AUTHOR=Kranen Sascha H. , Oliveira Ricardo S. , Bond Bert , Williams Craig A. , Barker Alan R. 

TITLE=The utility of the reperfusion rate of tissue oxygen saturation as a measure of vascular endothelial function in adolescents: reliability, validity and sensitivity

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1163474

DOI=10.3389/fphys.2023.1163474

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> The near-infrared spectroscopy (NIRS)-derived reperfusion rate of tissue oxygen saturation (slope 2 StO<sub>2</sub>) may provide a surrogate measure of vascular function, however, this has yet to be examined in a paediatric population. This study investigated in adolescents: 1) the between-day reliability of NIRS-derived measurements; 2) the relationship between slope 2 StO<sub>2</sub> and macro- (flow-mediated dilation, FMD) and microvascular (peak reactive hyperaemia, PRH) function; and 3) the effect of high-intensity interval exercise (HIIE) on slope 2 StO<sub>2</sub>, FMD, and PRH.</p><p><bold>Methods:</bold> Nineteen boys (13.3 ± 0.5 y) visited the laboratory on two occasions, separated by ∼ 1 week. On visit 1, participants underwent simultaneous assessment of brachial artery FMD and slope 2 StO<sub>2</sub> and PRH on the internal face of the forearm. On visit 2, participants completed a bout of HIIE with slope 2 StO<sub>2</sub>, FMD and PRH measured pre-, immediately post- and 1.5 h post-exercise.</p><p><bold>Results:</bold> Slope 2 StO<sub>2</sub> showed no mean bias (<italic>p</italic> = 0.18) and an intraclass correlation coefficient of 0.67 (<italic>p</italic> = 0.003) between visits. No significant correlation between slope 2 StO<sub>2</sub> and FMD or PRH was observed on visit 1 (<italic>r</italic> = −0.04, <italic>p</italic> = 0.89 and <italic>r</italic> = −0.30, <italic>p</italic> = 0.23, respectively) or visit 2 pre-exercise (<italic>r</italic> = −0.28, <italic>p</italic> = 0.25 and <italic>r</italic> = −0.31, <italic>p</italic> = 0.20, respectively). Compared to pre-exercise, FMD decreased immediately post-exercise (<italic>p</italic> &lt; 0.001) and then increased 1.5 h post-exercise (<italic>p</italic> &lt; 0.001). No significant change was detected for slope 2 StO<sub>2</sub> (<italic>p</italic> = 0.30) or PRH (<italic>p</italic> = 0.55) following HIIE.</p><p><bold>Conclusion:</bold> In adolescents, slope 2 StO<sub>2</sub> can be measured reliably, however, it is not correlated with FMD or PRH and does not follow the acute time course of changes in FMD post-exercise. Hence, the use of slope 2 StO<sub>2</sub> as a surrogate measure of vascular function in youth must be refuted.</p>