[Investigation of small airway function of occupational asthma at different stages]

Objective: To analyze the characteristics of small airway dysfunction in patients with occupational asthma, and explore the significance of small airway function indicators in the evaluation of occupational asthma. Methods: A total of 53 patients with occupational asthma diagnosed in our hospital from December 2008 to December 2018 were retrospectively collected in May 2020. 55 healthy people were included as the control group (NC group) and 58 bronchial asthma patients as BA group. The general information and baseline pulmonary function (FVC、FEV(1)、PEF) of the subjects were collected, the pulmonary function were reexamined and small airway function (FEF(25%)pred、FEF(50%)pred、FEF(75%)pred、MMEF(25-75%)pred) were tested at the time of diagnosis and remission. Results: There was no significant difference in pulmonary function and asthma control score (ACT) between OA group and BA group (P=0.356, 0.610, 0.364, 0.430, 0.533, 0.759, 0.426, 0.632) . The incidence of small airway dysfunction in OA group was 77.4%. The indexes of small airway function (FEF(25%)pred, FEF(50%)pred, FEF(75%)pred, MMEF(25-75%)pred) were lower than those in the NC group (P<0.001) . The small airway function indexes of mild and moderate OA patients in remission stage were improved (P=0.029, 0.182) , but the abnormal rate of small airway function was still 62.3%, and there was no significant difference compared with those at the time of diagnosis (P=0.091) . Small airway function (MMEF(25-75%)pred, FEF(50%)pred) was correlated with large airway function (FEV(1)% pred, PEF% pred) (P=0.001) . Conclusion: Small airway dysfunction often occurs and persists in patients with occupational asthma, and has a certain correlation with large airway function indexes.