Abstract
BackgroundPatients with severe refractory asthma (SRA), even when using high doses of multiple controller medications in a regular and appropriate way, can have persistent complaints of exercise limitation.MethodsThis was a cross-sectional study involving patients with SRA (treated with ≥ 800 μg of budesonide or equivalent, with ≥ 80% adherence, appropriate inhaler technique, and comorbidities treated), who presented no signs of a lack of asthma control other than exercise limitation. We also evaluated healthy controls, matched to the patients for sex, age, and body mass index. All participants underwent cardiopulmonary exercise testing (CPET) on a cycle ergometer, maximum exertion being defined as ≥ 85% of the predicted heart rate, with a respiratory exchange ratio ≥ 1.0 for children and ≥ 1.1 for adolescents. Physical deconditioning was defined as oxygen uptake (VO2) < 80% of predicted at peak exercise, without cardiac impairment or ventilatory limitation. Exercise-induced bronchoconstriction (EIB) was defined as a forced expiratory volume in one second ≥ 10% lower than the baseline value at 5, 10, 20, and 30 minutes after CPET.ResultsWe evaluated 20 patients with SRA and 19 controls. In the sample as a whole, the mean age was 12.9 ± 0.4 years. The CPET was considered maximal in all participants. In terms of the peak VO2 (VO2peak), there was no significant difference between the patients and controls, (P = 0.10). Among the patients, we observed isolated EIB in 30%, isolated physical deconditioning in 25%, physical deconditioning accompanied by EIB in 25%, and exercise-induced symptoms not supported by the CPET data in 15%.Conclusion and Clinical RelevancePhysical deconditioning, alone or accompanied by EIB, was the determining factor in reducing exercise tolerance in patients with SRA and was not therefore found to be associated with a lack of asthma control.
Highlights
Children and adolescents with asthma should be encouraged to engage in regular physical activity; one of the objectives of adjusting the treatment regimen is to allow the patients to engage in such activities without any limitations (Global Initiative for Asthma, 2020)
The present study aims to determine the causes of exercise limitation in children and adolescents with severe asthma that was refractory to regular, appropriate pharmacological treatment
Of the 60 patients in the cohort, 40 were excluded: 36 because they exhibited signs of a lack of asthma control other than exercise limitation or had used a short-acting bronchodilator in the last 4 weeks and 4 because they did not complete the protocol
Summary
Children and adolescents with asthma should be encouraged to engage in regular physical activity; one of the objectives of adjusting the treatment regimen is to allow the patients to engage in such activities without any limitations (Global Initiative for Asthma, 2020). Even after all of those basic factors have been optimized, some patients continue to complain of exercise-induced symptoms, which require investigation (McNicholl et al, 2011; Global Initiative for Asthma, 2020). Cardiopulmonary exercise testing (CPET) is the gold standard for the investigation of exercise limitation, which, in individuals with asthma, can be attributed to airway obstruction, ventilatory limitation, an increased level of perception of dyspnea, or exercise-induced bronchoconstriction (EIB) (Weisman et al, 2003; Minic and Sovtic, 2017). For the diagnosis of EIB, CPET is performed in conjunction with spirometry, and the best way to estimate exercise capacity is by measuring the oxygen uptake (VO2) (Weisman et al, 2003; Parsons et al, 2013). Patients with severe refractory asthma (SRA), even when using high doses of multiple controller medications in a regular and appropriate way, can have persistent complaints of exercise limitation
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