Comparison of two minimally invasive cardiac-output monitoring systems with different algorithms

Abstract

Objectives: Minimally invasive haemodynamic monitoring is important in goal-directed therapy. The algorithms used by the FloTrac/Vigileo (FV) and lithium dilution cardiac output rapid (LiDCOrapid) (LR) measurement systems for cardiac output (CO) monitoring differ. We examined correlations of FV and LR measurements with thermodilution measurements and determined responsiveness to phenylephrine using both systems. Methods: The FV system was used as the main arterial pressure line, and a second line was connected to the LR system. First, we measured CO at multiple time points using thermodilution and compared these measurements with those obtained simultaneously using the LR and FV systems. Second, CO, systemic vascular resistance and stroke volume (SV) were simultaneously measured using the LR and FV systems after phenylephrine administration. Results: Measurements obtained at 38 time points in 3 patients were compared. There were strong correlations of LR and FV measurements with thermodilution measurements. Bland–Altman analysis indicated that LR (percentage error, PE, 29.8%) and FV (PE, 31.6%) system measurements were equivalent to thermodilution measurements. Following phenylephrine administration, the LR system detected an increase in blood pressure following an increase in vascular resistance, with negligible change in SV. Conversely, the FV system detected little change in vascular pressure and a marked increase in SV. Conclusions: Compared with thermodilution, both the LR and FV systems demonstrated sufficient accuracy and precision for clinical use. The LR system was more accurate than the FV system in reflecting rapid changes in blood pressure, vascular resistance and CO following phenylephrine administration.

Keywords

• minimally invasive haemodynamic monitoring
• pulseco/lidcorapid
• flotrac/vigileo
• thermodilution
• cardiac output
• phenylephrine