Longitudinal changes in exercise capacity among adult cystic fibrosis patients

Longitudinal data regarding changes in exercise capacity among adult cystic fibrosis (CF) patients are currently scarce. The aim of this brief report was to assess changes in exercise capacity among adult CF patients with stable and mild-to-moderate disease eight years after their initial evaluation.

Maximum cardiopulmonary exercise testing (CPET) was utilized. Other assessments included Doppler echocardiography, the 6-minute walking test, spirometry, and lung volume evaluation.

Eleven (6 male, 5 female) patients completed both evaluations (initial and after eight years). During follow-up, indices of ventilatory impairment (such as ventilatory reserve; p=0.019, and ventilatory equivalent for carbon dioxide; p = 0.047) deterio-rated significantly following a decline in respiratory function measurements. Peak oxygen uptake (VO2), both as an absolute (26.6 ± 8.46 vs 23.89 ± 6.16 mL/kg/min; p = 0.098) and as a % of predicted value (71.21 ± 16.54 vs 70.60 ± 15.45; p = 0.872), did not deteriorate. This is also true for oxygen pulse (p = 0.743), left heart ejection fraction (p = 0.574), and pulmonary artery systolic pressure (p = 0.441). However, the anaerobic threshold, both as an absolute (p = 0.009) and as a % of predicted value (p = 0.047), was significantly lower during follow-up.

In adult CF patients with stable, mild-to-moderate disease, a peak VO2 may be preserved for several years. However, even in these patients, deconditioning is present.