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BACKGROUND: The pulmonary impairment in patients with bronchoconstriction induced by eucapnic voluntary hyperpnea(EVH) goes beyond the respiratory system, also impairing autonomic nervous modulation. This study aimed to evaluate the behavior of cardiac autonomic modulation in young asthmatics with and without EIB after the EVH test. RESEARCH DESIGN AND METHODS: A cross-sectional study design using 54 asthmatics(51.9% female), aged between 10 and 19 years, investigated with the EVH test. Forced expiratory volume in one second(FEV1) was measured at 5, 10, 15, and 30 min after EVH. Heart rate variability(HRV) measures of time were assessed pre and 30 min-post EVH. The diagnosis of Exercise-Induced bronchoconstriction with underlying clinical asthma(EIBA) was confirmed by a fall in FEV1 ≥10% compared to baseline. RESULTS: Thirty(55.5%) asthmatics had EIBA. Subjects with EIBA have reduced mean of the R-R intervals in relation to baseline until 15 minutes after EVH. Individuals without EIBA had increased parasympathetic activity compared to baseline(rMSSD) from 5 min after EVH(p < 0.05). This parasympathetic activity increase in relation to baseline was seen in individuals with EIBA after 25 minutes (rMSSD = 49.9 ± 5.3 vs 63.5 ± 7.2, p < 0.05). CONCLUSION: Young asthmatics with EIBA present a delay in the increase of the parasympathetic component after EVH when compared to asthmatics without EIBA.

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INTRODUCTION: Impulse oscillometry (IOS) parameters are obtained more easily and effortlessly in comparison to forced expiratory volume in the first second (FEV1). OBJECTIVE: To compare IOS parameters to FEV1 in exercise-induced bronchoconstriction (EIB) diagnosis. METHODS: Seventy-four (60.8% male; 39.2 female) young asthmatics aged between 7 and 17 years (mean 12.6 ± 2.8 years) were evaluated. EIB was defined as a reduction in FEV1 ≥ 10% compared with basal after standardized challenge by treadmill running (TR). IOS parameters and FEV1 were obtained at baseline and 5,15, and 30 min after TR. The area under the receiver operator characteristic curve (AUC) was calculated from the reduction in FEV1 ≥ 10% to evaluate the best psychometric characteristics of IOS parameters. RESULTS: Twenty-four individuals (32.4%) were diagnosed with EIB. A moderate inverse correlation was found between the IOS and FEV1 variables immediately after the TR, with resistance at 5 Hz (R5Hz), resonant frequency (Fres), and reactance area (AX), (r = -0.64, r = -0.53 and r = -0.69, respectively, all with p < 0.05). An increase of 25 kPa/l/s in R5 Hz, of 19k Pa/l/s in AX and 21 Hz in Fres were found to best correlate with EIB diagnosis by FEV1 (sensitivity 67% and specificity 62%, sensitivity 84% and specificity 50%, and sensitivity 84% and specificity 60%, respectively). CONCLUSION: IOS parameters have a significant inverse correlation with FEV1. This study presents cut-off points for EIB diagnosis for R5Hz, AX, and Fres, however, the findings in IOS parameters should be used and interpreted carefully if the goal is to replace spirometry.

