title: Exercise-Induced Changes in Exhaled NO Differentiates Asthma With or Without Fixed Airway Obstruction From COPD With Dynamic Hyperinflation.
abstract: Asthmatic patients with fixed airway obstruction (FAO) and patients with chronic obstructive pulmonary disease (COPD) share similarities in terms of irreversible pulmonary function impairment. Exhaled nitric oxide (eNO) has been documented as a marker of airway inflammation in asthma, but not in COPD. To examine whether the basal eNO level and the change after exercise may differentiate asthmatics with FAO from COPD, 27 normal subjects, 60 stable asthmatics, and 62 stable COPD patients were studied. Asthmatics with FAO (n = 29) were defined as showing a postbronchodilator FEV1/forced vital capacity (FVC) ≤70% and FEV1 less than 80% predicted after inhaled salbutamol (400 μg). COPD with dynamic hyperinflation (n = 31) was defined as a decrease in inspiratory capacity (ΔIC%) after a 6 minute walk test (6MWT). Basal levels of eNO were significantly higher in asthmatics and COPD patients compared to normal subjects. The changes in eNO after 6MWT were negatively correlated with the percent change in IC (r = -0.380, n = 29, P = 0.042) in asthmatics with FAO. Their levels of basal eNO correlated with the maximum mid-expiratory flow (MMEF % predicted) before and after 6MWT. In COPD patients with air-trapping, the percent change of eNO was positively correlated to ΔIC% (rs = 0.404, n = 31, P = 0.024). We conclude that asthma with FAO may represent residual inflammation in the airways, while dynamic hyperinflation in COPD may retain NO in the distal airspace. eNO changes after 6MWT may differentiate the subgroups of asthma or COPD patients and will help toward delivery of individualized therapy for airflow obstruction.
authors.affiliation: From the Department of Thoracic Medicine, Chang Gung Memorial Hospital, Cha-Yi (S-YH); Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (P-CC, T-YW, Y-LL, W-CJ, L-FC, T-FS, C-HW, H-PK); and Experimental Studies, National Heart and Lung Institute, Imperial College, London, UK (KFC).
authors.forename: Shu-Yi
authors.initials: SY
authors.lastname: Huang
authors.forename: Pai-Chien
authors.initials: PC
authors.lastname: Chou
authors.forename: Tsai-Yu
authors.initials: TY
authors.lastname: Wang
authors.forename: Yu-Lun
authors.initials: YL
authors.lastname: Lo
authors.forename: Wen-Ching
authors.initials: WC
authors.lastname: Joa
authors.forename: Li-Fei
authors.initials: LF
authors.lastname: Chen
authors.forename: Te-Fang
authors.initials: TF
authors.lastname: Sheng
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wang
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000402:Airway Obstruction / Q000378:metabolism*; D001249:Asthma / Q000378:metabolism*; D015415:Biomarkers; D015444:Exercise / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism*; D012129:Respiratory Function Tests
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide