Carotid Doppler Imaging as a Marker for Fluid Responsiveness.

Identifying fluid-responsive patients is essential in managing hemodynamic instability. Traditional static measures like central venous pressure (CVP) are often unreliable. Prior studies suggest that cardiac ultrasound (US), particularly carotid Doppler point-of-care ultrasound (POCUS), may correlate with pulmonary artery catheter (PAC)-derived cardiac output (CO), offering a noninvasive tool to assess fluid responsiveness. We aimed to evaluate the correlation between carotid ultrasound (US) parameters and pulmonary artery catheter (PAC) derived measurements in post cardiac surgery patients. We conducted a prospective cohort study on 50 postcardiac surgery patients from 2019 to 2022 in a single cardiothoracic ICU. Carotid US and PAC CO measurements were obtained at four intervals: pre- and post-passive leg raise (fluid challenge) on ICU admission, and one hour later. Fluid responsiveness was defined as a ≥10% increase in carotid blood flow, ≥7 ms increase in corrected flow time (FTc), or ≥10% change in respiratory peak carotid systolic velocity (ΔCDPV). Pearson's correlation and linear regression were used to assess associations between carotid US and PAC changes. Agreement in fluid responsiveness categorization (≥10% CO change) was evaluated using weighted Cohen's kappa. Significance was set at α = 0.05. No significant correlation was found between changes in carotid US parameters and the PAC cardiac index (CI) at baseline or one hour for ΔCDPV, FTc, or carotid blood flow. A moderate correlation was observed between carotid blood flow and FTc at one hour (r = 0.41, = 0.005). Regression and sensitivity analyses showed no significant associations. The carotid US parameters did not correlate with PAC-derived CO after passive leg raise. Further studies are needed to validate carotid POCUS in this setting.