Pleural Effusion

Pleural effusion is the abnormal accumulation of fluid between the two layers of the pleura, which is the space between the lungs and the chest. This thin membrane covers the lungs (visceral pleura) and the inside of the chest cavity (parietal pleura).

In healthy lungs, around 10-20 cm³ of pleural fluid is produced from plasma ultrafiltrate, which acts as a natural lubricant and facilitates the movement of the lungs when we breathe. This pleural fluid is produced through a balance between the fluid entering and exiting the body. When more fluid enters than necessary or is not properly expelled, pleural effusion can occur.

Depending on its characteristics, lung effusions are classified into two types:

• Exudative pleural effusion: Typically affects one side (unilateral). Its main characteristic is that the fluid is usually cloudy and high in protein. Its causes can be associated with processes such as infections, trauma, or neoplastic diseases.
• Transudative pleural effusion: In most cases, it is bilateral. The fluid usually appears serous, though sometimes watery, and contains a small amount of protein. It is often caused by systemic diseases such as heart failure, liver disorders, etc.

Benign pleural effusions, while they can be serious, are typically reversible with proper identification and treatment of the underlying cause, and they usually do not affect life expectancy. However, patients with malignant effusions typically have a survival rate ranging from three to twelve months.

Symptoms

The most common symptoms of pleural effusion include:

• Sharp chest pain, usually localized, which worsens when coughing or deeply inhaling. Pleural pain decreases as fluid accumulates, which can give a false impression of recovery.
• Dry cough.
• Hiccups.
• Difficulty breathing or rapid breathing.
• Fever.

Causes

There are several reasons why a pleural effusion can occur. Depending on the type, the most common causes include:

• Transudative pleural effusion: The main cause is typically heart failure, cirrhosis, nephrotic syndrome (kidney disease), or superior vena cava syndrome.
• Exudative pleural effusion: Associated with inflammatory or traumatic processes. Conditions related to this type include parapneumonic infections such as pneumonia or pancreatitis. Other causes include rheumatoid arthritis, lupus, pulmonary embolism, or neoplastic diseases (cancer).

Risk Factors

The risk of developing pleural effusion increases when one of the aforementioned diseases is diagnosed, in addition to excessive alcohol consumption, smoking, or prolonged asbestos exposure.

Complications

Pleural effusion alters the balance between the volume of the chest cavity and the organs within it, thus affecting the function of the respiratory system, heart, and diaphragm, which can have serious consequences:

• Lung damage or collapse (atelectasis): Excessive fluid accumulation causes compression of the lung and air loss in the alveoli, potentially leading to hypoxemia (low blood oxygen levels) or respiratory failure.
• Pulmonary empyema: Accumulation of pus.
• Pneumothorax: Air accumulation in the chest cavity.
• Pleural thickening.
• Cardiac tamponade: In rare cases, the increased intrapleural pressure caused by the effusion can raise the pressure in the pericardial space, interfering with the filling of the heart chambers, especially the right atrium and ventricle. This prevents the heart from pumping sufficient blood to the body and can be a life-threatening emergency.
• Diaphragmatic inversion: Extensive pleural effusion can alter the anatomy and function of the diaphragm, even causing it to invert. This condition induces abnormal movement of the affected diaphragmatic dome: upon inhalation, it rises instead of descending, which reduces alveolar ventilation and causes air to exit the lung instead of entering, significantly impacting respiratory function.

Prevention

To prevent pleural effusion, early diagnosis of the underlying pathology is crucial, though this is not always easy. Once pleural effusion has occurred and the patient has recovered, medications can be administered to prevent further fluid accumulation in the lungs.

What doctor treats pleural effusion?

Thoracic surgeons and pulmonologists can diagnose and treat pleural effusion. The initial evaluation is usually performed by a pulmonologist or emergency doctor, and definitive treatment after the evaluation is typically carried out by a thoracic surgery specialist.