Pleural Effusions for PA
Pleural Effusions for the Physician Assistant Licensing Exam
Pleural effusion is the accumulation of excess fluid in the pleural space, often resulting from systemic or local diseases. It is critical for nurse practitioners to differentiate between types of effusions and manage them appropriately.
Types of Pleural Effusions
Transudative vs. Exudative Effusions
The classification of pleural effusions into transudative or exudative helps in determining the underlying cause.
- Transudative Effusion: Caused by systemic factors that alter hydrostatic or oncotic pressures, typically due to heart failure or liver disease.
- Common causes:
- Heart failure: The most common cause, due to increased capillary hydrostatic pressure.
- Cirrhosis: Reduced oncotic pressure from hypoalbuminemia.
- Exudative Effusion: Results from local factors that increase capillary permeability or obstruct lymphatic drainage.
- Common causes:
- Pneumonia (parapneumonic effusion): Inflammatory process due to infection.
- Malignancy: Tumor obstructs pleural lymphatic drainage.
- Tuberculosis: Chronic infection causing lymphocyte-predominant effusion.
Light’s Criteria
Exudative effusions meet one of these criteria:
- Pleural fluid protein/serum protein ratio > 0.5.
- Pleural fluid LDH/serum LDH ratio > 0.6.
- Pleural fluid LDH > two-thirds of the upper limit of normal for serum LDH.
Clinical Features
- Symptoms:
- Dyspnea: The most common symptom, especially in large effusions.
- Pleuritic chest pain: Sharp pain that worsens with inspiration, more common in exudative effusions.
- Cough: Non-productive, commonly seen in both transudative and exudative effusions.
- Physical Exam:
- Dullness to percussion and decreased breath sounds over the affected area.
- Decreased tactile fremitus in the region of fluid accumulation.
Diagnosis and Treatment
Imaging
- Chest X-ray (CXR): Initial imaging shows blunting of the costophrenic angles.
- Ultrasound: More sensitive for detecting small effusions and guiding thoracentesis.
Thoracentesis
Thoracentesis is used for both diagnosis and symptomatic relief. Pleural fluid analysis determines if the effusion is transudative or exudative, guiding further management.
Management
- Heart failure: Diuretics are the first-line treatment.
- Parapneumonic effusion: Requires antibiotics, with chest tube drainage if complicated.
- Malignant effusions: Recurrent thoracentesis or pleurodesis.
Key Points
- Pleural effusions are categorized as transudative or exudative, with Light's criteria guiding classification.
- Transudative effusions are caused by systemic conditions like heart failure, while exudative effusions result from local processes such as infections or malignancy.
- Symptoms include dyspnea and pleuritic chest pain, with physical exam findings like dullness to percussion and decreased breath sounds.
- Imaging and thoracentesis are key for diagnosis, with treatment focused on managing the underlying cause.