WITHIN-DAY AND BETWEEN-DAY VARIABILITY IN TRANSCUTANEOUS DOPPLER ULTRASOUND MEASUREMENTS OF SUPERIOR MESENTERIC-ARTERY BLOOD-FLOW (SMABF) IN THE FASTED STATE

This study assessed within-and between-day variability of human superi or mesenteric artery blood flow (SMABF) using transcutaneous Doppler u ltrasound. Two groups of healthy volunteers were studied after fasting overnight; six subjects were studied for one visit of 90 min duration (group 1) and six other subjects attended the laboratory for three se parate visits of 30 min duration (group 2). Measurements of SMABF were made by a single, trained observer every 15 min, the angle of insonat ion of the Doppler beam being set both <30 degrees and >30 degrees eac h time. Within a day (group 1), the angle of insonation had little eff ect upon SMABF measurements (values differed by less than 6%) and vari ability was low (mean coefficient of variation below 5%). SMABF measur ements between days (group 2) were consistent (mean coefficient of var iation ranging from 6 to 12%), but measurements made at angles of <30 degrees had slightly lower standard error of the mean (SEM) and coeffi cient of variation (CV) than those above 30 degrees. Thus, in fasted s ubjects there is small within-visit or between-visit variability in SM ABF assessed by a single trained observer using Doppler ultrasound. Sl ightly less variability is observed when scanning at angles of <30 deg rees, but this effect was not substantial and the correction factor fo r angle contained within the software of the ultrasound machine appear ed to be reliable.