Evaluating carotid and aortic peak velocity variation as an alternative index for stroke volume and pulse pressure variation: a method comparison study

The peak velocity variation within the carotid artery ( VpeakCCA) and left ventricular outflow tract ( VpeakLVOT) is derived from the pulsed wave Doppler waveform and may predict fluid responsiveness. The aim of this study was to evaluate VpeakCCA and VpeakLVOT against calibrated stroke volume variation (SVV) and pulse pressure variation (PVV). Therefore, eighteen cardiac surgery patients were included in this prospective observational study. Doppler measurements were performed after induction of anesthesia, after a passive leg raise, and at the end of surgery. Simultaneously, SVV and PPV were measured by pulse-contour-analysis (PiCCO). The correlation, methodological agreement, concordance, and clinical agreement between Doppler and PiCCO measurements were assessed. The correlation between SVV and VpeakCCA was strong (p = 0.88). Bland-Altman analysis demonstrated a bias of 0.01%, and LOA +/- 4.6%, acceptable concordance (93%), and close to acceptable clinical agreement (88%). For PPV and VpeakCCA correlation was also strong (p = 0.73), bias was -0.2%, LOA +/- 7.6%, with intermediate acceptable concordance (90%), and low clinical agreement (72%). Analysis of VpeakLVOT measurements demonstrated poor statistical agreement with SVV and PPV. In conclusion, in cardiac surgery patients VpeakCCA, as opposed to VpeakLVOT, has acceptable statistical and clinical agreement with SVV measurements. VpeakCCA may qualify as a potential tool for non-invasive assessment of fluid responsiveness.