Assessment of Carotid Doppler Parameters to Evaluate Volume Status: A Prospective Observational Study

Q: What are the key findings of this study?

Carotid Doppler ΔFTc and ΔVTI after passive leg raise showed moderate accuracy for discriminating dehydration from hydration (AUC 0.715 and 0.708, respectively).

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Hydration status and preload responsiveness (fasting-induced relative dehydration) (n=202). Intervention: Carotid Doppler ultrasound parameters (corrected flow time [FTc] and velocity-time integral [VTI]) before and after passive leg raise (PLR) across hydration states vs. Nonfasting normal hydration state (n=99) and post-rehydration state (~4 hours after breaking fast). Primary outcome: Diagnostic performance (ROC AUC) of relative percent changes in carotid FTc (ΔFTc) and VTI (ΔVTI) after passive leg raise for discriminating presumed dehydrated from presumed hydrated states (AUC 0.715 for ΔFTc; AUC 0.708 for ΔVTI, 95% CI 0.643-0.786, p=<0.001).

Q: What does this research mean for the field?

Carotid Doppler-derived changes in corrected flow time and velocity-time integral following passive leg raise demonstrate moderate accuracy for distinguishing dehydration from hydration states. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

To assess the diagnostic utility of carotid Doppler-derived corrected flow time (FTc) and velocity-time integral (VTI), and their changes after passive leg raise, for evaluating volume status and preload responsiveness.

Haya Farhat; Gilbert Abou Dagher; Teisir Zaatari; Maha H. Makki; Hani Tamim; Ralphe Bou Chebl

doi:10.1016/j.acepjo.2026.100533

October 20, 2026Journal of the American College of Emergency Physicians OpenOpen Access

Assessment of Carotid Doppler Parameters to Evaluate Volume Status: A Prospective Observational Study

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Key result

Carotid Doppler changes after passive leg raise moderately detect dehydration with ~0.71 AUC.

AUC 0.715 for ΔFTc; AUC 0.708 for ΔVTI
95% CI 0.643-0.786
P<0.001
n=202

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Why the study?

Accurate assessment of volume status is essential to avoid fluid overload, and carotid Doppler ultrasound has emerged as a rapid, noninvasive alternative to technically demanding echocardiographic measures. This study evaluated the utility of carotid Doppler-derived corrected flow time and velocity-time integral changes after passive leg raise in assessing volume status and preload responsiveness.

Do passive leg raise-induced changes in carotid Doppler-derived corrected flow time (ΔFTc) and velocity-time integral (ΔVTI) accurately discriminate between dehydrated and hydrated states in healthy volunteers?

Key Points

To assess the diagnostic utility of carotid Doppler-derived corrected flow time (FTc) and velocity-time integral (VTI), and their changes after passive leg raise, for evaluating volume status and preload responsiveness.
Prospective observational study enrolling 202 participants, including 99 presumed hydrated controls and 103 fasting study participants evaluated during fasting (mean duration 12.36 ± 1.09 hours) and after rehydration (consuming a mean of 920.39 ± 351.78 mL of fluid).
Carotid Doppler ultrasound measurements of FTc and VTI were recorded before and after a passive leg raise maneuver across all hydration states.
Diagnostic performance of percent changes in FTc (ΔFTc) and VTI (ΔVTI) for distinguishing dehydrated from hydrated states was analyzed using receiver operating characteristic (ROC) curves.
Following passive leg raise, a ≥10% increase in VTI occurred in 57.2% of presumed dehydrated participants compared with 26.3% of hydrated controls and 20.4% after rehydration, while a ≥5% increase in FTc occurred in 47.6%, 17.2%, and 22.3%, respectively.
ROC analysis showed moderate discriminatory ability for presumed dehydration, with an area under the curve of 0.708 (95% CI 0.635-0.780) for ΔVTI and 0.715 (95% CI 0.643-0.786) for ΔFTc.
Optimal diagnostic cutoff values to distinguish dehydration were 5.92% for ΔVTI (sensitivity 0.79, specificity 0.60) and 5.05% for ΔFTc (sensitivity 0.47, specificity 0.75).

Study Design

Type

Cohort (n=202)

Blinding

Open-label

Multicenter

No

Structured PICO

Do passive leg raise-induced changes in carotid Doppler-derived corrected flow time (ΔFTc) and velocity-time integral (ΔVTI) accurately discriminate between dehydrated and hydrated states in healthy volunteers?

P

Population

202 healthy emergency department volunteers in Lebanon (mean age ~34.7 years, 38.6% female), including 103 participants undergoing ~12.4 hours of Ramadan fasting assessed before and ~3.8 hours after rehydration and 99 nonfasting hydrated controls.

E

Exposure

Carotid Doppler ultrasound evaluation of corrected flow time (FTc, calculated via Wodey formula) and velocity-time integral (VTI) before and after a passive leg raise (PLR) maneuver during presumed dehydration (mean 12.36 ± 1.09 hours of Ramadan fasting).

