Pleural Effusion: Pathophysiology, Diagnosis, and Nursing Care

Pleural effusion is the abnormal accumulation of fluid in the pleural space and is a complication of many underlying diseases rather than a disease itself. This note reviews the pathophysiology, classification, diagnostic workup (including Light's criteria), thoracentesis procedure and nursing care, and key management priorities for the NCLEX.

What Is Pleural Effusion?

• Pleural effusion is an abnormal accumulation of fluid in the pleural space between the visceral and parietal pleura.
• The pleural space normally contains only a small amount of lubricating fluid.
• Fluid accumulates when production exceeds absorption.
• It is a complication of an underlying disease, not a primary disease.

Types of Pleural Effusion

Pathophysiology

• Fluid enters the pleural space from capillaries in the parietal pleura.
• Fluid is normally absorbed by lymphatic vessels in the parietal pleura.
• Effusion occurs when fluid production exceeds lymphatic absorption.
• Transudative effusions result from increased hydrostatic pressure or decreased oncotic pressure.
• Exudative effusions result from increased capillary permeability due to infection or inflammation.

Clinical Presentation

Symptoms

• Dyspnea is the most common symptom and worsens with exertion.
• Pleuritic chest pain is sharp and worsens with deep breathing or coughing.
• Non-productive cough may be present.

Signs on Examination

• Decreased or absent breath sounds over the effusion area.
• Dullness to percussion over the fluid collection.
• Decreased tactile fremitus.
• Egophony (E-to-A change) above the fluid level.
• Tracheal deviation away from the effusion in large effusions.

Diagnostic Tests

Light's Criteria for Exudative Effusion

Fluid is exudative if one or more of the following are met:

• Pleural fluid protein / serum protein >0.5
• Pleural fluid LDH / serum LDH >0.6
• Pleural fluid LDH >2/3 of the upper normal serum LDH

Common Causes

• Heart failure is the most common cause of transudative effusion.
• Cirrhosis and nephrotic syndrome also cause transudative effusions.
• Pneumonia causes parapneumonic effusion, which can progress to empyema.
• Malignancy (lung cancer, breast cancer, lymphoma) causes exudative effusions.
• Pulmonary embolism, tuberculosis, and pancreatitis also cause exudative effusions.

Thoracentesis

Indications

• Diagnostic — to determine the cause of effusion.
• Therapeutic — to relieve dyspnea from a large effusion.

Procedure

• Patient sits upright, leaning forward with arms supported.
• Ultrasound is used to locate fluid and mark the insertion site.
• Needle is inserted above the rib to avoid intercostal vessels.
• Up to 1 to 1.5 liters of fluid is removed at one time.

Nursing Care

Before procedure:

• Obtain informed consent.
• Position patient sitting upright.
• Explain the procedure and expected sensations.

During procedure:

• Remain with patient to provide support.
• Monitor vital signs.
• Instruct patient to avoid coughing or deep breathing during needle insertion.

After procedure:

• Position patient on the unaffected side for one hour.
• Monitor for complications: pneumothorax, bleeding, infection.
• Send specimens to the lab with appropriate tubes.

Complications of Thoracentesis

• Pneumothorax — occurs if the needle punctures the lung (most common complication).
• Re-expansion pulmonary edema — can occur if fluid is removed too rapidly.
• Bleeding or hemothorax if intercostal vessels are injured.
• Infection or empyema.
• Vasovagal response.

Management

Treatment of Underlying Cause

• Heart failure — diuretics and fluid restriction.
• Cirrhosis — sodium restriction and diuretics.
• Pneumonia — antibiotics.
• Malignancy — chemotherapy or radiation.

Therapeutic Thoracentesis

• Removes fluid to relieve dyspnea.
• May need to be repeated if fluid reaccumulates.

Pleurodesis

• Chemical or mechanical procedure that obliterates the pleural space.
• Used for recurrent malignant effusions.
• Talc or doxycycline is instilled to cause adhesion.

Chest Tube for Empyema

• Large-bore chest tube is placed for drainage.
• Intrapleural fibrinolytics may be used.
• Surgical decortication for chronic empyema.

Nursing Care

Assessment

• Monitor respiratory rate, depth, and effort.
• Auscultate lung sounds for decreased or absent breath sounds.
• Assess oxygen saturation and titrate oxygen as needed.
• Monitor for signs of respiratory distress.
• Assess for chest pain and dyspnea.

Interventions

• Position patient in high-Fowler's to facilitate breathing.
• Administer oxygen as ordered.
• Assist with thoracentesis and monitor for complications.
• Administer medications for the underlying condition.
• Monitor for signs of re-expansion pulmonary edema after thoracentesis.

Patient Teaching

• Explain the purpose and procedure of thoracentesis.
• Report increased shortness of breath or chest pain immediately.
• Keep follow-up appointments for repeat imaging.
• Take medications as prescribed for the underlying condition.
• Report signs of infection: fever, redness, or drainage at the site.

Common NCLEX Traps

• Transudate = heart failure; exudate = infection or malignancy.
• Light's criteria differentiate transudate from exudate.
• Chest X-ray shows blunted costophrenic angle; CT provides detailed anatomy.
• Thoracentesis needle is inserted above the rib to avoid intercostal vessels.
• Remove no more than 1 to 1.5 liters at one time to prevent re-expansion pulmonary edema.
• Position patient sitting upright for thoracentesis.
• Position patient on the unaffected side after thoracentesis.
• Pneumothorax is the most common complication of thoracentesis.
• Empyema requires chest tube drainage, not just thoracentesis.

Key takeaways

• Pleural effusion is classified as transudative (heart failure, cirrhosis, nephrotic syndrome) or exudative (infection, malignancy, inflammation).
• Hallmark findings: dyspnea, pleuritic chest pain, decreased breath sounds, dullness to percussion, and decreased tactile fremitus.
• Diagnosis starts with chest X-ray (blunted costophrenic angle); Light's criteria confirm whether fluid is exudative.
• During thoracentesis, position the patient upright leaning forward, insert the needle above the rib, and remove no more than 1–1.5 L at a time to prevent re-expansion pulmonary edema.
• After thoracentesis, position on the unaffected side and monitor for pneumothorax, the most common complication.
• Empyema requires chest tube drainage; recurrent malignant effusions may need pleurodesis.