstructive pulmonary disease (COPD).
• Infections.
• Inflammatory processes.
• Diabetes.
• Thrombosis.
• Smoke inhalation.
• Alcohol intoxication.
• Illicit drug use.
• Obesity.
• Pregnancy.

Complications

The most common complications of pulmonary edema include:

• Pulmonary hypertension: increased pressure in the pulmonary arteries.
• Hypoxemia: low blood oxygen levels.
• Respiratory failure: impaired gas exchange in the lungs, making it difficult to eliminate carbon dioxide and deliver oxygen to the body.
• Chronic lung damage: airflow is impaired due to inflammation of the airways, as seen in emphysema, chronic bronchitis, or COPD.
• Death: in untreated cases of acute pulmonary edema, accumulated fluid may lead to cardiorespiratory failure.

Prevention

Although pulmonary edema cannot always be prevented, maintaining a healthy lifestyle reduces the risk. Recommendations include:

• Monitoring blood pressure and blood cholesterol levels.
• Not smoking.
• Limiting alcohol consumption.
• Reducing salt intake.
• Following a balanced diet rich in fruits and vegetables.
• Exercising regularly.

Which physician treats pulmonary edema?

Pulmonary edema is usually managed urgently in Emergency Department and subsequently by specialists in Pulmonology and Cardiology, depending on the cause. In severe cases, Intensive care medicine and other healthcare professionals are also involved.