ABC | Volume 113, Nº2, August 2019

Original Article Coll et al Non-invasive cardiac output measurement Arq Bras Cardiol. 2019; 113(2):231-239 Figure 1 – Relationships between the CPO and established cardiorespiratory and echocardiographic characteristics. CPO: cardiac power output; VO 2peak: peak oxygen uptake; VAT: ventilatory anaerobic threshold; EF: ejection fraction; E/E‘: ratio between early mitral inflow velocity and mitral annular early diastolic velocity; r: Pearson correlation coefficient; R 2 : coefficient of determination. 10.0 8.0 (A) (B) (C) (D) (E) (F) 6.0 4.0 2.0 0.0 0.5 1.5 2.5 3.5 4.5 10.0 8.0 6.0 4.0 2.0 0.0 0.5 0.0 0.0 4.0 8.0 12.0 16.0 20.0 1.5 1.0 2.5 2.0 3.0 VO 2 peak (l/min) EF (%) IVSd (mm) LVed (mm) E/E’ CPO (W) 10.0 8.0 6.0 4.0 2.0 0.0 50.0 35.0 40.0 45.0 50.0 60.0 55.0 5.0 7.0 9.0 11.0 13.0 55.0 60.0 70.0 80.0 75.0 65.0 CPO (W) 10.0 8.0 6.0 4.0 2.0 0.0 CPO (W) 10.0 8.0 6.0 4.0 2.0 0.0 CPO (W) 10.0 8.0 6.0 4.0 2.0 0.0 CPO (W) VAT (l/min) CPO (W) y = 1.1226x + 1.6342 r = 0.68; R 2 = 0.47 y = –0.0669x + 8.7339 r = –0.32; R 2 = 0.11 y = 0.2786x + 1.6329 r = 0.33; R 2 = 0.11 y = 0.0932x + 0.0549 r = 0.38; R 2 = 0.14 y = 0.0686x + 3.7348 r = 0.20; R 2 = 0.04 y = 1.3654x + 2.2836 r = 0.55; R 2 = 0.31 In sports medicine, monitoring of the training status is essential to guide the training process. Training leads to significant structural and functional changes of the cardiovascular system. 6 In a randomized cross-over study, Marshall et al. 38 assessed the effect of moderate exercise training on cardiac performance in non-athletic adults. Due to training, the CPO peak increased by 16%, whereas the CPO at rest remained unchanged. In highly trained endurance athletes, Schlader et al. 37 found double CPO peak values compared to non-athletes. These results have been confirmed by Klasnja et al. 3 in football and basketball players. In our study, the CPO peak showed superior reliability than the underlying physiological single parameters. However, it should be noted that the reliability of the CPO was potentially influenced by the reliability of the MAP (which was higher) rather than that of the SV and CO (which were lower). Thus, CPO measuring by TB seems to be feasible due to its surrogate character. It is, however, important to mention that we have averaged all our beat-by-beat measured TB data, including the CPO, over 60 s, which might have also artificially improved our statistical outcomes. The reason for our data processing method was that we aimed to investigate 236