What are the indications for heliox (helium‑oxygen) therapy?

Heliox Therapy Indications

The primary indication for heliox therapy is mechanical upper airway obstruction or postoperative stridor, where it can be used as a therapeutic trial to reduce work of breathing while avoiding intubation. 1

Evidence-Based Indications

Recommended Use: Upper Airway Obstruction

Heliox (typically 80:20 or 70:30 helium-oxygen mixture) is most effective when density-dependent turbulent flow increases airway resistance, particularly in:

• Mechanical upper airway obstruction (Grade D recommendation) 1
• Postoperative stridor (Grade D recommendation) 1

The reduced gas density of heliox decreases resistance to airflow in narrowed airways, thereby reducing work of breathing. While formal clinical trials are lacking due to the rarity and emergency nature of these presentations, case reports demonstrate benefit without side effects beyond temporary voice alteration 1.

NOT Recommended: Lower Airway Disease

Heliox should NOT be routinely used for asthma or COPD exacerbations 1. The evidence is clear:

• Asthma: Insufficient evidence to support use in acute exacerbations, either as inhaled gas or nebulizer driving gas (Grade D) 1
• COPD: Does not reduce intubation rates, length of mechanical ventilation, or mortality (Level 1+ evidence) 2
• Only consider in clinical trials or specialist hands for severe exacerbations failing standard treatment 1

The 2017 BTS guidelines explicitly state there is little evidence that heliox has any benefit over air-oxygen mixtures in asthma or COPD, and it is more expensive 1.

Clinical Decision Algorithm

When to Consider Heliox:

1. Patient presents with upper airway obstruction (e.g., tumor, angioedema, post-surgical edema)

   • Initiate heliox trial immediately
   • Monitor for rapid improvement in work of breathing
   • Effect should be evident quickly

2. Postoperative stridor develops

   • Trial heliox before considering reintubation
   • Assess response within minutes to hours

3. Severe asthma/COPD NOT responding to standard therapy

   • Only in specialist/ICU setting
   • Only when standard bronchodilators, corticosteroids, and NIV have failed
   • Consider as bridge therapy, not definitive treatment

When NOT to Use Heliox:

• Routine asthma exacerbations
• Routine COPD exacerbations
• When oxygen requirements exceed 40% (heliox loses benefit at higher oxygen concentrations) 2
• Lower airway disease without specialist consultation

Important Caveats

Technical Considerations:

• Heliox affects calibration of flow meters and spirometry equipment 1
• Requires specialized delivery systems and monitoring
• Must directly monitor actual tidal volume and FiO2 when used with mechanical ventilation 3
• Connect heliox to air inlet of ventilator for consistent delivery 3

Practical Limitations:

• More expensive than standard oxygen-air mixtures 1
• Requires continuous monitoring to avoid technical complications 4
• Beneficial effects should become evident rapidly; if no improvement within short period, discontinue 4

Pediatric Note: While 73% of heliox use in one critical care study was pediatric 1, the same principles apply—most effective for upper airway obstruction, not routinely indicated for bronchiolitis or lower airway disease without specialist involvement.

The evidence consistently shows heliox has a narrow but important role: use it for upper airway obstruction where its physical properties directly address the pathophysiology, but avoid routine use in lower airway disease where evidence of benefit is lacking and standard therapies are superior.