Objective To investigate the changes of small airway function and diffusing capacity in patients with mild asthma before and after bronchial provocation test (BPT).Methods BPT was performed in suspected asthma patients with chief complaints of paroxysmal wheeze,chest tightness and cough，but with normal chest X-ray and baseline pulmonary function.BPT positive group was regarded as asthma group，while BPT negative group as control group.Lung volume，ventilatory function and diffusing capacity were measured before and after BPT and compared between the asthma and control groups.Results （A）No statistical differences were found in FEV1%，FEV1/FVC，FVC%，VC%，TLC%，FRC%，RV%，RV/TLC between the asthma and control groups before BPT.FEV1/FVC and FVC% were significantly decreased (all Plt;0.01)，while FRC% (Plt;0.05)，RV% (Plt;0.01) and RV/TLC (Plt;0.01) increased significantly in the asthma group after BPT compared with the control group.The decline rate of FEV1/FVC and FVC% and the increase rate of TLC%，RV%，RV/TLC were significantly higher in the asthma group than those in the control group (all Plt;0.01).（B）Compared with the control group，FEF25%-75% (Plt;0.05)，Vmax75% (Plt;0.01) and Vmax50% (Plt;0.05) were significantly lowered before BPT，while the above parameters and Vmax25% were significantly decreased after BPT in the asthma group (all Plt;0.01).The decline rate of FEF25%-75%，Vmax75%，Vmax50% and Vmax25% was significantly higher in the asthma group than those in the control group (all Plt;0.01).（C）There was no statistical difference in DLCO in both groups before and after BPT.Conclusions Patients with mild asthma had small airways impairment before BCT which further declined after BPT.However,no impairment of diffusion capacity was found before or after BPT.
小气道病变曾经是全球呼吸界研究的热点，许多肺功能测定方法和指标被用于小气道功能的诊断，其后热度骤减，最近又引起一些学者的重视。
Objective To investigate the relationship of small airway function with airway sensitivity and reactivity and assess the factors influencingairway hyperresponsiveness (AHR).Methods Data of consecutive subjects with suspected asthma who had a≥20% reduction in FEV1 after ≤12.8 mmol/L cumulative doses of methacholine were analyzed from January 2005 to April 2006.Airway sensitivity was assessed by the cumulative dose of methacholine required to cause 20% reduction in FEV1 (PD20).Airway reactivity was analyzed using the slope of the dose-response curve (DRS).The DRS was defined as the reduction in FEV1 from baseline after the final dose of methacholine inhaled divided by the cumulative dose inhaled.Because of their highly skewed distribution，DRS was logarithmically transformed (log10) for all analysis.Results A total of 184 consecutive subjects aged 16 to 80 years was enrolled.There were 70 male (38.0%) and 114 female (62.0%) subjects.Subjects with higher airway sensitivity，indicated by lower PD20，also had a lower Vmax50% and Vmax25%，and vise versa.PD20 was negatively correlated wit log10DRS (r=-0.874，Plt;0.01).In a simple linear regression model，log10DNS was significantly correlated with FEV1%，Vmax50% or Vmax25% respectively (the determinant r2 were 0.062，0.097 and 0.085，respectively，all Plt;0.01).In a multiple linear regression model that included age，height，and percentage of predicted FEV1，Vmax50% and Vmax25% accounted for 3.9% and 2.6%，respectively，of variability in airway reactivity.The association between Vmax50% and log10DNS was significant in both male and female subjects.The r2 was higher in male subjects.The subjects were divided into three age groups and the association between Vmax50% or Vmax25% and log10DNS was higher in female than in male for age≤25 years，higher in male than in female for 25 -45 years.No association was found for agegt;45 years in both males and females.Conclusions Impaired small airway function is associated with higher airway sensitivity and reactivity to methacholine in subjects with suspected asthma.
Objective To investigate the changes of small airway function，airway resistance and responsiveness of extrathoracic airway in chronic cough patients before and after bronchial provocation test (BPT)．Methods 68 chronic cough patients were requested to conduct lung function test and BPT．The airw ay resistance were measured via forced oscillationary technology before and after BPT．Results BPT revealed airway hyperresponsiveness in 52％subjects．MEF50 and R0 before BPT were significantly different between the patients with or without airway hyperresponsiveness．Post BPT changes in MEF50(MEF50％) were correlated positively to the changes in FEV1(FEVl％)，and negatively to the changes in R0[Ro-d]． Extrathoracic airway hyperresponsivenes(EAHR)was f0und in13 patients，in which 6 patients were not revealed by routine BPT．Conclusion There is small airway function abnormalities in chronic cough patients．Extrathoracic airway responsiveness test is a valuable supplementary index to routine BPT．
Objective To evaluate the relationship between small airway disease and the progression of chronic obstructive pulmonary disease (COPD), and explore the application value of high resolution computed tomography (HRCT) and impulse oscillometry system (IOS) in assessing small airways in COPD patients. Methods A total of 132 stable COPD patients and 43 healthy controls volunteered to take the IOS and pulmonary function test. The correlations between resonance frequency (Fres), small airway resistance (R5-R20) and spirometry were analyzed. The patients were also examined by HRCT to measure the thickness of the third generation of apical bronchus of the right upper lobe (WT), the adjacent pulmonary artery diameter (BWT) and the degree of emphysema (LAA%). The ratio of WT to BWT (WT/BWT) was calculated to estimate bronchial wall thickening. Relationships between WT/BWT, emphysema and spirometry, IOS were also studied. Results There were negative correlations between Fres and FEV1%pred, FEF25%-75%%pred, FEF50%%pred (r=-0.694, -0.561, -0.619, all P<0.01). R5-R20 was negatively associated with FEV1%pred, FEF25%-75%%pred and FEF50%%pred as well (r=-0.622, -0.537, -0.560, P<0.01). The analysis of receiver operating characteristic curve showed larger areas under the Fres and R5-R20 curves, and the cutoff points to diagnose COPD were 13.93 Hz and 0.055 kPa·L-1·s-1, respectively. LAA% and WT/BWT increased with airflow limitation (F=4.859, 9.792, both P<0.01). WT/BWT was negatively associated with FEV1%pred (r=-0.329, P<0.05), and positively with Fres and R5-R20 (r=0.259, 0.241, P<0.05). LAA% was negatively correlated with FEV1%pred (r=-0.566, P<0.05), and correlations also existed between LAA% and physiological indices of small airways such as FEF25%-75%%pred, FEF50%%pred, Fres and R5-R20 (r=-0.456, -0.474, 0.466, 0.340, all P<0.05). Conclusions The peripheral airway resistance is increased and bronchial wall thickens in patients with COPD, and these changes can reflect the severity of the disease. Small airway disease measured by HRCT and IOS are related to the spirometric indices, and represent the structural and functional changes of small airways. Combinations of these two tests with spirometry will be possible to make early diagnosis and better control the disease.