Relationships between Fraction of Nitric Oxide, Airway Hyperresponsiveness, Blood Eoshinophil Counts and Serum Eosinophil Cationic Protein in Asthmatic Children / 소아알레르기및호흡기학회지

PURPOSE: The measurement of fraction of nitric oxide (FeNO) is a noticeable tool that reflects airway inflammation in asthmatic patients. We wanted to find out the relationship between pulmonary function, bronchial hyperresponsiveness (AHR), blood eosinophilic inflammatory markers and FeNO level before and after methacholine bronchoprovocation test in asthmatic patients. METHODS: Fifty-five children, who visited the Allergy Clinic of Korea University Anam Hospital from March 2011 to February 2012, due to asthmatic symptoms, such as history of episodic wheezing or dyspnea during the previous year and resolved after using bronchodilators, were enrolled. We performed the baseline pulmonary function and methacholine bronchoprovocation test in the enrolled patients. Blood eosinophil counts and blood eosinophil cationic protein (ECP) were measured. FeNO levels were measured before and after the methacholine bronchoprovocation test. RESULTS: The mean FeNO levels (36.3 ppb) fell after methacholine bronchoprovocation test (25.7 ppb). Forced expiratory volume in one second (FEV1) %pred inversely correlated both with FeNO level before (R2=0.07, P=0.029) and after (R2=0.059, P=0.01) methacholine bronchoprovocation test. The provocative concentration, causing a 20% decrease in FEV1 to methacholine (methacholine PC20) inversely correlated both with FeNO levels before (R2=0.086, P=0.001) and after (R2=0.141, P=0.001) the challenge. FeNO level measured at bronchoconstriction state significantly correlated with blood eosinophil counts (R2=0.112, P=0.028). Serum ECP levels correlated FeNO level, neither before nor after bronchoprovocation. CONCLUSION: The baseline FeNO levels were higher in asthmatic children. However, FeNO levels rather decreased after methacholine induced bronchoconstriction. Repeated spirometry maneuver was considered to have an effect on reducing FeNO levels. FeNO correlated with pulmonary function, airway AHR and blood eosinophil counts.

Correlation of Exercise-Induced Bronchoconstriction to PC20 and Maximal AirwayNarrowing on the Dose-Response Curve to Methacholine / 결핵

BACKGROUND: Exercise is one of the most common precipitants of acute asthma encountered in clinical practice. The development of airflow limitation that occurs several minutes after vigorous exercise, i. g. exercise-induced bronchoconstriction(EIB), has been shown to be closely correlated with the nonspecific bronchial hyperresponsiveness, which is the hallmark of bronchial asthma. All previous reports that assessed the correlation of EIB to nonspecific bronchial hyperresponsiveness have focused on airway sensitivity(PC20) to inhaled bronchoconstrictor such as methacholine or histamine. However, maximal airway narrowing(MAN), reflecting the extent to which the airways can narrow, when being exposed to high dose of inhaled stimuli, has not been studied in relation to the degree of EIB. METHODS: Fifty-six children with mild asthma(41 boys and 15 girls), aged 6 to 15 years(mean +/- SD, 9.9 +/- 2.5 years) completed this study. Subjects attended the laboratory on two consecutive days. Each subject performed the high-dose methacholine inhalation test at 4 p.m. on the first day. The dose-response curves were characterized by their position(PC20) and MAN, which was defined as maximal response plateau(MRP: when two or three data points of the highest concentrations fell within a 5% response range) or the last of the data points(when a plateau could not be measured). On the next day, exercise challenge, free running outdoors for ten minutes, was performed at 9 a.m.. FEV1 was measured at graduated intervals, 3 to 10 minutes apart, until 60 minutes after exercise. Response(the maximal DeltaFEV1 from the pre-exercise value) was classified arbitrarily into three groups; no response ((-) EIB: DeltaFEV1 20%). RESULTS: 1) When geometric mean PC20 of the three groups were compared, PC20 of (+) EIB group was significantly lower than that of (-)EIB group. 2) There was a close correlation between PC20 and the severity of EIB in the whole group(r= -0.568, p<0.01). 3) Of the total 56 subjects, MRP could be measured in 36 subjects, and the MRP of these subjects correlated fairly with the severity of EIB(r= 0.355, p<0.05) 4) The MAN of (+) EIB group was significantly higher than that of (-)EIB group(p<0.01). 5) The MAN correlated well with the severity of EIB in the whole group(r=0.546, p<0.01). CONCLUSION: The degree of MAN as well as bronchial sensitivity (PC2o) to methacholine is correlated well with the severity of EIB. The results suggest that the two main components of airway hyperresponsiveness may be equally important determinants of exercise reactivity, although the mechanism may be different from each other. The present study also provides further evidence that EIB is a manifestation of the increased airway reactivity characteristic of bronchial asthma.