Carotid corrected flow time as a sensitive indicator for early diagnosis and dynamic monitoring of hemorrhagic shock: A translational study from porcine model to clinical practice.

purposeEarly identification of hemorrhagic shock remains a clinical challenge, as traditional vital signs often fail to detect hypovolemia during the compensatory phase. Carotid corrected flow time (CCFt), derived from Doppler ultrasound, has been proposed as a surrogate for stroke volume. However, its precise correlation with quantitative blood loss and its diagnostic value in the early stages of shock remain to be fully elucidated. This study aimed to systematically evaluate the sensitivity and diagnostic efficacy of CCFt in graded hemorrhagic shock through both animal experiments and clinical validation.

methodsThe study consisted of 2 phases. In the animal phase, a controlled, graded hemorrhage model was established in 7 Bama miniature pigs. Hemodynamic parameters and carotid ultrasound indices (CCFt, peak systolic velocity, and diameter) were measured at baseline and after cumulative blood loss intervals (0 - 1000 mL). In the clinical phase, a case-control study was conducted comparing 18 patients (admitted between November 2024 and February 2026) with hemorrhagic shock to 36 non-shock controls. Diagnostic accuracy was assessed using receiver operating characteristic curve analysis, and dynamic changes in CCFt were monitored during fluid resuscitation in representative cases.

resultsIn the animal model, CCFt demonstrated a strong negative linear correlation with quantitative blood loss (R = 0.870, p < 0.001). Notably, CCFt decreased significantly at the early stage of hemorrhage (<300 mL), exhibiting high diagnostic accuracy for early/mild shock (area under the curve (AUC) = 0.900). In the clinical cohort, CCFt was significantly lower in the shock group than in controls (p < 0.001), yielding an AUC of 0.991 for the diagnosis of hemorrhagic shock, with an optimal cutoff of 311 ms. Longitudinal monitoring revealed that changes in CCFt were highly concordant with clinical response to fluid resuscitation and lactate clearance.

conclusionCCFt is a sensitive, non-invasive indicator of blood volume loss that correlates closely with hemorrhage severity and enables early detection of compensated hemorrhagic shock. CCFt may serve as a valuable adjunctive tool for bedside assessment and precision-guided resuscitation in emergency and critical care settings.