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

Area of Science:

• Pediatric Pulmonology
• Respiratory Medicine
• Exercise Physiology

Background:

• Inappropriate hyperventilation during exercise is a potential subtype of dysfunctional breathing (DB).
• Children with unexplained exertional dyspnea often present with normal spirometry and echocardiography, complicating diagnosis.

Purpose of the Study:

• To evaluate the efficacy of the Nijmegen questionnaire and the hyperventilation provocation test (HVPT) in distinguishing inappropriate hyperventilation from other DB subtypes in children.
• To assess the clinical relevance of inappropriate hyperventilation as a distinct DB subtype in pediatric patients.

Main Methods:

• Compared two matched subgroups of 25 children each: one with inappropriate hyperventilation (identified by increased V'E/V'CO2 slope during CPET) and one with DB without hyperventilation.
• Assessed anxiety using the State-Trait Anxiety Inventory for Children.
• Utilized cardiopulmonary exercise testing (CPET) and HVPT, measuring parameters like tidal volume, vital capacity, and fractional end-tidal CO2 (FETCO2).

Main Results:

• Children with inappropriate hyperventilation exhibited shallow breathing (lower tidal volume/vital capacity) during peak exercise.
• The Nijmegen score positively correlated with dyspnea during CPET and HVPT, and with anxiety scores.
• No significant differences were found between the groups regarding positive Nijmegen scores, HVPT indices (FETCO2 at 3-min and 5-min recovery), or symptoms during the test.

Conclusions:

• The study questions the validity of the Nijmegen questionnaire and HVPT for discriminating specific DB subtypes in children.
• The clinical relevance and distinctness of the inappropriate hyperventilation subtype itself are also called into question based on the findings.