Exercise Limitation in Children and Adolescents With Severe Refractory Asthma: A Lack of Asthma Control?

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.

Exercise Limitation in Children and Adolescents with Mild-to-Moderate Asthma

“…Indeed, 60.7% of our children with asthma who were categorized as inactive were also physically deconditioned, while all children with asthma and physical deconditioning were inactive. To our knowledge, only one other study has explored the underlying mechanisms of reduced exercise capacity in children with asthma by means of CPET; 15 that study focused on subjects with severe refractory asthma and reached conclusions similar to ours regarding the contribution of physical deconditioning. Of note, maximal incremental CPET has been shown to be the only reliable method to systematically assess the underlying etiology of reduced exercise capacity.…”

“… 13 , 14 A recent case-control study confirmed that children with severe refractory asthma may be less tolerant to exercise. 15 Using a CPET protocol similar to ours, the investigators also showed that EIB (documented in 30% of cases), physical deconditioning (25% of cases), and a combination of the two (25% of cases) could explain the reduced exercise capacity in that cohort. 15 Similar studies in adults have yield contradictory results.…”

“… 15 Using a CPET protocol similar to ours, the investigators also showed that EIB (documented in 30% of cases), physical deconditioning (25% of cases), and a combination of the two (25% of cases) could explain the reduced exercise capacity in that cohort. 15 Similar studies in adults have yield contradictory results. Earlier reports suggest that the reduced O 2 peak in patients with controlled moderate-to-severe asthma cannot be attributed to airflow limitation, 28 while others have shown that the reduced exercise capacity is linked to small airways disease, especially in subjects with EIB.…”

“… 32 In a study methodologically comparable to ours, EIB was documented in 55% of participants with asthma and emerged as major determinant of reduced exercise capacity, but that study enrolled only subjects with severe refractory disease (ACT scores between 18 and 23). 15 …”

“…The aim of this study was to explore the underlying mechanisms of reduced exercise capacity in children with controlled mild-to-moderate asthma using CPET. Based on evidence from children with uncontrolled disease, 15 we hypothesized that ventilatory limitation and EIB may have minimal contribution to the level of exercise capacity in this population.…”