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In-Field Validity and Inter-Unit Variability of Metabolic Carts During Simulated Exercise
Bas Van Hooren1, Tjeu Souren2, Bart C Bongers1,3
1Department of Nutrition and Movement Sciences, Institute of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands.
Summary
Cardiopulmonary exercise testing (CPET) systems show significant variability in accuracy, even identical units. Caution is advised when using CPET devices interchangeably due to potential measurement errors.
Area of Science:
- Cardiopulmonary physiology
- Medical device validation
- Exercise science
Background:
- Cardiopulmonary exercise testing (CPET) is crucial for assessing cardiorespiratory fitness and diagnosing conditions.
- The accuracy of CPET systems relies on precise measurement of respiratory gases.
- Variability in CPET device performance can impact clinical and research outcomes.
Purpose of the Study:
- To evaluate the in-field accuracy of commercial CPET systems under typical usage conditions.
- To quantify accuracy variability among identical CPET units.
- To investigate the influence of device age and maintenance on CPET accuracy.
Main Methods:
- Fifty-seven CPET systems were tested in clinical, research, and sports settings.
- Systems were assessed against a metabolic simulator for breath-by-breath gas exchange accuracy.
- Measured variables included minute ventilation (V̇E), oxygen uptake (V̇O2), carbon dioxide production (V̇CO2), and respiratory exchange ratio (RER).
Main Results:
- Absolute percentage errors varied significantly across systems, with V̇E errors up to 24.6%.
- Inter-unit variability for V̇O2, V̇CO2, and RER often exceeded intra-unit test-retest variability.
- No consistent correlation was found between system age, maintenance practices, and measurement accuracy.
Conclusions:
- Commercial CPET systems exhibit substantial in-field accuracy variations, even among identical units.
- Inter-unit variability necessitates caution when using different CPET devices interchangeably.
- Both technological and user-related factors contribute to inaccuracies, highlighting the need for comprehensive error identification.
