Introduction Cardiopulmonary exercise testing (CPET) is the gold standard test of aerobic fitness in Cystic Fibrosis (CF). CPET is measured by peak oxygen uptake (VO2 peak) during maximal exercise. It can be used to identify the cause of exercise intolerance, prescribe exercise programmes, evaluate therapeutic interventions1 and predict prognosis.2 The American Thoracic Society defines a normal VO2 peak as >84% predicted.3 In our centre, CPET was included in the CF annual reviews from 2013. Currently no guidelines exist as to the frequency of CPET in CF patients.
Aims To determine whether CPET was a useful and feasible routine test in children with CF and to assess whether VO2 peak correlated with Forced Expiratory Volume in 1 s (FEV1), disease severity, gender, genotype or previous intravenous antibiotics.
Method A pilot observational study was performed. Body mass index (BMI) was used as a marker of disease severity. Genotype was divided into 3 groups; DF508 homozygous, heterozygous and all other genotypes. Data was retrieved from case notes and our CF database.
Results 38 patients (17 male, 21 female) underwent CPET. Age range 7–14 (mean 9.8) years. 36/38 had technically satisfactory CPET. Mean VO2 peak was 107% predicted, standard deviation 18%. Only 8% had an abnormal VO2 peak. Mean FEV1 was 91% predicted, standard deviation 15%. There was no relationship between VO2 peak and FEV1 [p = 0.297] or BMI [p = 0.382] (Pearson correlation). Additionally, no correlation was demonstrated between VO2 peak and genotype [p = 0.236] (one-way ANOVA), gender [p = 0.902] or patients who had received at least one course of intravenous antibiotics in the past year [p = 0.253] (two-sample T test).
Conclusions CPET is a feasible test with 95% of our patients achieving technically satisfactory assessments and reassuringly, VO2 peak was largely normal. We could not demonstrate a relationship with FEV1 or disease severity although our study is limited by the small sample size. It is recognised that the CF annual review is already a long day for patients and we plan to reserve CPET for those showing exercise intolerance rather than performing it annually.
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Nixon PA, Orenstein DM, Kelsey SF, et al. The prognostic value of exercise testing in patients with cystic fibrosis. N Engl J Med 1992;327:1785–88
American Thoracic Society/American College of Chest Physicians. ATS/ACCP statement on cardiopulmonauy exercise testing. Am J Respir Crit Care Med 2003;167:211–77
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