The Diagnostic Utility of Sonographic Carotid Flow Time in Determining Volume Responsiveness

J Crit Care. 2017 Apr;38:231-235. doi: 10.1016/j.jcrc.2016.10.025. Epub 2016 Nov 9.


Objective: We aimed to predict volume responsiveness and to assess the diagnostic accuracy of carotid flow time (FTc) with the change in hydration status before and after a passive leg raise (PLR) maneuver.

Methods: Participants who presented at a community health fair in a dehydrated state following a prolonged fast while observing the month of Ramadan were recruited. Sonographic FTc measurements were obtained in the semi-Fowler position and after a PLR maneuver while participants were in a fasting state and repeated approximately 3 hours after breaking their fast.

Results: In total, 123 participants with mean age of 47±14 years, 55% male, were enrolled. Participants had fasted for an average of 16.9 hours and consumed an average of 933 mL between the 2 ultrasound measurements. Mean FTc values were significantly lower in the fasting state compared with the nonfasting state (312±22 vs 345±25milliseconds, P value < .001). Relative increases in FTc following a PLR maneuver demonstrated strong discrimination of volume status (area under the receiver operating curve: 0.86 [95% confidence interval, 0.81-0.91]).

Conclusions: The use of point-of-care ultrasound to measure FTc may provide a noninvasive alternative to determine fluid status. Percentage change in FTc of ≥5% provides a reliable diagnostic accuracy for predicting fluid status.

Keywords: Carotid Doppler; Carotid flow time; Dehydration; Shock; Ultrasound; Volume status.

Publication types

  • Evaluation Study

MeSH terms

  • Carotid Arteries / physiology*
  • Critical Care
  • Dehydration / diagnosis
  • Dehydration / diagnostic imaging*
  • Dehydration / physiopathology
  • Dehydration / therapy
  • Female
  • Fluid Therapy*
  • Hemodynamics / physiology*
  • Humans
  • Male
  • Middle Aged
  • Posture
  • Prospective Studies
  • ROC Curve
  • Regional Blood Flow
  • Reproducibility of Results
  • Stroke Volume
  • Ultrasonography