Comparison of baseline brachial artery measurements and effect on peak flow-mediated dilation

Background: Flow-mediated dilation (FMD) following reactive hyperaemia can use different time-point measures for baseline diameter. The aim of this study is to compare preocclusion, occlusion and postocclusion baseline brachial artery measurements on the calculation of peak FMD. Study Design: Ultrasound imaging of the brachial artery following reactive hyperaemia was conducted in 418 children and 533 adults. Baseline brachial artery measures were a 10-s average before (preocclusion), during (occlusion) and after (postocclusion) hyperaemia. Peak FMD was defined as the greatest percent change from baseline to the peak brachial artery diameter following reactive hyperaemia. Results: Preocclusion, occlusion and postocclusion baseline measures of brachial artery diameter were not significantly different in children (3·15 ± 0·51, 3·14 ± 0·50 versus 3·11 ± 0·50 mm, P = 0·179) or adults (3·81 ± 0·72, 3·81 ± 0·73 versus 3·79 ± 0·73 mm, P = 0·201). Peak FMD values were not significantly different when calculated from preocclusion, occlusion or postocclusion baselines in children (6·77 ± 5·78, 6·93 ± 4·03 versus 7·85 ± 3·62%, P = 0·208) or adults (6·07 ± 5·53, 6·14 ± 3·94 versus 6·62 ± 3·70%, P = 0·266). Conclusion: We found no difference in FMD regardless of the baseline brachial artery diameter used in children and adults. Therefore, compilation of data and comparison of results from studies utilizing different measures of baseline brachial diameter may be able to be conducted.