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Is static hyperinflation a limiting factor during exercise in adolescents with cystic fibrosis?
Author(s) -
Werkman M.S.,
Hulzebos H.J.,
Arets H.G.M.,
van der Net J.,
Helders P.J.M.,
Takken T.
Publication year - 2011
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.21329
Subject(s) - medicine , hyperinflation , lung volumes , vo2 max , functional residual capacity , cardiology , dynamic hyperinflation , ventilation (architecture) , cystic fibrosis , heart rate , lung , blood pressure , monetary policy , mechanical engineering , monetary economics , economics , engineering
Increased work of breathing is considered to be a limiting factor in patients with cystic fibrosis (CF) performing aerobic exercise. We hypothesized that adolescents with CF and with static hyperinflation are more prone to a ventilatorily limited exercise capacity than non‐static hyperinflated adolescents with CF. Exercise data of 119 adolescents with CF [range 12–18 years], stratified for static hyperinflation, defined as ratio of residual volume to total lung capacity (RV/TLC) > 30%, were obtained during a progressive bicycle ergometer test with gas analysis and analyzed for ventilatory limitation. Static hyperinflation showed a significant, though weak association (Φ 0.38; P < 0.001) with a ventilatorily limited exercise capacity (breathing reserve index at maximal effort >0.70; FEV 1 < 80% predicted and reduced exercise capacity, defined as VO 2peak < 85% predicted). Analysis of association for increasing degrees of hyperinflation showed an increase to Φ 0.49 ( P < 0.001) for RV/TLC > 50%. In adolescents with static hyperinflation, peak work rate (W peak ; 3.1 ± 0.7 W/kg (75.1 ± 17.3% of predicted), peak oxygen uptake (VO 2peak /kg (ml/min/kg); 39.2 ± 9.2 ml/min/kg (91.0 ± 20.3% of predicted), peak heart rate (HR peak ; 176 ± 19 beats/min) were significantly ( P < 0.05) decreased when compared with non‐static hyperinflated adolescents (W peak 3.5 ± 0.5 W/kg (81.4 ± 10.0% of predicted)); VO 2peak /kg (ml/min/kg); 43.1 ± 7.5 ml/min/kg (98.0 ± 15.1% of predicted); and HR peak 185 ± 14 beats/min). Additionally, no difference was found in the degree of association of FEV 1 (%) and RV/TLC (%) with VO 2peak /kg pred and W peak /kg Pred , but we found the RV/TLC (%) to be a slightly stronger predictor of VO 2peak /kg pred and W peak /kg Pred than FEV 1 (%). These results indicate that the presence of static hyperinflation in adolescents with CF by itself does not strongly influence ventilatory constraints during exercise and that static hyperinflation is only a slightly stronger predictor of W peak /kg Pred and VO 2peak /kg Pred than airflow obstruction (FEV 1 (%)). Pediatr. Pulmonol. 2011; 46:119–124. © 2011 Wiley‐Liss, Inc.