Diagnostic tests and subtypes of dysfunctional breathing in children with unexplained exertional dyspnea.

BACKGROUND: Inappropriate hyperventilation during exercise may be a specific subtype of dysfunctional breathing (DB). OBJECTIVE: To assess whether Nijmegen questionnaire and hyperventilation provocation test (HVPT) are able to differentiate inappropriate hyperventilation from other DB subtypes in children with unexplained exertional dyspnea, and normal spirometry and echocardiography. METHODS: The results were compared between a subgroup of 25 children with inappropriate hyperventilation (increased V'E/V'CO2 slope during a cardiopulmonary exercise test (CPET)) and an age and sex matched subgroup of 25 children with DB without hyperventilation (median age, 13.5 years; 36 girls). Anxiety was evaluated using State-Trait Anxiety Inventory for Children questionnaire. RESULTS: All children were normocapnic (at rest and peak exercise) and the children with hyperventilation had lower tidal volume/vital capacity on peak exercise (shallow breathing). The Nijmegen score correlated positively with dyspnea during the CPET and the HVPT (p = 0.001 and 0.010, respectively) and with anxiety score (p = 0.022). The proportion of children with a positive Nijmegen score (≥19) did not differ between hyperventilation (13/25) and no hyperventilation (14/25) groups (p = 0.777). Fractional end-tidal CO2 (FETCO2 ) at 5-min recovery of the HVPT was < 90% baseline in all children (25/25) of both subgroups. Likewise, there was no significant difference between the two subgroups for other indices of HVPT (FETCO2 at 3-min recovery and symptoms during the test). CONCLUSION: The validity of the Nijmegen questionnaire and the HVPT to discriminate specific subtypes of dysfunctional breathing, as well as the relevance of the inappropriate hyperventilation subtype itself may both be questioned.

Cross-sectional assessment of exertional dyspnea in otherwise healthy children.

OBJECTIVES: Exertional dyspnea during sport at school in children with asthma or in otherwise healthy children is commonly attributed to exercise-induced asthma (EIA), but when a short-acting beta agonist (SABA) trial fails to improve symptoms the physician is often at a loose end. DESIGN: The aims were to prospectively assess the causes of exertional dyspnea in children/adolescents with or without asthma using a cardiopulmonary exercise test while receiving a SABA and to assess the effects of standardized breathing/reassurance therapy. RESULTS: Seventy-nine patients (12.2 ± 2.3 years, 41 girls, 49 with previously diagnosed asthma) with dyspnea unresponsive to SABA were prospectively included. Exercise test outcomes depicted normal or subnormal performance with normal ventilatory demand and capacity in 53/79 children (67%) defining a physiological response. The remaining 26 children had altered capacity (resistant EIA [n = 17, 9 with previous asthma diagnosis], vocal cord dysfunction [n = 2]) and/or increased demand (alveolar hyperventilation [n = 3], poor conditioning [n = 7]). Forty-two children who had similar characteristics than the remaining 37 children underwent the two sessions of standardized reassurance therapy. They all demonstrated an improvement that was rated "large." The degree of improvement correlated with % predicted peak V'O2 (r = -0.37, P = 0.015) and peak oxygen pulse (r = -0.45, P = 0.003), whatever the underlying dyspnea cause. It suggested a higher benefit in those with poorer conditioning condition. CONCLUSIONS: The most frequent finding in children/adolescents with mild exertional dyspnea unresponsive to preventive SABA is a physiological response to exercise, and standardized reassurance afforded early clinical improvement, irrespective of the dyspnea cause.