Summary: In a small validation study in people with type 2 diabetes, the Vyntus CPX metabolic cart gave reliable indirect-calorimetry measurements of energy expenditure and respiratory quotient comparable to the established Vmax Encore 29N, with only minor device differences.
PICO Summary
| Element | Detail |
|---|---|
| Population | 5 participants with type 2 diabetes (mean age 49, BMI 32.6) from the German Diabetes Study; randomised crossover validation study, 16 measurements per device. |
| Intervention | Whole-body energy metabolism measured by indirect calorimetry using the Vyntus CPX. |
| Comparison | The Vmax Encore 29N metabolic cart, measured in randomised order. |
| Outcome | Coefficients of variation were similar between devices for carbon dioxide production (3.5% vs 5.3%), oxygen consumption (3.4% vs 5.7%), respiratory quotient (3.6% vs 2.3%), and resting energy expenditure (3.1% vs 5.6%), with confidence intervals spanning zero. Post-calorimetric calibration did not consistently affect RQ or REE. The authors concluded the Vyntus CPX is a suitable replacement. |
Expert Commentary
This is a narrow methodological validation study, and it should be judged as such rather than as clinical research with patient outcomes. Its purpose is sound and genuinely useful, since metabolic-cart systems are periodically replaced and multi-site studies often mix equipment, so knowing whether a newer device agrees with an established one protects data comparability, and the crossover design measuring the same individuals on both systems is the right approach for that question. The conclusion of broad equivalence with only minor device-specific variation is reassuring for laboratories making this transition. The dominant limitation is unavoidable and must be stated plainly: only five participants were studied, so while the within-subject repeated-measures design provides many measurements, the tiny sample limits confidence in detecting small systematic differences and in generalising, and the study addressed resting rather than exercise calorimetry. Can I use this with my patients? Not directly, since this informs research and specialised metabolic-laboratory practice rather than bedside care. For clinicians who rely on indirect calorimetry for nutritional assessment, it offers modest reassurance that results are interpretable across these two platforms with proper calibration, while the small sample means laboratories should still verify agreement locally.
References
Trinks N, Pützer J, Sutkowski A, Burkart V, Roden M, Kuss O. 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. BMJ Open. 2025;15(12):e104761. doi:10.1136/bmjopen-2025-104761