Abstract: Objective  To observe the effect of magnesium sulfate atomization inhalation as adjuvant therapy on airway resistance, pulmonary function and inflammatory factors in children with severe bronchiolitis. 
Methods  A total of 88 patients with severe bronchiolitis who were treated in the hospital were selected. They were divided into two groups by random number table method: the research group (treated with magnesium sulfate atomization inhalation as an auxiliary therapy to conventional treatment, n=44) and control group (treated with conventional treatment, n=44). Both groups were treated for 7 consecutive days. Before and after treatment, the inflammatory indicators ［tumor necrosis factor-α (TNF-α), soluble vascular cell adhesion molecule-1 (sVCAM-1), Nod-like receptor pyrin domain-3 (NLRP3), eosinophil cationic protein (ECP) levels］, airway resistance indicators ［proximal airway viscous resistance (R20), total airway resistance (Z5), total airway viscous resistance (R5), pulmonary neurogenic substance P level］, and pulmonary function indicators ［effective airway resistance (Reff), forced expiratory volume in 1 second (FEV1), maximum mid-expiratory flow (MMF) and fractional exhaled nitric oxide (FeNO) levels］ in the two groups were detected. The disappearance time of fever, wet rales, wheezing, and cough was recorded in the two groups of children. 
Results  The levels of TNF-α, sVCAM-1, ECP and NLRP3 in the research group were lower than those in the control group (P＜0.05), and the levels of Z5, R20, R5 and pulmonary neurogenic substance P in the research group were lower than those in the control group (P＜0.05). The levels of MMF and FeNO in the research group were higher than those in the control group (P＜0.05), while the levels of Reff and FeNO in the research group were lower than those in the control group (P＜0.05). The disappearance time of fever, wet rales, wheezing, and cough in the research group was shorter than that in the control group (P＜0.005). 
Conclusion  Magnesium sulfate atomization inhalation as adjuvant therapy for children with severe bronchiolitis can inhibit the inflammatory response, improve the airway resistance and the pulmonary function, and relieve the clinical symptoms of the children. 

Key words: bronchiolitis, magnesium sulfate, airway resistance