ABC | Volume 113, Nº2, August 2019

Original Article Coll et al Non-invasive cardiac output measurement Arq Bras Cardiol. 2019; 113(2):231-239 Table 2 – Anthropometric, echocardiographic, and maximal exercise characteristics of the participants (male: n = 10; female: n = 7) Variable Mean ± 90% CI Age (years) 46 ± 1 BMI (kg/m 2 ) 23.9 ± 0.9 IVSd (mm) 9.6 ± 0.5 LVed (mm) 46.9 ± 1.8 PLWd (mm) 9.9 ± 0.5 FS (%) 26.9 ± 2.0 EF (%) 66.0 ± 2.2 E´ (cm/s) 9.9 ± 1.1 E/E´ 8.5 ± 1.3 Tlim (min:s) 19:42 ± 4:39 Pmax (W) 187 ± 23 VO 2peak (ml/min/kg) 33 ± 4 VAT (%VO 2peak ) 60.7 ± 4.0 CI: confidence interval; BMI: body mass index; IVSd: interventricular septal diastole; LVed: left ventricle end-diastolic diameter; PLWd: left ventricular posterior wall thickness; FS: fractional shortening; EF: ejection fraction; E`: peak mitral annular velocity during early filling; E/E`: ratio between early mitral inflow velocity and mitral annular early diastolic velocity; Tlim: time to exhaustion; Pmax: maximum workload; VO 2peak: peak oxygen uptake; VAT: ventilatory anaerobic threshold. Table 4 summarizes the relative and absolute reliability expressed by ICCs and TEs, respectively, for all measured parameters. The ICCS ranged from moderate (ICC: 0.59) to very high (ICC: 0.98), whereas the TEs ranged from small (ES: 0.3) to large (ES: 1.8). CPO demonstrated superior relative and absolute reliability under all measurement conditions (ICC: 0.80-0.85; ES: 0.9-1.1) than its underlying parameters (ICC: 0.59-0.98; ES: 0.3-1.8). Relationships Figure 1 shows the relationships between echocardiographic measures of cardiac structure and function, traditional cardiopulmonary exercise parameters, and peak CPO. The peak CPO correlated moderately with VO 2peak (Figure 1A: r = 0.68; R 2  = 0.47) and VAT (Figure 1B: r = 0.55; R 2  = 0.31), but only small with left ventricular wall thickness (Figure 1E: r = 0.33; R 2 = 0.11), left ventricular end-diastolic diameter (Figure 1F: r = 0.38; R 2  = 0.14), and systolic (Figure 1C: r = –0.32; R 2  = 0.11) as well as trivial with diastolic function (Figure 1D: r = 0.20; R 2  = 0.04). Discussion Our main findings were: (1) there were no systematic bias for all measured parameters during all conditions, (2) all noninvasively measured hemodynamic parameters showed Table 3 – Changes in means of the resting, submaximal and maximal hemodynamic and cardiorespiratory characteristics Variable Test 1 Mean ± 90% CI Test 2 Mean ± 90% CI Bias Mean ± 90% CI SWD Likelihood (%) for Bias beeing higher/trivial/lower than SWD ES ± 90% CI Rest CPO (W) 1.2 ± 0.1 1.2 ± 0.1 0.0 ± 0.1 0.1 11.3/77.4/11.3 (unclear) 0.2 ± 0.3 (small) CO (l/min) 5.61 ± 0.30 6.04 ± 0.31 +0.43 ± 0.19 0.47 43.6/56.4/0.0 (possibly trivial) 0.6 ± 0.3 (moderate) SV (ml) 83 ± 6 87 ± 7 +4 ± 3 10 13.2/86.2/0.6 (likely trivial) 0.3 ± 0.2 (small) HR (1/min) 71 ± 4 74 ± 5 +3 ± 2 7 15.1/84.4/0.5 (likely trivial) 0.3 ± 0.2 (small) MAP (mmHg) 96 ± 4 92 ± 4 -4 ± 3 6 8.5/53/38.5 (unclear) 0.2 ± 0.2 (small) Submaximal CPO (W) 3.6 ± 0.5 3.4 ± 0.4 -0.2 ± 0.3 0.7 9.1/89.9/1.0 (likely trivial) 0.2 ± 0.3 (small) CO (l/min) 13.95 ± 1.23 13.66 ± 1.04 -0.29 ± 1.07 1.77 1.6/92.5/5.9 (likely trivial) 0.1 ± 0.5 (small) SV (ml) 100 ± 7 100 ± 8 -1 ± 6 12 2.9/94.2/2.9 (likely trivial) 0.1 ± 0.4 (small) HR (1/min) 133 ± 10 131 ± 10 -3 ± 2 15 2.4/91.1/6.5 (likely trivial) 0.1 ± 0.1 (small) MAP (mmHg) 115 ± 6 112 ± 6 -3 ± 1 9 0.8/90.7/8.5 (likely trivial) 0.2 ± 0.1 (small) Maximal CPO (W) 4.4 ± 0.5 4.2 ± 0.5 -0.2 ± 0.3 0.7 11.3/87.0/1.7 (likely trivial) 0.2 ± 0.3 (small) CO (l/min) 16.09 ± 1.31 15.51 ± 1.28 -0.58 ± 1.01 2.01 1.0/89.9/9.1 (likely trivial) 0.2 ± 0.4 (small) SV (ml) 98 ± 9 95 ± 10 -3 ± 7 14 1.7/90.1/8.2 (likely trivial) 0.2 ± 0.4 (small) HR (1/min) 164 ± 7 161 ± 7 -3 ± 3 11 1.0/89.9/9.1 (likely trivial) 0.2 ± 0.2 (small) MAP (mmHg) 123 ± 6 122 ± 6 -1 ± 4 9 1.8/94.2/4.0 (likely trivial) 0.1 ± 0.3 (small) P (W) 187 ± 23 190 ± 25 +3 ± 6 38 3.2/95.0/1.8 (very likely trivial) 0.1 ± 0.1 (small) VO 2 (l/min) 2.40 ± 0.27 2.39 ± 0.29 -0.01 ± 0.07 0.43 3.1/93.2/3.7 (likely trivial) 0.0 ± 0.1 (small) CI: confidence interval; SWD: smallest worthwhile differences; ES: effect size; CPO: cardiac power output; CO: cardiac output; SV: stroke volume; HR: heart rate; MAP: mean aterial pressure; P: workload; VO 2: oxygen uptake. 234