Systemic vascular resistance has an impact on the reliability of the Vigileo-FloTrac system in measuring cardiac output and tracking cardiac output changes.

Abstract

The aim of this study was to examine the ability of the Vigileo-FloTrac system to measure cardiac output (CO) and track changes in CO induced by increased vasomotor tone, under different states of systemic vascular resistance (SVR). Forty patients undergoing cardiac surgery were enrolled. Haemodynamic variables including CO measured by the Vigileo-FloTrac system (version 3.02) (APCO), CO measured by a pulmonary artery catheter (ICO), and SVR index (SVRI) were recorded before (T1) and 2 min after (T2) phenylephrine administration (100 μg). Bland and Altman analysis was used to compare ICO and APCO at T1. We used four-quadrant plots and polar plots to compare the trending abilities between ICO and APCO. Patients were divided into three groups according to the SVRI value at T1, with low (<1200 dyn cm(-5) m(2)), normal (1200-2500 dyn cm(-5) m(2)), and high (>2500 dyn cm(-5) m(2)) SVRI states. A total of 155 paired data were collected. The adjusted percentage error was 46.3%, 26.4%, and 61.4%, and the concordance rate between ΔICO and ΔAPCO was 67.5%, 28.8%, and 7.7% in the low, normal, and high SVRI state, respectively. The polar plot analysis showed that the mean angular bias was -22.3°, -46.0°, and -3.51°, and the radial limits of agreement were 70°, 85°, and 87°, in the low, normal, and high SVRI state, respectively. These results indicate that the reliability of the Vigileo-FloTrac system to measure CO and track changes in CO induced by phenylephrine administration was not clinically acceptable.