Inaccuracy of the FloTrac/Vigileo™ system in patients with low cardiac index.

Abstract

The goal of this study was to compare cardiac output derived from the FloTrac/Vigileo™ system (CO(FT)) 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. Prospective clinical study. Cardiac surgery operating room of a single cardiovascular center. Forty-one patients undergoing elective cardiac resynchronization therapy lead implantation. CO3D as the reference method and CO(FT) were determined simultaneously after induction of anesthesia. Linear regression analysis showed a poor correlation between CO3D and CO(FT) (R² = 0.16). Bland-Altman plots showed wide limits of agreement between CO3D and CO(FT.). 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 CO(FT) was 74.1% in patients with a cardiac index<2.2 L/min/m(2) and 17.2% in patients with a cardiac index ≥ 2.2 L/min/m(2). Systemic vascular resistance index was significantly higher in patients with a cardiac index<2.2 L/min/m(2) (3,037 ± 820 v 2,461 ± 878; p = 0.039). The FloTrac/Vigileo™ system is not accurate in patients with low cardiac output, especially those with a cardiac index<2.2 L/min/m(2). A high systemic vascular resistance index in patients with low cardiac index may contribute to this inaccuracy.