Bronchiolitis is the leading cause of hospitalisation among infants in high-income countries. Common symptoms include a runny nose, cough and dyspnoea (difficulty breathing) often with bronchospasm (sudden narrowing of the airways) and resultant wheezing. Approximately 20% of all infants experience wheezing associated with respiratory syncytial virus in the first year of life, and 2% to 3% require hospitalisation for this illness. In this review, we selected trials that objectively assessed the effect of the addition of heliox to standard medical care for acute bronchiolitis. Heliox is a mixture of oxygen and the gas helium.
We retrieved four trials involving children under two years of age with respiratory distress secondary to bronchiolitis, which was sufficiently life-threatening to lead to hospitalisation in a paediatric intensive care unit. Pooled results from two trials (where the following data were available) failed to demonstrate a reduction in the need for mechanical ventilation, the rate of intubation (placement of a tube in the airway) or in the length of stay in a paediatric intensive care unit. However, three trials, involving 69 infants, used a clinical respiratory score system, with increased severity receiving a higher score. The pooled results show that infants treated with heliox inhalation had a statistically significant reduction in this respiratory score in the first hour. The only trial which assessed changes after 24 hours of heliox treatment failed to demonstrate any significant reduction in any of our outcome measures.
The trials included in this review had several potential biases and also used four different methods for delivering heliox. Also, importantly, only two trials assessed the reduction in the need for intubation for infants with acute bronchiolitis (58 infants, all hospitalised in a paediatric intensive care unit).
Further studies which all use the same method of heliox application are needed. Such studies would provide necessary information about the appropriate place of heliox in the management of severe bronchiolitis.