The accuracy and trending ability of cardiac index measured by the fourth-generation FloTrac/Vigileo system™ and the Fick method in cardiac surgery patients.

To compare the accuracy and trending ability of the cardiac index (CI) measured by FloTrac/Vigileo™ (CI) or derived by the Fick equation (CI) using E-CAiOVX (enables continuous monitoring of oxygen consumption) with that measured by thermodilution (CI) in patients with off-pump coronary artery bypass surgery. Twenty-two patients undergoing elective off-pump coronary artery bypass surgery were included. CI and CI were determined simultaneously at six time-points during off-pump coronary artery bypass surgery. At each time-point, phenylephrine (50 µg) was administered to increase systematic vascular resistance, with CI measured before and after administration (CI used as reference method). Agreement of each method was evaluated by Bland-Altman analysis, while trending ability was evaluated by four-quadrant plot analysis and polar plot analysis. By Bland-Altman analysis, CI and CI showed percentage errors of 49.5% and 78.6%, respectively, compared with CI. Subgroup analysis showed a percentage error between CO and CO of 28.9% in patients with a CI ≥ 2.4 L/min/m, and 78.1% in patients with a CI ≥ 2.4 L/min/m. The concordance rate of four-quadrant plot analysis was 93.3% for CI and 66.7% for CI in datasets where CI ≥ 2.4 L/min/m before and after phenylephrine administration were included. CI and CI had wide limits of agreement with CI, and were below acceptable limits for tracking phenylephrine-induced CI changes. However, subgroup analysis showed improved accuracy and trending ability of CI when only points where CI ≥ 2.4 L/min/m were included, while there was no improvement in CI accuracy or trending ability.