Helium-oxygen in bronchiolitis-A systematic review and meta-analysis.

Introduction: Bronchiolitis is common reason for infant hospitalization. The aim of our systematic review and meta-analysis was to evaluate helium-oxygen (heliox) in bronchiolitis.

Methods: We screened 463 studies, assessed 22 of them, and included six randomized controlled trials. Primary outcomes were the need for continuous positive airway pressure (CPAP) or intubation, hospitalization duration, and change in the modified Woods Clinical Asthma Scale (M-WCAS). We calculated mean differences with 95% confidence intervals (CIs) for continuous outcomes and risk ratios (RRs) for dichotomous outcomes.

Results: Six studies (five double- and one single-blinded) with 560 infants were included. The risk of bias was high in one, moderate in four, and low in one. The RR for the need for CPAP (three studies) was 0.87 (CI: 0.56-1.35), and for intubation (four studies) was 1.39 (CI: 0.53-3.63), heliox compared to air-oxygen. The hospital stay (four studies) was 0.25 days longer (CI: -0.22 to 0.71) in the heliox group. The mean decrease in M-WCAS from the baseline (three studies) was 1.90 points (CI: 1.46-2.34) greater in the heliox group.

Conclusion: We found low-quality evidence that heliox does not reduce the need for CPAP, intubation, or length of hospitalization for bronchiolitis. Based on the M-WCAS scores, heliox seems to relieve respiratory distress symptoms rapidly after its initiation. The included studies had high heterogeneity in their methods and included relatively mild cases of bronchiolitis. A larger randomized controlled trial with more severe cases of bronchiolitis with enough power to analyze the need for intubation is needed in the future.