Original ArticleImproved Performance of the Fourth-Generation FloTrac/Vigileo System for Tracking Cardiac Output Changes

ObjectivesThe aims of this study were to compare cardiac output (CO) measured by the new fourth-generation FloTracTM/VigileoTM system (Version 4.00) (COFVS) with that measured by a pulmonary artery catheter (COREF), and to investigate the ability of COFVS to track CO changes induced by increased peripheral resistance.DesignProspective study.SettingUniversity Hospital.ParticipantsTwenty-three patients undergoing cardiac surgery.InterventionsPhenylephrine (100 µg) was administered.Measurements and Main ResultsHemodynamic variables, including COREF and COFVS, were measured before and after phenylephrine administration. Bland-Altman analysis was used to assess the discrepancy between COREF and COFVS. Four-quadrant plot and polar-plot analyses were utilized to evaluate the trending ability of COFVS against COREF after phenylephrine boluses. One hundred thirty-six hemodynamic interventions were performed. The bias shown by the Bland-Altman analysis was−0.66 L/min, and the percentage error was 55.4%. The bias was significantly correlated with the systemic vascular resistance index (SVRI) before phenylephrine administration (p<0.001, r2 = 0.420). The concordance rate determined by four-quadrant plot analysis and the angular concordance rate calculated using polar-plot analysis were 87.0% and 83.0%, respectively. Additionally, this trending ability was not affected by SVRI state.ConclusionsThe trending ability of the new fourth-generation FloTracTM/VigileoTM system after increased vasomotor tone was greatly improved compared with previous versions; however, the discrepancy of the new system in CO measurement was not clinically acceptable, as in previous versions. For clinical application in critically ill patients, this vasomotor tone-dependent disagreement must be decreased.