Is there any clinical benefit to using heliox (helium-oxygen mixture) in patients?

Clinical Benefits of Heliox (Helium-Oxygen Mixture)

There is insufficient evidence to support the routine use of heliox in most clinical scenarios, with limited benefit demonstrated only in specific conditions such as mechanical upper airway obstruction or postoperative stridor. 1, 2

Evidence Summary and Recommendations

General Clinical Utility

• The British Thoracic Society (BTS) guidelines clearly state that there is little overall evidence suggesting heliox has any benefit over standard air-oxygen mixtures in most respiratory conditions 1, 2
• Heliox is more expensive than standard oxygen-air mixtures, limiting its cost-effectiveness 1, 2

Specific Clinical Scenarios

Asthma

• Despite theoretical benefits of reduced airflow resistance, clinical trials have not demonstrated significant improvements in mortality or need for mechanical ventilation 2
• Meta-analyses have concluded that heliox does not significantly improve outcomes in acute asthma 3, 4
• A 2014 meta-analysis did show some benefit when heliox was used as a driving gas for β2-agonist nebulization, with improvements in peak expiratory flow and decreased hospitalizations, particularly in severe and very severe asthma 5

COPD

• Heliox use in COPD has been less studied than in asthma 1
• A Cochrane review found insufficient evidence to support heliox use in acute exacerbations of COPD 6
• When combined with non-invasive ventilation, heliox has not been shown to reduce rates of intubation, duration of ventilatory support, or mortality in AECOPD 2

Upper Airway Obstruction

• The strongest evidence for heliox benefit exists for mechanical upper airway obstruction or postoperative stridor 1, 2
• Case reports suggest benefit in these scenarios, though formal clinical trials are lacking due to the emergent nature of these presentations 1

Clinical Application Algorithm

1. First-line consideration (strongest evidence):

   • Mechanical upper airway obstruction
   • Postoperative stridor

2. Consider only in exceptional circumstances:

   • Severe exacerbations of asthma or COPD not responding to standard treatment
   • Only under specialist supervision
   • Preferably as part of clinical trials

3. Not recommended for routine use in:

   • Mild to moderate asthma exacerbations
   • Routine COPD exacerbations
   • As a driving gas for nebulizer therapy outside of specialized settings

Important Caveats and Limitations

• At oxygen concentrations >40%, heliox loses its theoretical advantages due to increased gas density 2
• Technical challenges exist in administering heliox, including equipment calibration issues 1
• Cost considerations significantly limit routine use 1, 2, 7
• Most studies showing any benefit have small sample sizes and methodological limitations 3, 4

Conclusion

While heliox has theoretical benefits in reducing airway resistance and work of breathing due to its lower density, these physiological advantages have not translated into meaningful clinical outcomes in most respiratory conditions. The BTS guidelines recommend restricting its use to specific scenarios like upper airway obstruction or as a last resort in severe respiratory exacerbations under specialist supervision.