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PURPOSE: Exercise-induced bronchoconstriction (EIB) affects approximately 50% of young asthma patients, impairing their participation in sports and physical activities. Eucapnic voluntary hyperpnea (EVH) is an approved surrogate challenge to exercise for objective EIB diagnosis, but the required minimum target hyperventilation rates remain unexplored in this population. This study aimed to evaluate the association between the achieved ventilation rates (VRs) during a challenge and EIB-compatible response (EIB-cr) in young asthma patients. METHODS: This cross-sectional study included 72 asthma patients aged 10-20 years. Forced expiratory volume in the first second (FEV1) was measured before and 5, 15, and 30 min after the EVH. The target VR was set at 21 times the individual's baseline FEV1. A decrease of > 10% in FEV1 after the challenge was considered an EIB-cr. The challenge was repeated after 48-72 h in those without an EIB-cr. RESULTS: Thirty-six individuals had an EIB-cr at initial evaluation. The median VRs achieved was not different between individuals with and without an EIB-cr (19.8 versus 17.9; p = 0.619). The proportion of individuals with an EIB-cr was nor different comparing those who achieved (12/25) or not (24/47) the calculated target VRs (p = 0.804). At the repeated EVH challenge an EIB-cr was observed in 14/36 individuals with a negative response in the first evaluation, with no differences in achieved VRs between the two tests (p = 0.463). CONCLUSION: Irrespective of the achieved VR, an EIB-compatible response after an EVH challenge must be considered relevant for clinical and therapeutic judgment and negative tests should be repeated.

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OBJECTIVE: To evaluate the exercise capacity of children and adolescents with severe therapy resistant asthma (STRA) aiming to identify its main determinants. METHODS: Cross-sectional study including individuals aged 6-18 years with a diagnosis of STRA. Clinical (age and gender), anthropometric (weight, height and body mass index) and disease control data were collected. Lung function (spirometry), cardiopulmonary exercise testing (CPET) and exercise-induced bronchoconstriction (EIB) test were performed. RESULTS: Twenty-four patients aged 11.5 ± 2.6 years were included. The mean forced expiratory volume in one second (FEV1) was 91.3 ± 9.2%. EIB occurred in 54.2% of patients. In CPET, the peak oxygen uptake (VO2peak) was 34.1 ± 7.8 mL kg-1 min-1. A significant correlation between ventilatory reserve and FEV1 (r = 0.57; p = 0.003) was found. Similarly, there was a significant correlation between CPET and percent of FEV1 fall in the EIB test for both VE/VO2 (r = 0.47; p = 0.02) and VE/VCO2 (r = 0.46; p = 0.02). Patients with FEV1<80% had lower ventilatory reserve (p = 0.009). In addition, resting heart rate correlated with VO2peak (r=-0.40; p = 0.04), VE/VO2 (r = 0.46; p = 0.02) and VE/VCO2 (r = 0.48; p = 0.01). CONCLUSIONS: Exercise capacity is impaired in approximately 30% of children and adolescents with STRA. The results indicate that different aspects of aerobic fitness are influenced by distinct determinants, including lung function and EIB.

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BACKGROUND: Respiratory symptoms after exercise are frequently reported by asthmatic patients, and exercise-induced bronchoconstriction (EIB) is a frequent cause, which requires objective testing for diagnosis. Eucapnic voluntary hyperpnea (EVH) is recommended as a surrogate stimulus for this purpose. Its short-term reproducibility is not yet established in children and young adolescents with asthma. OBJECTIVE: To evaluate the short-term test-retest agreement and reproducibility of FEV1 changes after EVH in this population. METHODS: Asthmatic patients aged between 10 and 20 years underwent EVH for EIB diagnosis on two occasions 2-4 days apart at a specialized university clinic. FEV1 was measured at 5, 15, and 30 min after EVH with a target ventilation rate 21 times the baseline FEV1 . EIB was diagnosed as a decrease ≥10% in FEV1 from baseline. RESULTS: A total of 26 of 62 recruited individuals tested positive for EIB on both visits (positive group) and 17 on one visit only (divergent group), while 19 tested negative on both visits (negative group). The overall agreement was 72.5% (95%CI 61.6%, 83.6%), and Cohen's kappa coefficient was 0.452. Low bias (0.87%) and high intra-class correlation coefficient (0.854, 95%CI 0.758,0.912; p < .001) for FEV1 response between test days were found, but with wide limits of agreement (±20.72%). There were no differences in pre-challenge FEV1 or achieved ventilation rate between visits either between groups (p = .097 and p = .461) or within groups (p = .828 and p = .780). There were no safety issues. CONCLUSIONS: More than one EVH test should be performed in children and young adolescents with asthma to exclude EIB and minimize misdiagnosis and mistreatment.

