What is the cause of an exudative effusion (pleural effusion)?

From the Guidelines

Thoracentesis is the recommended first-line procedure for managing an educative effusion, as it provides both diagnostic and therapeutic relief. When managing an educative effusion, it is essential to follow a systematic approach to investigation, as outlined in the British Thoracic Society guideline for pleural disease 1. The initial step involves a careful history and physical examination of the patient, which can often elucidate the likely cause of the effusion.

Key Considerations

• A diagnostic algorithm for the investigation of a pleural effusion should be followed, as shown in the BTS guidelines 1.
• Thoracic ultrasound (TUS) should be performed on every patient at their initial presentation and again whenever a pleural procedure is being performed, as it provides valuable information on the size and character of the effusion 1.
• If it is not safe to proceed with a pleural aspiration, a CT scan should be obtained as the next step, including the chest, abdomen, and pelvis if malignancy is suspected 1.

Diagnostic and Therapeutic Approach

• For diagnostic purposes, collect at least 50-60 mL of fluid and send samples for cell count, protein, LDH, glucose, pH, cytology, and microbiological studies.
• If the effusion is large and causing respiratory distress, remove up to 1-1.5 liters of fluid during the same procedure for symptomatic relief.
• Following thoracentesis, patients should be monitored for pneumothorax and re-expansion pulmonary edema.
• The underlying cause of the effusion must be treated with appropriate therapy, such as diuretics for heart failure, antibiotics for parapneumonic effusions, or chemotherapy for malignant effusions.

Recent Guidelines and Recommendations

• The British Thoracic Society guideline for pleural disease 1 and the ACR Appropriateness Criteria for workup of pleural effusion or pleural disease 1 provide valuable guidance on the management of pleural effusions.
• These guidelines emphasize the importance of prompt diagnosis and treatment to aid in patient management and improve outcomes.

From the Research

Definition and Causes of Pleural Effusion

• Pleural effusion is defined as an abnormal amount of pleural fluid accumulation in the pleural space, resulting from an imbalance between excessive pleural fluid formation and pleural fluid absorption 2.
• The most common causes of pleural effusions are congestive heart failure, cancer, pneumonia, and pulmonary embolism 3, 4.
• Other causes of pleural effusions include acute idiopathic pericarditis, postcardiac injury syndrome, and malignancy 5.

Diagnosis of Pleural Effusion

• Pleural fluid puncture (pleural tap) enables the differentiation of a transudate from an exudate, which remains the foundation of the further diagnostic work-up 3.
• Point-of-care ultrasound is recommended for evaluating the pleural space, detecting small effusions, and guiding thoracentesis 4.
• Chest radiography is helpful in determining laterality and detecting moderate to large pleural effusions 4.
• Computed tomography of the chest can exclude other causes of dyspnea and suggest complicated parapneumonic or malignant effusion 4.

Treatment of Pleural Effusion

• The treatment of pleural effusion depends on the underlying cause, and may include pleurodesis, thoracoscopy, video-assisted thoracoscopy, and the placement of a permanently indwelling pleural catheter 3.
• The combination of nonsteroidal anti-inflammatory drugs and colchicine, along with therapeutic thoracenteses for moderate-to-large effusions, is the mainstay treatment approach for pleural effusions in acute idiopathic pericarditis and postcardiac injury syndrome 5.
• Antibiotic regimens for parapneumonic effusions should be based on current pneumonia guidelines, and anaerobic coverage should be included in the case of empyema 6.