Original ArticleInaccuracy of the FloTrac/Vigileo™ System in Patients With Low Cardiac Index

ObjectivesThe goal of this study was to compare cardiac output derived from the FloTrac/Vigileo™ system (COFT) with cardiac output measured by 3-dimensional transesophageal echocardiography (CO3D) in patients with severe heart failure undergoing cardiac resynchronization therapy. The impact of preoperative systemic vascular resistance index on the accuracy of the FloTrac/Vigileo™ system also was investigated.DesignProspective clinical study.SettingCardiac surgery operating room of a single cardiovascular center.ParticipantsForty-one patients undergoing elective cardiac resynchronization therapy lead implantation.InterventionsCO3D as the reference method and COFT were determined simultaneously after induction of anesthesia.Measurements and Main ResultsLinear regression analysis showed a poor correlation between CO3D and COFT (R² = 0.16). Bland-Altman plots showed wide limits of agreement between CO3D and COFT.. Bias was 0.60±0.63 L/min with a high percentage error of 58.2%. Subgroup analysis showed that the percentage error between CO3D and COFT was 74.1% in patients with a cardiac index<2.2 L/min/m2 and 17.2% in patients with a cardiac index≥2.2 L/min/m2. Systemic vascular resistance index was significantly higher in patients with a cardiac index<2.2 L/min/m2 (3,037±820 v 2,461±878; p = 0.039).ConclusionsThe FloTrac/Vigileo™ system is not accurate in patients with low cardiac output, especially those with a cardiac index<2.2 L/min/m2. A high systemic vascular resistance index in patients with low cardiac index may contribute to this inaccuracy.