C

Comparator

Nonfasting presumed hydrated control group (n=99) and presumed rehydrated state in the fasting group assessed 3.81 ± 0.58 hours after breaking fast (mean fluid intake 920.39 ± 351.78 mL).

O

Outcome

Diagnostic performance (area under the ROC curve) of relative percent changes in carotid FTc (ΔFTc) and VTI (ΔVTI) after PLR for discriminating between presumed dehydrated and presumed hydrated states.surrogate

Main Result

Effect estimate: AUC 0.715 for ΔFTc; AUC 0.708 for ΔVTI (95% CI 0.643-0.786)

Absolute Event Rate: 57.2% vs 26.3%

p-value: p=<0.001

Carotid Doppler-derived ΔFTc and ΔVTI in response to passive leg raise offer a practical, noninvasive bedside method with moderate accuracy for detecting relative volume depletion and preload responsiveness.

Limitations

Study population consisted of healthy volunteers rather than critically ill patients, limiting generalizability to shock populations
Hydration status was defined according to fasting and rehydration status rather than invasive hemodynamic monitoring or laboratory biomarkers
Fluid responsiveness was not confirmed using invasive cardiac output monitoring
Carotid Doppler measurements may be affected by operator technique and BMI was not collected
Ultrasound operators were not blinded to participants' fasting or hydration status
Healthy volunteer population rather than critically ill patients, limiting generalizability to ED or ICU patients with shock
Hydration status was defined by fasting and rehydration status rather than invasive hemodynamic monitoring or laboratory biomarkers
Potential operator dependence of carotid Doppler measurements and lack of BMI data

Ask about this paper

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Implication

May support further study of carotid Doppler for volume assessment; leaves open validation before clinical use in patients.

Abstract

Objectives: Accurate assessment of volume status and fluid responsiveness is essential to guide fluid therapy, as unnecessary fluid administration may lead to fluid overload and adverse outcomes. Carotid Doppler ultrasound has emerged as a rapid, noninvasive alternative to more technically demanding echocardiographic measures. This study evaluated the utility of carotid Doppler-derived corrected flow time (FTc) and velocity-time integral (VTI), and their changes after passive leg raise (PLR), in assessing volume status and preload responsiveness. Methods: were obtained before and after PLR. Diagnostic performance of percent changes in FTc (ΔFTc) and VTI (ΔVTI) was evaluated using receiver operating characteristic analysis. Results: Participants in the fasting group underwent a mean fasting duration of 12.4 ± 1.1 hours and consumed a mean of 920 ± 352 mL of fluid after breaking the fast. PLR induced significantly greater increases in FTc and VTI during presumed relative dehydration. A ≥10% increase in VTI was observed in 57.2% of presumed relative dehydrated participants compared with 26.3% of hydrated controls and 20.4% of rehydrated participants. Similarly, a ≥5% increase in FTc was observed in 47.6%, 17.2%, and 22.3% of participants, respectively. Receiver operating characteristic analysis demonstrated moderate discriminatory performance for presumed relative dehydration, with areas under the curve of 0.708 for ΔVTI and 0.715 for ΔFTc. Optimal cutoff values were 5.92% for ΔVTI and 5.05% for ΔFTc. Conclusion: Carotid Doppler-derived FTc and VTI are promising noninvasive markers of volume status and preload responsiveness. ΔVTI demonstrated greater sensitivity, whereas ΔFTc provided higher specificity, supporting the potential role of carotid Doppler ultrasound as a practical bedside tool for hemodynamic assessment.

Discussion

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Cite This Study

Farhat et al. (2026) conducted a cohort in Hydration status and preload responsiveness (fasting-induced relative dehydration) (n=202). Carotid Doppler ultrasound parameters (corrected flow time [FTc] and velocity-time integral [VTI]) before and after passive leg raise (PLR) across hydration states vs. Nonfasting normal hydration state (n=99) and post-rehydration state (~4 hours after breaking fast) was evaluated on Diagnostic performance (ROC AUC) of relative percent changes in carotid FTc (ΔFTc) and VTI (ΔVTI) after passive leg raise for discriminating presumed dehydrated from presumed hydrated states (AUC 0.715 for ΔFTc; AUC 0.708 for ΔVTI, 95% CI 0.643-0.786, p=<0.001). Carotid Doppler ΔFTc and ΔVTI after passive leg raise showed moderate accuracy for discriminating dehydration from hydration (AUC 0.715 and 0.708, respectively).

synapsesocial.com/papers/6af10ed2a61b6e74a6de157f https://doi.org/10.1016/j.acepjo.2026.100533

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Assessment of Carotid Doppler Parameters to Evaluate Volume Status: A Prospective Observational Study

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Assessment of Carotid Doppler Parameters to Evaluate Volume Status: A Prospective Observational Study

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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