Correlation of Carotid Doppler Blood Flow With Invasive Cardiac Output Measurements in Cardiac Surgery Patients

Objective: Carotid Doppler ultrasound has been a topic of recent interest, as it may be a promising noninvasive hemodynamic monitoring tool. In this study, the relation between carotid artery blood flow and invasive cardiac output (CO) was evaluated. Design: A prospective, observational study. Setting: A single-institution, tertiary referral hospital. Participants: Eighteen elective cardiac surgery patients. Interventions: CO was measured by calibrated pulse contour analysis. Simultaneously, carotid artery pulsed-wave Doppler measurements were obtained in the operating room in three clinical settings: after induction of anesthesia (T1), after a passive leg raise maneuverer (T2), and at the end of surgery (T3). Measurements and Main Results: Correlation and trending between carotid artery blood flow and invasive CO were evaluated. Furthermore, two Bland-Altman plots were constructed to evaluate the level of agreement between carotid artery-derived CO and invasive CO measurements. Carotid artery blood flow correlated moderately with invasive CO (ρ = 0.67, 95% confidence interval 0.56-0.76, p < 0.05). Concordance between the percentage change of carotid artery blood flow and invasive CO from T1 to T3 was 72%. The level of agreement between carotid artery-derived CO and invasive CO was ±2.29; ±2.57 L/min, with a bias of 0.1; –0.54 L/min, and mean error of 50% and 48%, for the two Bland-Altman analyses, respectively. Intraexamination precision was acceptable. Conclusions: In cardiac surgery patients, carotid artery blood flow correlated moderately with invasive CO measurements. However, the trending ability of carotid artery blood flow was poor, and carotid artery-derived CO tended not to be interchangeable with invasive CO

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 (ΔVpeakCCA) and left ventricular outflow tract (ΔVpeakLVOT) is derived from the pulsed wave Doppler waveform and may predict fluid responsiveness. The aim of this study was to evaluate ΔVpeakCCA and ΔVpeakLVOT 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 ΔVpeakCCA was strong (ρ = 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 ΔVpeakCCA correlation was also strong (ρ = 0.73), bias was −0.2%, LOA +/− 7.6%, with intermediate acceptable concordance (90%), and low clinical agreement (72%). Analysis of ΔVpeakLVOT measurements demonstrated poor statistical agreement with SVV and PPV. In conclusion, in cardiac surgery patients ΔVpeakCCA, as opposed to ΔVpeakLVOT, has acceptable statistical and clinical agreement with SVV measurements. ΔVpeakCCA may qualify as a potential tool for non-invasive assessment of fluid responsiveness

Evaluating corrected carotid flow time as a non-invasive parameter for trending cardiac output and stroke volume in cardiac surgery patients

PURPOSE: The corrected carotid flow time (ccFT) is derived from a pulsed-wave Doppler signal at the common carotid artery. Several equations are currently used to calculate ccFT. Its ability to assess the intravascular volume status non-invasively has recently been investigated. The purpose of this study was to evaluate the correlation and trending ability of ccFT with invasive cardiac output (CO) and stroke volume (SV) measurements. METHODS: Eighteen cardiac surgery patients were included in this prospective observational study. ccFT measurements were obtained at three time points: after induction of anesthesia (T1), after a passive leg raise (T2), and post-bypass (T3). Simultaneously, CO and SV were measured by calibrated pulse contour analysis. Three different equations (Bazett, Chambers, and Wodey) were used to calculate ccFT. The correlation and percentage change in time (concordance) between ccFT and CO and between ccFT and SV were evaluated. RESULTS: Mean ccFT values differed significantly for the three equations (p < 0.001). The correlation between ccFT and CO and between ccFT and SV was highest for Bazett's (ρ = 0.43, p < 0.0001) and Wodey's (ρ = 0.33, p < 0.0001) equations, respectively. Concordance between ΔccFT and ΔCO and between ΔccFT and ΔSV was highest for Bazett's (100%) and Wodey's (82%) equations, respectively. Subgroup analysis demonstrated that correlation and concordance between SV and ccFT improved when assessed within limited heart rate (HR) ranges. CONCLUSION: The use of different ccFT equations leads to variable correlation and concordance rates between ccFT and CO/SV measurements. Bazett's equation acceptably tracked CO changes in time, while the trending capability of SV was poor