Target Drainage for Pleural Effusions
Large pleural effusions should be drained in a controlled fashion avoiding evacuation of more than 1-1.5 L at one time or slowed to about 500 mL/hour to reduce the risk of re-expansion pulmonary edema. 1
Drainage Principles
- The drainage volume should be guided by patient symptoms (cough, chest discomfort) and should generally be limited to 1-1.5 L at a single time 1
- Aspiration should be discontinued if the patient develops chest discomfort, persistent cough, or vasovagal symptoms 1
- After initial drainage, the rate should be slowed to approximately 500 mL/hour if continued drainage is needed 1
- The primary goal is to achieve radiographic confirmation of fluid evacuation and lung re-expansion rather than targeting a specific daily drainage volume 1
Rationale for Controlled Drainage
- Re-expansion pulmonary edema (RPO) is a rare but potentially life-threatening complication following rapid expansion of a collapsed lung through evacuation of large amounts of pleural fluid 1
- Pathophysiological mechanisms of RPO include reperfusion injury of the underlying hypoxic lung, increased capillary permeability, and local production of neutrophil chemotactic factors 1
- While rare (clinical RPO occurs in approximately 0.5% of cases), the consequences can be severe, including respiratory failure 2
Drainage Techniques
- Small bore tubes (10-14F) should be considered initially for drainage of malignant effusions due to reduced patient discomfort and comparable success rates to large bore tubes 1
- Imaging guidance (ultrasound or CT) should be used for chest tube insertion 3
- The trocar technique should be avoided in favor of blunt dissection or the Seldinger technique 3
Special Considerations
- For therapeutic pleural aspiration in patients with very short life expectancy, the same volume limitations apply (1-1.5 L per session) 1
- Once effusion drainage and lung re-expansion have been radiographically confirmed, pleurodesis (if planned) should not be delayed while waiting for cessation of pleural fluid drainage 1
- Suction is usually unnecessary for pleural drainage but if applied, a high volume, low pressure system is recommended with gradual increment in pressure to about -20 cm H₂O 1
Monitoring During Drainage
- Chest radiograph should be obtained after drainage to confirm lung re-expansion and position of the intercostal tube 1
- Patients should be monitored for symptoms of RPO including dyspnea, cough, chest discomfort, and oxygen desaturation 4
- Drainage should be stopped immediately if these symptoms develop 1
Recent Evidence
- Some recent research suggests that larger volumes can be safely drained as long as chest discomfort or end-expiratory pleural pressure less than -20 cm H₂O does not develop 2
- However, the established clinical practice guidelines still recommend the 1-1.5 L limit as a prudent approach to minimize risk 1