Cut-off values to evaluate exercise-induced asthma in eucapnic voluntary hyperventilation test for children

BACKGROUND AND AIM

The eucapnic voluntary hyperventilation (EVH) testing is a diagnostic tool for diagnostics of exercise-induced bronchoconstriction; while the testing has become more common among children, data on the test's feasibility among children remain limited. Our aim was to investigate EVH testing feasibility among children, diagnostic testing cut-off values, and which factors affect testing outcomes.

METHODS

We recruited 134 patients aged 10-16 years with a history of exercise-induced dyspnoea and 100 healthy control children to undergo 6-min EVH testing. Testing feasibility was assessed by the children's ability to achieve ≥70% of the target minute ventilation of 30 times forced expiratory volume in 1 s (FEV1). Bronchoconstriction was assessed as a minimum of 8%, 10%, 12%, 15% or 20% fall in FEV1. Patient characteristics were correlated with EVH outcomes.

RESULTS

Overall, 98% of the children reached ≥70%, 88% reached ≥80%, 79% reached ≥90% and 62% reached ≥100% of target ventilation in EVH testing; of children with a history of exercise-induced dyspnoea, the decline percentages were as follows: 24% (≥8% fall), 17% (≥10% fall), 10% (≥12% fall), 6% (≥15% fall) and 5% (≥20% fall) in FEV1, compared to 11%, 4%, 3%, 1% and 0% among the healthy controls, respectively. Healthy controls and boys performed testing at higher ventilation rates (p < .05).

CONCLUSION

Eucapnic voluntary hyperventilation testing is feasible among children aged 10-16 years and has diagnostic value in evaluating exercise-induced dyspnoea among children. A minimum 10% fall in FEV1 is a good diagnostic cut-off value. Disease status appears to be important covariates.

Eucapnic voluntary hyperventilation test in children

BACKGROUND

In children, exercise-induced dyspnea is a common symptom that can be due to dysfunctional breathing. EVH test has bee used especially in elite athletes as bronchoprovocation test. Currently, there are only few studies on the EVH test. New research methods are required alongside the traditionally used tests especially due to dysfunctional breathing disorder.

PURPOSE

The purpose of the "pilot study" was to study the usability of the EVH test with real time biofeedback in children of 10-16 years of age in the diagnostics of exercise-induced dyspnea.

METHODS

Six 10-16-year-old teenagers with history of exercise-induced dyspnea and three healthy control subjects were selected for the study. A 6-minute EVH test with realtime biofeedback was performed on the patients and the diagnosis was confirmed on the basis of clinical findings and spirometry follow-up either as normal, asthma or dysfunctional breathing.

RESULTS

The study was successful in the patients. In the spirometry follow-up, three patients had bronchoconstriction (FEV1 decline over 10%), dysfunctional breathing condition was observed in three patients and three control patients experienced no symptoms. Only two DFB-patients didn't reach the target level of minute ventilation due to a clinical symptom (inspiratory stridor).

CONCLUSION

The EVH test was successful in the 10-16-year-old children having participated in the study and the test was well tolerated. Through the study, it was possible to provoke both dysfunctional breathing disorder and bronchoconstriction in the symptomatic patients. Based on the pilot study, EVH test seems to be usable in the diagnostics of pediatric exercise-induced dyspnea but larger studies are warranted to confirm our preliminary findings.