Method Validation of Cardiopulmonary Exercise Testing: Intra- and Inter-Device Comparisons Across Four Metabolic Carts

Background: Cardiopulmonary exercise testing (CPET) is the gold standard for assessing exertional dyspnea, providing peak oxygen uptake (VO2), and the VE/VCO2 slope. Different metabolic carts, may introduce systematic variability, confounding longitudinal assessments and multicenter trials.We evaluated intra-device reliability and inter-device comparability of CPET parameters. Methods: In this prospective, single-center, within-subject, repeated-measures, multi-device comparison study 34 healthy adults (35±11 years; 59% males) completed eight CPETs: two per cart, on four systems (MGC Ultima™ CPX, COSMED Quark CPET™, Schiller PowerCube® Ergo, Vyaire Vyntus™ CPX). Tests used randomized order, ramp protocols on cycle ergometer, and standardized calibration, masks, and timing (2-10 days apart; within 40 days). Breath by breath data were 10-second averaged. Analyses included paired tests for intra-device reliability, repeated-measures ANOVA for inter-device comparisons, and iso-workload evaluation at 25-100% of lowest peak workload (ISO-Wpeak). Results: Intra-device reliability was high, with no significant differences in VO2, heart rate or workload at anaerobic threshold (AT), respiratory compensation point (RCP) or peak. Minor variances occurred in resting VO2 (COSMED: 56ml/min, p=0.0427) and peak ventilation (Medical Graphic 9 l/min, p<0.05). Inter-device comparability showed no differences in peak VO2 and the VE/VCO2 slope calculated up to the RCP. The VE/VCO2 slope assessed as the full slope however, showed significant differences between machines (p=0.0048). Across standardized ISO-Wpeak (25%, 50%, 75%, and 100% of ISO-Wpeak), VO2 values were largely comparable between devices, with significant differences only for VO2 (ml/kg/min) at 25% ISO-Wpeak (p=0.022). Conclusion: Under standardized conditions, the tested metabolic carts yield comparable values both for intra-device reliability and inter-device comparability.