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

Abstract

Background: 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).

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Vigileo-FloTrac system; cardiac output; phenylephrine; systemic vascular resistance.