Exhaled nitric oxide and exercise-induced bronchospasm assessed by FEV1, FEF25-75% in childhood asthma.
ABSTRACT The relationship between exhaled nitric oxide (eNO) and bronchial hyperresponsiveness (BHR) should be clarified. The aim of this study was to determine the relationship between eNO and exercise-induced bronchospasm (EIB) by estimation of the each lung parameter in asthmatic children who performed a bicycle ergometer exercise test. Twenty children with asthma were recruited. eNO concentration was examined by the recommended online method. To evaluate BHR, an exercise stress test was performed on a bicycle ergometer. The mean baseline eNO value was significantly correlated with the mean maximum % fall in forced expiratory volume in 1 second (FEV1), forced expiratory flow between 25% and 75% (FEF25-75%) after exercise (r=0.53, r=0.65, respectively). eNO in the EIB-positive group was significantly higher than that in the EIB-negative group by assessing FEV1, FEF25-75% (p<0.005, p=0.005). We demonstrated that the most important lung parameter assessed the occurrence of EIB by a bicycle ergometer exercise test was not only FEV1 but FEF25-75%, which significantly correlated with eNO. This suggests that not only FEV1 but FEF25-75% can be used to evaluate the correlations between BHR (EIB) and airway inflammation (eNO) in asthmatic children. A low eNO is useful for a negative predictor for EIB.
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ABSTRACT: The objectives are: (1) To assess diagnostic test characteristics of six alternative index tests compared with the selected reference standard-a standardized exercise challenge test (ECT) in patients with suspected exercise-induced bronchoconstriction or asthma (EIB/EIA); (2) to determine the efficacy of a single prophylactic dose of four pharmacologic and one nonpharmacologic interventions vs. placebo to attenuate EIB/EIA in patients with diagnosed EIB/EIA; and (3) to determine if regular daily treatment with short-acting or long-acting beta-agonists (SABA or LABA) causes patients with EIA to develop tachyphylaxis when additional prophylactic doses are used pre-exercise. A systematic and comprehensive literature search was conducted in 14 electronic databases (Diagnosis) and the Cochrane Airways Register (Therapy). Study selection, quality assessment, and data extraction were conducted independently by two reviewers. The primary outcome was the maximum percent fall in the post-exercise forced expiratory volume in 1 second (percent fall FEV1). The diagnostic threshold for a positive ECT was a percent fall FEV1 of 10% or more. Sensitivity (SN) and specificity (SP) were calculated. For therapy, mean differences (MD) in the percent fall FEV1 and 95% confidence intervals (CI) (random effects model) were calculated. A positive MD indicates the intervention works better than the control. For the diagnostic reviews, 5,318 citations yielded 28 relevant studies; for the therapy reviews, 1,634 citations yielded 109 relevant RCTs. Diagnostic test results versus ECT: self-reported history (2 studies) SN=36-8 percent; SP=85-86 percent; sport specific challenges (5 studies) SN=0-100 percent, SP=0-100 percent; eucapnic voluntary hyperpnea (7 studies) SN=25-90 percent, SP=0-71 percent; free running asthma screening test (3 studies) SN=60-67 percent, SP=47-67 percent; mannitol (3 studies) SN=58-96 percent, SP=65-78 percent. All SN and SP calculations indicated substantial heterogeneity that could not be explained by sensitivity or subgroup analyses. Therapy results: SABA offered greater protection than mast cell stabilizers (MCS) (12 studies); MD=6.8 (95 percent CI: 4.5, 9.2) but combining them offered no additional benefit; SABA versus MCS plus SABA (5 studies) MD=1.3 (95 percent CI: -6.3, 8.9). Leukotriene receptor antagonists (LTRA), MCS, ipratropium bromide, and interval warmup routines provided statistically significant attenuation of EIA when compared with placebo; inhaled corticosteroids (ICS) and other warmup routines did not. Single-dose intervention versus placebo results are: LTRA (9 studies) MD=8.9 (95 percent CI: 6.9, 11.0); MCS (nedocromil sodium) (17 studies) MD=15.6 (95 percent CI: 13.2, 18.2); interval warmup versus no warmup (4 studies) MD=10.6 (95 percent CI: 6.5, 14.7); ICS (4 studies) MD=5.0 (95 percent CI: 0.0, 9.9); continuous low intensity warmup versus no warmup (3 studies) MD=12.6 (95 percent CI: -1.5, 26.7); continuous high intensity warmup versus no warmup (2 studies) MD=9.8 (95 percent CI: -6.4, 26.0). After daily LABA (salmeterol) use for 3 to 4 weeks (4 studies), the percent fall FEV1 following an ECT at 2 and 4 weeks was greater than at day 1 in the LABA arm indicating that tachyphylaxis to prophylactic LABA use occurred. Daily SABA use for 1 week (1 study) also indicated development of tachyphylaxis. However, both LABA and SABA continued to have an attenuating effect on EIA. Given the small number of studies comparing EIB/EIA diagnostic tests, the heterogeneity of the study populations, and the varied study methodologies, there is no clear evidence that any of the index tests are a suitable replacement for a standardized ECT to diagnose EIB/EIA in the general population. All bronchodilator agents and most anti-inflammatory agents when used as pretreatment are somewhat effective in attenuating the percent fall FEV1 associated with EIA.Evidence report/technology assessment 01/2010;
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ABSTRACT: Although the importance of cysteinyl leukotrienes (Cys-LTs) in exercise-induced bronchoconstriction (EIB) is supported by various sources of evidence, how the concentration of these mediators change during the development of EIB has not been investigated. Our goal was to determine the effect of exercise on the concentration of airway Cys-LT in asthmatic patients by measuring Cys-LT in exhaled breath condensate (EBC). Seventeen atopic asthmatic patients with a previous history of EIB and six healthy volunteers were studied. Before and two times within 10 minutes after exercise challenge, FEV₁ was measured and EBC was collected for Cys-LT measurement. Exhaled nitric oxide level, a marker of airway inflammation, was also determined at baseline. Baseline Cys-LT level was higher in the asthmatic group versus healthy subjects (168 pg/mL /112-223/ vs. 77 pg/mL /36-119/, p = .03). EBC Cys-LT concentration increased in all asthmatic patients post-exercise (n = 17, p = .03), with the increase significantly greater in patients developing exercise-induced bronchospasm (n = 7, p = .03), whereas no change was observed in healthy controls (p = .59). The exercise-induced fall in FEV(1) in asthmatics was related to the increase in EBC Cys-LT concentration (r = -0.40, p = .03). Our study shows that Cys-LT concentration of EBC is elevated minutes after physical exercise in asthmatic patients and strongly supports the concept that the release of this mediator is involved in the development of EIB.Journal of Asthma 11/2010; 47(9):1057-62. · 1.85 Impact Factor
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ABSTRACT: Our study tried to find a relationship between baseline FEF25-75% and airway hyperresponsiveness (AHR) and whether a greater FEF25-75% impairment may be a marker of a more severe hyperresponsiveness in subjects with normal FEV1 and FEV1/FVC and suggestive asthma symptoms. Besides, we tried to asses a FEF25-75% cut-off value to identify hyper-reactive subjects.Allergy, asthma & immunology research 05/2014; 6(3):242-51. · 2.65 Impact Factor