Intrapleural Fibrinolysis Increases Pleural Fluid Drainage
Yes, pleural fluid volume increases substantially after intrapleural fibrinolytic therapy—this is the intended therapeutic effect and indicates successful treatment. The fibrinolytic agents lyse fibrinous septations and clear lymphatic pores, which allows previously trapped, loculated fluid to drain freely through the chest tube 1.
Mechanism and Expected Response
The increase in pleural fluid drainage after fibrinolytic administration represents successful breakdown of fibrinous strands that were preventing effective fluid clearance 2. Studies consistently demonstrate:
- Increased daily drainage volumes in 93-100% of treated patients 2
- Substantial increase in pleural fluid output occurs in both loculated and non-loculated effusions after urokinase administration 1
- Greater radiological improvement with 85% showing >40% reduction in pleural opacity versus 35% with placebo 2
This enhanced drainage is the primary mechanism by which fibrinolytics improve outcomes, allowing the pleural space to clear infected or malignant fluid that was previously trapped by septations 1, 2.
Clinical Context by Effusion Type
Complicated Parapneumonic Effusions and Empyema
Fibrinolytic therapy results in significantly increased fluid drainage, which translates to:
- Shorter hospital stays (mean 6.2 days versus 8.7 days with drainage alone) 2, 3
- Reduced need for surgical intervention (OR 0.37,95% CI 0.21-0.68) 4
- Greater radiological lung expansion compared to drainage alone 2, 3
The British Thoracic Society recommends administering streptokinase 250,000 IU twice daily or urokinase 100,000 IU once daily for 3 days, with reassessment at 5-8 days 3.
Malignant Pleural Effusions
In multiloculated malignant effusions, fibrinolytics increase fluid drainage volume and improve radiological appearance in 83-93% of patients 1, 2. However, this increased drainage does not improve clinical outcomes such as dyspnea or pleurodesis success rates in malignant effusions 2, 5. The British Thoracic Society recommends fibrinolytics specifically for relief of distressing dyspnea due to multiloculated malignant effusion resistant to simple drainage 1.
Monitoring the Response
Evaluate treatment effectiveness at 5-8 days after initiating therapy 3. Key indicators of successful fibrinolysis include:
- Resolution of fever and sepsis 3
- Increased daily drainage output (expect >250 mL/day initially) 1
- Radiographic improvement with reduction in pleural opacity 2, 4
Critical Pitfalls to Avoid
- Do not misinterpret increased drainage as treatment failure—this is the expected therapeutic response indicating successful lysis of septations 1, 2
- Ensure chest tube patency before attributing poor drainage to loculations—flush with 20-50 mL normal saline if blockage is suspected 3
- Do not delay surgical consultation beyond 5-8 days if drainage remains inadequate despite fibrinolytic therapy 3, 6
- Limit initial thoracentesis to 1-1.5 L to avoid re-expansion pulmonary edema, but after fibrinolysis, expect and allow higher drainage volumes through the chest tube 1, 5
Safety Considerations
The increased fluid drainage after fibrinolysis is generally safe, with:
- Low bleeding complication rates (2-8.5% of patients) 2
- No clear evidence of increased adverse effects compared to placebo (OR 1.28,95% CI 0.36-4.57), though this cannot be definitively excluded 4
- Fever is common, particularly with streptokinase due to its bacterial origin 2, 3
Patients receiving streptokinase must be given a streptokinase exposure card and should receive urokinase or tissue plasminogen activator for any future systemic indications due to antibody formation 3.