Evaluation of Carotid Flow Time to Assess Fluid Responsiveness in the Emergency Department

Abstract

Background: Assessing fluid responsiveness in critically ill patients is challenging. Objective, noninvasive tests that are easy to perform are needed. Doppler measurements of dynamic carotid artery parameters such as carotid blood flow (CBF) and carotid flow time (CFT) are being studied as the potential indicators of volume responsiveness, but the data supporting its use are sparse. Methods: This prospective, observational study was conducted in the adult emergency department from June to September 2018. Patients who were prescribed a bolus of 500 ml of crystalloid for any indication were enrolled. Carotid Doppler was performed before and after a fluid bolus to measure the change in CBF and CFT. The aim of our study was to determine if CFT can be used as a marker of fluid responsiveness. Results: During the 4-month study period, 209 patients were recruited through convenient sampling after obtaining informed written consent. 29.6% of patients presented with a mean arterial pressure (MAP) <65, among whom 58.1% had septic shock. The baseline CBF was 643.0 ± 212.7 ml/min, and it was 583.9 ± 207.1 ml/min and 668 ± 210.8 ml/min in hypotensive and normotensive patients, respectively. Considering a >10% increase in CBF as fluid response, there were 59% responders and 41% nonresponders. The MAP increased by 9.5% in the responders, while there was no significant change in CFT after the fluid bolus. There was no difference in CFT among the responders as compared to the nonresponders. There was no correlation between the change of CBF and CFT ( r [207] = 0.013, P = 0.061) after the fluid bolus. Conclusion: Though easy to perform, CFT is probably not a good indicator of fluid responsiveness.

Dynamic Carotid Doppler Indices Predict Fluid Responsiveness in PostOperative Cardiac Patients

“…Many studies mentioned that corrected flow time could be appropriate surrogate for the patients`volume position. To the contrary of our finding, Judson PI, et al, (18) establish that there was no alteration in CFT among the fluid responder and non-responder patients. In addition, they mentioned that Neither cerebral blood flow nor cerebral vascular resistance changed in tandem with cerebral vascular resistance.This study was conducted in the ED, among patients with varied diagnosis and volume status, in contrast to our post-operative cardiac cohort.…”

The Correlation between Carotid Artery Corrected Flow Time and Velocity Time Integral during Central Blood Volume Loss and Resuscitation

“…who found a poor relationship between carotid blood flow and ccFT in septic patients receiving intravenous fluids. [ 18 ] Although there are many differences between their investigation and ours, we suspect that at least one key mediator is the number of consecutive cardiac cycles considered in their study, which was only 3. This number of sampled heartbeats is common in Doppler studies, but our data illustrate why this could be problematic.…”

“…[ 16 17 ] However, we did not correlate changing carotid VTI with ccFT during these maneuvers which represents a noteworthy gap in our knowledge, given that one group found a poor relationship between ccFT and carotid blood flow. [ 18 ]…”

Novel Methods for Predicting Fluid Responsiveness in Critically Ill Patients—A Narrative Review

“…The CFTc change threshold value of 7 ms was identified as the best predictor of fluid responsiveness with a high degree of diagnostic accuracy (ROC AUC 0.88). On the other hand, Judson et al observed an increase in MAP after administering a fluid challenge to patients in septic shock without a corresponding change in CFTc [ 70 ].…”