Accuracy and precision of CPET equipment: A comparison of breath-by-breath and mixing chamber systems

Abstract

Cardiopulmonary exercise testing (CPET) has become an important diagnostic tool for patients with cardiorespiratory disease and can monitor athletic performance measuring maximal oxygen uptake Vo2_{; max}. The aim of this study is to compare the accuracy and precision of a breath-by-breath and a mixing chamber CPET system, using two methods. First, this study developed a (theoretical) error analysis based on general error propagation theory. Second, calibration measurements using a metabolic simulator were performed. Error analysis shows that the error in oxygen uptake (Vo2) and carbon dioxide production (Vco2) is smaller for mixing chamber than for breath-by-breath systems. In general, the error of the flow sensor δV, the error in temperature of expired air δT_B and the delay time error δt_delay are significant sources of error. Measurements using a metabolic simulator show that breath-by-breath systems are less stabile for different values of minute ventilation than mixing chamber systems.

Keywords::

• Cardiopulmonary exercise testing
• Error analysis
• Metabolic simulator
• Breath-by-breath
• Mixing chamber

Acknowledgements

We thank Cosmed Italy for providing the CPET equipment and Accuramed Belgium for providing the metabolic simulator used in this study. The authors have no financial or business interests in any of the companies mentioned in this paper.

Declaration of interest: The authors report no declarations of interest.