WS16.2 the reliability of maximal cardiopulmonary exercise testing for young cystic fibrosis patients

Background: Maximal cardiopulmonary exercise testing (CPET) is the most precise method for evaluating physical function of patients with mild-to-moderate cystic fibrosis (CF). This study sought to establish the between trial variation of CPET parameters across three different time points.

Methods: Fourteen 7−18 year olds (10 male) completed an incremental ramp cycle test to exhaustion. Peak oxygen uptake (V˙ O2peak), power output (Wpeak), heart rate (HRpeak ) and end-exercise oxygen saturation (SaO2%) and breathlessness (RPD) were determined. Following 15-min recovery supramaximal exercise to exhaustion was performed at a work rate (WR) equal to 110% ramp Wpeak (T1). Testing was repeated 48 h (T2) and 4−6 weeks later (T3). Intra-class retest correlations, change in the mean score [V˙ O2peak] and the typical error for all measurements assessed reliability.

Results: Intra-class correlations ranged from r = 0.57–0.99 and were highest for WR. No significant differences in mean (SD) V˙ O2peak were found between T1-T2; 1.91 (0.80) and 1.93 (0.66) L×min−1, p = 0.79; T2-T3 1.81 (0.48) and 1.68 (0.50) L×min−1, n = 13, p = 0.20 and T1-T3 1.77 (0.63) and 1.68 (0.50) L×min−1, n = 13, p = 0.25, respectively. The highest typical error for HRpeak (T1-T2), WR (T2-T3), RPD (T1-T2), SaO2% (T2-T3), and V˙ O2peak (T1-T2) were 12, 9.3, 1.4, 1.3 and 0.3%, respectively.

Conclusion: CPET derived variables especially V˙ O2peak are highly reproducible between 1 and 42 days. Clinicians can have confidence in precisely reproducing the effect of exercise/pharmacological interventions or CF disease on parameters obtained during CPET. Acknowledgments: Supported by the Peninsula NIHR Research Facility.