Role of carotid corrected flow time and peak velocity variation in predicting fluid responsiveness: a systematic review and meta-analysis

Background: Dynamic parameters used for predicting fluid responsiveness require special equipment and are minimally invasive. Therefore, recent interest in the use of carotid ar-tery ultrasound parameters, such as carotid corrected flow time (FTc) and peak velocity variation (Delta Vpeak) has grown. Therefore, we performed this systematic review and me-ta-analysis to assess the ability of carotid FTc and/or Delta Vpeak to accurately predict fluid re-sponsiveness.Methods: We searched the PubMed and Embase databases for articles evaluating the diag-nostic accuracy of carotid FTc or Delta Vpeak for predicting fluid responsiveness. Two inde-pendent authors performed the search and selected studies published until May 2022. The studies were assessed for the inclusion and exclusion criteria using Rayyan (Rayyan Sys-tems Inc., 2022).Results: Ten studies (n = 438) that fulfilled the inclusion criteria were selected. Studies were divided into those assessing carotid FTc and those assessing carotid Delta Vpeak. Five studies (six datasets) assessed FTc. The pooled sensitivity and specificity of carotid FTc were 0.76 and 0.88, respectively. The summary receiver operating characteristic (SROC) curve for carotid FTc had an area under the curve (AUC) of 0.9092, with a Q value of 0.8412. Seven studies calculated carotid Delta Vpeak. The pooled sensitivity and specificity for Delta Vpeak were 0.83 and 0.81, respectively. The SROC curve had an AUC of 0.8941 and a Q value of 0.8250.Conclusions: Our meta-analysis showed that both carotid FTc and Delta Vpeak are useful for predicting fluid responsiveness in anesthesia and critical care settings with good specificity and sensitivity.