BackgroundWhatever the initial stimulus for the exercise-induced bronchoconstriction (EIB) observed in asthmatic patients after exercise, the final effect is release of bronchoactive mediators, especially cysteinyl leukotrienes. Exercise rehabilitation training programs have been reported to protect against EIB. The exact mechanism(s) involved are not well understood. However, this protective effect may be related to adaptation and better coordination during exercise, depletion of cysteinyl leukotrienes, and/or a sluggish cysteinyl leukotriene response to exercise. The aim of the present work was to test the hypothesis that improvement in the incidence and severity of post-exercise bronchoconstriction after a rehabilitation training program is related to a change in leukotriene levels in response to exercise.MethodsTwenty asthmatic children aged 6–12 years and known to develop EIB were enrolled in an exercise training program for 12 weeks. The severity and incidence of EIB before and after training was assessed. Baseline and post-exercise sputum cysteinyl leukotriene levels were assessed before and after the training program.ResultsThe training program offered significant protection against EIB with a concomitant decrease in sputum cysteinyl leukotriene levels in response to exercise.ConclusionA training program can result in depletion and/or a sluggish cysteinyl leukotriene response to exercise and may be responsible for the protective effect of training programs on EIB. It is recommended to use an exercise rehabilitation training program as a complementary tool in the management of bronchial asthma, especially EIB.
Purpose: This study aimed at demonstrating the reliability of surface area under the maximum expiratory flow volume curve (Aex) and rectangular area ratio (RAR) to define the type of ventilatory impairment and assessing potential clinical value of Aex ratio (measured / predicted Aex) to indicate the severity of ventilatory obstruction. Methods: Spirometric data of 75 subjects were analyzed by qualified pulmonologists to distinguish between different spirometric patterns representing expert decision. Computerized graphic analysis methodology was used, Aex was used to calculate other parameters (area of concavity and RAR) and an algorithm for diagnosis was proposed. For validation of the proposed grading and cutoff values, we compared them with expert decision using classification and regression trees (CART). Results: According to calculated parameters, obstructive pattern is realized if area of concavity (Au) has positive value and RAR is less than 0.5. While convexity/linearity is indicated if RAR ≥ 0.5 and Au has negative value or equal zero, indicating normal or restrictive pattern. Aex ratio was selected as second-best predictor of restriction at a cut-off value of 49%. Furthermore, the diagnostic performance of Aex ratio in predicting moderate-to-severe obstructive lung disease was excellent. Conclusion: The proposed computerized technique succeeded using RAR and Aex in differentiating between restriction, obstruction and normal patterns. Additionally, Aex ratio may be a valid parameter to grade the severity of obstruction.
Exercise-induced bronchoconstriction (EIB) in asthmatic children has been associated with obesity. Leptin, the proinflammatory adipokine, is typically increased in obesity, whereas cysteinyl leukotrienes (cysLTs) are the main inflammatory mediators implicated in the pathogenesis of EIB. The aim of this work was to study the possible impact of obesity on the severity of EIB in asthmatic children and the possible association with the adipokine leptin. The study included eighty pre-pubertal asthmatic children divided according to their body mass index (BMI) and response to exercise into four groups; obese exercise-responders (n=20), normalweight exercise-responders (n=20), obese exercise non-responders (n=20), and normal-weight exercise non-responders (n=20). A baseline spirometry test and a standardized exercise challenge test (ECT) were performed. The severity of EIB was assessed by the maximum percentage fall in forced expiratory volume in 1 second (MF%FEV1) after exercise. The level of fasting serum leptin and the release of cysLTs during exercise were compared between the 4 groups. The MF%FEV1 during exercise was significantly greater in obese responder compared to normalweight responder patients (p=0.004) and MF%FEV1 was positively correlated with cysLT release during exercise, BMI z-score, waist circumference and serum leptin. CysLT release during exercise was positively correlated with the level of serum leptin (r =0.514, p=0.001). This study reports that the severity of EIB is significantly greater in obese compared to normal-weight asthmatic children and suggests an association between leptin and airway hyperresponsiveness to exercise in obese asthmatic children through a mechanism related to cysLT release.
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