Non-Invasive Ventilation for Undrained Pleural Effusion
Current Evidence on NIV for Pleural Fluid Absorption
Based on the available evidence, there are no specific articles that indicate the use of NIV for undrained pleural effusion as a way to accelerate pleural fluid absorption or promote lung expansion. In fact, undrained pleural effusion is listed as a contraindication to NIV in established clinical guidelines 1.
Contraindications to NIV
The British Thoracic Society (BTS) guidelines explicitly list undrained pleural effusion among the contraindications to non-invasive ventilation 1. This is included in the same category as:
- Facial trauma/burns
- Fixed obstruction of the upper airway
- Inability to protect airway
- Life threatening hypoxaemia
- Haemodynamic instability
- Severe co-morbidity
- Impaired consciousness
- Confusion/agitation
- Vomiting
- Bowel obstruction
- Copious respiratory secretions
- Focal consolidation on chest radiograph
- Undrained pneumothorax
Pneumothorax Comparison
While the guidelines note that "NIV has been used in patients with an undrained pneumothorax without apparently causing the pneumothorax to increase in size," they still recommend that "in most patients with a pneumothorax an intercostal drain should be inserted before commencing NIV" 1. This suggests a similar approach would be warranted for pleural effusions.
Clinical Implications
The absence of evidence supporting NIV for pleural fluid absorption has important clinical implications:
- Drainage First Approach: The standard of care appears to be drainage of significant pleural effusions before considering NIV
- Risk of Complications: Applying positive pressure ventilation to a patient with undrained pleural effusion may potentially:
- Worsen respiratory mechanics
- Increase work of breathing
- Lead to ventilation-perfusion mismatch
- Delay appropriate drainage procedures
Special Considerations
In certain circumstances, NIV might still be used despite contraindications:
- When NIV is considered the "ceiling" of treatment (i.e., when a patient is not a candidate for invasive ventilation) 1
- When contingency plans for drainage and possible intubation have been made
Monitoring Requirements
If NIV is used in a patient with pleural effusion, the BTS guidelines recommend:
- Clinical assessment
- Pulse oximetry
- Arterial blood gas tensions
- Location-appropriate monitoring (ICU/HDU settings would have more intensive monitoring) 1
Conclusion
The current evidence does not support the use of NIV specifically to accelerate pleural fluid absorption or promote lung expansion in patients with undrained pleural effusion. In fact, undrained pleural effusion is listed as a contraindication to NIV in established guidelines. The standard approach would be to drain significant pleural effusions before initiating NIV therapy.