Use of cardiopulmonary exercise testing to identify mechanisms of exertional symptoms in children with long COVID.

Background: Little is known about the mechanisms of exercise intolerance and exertional symptoms in children with long COVID. Through utilization of cardiopulmonary exercise testing (CPET), this study is the first of its kind to evaluate exertional symptoms and attempt to identify potential mechanism of long COVID-19 in children.

Objective: To determine if CPET will uncover potential reasons for persistent symptoms of long COVID when there is no indication of cardiopulmonary or upper airway disease.

Methods: We performed a retrospective chart review study involving children 6-17 years of age with symptoms of long COVID at Phoenix Children''s Hospital from January 1, 2021, to June 1, 2022. Symptoms included but were not limited to exercise intolerance, fatigue, shortness of breath, dyspnea on exertion, and chest pain. We recorded any measurable abnormalities present on CPET after comparing it to established normal reference ranges. Range, median, and SD of data points were calculated and p values were determined using the Mann-Whitney U and Fisher's exact test.

Results: Twenty-three children with exertional symptoms consistent with long COVID were identified. The most frequent symptoms reported during exercise include dyspnea on exertion (35%), followed by chest pain (30%) and dizziness (13%). Nearly half of the children (47%) demonstrated decreased exercise capacity with 30% displaying limitations due to deconditioning, 22% limited by body habitus, and 13% due to bronchospasm. Other contributing factors include ventilation to perfusion mismatch and volitional hyperventilation.

Conclusion: Decreased aerobic activity due to multiple factors was found in 47% of children with a history of COVID-19. This study illustrates the importance of ongoing research into this phenomenon to elucidate its mechanism and assist physicians in making decisions regarding referral to specialists for further testing.