Carotid systolic flow time with passive leg raise correlates with fluid status changes in patients undergoing dialysis

Abstract

Corrected carotid systolic flow time (CFTc) has been proposed as a measure of volume status in acutely ill patients. This study endeavors to determine whether the change in CFTc with passive leg raise (PLR) maneuver correlates with volume status changes.Dialysis patients at Kingston General Hospital (Kingston, Canada) underwent point-of-care carotid ultrasonography at the beginning and the end of dialysis. With each measurement, 2 values were recorded: the absolute CFTc, and the difference in CFTc before and after the PLR maneuver.A total of 49 measurements were collected during the study period. CFTc changed with PLR by 5±22milliseconds (2.0%) pre-dialysis and by 40±19milliseconds (13.0%) post-dialysis (P<.0001). Incorporating PLR to the CFTc measurement improved the area under the ROC from 0.64 to 0.91. Particularly, in our sample of patients, a 30milliseconds increase in CFTc with PLR predicted the post-dialysis volume state (LR+=11) whereas an increase of less than 20milliseconds argued against it (LR−=0.079).The assessment of CFTc pre- and post-PLR correlates with intravascular volume changes in patients undergoing dialysis. Alternative to the currently available bedside modalities, this technique is non-invasive, objective, simple to perform at the bedside, and reversible with respect to volume challenge.