Correlation of corrected flow time in the carotid artery with changes in intravascular volume status

Assessment of volume status remains a challenge in critical care. Our purpose was to determine if Doppler waveform analysis of carotid artery blood flow correlates with changes in volume status. Dehydrated patients receiving an intravenous fluid bolus were enrolled with exclusions including age less than 18 years, pregnancy, vasopressor administration, or atrial fibrillation. Ultrasound examination with Doppler analysis of the carotid artery was performed with measurements taken to calculate corrected flow time (FTc). Corrected flow time, mean arterial pressure, and pulse rate before and after fluid administration were compared using Wilcoxon matched-pairs signed rank test. Fifty-six patients were enrolled with mean fluid administration of 1110 mL. Corrected flow time increased with fluid resuscitation from prefluid mean of 299 milliseconds (95% confidence interval [CI], 282-317 milliseconds) to a postfluid mean of 340 milliseconds (95% CI, 323-358 milliseconds) (P < .0001). Mean percentage change in FTc was 14.9% (95% CI, 8.4-21.3). There were no significant changes in mean arterial pressure or heart rate from pre– to post–fluid administration. Intravenous fluid administration in dehydrated patients resulted in significant changes in FTc in the carotid artery despite no change in vital signs. Corrected flow time measured from carotid arterial blood flow may be a useful means of assessing volume status in volume-depleted patients.