摘要Objective:To observe the small airways function changes of asthmatic patients in different clinical phases and to discuss its clinical significance.Methods:A total of 127 patients diagnosed as asthma were selected randomly and pulmonary function (PF) of them was determined by conventional method. Then they were divided into A, B and C group based on PF results. All 34 patients in A group suffered from acute asthma attack for the first time. All 93 patients in B group had been diagnosed as asthma but in remission phase. C Group was regarded as Control group with 20 healthy volunteers. Then FEV1, FEF50%, FEF75% levels of patients in each group were analyzed, and FEV1, FEF75% and FEF50% levels of patients in each group were compared after bronchial dilation test.Results:It was found that most patients in group A and B had abnormal small airways function, and their small airways function was significantly different compared with that of group C (P<0.01). In addition, except for group C, FEF75%, FEF50% levels in A and B group were improved more significantly than FEV1 levels (P<0.01).Conclusions:Asthma patients in acute phase all have abnormal small airways function. Most asthma patients in remission phase also have abnormal small airways function. After bronchial dilation test, whether patients in acute phase or in remission phase, major and small airways function of them are improved, but improvement of small airways function is weaker than that of major airways. This indicates that asthma respiratory tract symptoms in different phases exists all the time and so therapeutic process is needed to perform step by step.