Repeatability and methodology of resting energy expenditure in patients with cystic fibrosis

In this study, intra-individual variation of resting energy expenditure (REE) in adults with cystic fibrosis (CF) and the effect of measurement duration were determined. Twelve adults with CF and chronic Pseudomonas aeruginosa (Ps. aeruginosa) infection and 12 healthy volunteers, matched for age and sex were studied whilst clinically stable on days 1.2, and 15. Respiratory gas exchange was monitored by continuous measurement of oxygen uptake (VO2) and carbon dioxide production (VCO2) using a ventilated hood indirect calorimeter. Coefficients of variation (CVs) were 4.3% in patients and 2.4% in controls comparing days 1 and 2. The CV for patients was 5.0% and for controls 2.9% comparing days 1 and 15. The effect of measurement duration on REE was assessed in eight of the CF patients. REE remained stable for 40 min but tended to rise by 80 min. Plasma catecholamine concentrations were stable between study days in patients but fell with time in controls suggesting some adaptation to experimental procedure. The greater variability of REE in patients was related to change in serum CRP over 2 weeks. REE is a repeatable measurement in clinically stable patients with CF, though variability was greater in patients than healthy subjects. This has implications for the design and interpretation of longitudinal studies of REE in patients with chronic lung disease.