Early oxygen uptake recovery following exercise testing in children with chronic chest diseases

The value of exercise testing as an objective measure of disease severity in patients with chronic chest diseases (CCD) is becoming increasingly recognized. The aim of this study was to investigate changes in oxygen uptake ( . V O₂) during early recovery following maximal cardiopulmonary exercise testing (CPXT) in relation to functional capacity and markers of disease severity. Twenty‐seven children with CCD (age 12.7 ± 3.1 years; 17 female) [19 children with Cystic fibrosis (CF) (age 13.4 ± 3.1 years; 10 female) and 8 with other stable non‐CF chest diseases (NON‐CF) (age 11.1 ± 2.2 years; 7 female)] and 27 healthy controls (age 13.2 ± 3.3 years; 17 female) underwent CPXT on a cycle ergometer. On‐line respiratory gas analysis measured ( . V O₂) before and during CPXT to peak ( . V O₂) ( . V O₂) peak, and during the first 10 min of recovery. Early ( . V O₂) recovery was quantified by the time (sec) to reach 50% of the ( . V O₂) peak value. Early ( . V O₂) recovery was correlated against spirometry [forced expiratory volume in 1 sec (FEV1) and forced expiratory flow between 25% and 75% of the forced vital capacity (FEF25–75)] and aerobic fitness ( . V O₂) peak as a measure of functional capacity. Disease severity was graded in the CF patients by the Shwachman score (SS). Compared to controls, children with CCD demonstrated a significantly reduced ( . V O₂) peak (P = 0.011), FEV1 (P < 0.001), FEF25–75 (P < 0.001), and a significantly prolonged early ( . V O₂) recovery (P = 0.024). In the CF patients the SS was significantly correlated with early ( . V O₂) recovery (r = −0.63, P = 0.004), FEV1 (r = 0.72, P = 0.001), and FEF25–75 (r = 0.57, P = 0.011). In the children with CCD, FEV1, FEF25–75, and BMI were not significantly correlated with ( . V O₂) peak or early ( . V O₂) recovery. Lung function does not necessarily reflect aerobic fitness and the ability to recover from exercise in these patients. A significant relationship was found between ( . V O₂) peak and early ( . V O₂) recovery (r = −0.39, P = 0.044) in the children with CCD, showing that a greater aerobic fitness corresponded with a faster recovery. Pediatr Pulmonol. 2009; 44:480–488.