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Asthma is a chronic obstructive respiratory disease with high prevalence in children. Several factors may trigger asthma symptoms, including exercise, which can lead to exercise-induced bronchoconstriction (EIB). Although physical exercise may represent a risk factor for triggering bronchial obstruction in asthmatics, studies have also indicated several positive effects. Thus, this article aimed to summarize current evidence on the effects of exercise training in children with asthma. There is substantial available evidence on the topic. Most of the findings show that exercise induce positive effects, including the increase of aerobic fitness, decrease of EIB levels, as well as an increase in both disease control and quality of life levels in asthmatic children. As for possible influencing factors in order to obtain exercise-induced positive effects, an adequate prescription of exercise intensity highlights and should be personalized, as well as established close to the anaerobic threshold. Thus, considering the evidence showing beneficial effects and the fact that the practice of physical exercise consists of a low cost and safe non-pharmacological therapy, supervised, personalized and individual recommendation of exercise training by health professionals are indicated to asthmatic children.

El asma es una enfermedad respiratoria obstructiva crónica con alta prevalencia en niños. Varios factores pueden desencadenar síntomas de asma, incluido el ejercicio, que puede conducir a la broncoconstricción inducida por el ejercicio (BIE). Aunque el ejercicio físico puede representar un factor de riesgo para desencadenar la obstrucción bronquial en los asmáticos, estudios también han indicado varios efectos positivos. Este artículo tiene como objetivo resumir la evidencia actual sobre los efectos del entrenamiento físico en niños con asma. Hay evidencia sustancial disponible sobre el tema. La mayoría de los hallazgos muestran que el ejercicio induce efectos positivos, incluido el aumento de la aptitud aeróbica, la disminución de los niveles de la BEI, así como un aumento tanto en el control de la enfermedad como en los niveles de calidad de vida en niños asmáticos. Se destaca la importancia de una prescripción de la intensidad del ejercicio adecuada y personalizada, cerca del umbral anaeróbico, para obtener los efectos positivos inducidos por el ejercicio. Por lo tanto, considerando la evidencia que muestra efectos beneficiosos y el hecho de que la práctica del ejercicio físico consiste en una terapia no farmacológica, segura y de bajo costo, el entrenamiento físico supervisado, personalizado e individualizado por parte de profesionales de la salud es recomendado para niños asmáticos.

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AIM: This systematic review and meta-analysis aimed to estimate the global prevalence of exercise-induced bronchoconstriction (EIB) in children and adolescents. METHOD: We searched PubMed, Google Scholar, and the Virtual Health Library-BIREME from inception to December 23, 2017. We selected observational studies that reported the prevalence of EIB (diagnosed by exercise challenge test) in children and adolescents aged 5-18 years. We conducted random-effects meta-analyses to estimate the pooled prevalence of EIB and 95% CI. RESULTS: We included 66 studies (55 696 participants, 5670 cases of EIB) in the review, of which 33 in general population of children and adolescents, 10 in child and adolescent athletes and 23 in children and adolescents with asthma. The global mean prevalence of EIB in the general population of children and adolescents was 9% (IC95%: 8-10%), with a higher rate (12%) in Asia-Pacific and America. The mean prevalence of EIB was 15% (95% CI: 9-21%) in child and adolescent athletes, and 46% (95% CI: 39-53%) in children and adolescents with asthma. We estimated that, globally, around 16.5 million (95% CI: 15-18 million) children and adolescents up to 18 years of age may have EIB. CONCLUSION: EIB in childhood should be considered as a global public health problem that needs more attention. The substantial heterogeneity between studies highlights the need for evidence-based guidelines for diagnosis of EIB in this age group.

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