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Flow Trac™ cardiac output determination correlates with echocardiography


A new device may be used in intensive care to measure the cardiac output (CO) by arterial pulse pressure waveform analysis, but few studies have evaluated the reliability of this method and the correlation with other methods of CO determination. The aims of this study were to evaluate the CO obtained using the Flow Trac™ Vigileo™ and the correlation with CO obtained by transthoracic echocardiography (TTE).

Materials and methods

Ten critical care patients admitted to a general ICU were enrolled in the study. All patients were mechanically ventilated (tidal volume 6–8 ml/kg, plateau pressure < 30 cmH2O) and connected to an integrated monitoring system (Flow Trac™/Vigileo™; Ewdards Lifescience, Irvine, CA, USA) that attaches to an arterial cannula. After haemodynamic stabilization the CO was calculated from an arterial pressure-based algorithm that utilises the relationship between pulse pressure and stroke volume. At the same time a TTE examination was performed (Hewlett Packard, SONO 1000) and the CO was calculated by Doppler measurement of the left ventricular outflow area (LVOT) and the velocity-time integral (VTI LVOT), assuming stroke volume = cross-sectional area × VTI. Every patient had two CO determinations by TTE during Flow Trac™ measurement. A regression analysis and Bland–Altman analysis were used to compare the two methods of CO determination.


A total of 40 CO determinations were performed in 10 patients. Table 1 reports the main results.

Table 1 abstract


CO measurements obtained by Flow Trac™ show agreement with CO TTE with no clear bias, but comparative studies with thermodilution are warranted.

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Turani, F., Falco, M., De Chiara, A. et al. Flow Trac™ cardiac output determination correlates with echocardiography. Crit Care 11 (Suppl 2), P300 (2007).

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