Diagnostic Performance of Corrected Carotid Flow Time for Assessing Fluid Responsiveness in Patients With Septic or Hypovolemic Shock: A Prospective Diagnostic Accuracy Study

BackgroundPredicting fluid responsiveness in patients with hemodynamic instability remains challenging.Corrected carotid flow time (CFTc) is a non-invasive bedside Doppler measure proposed to identify fluid responsiveness, but its reported performance is inconsistent.We evaluated baseline CFTc as a predictor of fluid responsiveness and assessed whether the post-bolus percentage change in CFTc corresponded with the echocardiographic change in stroke volume. Materials and methodsThis prospective diagnostic accuracy study included 80 adult patients presenting with new-onset shock of presumed septic and/or hypovolemic origin.All received a clinically indicated first bolus of 10 mL/kg Ringer's lactate.Stroke volume (SV) measured by transthoracic echocardiography and CFTc by carotid Doppler were obtained at baseline (T1) and 20 minutes after the bolus (T2).Responders were defined by a ≥15% rise in SV.Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic performance of CFTc and its percentage change. ResultsAn infective focus was identified in 61 patients (76.2%), with no source documented in 19 patients (23.8%).Thirty-two patients (40.0%) were responders.A baseline CFTc cut-off of ≤324.03 ms predicted responders with 71.9% sensitivity and 47.9% specificity (AUROC 0.563, 95% CI 0.435-0.691;p = 0.343).The percentage change in CFTc showed poor discrimination for fluid responsiveness (AUROC 0.568, 95% CI 0.436-0.700;p = 0.305) and corresponded weakly with the percentage change in SV (Spearman rho = 0.141; p = 0.213).Nonresponders experienced recurrent hypotension more often and required earlier initiation of vasopressors. ConclusionIn adults with new-onset shock, baseline CFTc did not usefully discriminate echocardiography-defined fluid responders, and the post-fluid change in CFTc showed weak correspondence with the change in stroke volume.CFTc should not be relied on alone to guide fluid resuscitation in this population.