Exploring the appropriate dose of nebulized hypertonic saline for bronchiolitis: a dose-response meta-analysis

Nebulized hypertonic saline (HS) has gathered increasing attention in bronchiolitis. This study aims to evaluate the relationship between the dose of nebulized HS and the effects on bronchiolitis. Five electronic databases-PubMed, EMBASE, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and ISRCTN-were searched until May 2021. Randomized controlled trials (RCTs) that investigated the effect of HS on bronchiolitis were included. A total of 35 RCTs met the eligibility criteria. HS nebulization may shorten the length of stay (LOS) in hospital (mean difference -0.47, 95% CI -0.71 to -0.23) and improve the 24-hour, 48-hour, and 72-hour Clinical Severe Score (CSS) in children with bronchiolitis. The results showed that there was no significant difference between 3% HS and the higher doses (>3%) of HS in LOS and 24-hour CSS. Although the dose-response meta-analysis found that there may be a linear relationship between different doses and effects, the slope of the linear model changed with different included studies. Besides, HS nebulization could reduce the rate of hospitalization of children with bronchiolitis (risk ratio 0.88, 95% CI 0.78 to 0.98), while the trial sequential analysis indicated the evidence may be insufficient and potentially false positive. This study showed that nebulized HS is an effective and safe therapy for bronchiolitis. More studies are necessary to be conducted to evaluate the effects of different doses of HS on bronchiolitis.