Iurnal Variability of Airway Hyperresponsiveness in Asthma Patients

Abstract

BackgroundThere are daytime variability in pulmonary function indexes such as peak expiratory flow (PEF) and forced expiratory volume in 1 second (FEV1) in asthma patients. Studies evaluating the effects of drug therapy on lung function and airway hyperresponsiveness (AHR) in asthma patients all required patients to perform spirometry and bronchial challenge test in the same time point of the days. However, whether there is a daily diurnal AHR variability is still not clear.ObjectiveTo explore the characteristics and diurnal variability of AHR in asthma patients.MethodsThe data of 202 patients with asthma who consulted in respiratory department of the First Affiliated Hospital of Guangzhou Medical University from January 2018 to September 2020 were included for statistical analysis. All patients completed the methacholine bronchial provocation tests, they were divided into the morning detection group (morning group) with 81 cases and the afternoon detection group (afternoon group) with 121 cases; according to the disease course, 98 cases were divided into the initial diagnosis group if the disease course was ≤6 months, and 104 cases were divided into the follow-up group if the disease course was >6 months. The initial diagnosis group and the follow-up group were divided into the initial diagnosis morning group, the initial diagnosis afternoon group, the follow-up morning group, and the follow-up afternoon group according to the detection time; according to the AHR, the patients were divided into very mild, mild, moderate and severe groups. The characteristics of AHR and the main pulmonary function indexes including FVC%pred, FEV1%pred, PEF%pred, MMEF%pred, MEF50%pred, MEF25%pred, PD20-FEV1, PD20-PEF, PD20-MMEF, PD20-MEF25%, PD20-MEF50% of these groups were analyzed and compared.ResultsThere were no significant differences of the math pulmonary function indexes and PD20 between morning and afternoon groups (P<0.05) . FEV1%pred and PD20-PEF were significantly higher in initial diagnosed group than follow-up group (P<0.05) . There was no significant difference in FVC%pred, PEF%pred, MMEF%pred, MEF50%pred, MEF25%pred, PD20-FEV1, PD20-MMEF, PD20-MEF25%, and PD20-MEF50% between the initial visit group and the follow-up visit group (P>0.05) . In follow-up group, MMEF%pred and MEF50%pred were higher in afternoon than in morning (P<0.05) . There were no differences of lung function and AHR between morning and afternoon in initial diagnosed group (P<0.05) . No obvious correlations were found between disease history and PD20. There were no significant differences of PD20-FEV1 between the morning and afternoon, initial diagnosed and follow-up (P>0.05) .ConclusionThe longer the duration of asthma, more serious impairment of lung function found in asthma, while the AHR had no significant difference between morning and afternoon.

Keywords

• |asthma|respiratory function tests|lung function|airway hyperresponsiveness|bronchial provocation test