REPRODUCIBILITY OF BRACHIAL VASCULAR CHANGES WITH ALTERATIONS IN END-TIDAL CARBON DIOXIDE

The purpose of this study was to examine the reproducibility of the peripheral vascular response to hypercapnia. Healthy college-aged men (n = 7) and women (n = 10) underwent an iso-oxic 10-mm Hg increase in PetCO2 for 12 min. Brachial artery diameter changes were measured using ultrasound imaging. Two tests were completed on day 1 with 15 min of rest between tests. Tests were repeated on day 2. Paired t-tests, Bland-Altman plots and intra-class correlations (ICCs) determined reproducibility. There were no significant differences in peak dilation within day (5.33 +/- 3.73% vs. 4.52 +/- 2.49%, p = 0.378). The within-day ICC was poor (0.213). Within-day time-to-peak dilation did not significantly differ (660.0 +/- 231.8 s vs. 602.7 +/- 259.9 s, p = 0.379), and the ICC was fair (0.416, p = 0.113). Between-day peak dilation did not significantly differ (5.24 +/- 3.84% vs. 4.71 +/- 3.17%, p = 0.123), and the ICC was fair (0.419). Hypercapnia-induced brachial artery dilation is similar within day and between days. The ICC for peak dilation suggests the methodology is not reproducible. (C) 2016 World Federation for Ultrasound in Medicine & Biology.