Comparison of Vyntus CPX and Vmax Encore 29N for indirect calorimetry: a randomised crossover study in participants of the German Diabetes Study with type 2 diabetes.

Abstract

This study compared the reliability of two metabolic cart systems, Vyntus CPX and Vmax Encore 29N, to measure whole-body energy metabolism by indirect calorimetry (IC) in individuals with type 2 diabetes (T2D). Randomised, prospective, crossover study. Single-centre study conducted in the clinical research centre of the German Diabetes Study (GDS). Five participants (3 men, 2 women, mean age 49±6 years, body mass index (BMI) 32.62±4.2 kg/m²) with T2D completed the study protocol. Eligibility requires existing participation in GDS and availability for four consecutive study days. Participants underwent four IC measurements per day on four consecutive days, totalling 16 measurements per device. On each study day, two measurements with both devices, Vyntus CPX and Vmax Encore 29N, were performed in randomised order. Postcalorimetric gas calibration with normalisation was applied after each measurement. Reliability of respiratory quotient (RQ) and resting energy expenditure (REE), as assessed from the coefficient of variation (CV) and 95% CIs. Device comparison showed minor differences in CV (95% CI) for carbon dioxide production (VCO_₂) (3.5% vs 5.3%; 95% CI -8.2% to 8.0%), oxygen consumption (VO_₂) (3.4% vs 5.7%; 95% CI -9.3% to 8.2%), RQ (3.6% vs 2.3%; 95% CI -3.5% to 3.7%) and REE (3.1% vs 5.6%; 95% CI -8.4% to 7.8%). Postcalorimetric calibration did not consistently affect RQ or REE.  CONCLUSIONS: Vyntus CPX provides reliable IC measurements comparable to Vmax Encore 29N and may serve as a suitable replacement in clinical settings. ClinicalTrials.gov identifier: NCT01055093.