Is supra-ventricular arrhythmia a reason for the bad performance of the FlowTrac device?

In their recent paper evaluating arterial waveform analysis as a tool to measure cardiac output (CO), Michael Sander and colleagues do not provide data on the heart rhythms of their cardiac surgery patients [1]. As the FloTrac (Flowtrac/Vigileo, Edwards Lifescience, Munich, Germany) device calculates CO from an arterial pressure-based algorithm, integrating vessel compliance and peripheral resistance effects, it seems plausible that these measurements may be influenced by cardiac arrhythmia.