Will high flow oxygen (FiO2) therapy by mask help resolve capnothorax?

High Oxygen Therapy for Capnothorax Resolution

High-flow oxygen therapy by mask will accelerate the resolution of capnothorax by increasing the rate of carbon dioxide absorption from the pleural space. 1

Mechanism of Action

Capnothorax (carbon dioxide pneumothorax) resolution can be enhanced through high-flow oxygen therapy due to the following mechanisms:

• Oxygen therapy creates a concentration gradient that accelerates gas absorption from the pleural space
• The "nitrogen washout" effect occurs when breathing high concentrations of oxygen, which reduces nitrogen in the blood, creating a greater pressure gradient for gas absorption 2
• Carbon dioxide is approximately 20 times more soluble in blood than nitrogen, making it naturally absorb faster than air pneumothorax 3

Evidence-Based Approach

Oxygen Therapy for Pneumothorax Resolution

The British Thoracic Society guidelines specifically recommend high-flow oxygen therapy to increase pneumothorax reabsorption rates:

• High-flow oxygen therapy increases pneumothorax reabsorption rate four-fold compared to room air 4, 1
• For patients with pneumothorax under observation without drainage, a reservoir mask at 15 L/min is recommended to achieve the highest possible oxygen concentration 4
• The target oxygen saturation should be 94-98% for most patients (or 88-92% if at risk of hypercapnic respiratory failure) 4

Research Supporting Oxygen Therapy

Multiple studies demonstrate the effectiveness of oxygen therapy for pneumothorax resolution:

• Oxygen therapy accelerates pneumothorax resolution by more than three times compared to room air (4.2% vs 1.25% per day) 5
• A dose-dependent relationship exists between oxygen concentration and resolution time:
  • Room air (21%): 61.65 ± 12.30 hours
  • 30% FiO2: 42.90 ± 5.97 hours
  • 40% FiO2: 35.80 ± 4.26 hours
  • 50% FiO2: 33.80 ± 4.66 hours 6
• Even with ongoing pleural air leak, supplemental oxygen improves resolution rates 7

Practical Application for Capnothorax

For capnothorax specifically:

• Use a reservoir mask at 15 L/min to deliver the highest concentration of oxygen 4
• Carbon dioxide's higher solubility compared to nitrogen means capnothorax may resolve faster than regular pneumothorax 3
• In cases where capnothorax was intentionally created (e.g., during procedures), the CO2 may resolve spontaneously without intervention due to its high solubility 3

Monitoring and Precautions

While administering high-flow oxygen:

• Monitor for signs of clinical deterioration including increasing dyspnea, tachycardia, hypotension, and cyanosis 1
• Use caution in patients with COPD or other risk factors for hypercapnic respiratory failure; aim for oxygen saturation of 88-92% in these patients 4
• Consider high-flow humidified nasal cannula as an alternative to reservoir mask for patient comfort if extended therapy is needed 4

Conclusion

High-flow oxygen therapy by mask is an effective non-invasive treatment for capnothorax that accelerates resolution by creating favorable gas exchange gradients. The British Thoracic Society recommends using a reservoir mask at 15 L/min to achieve the highest possible oxygen concentration, which can increase absorption rates up to four times faster than breathing room air.