title: Repeatability of vascular responsiveness measures derived from near-infrared spectroscopy.
abstract: Near-infrared spectroscopy (NIRS)-derived measures of tissue oxygen saturation (StO2) have been recently shown to significantly correlate with the widely used method for noninvasively assessing vascular endothelial function, flow-mediated dilation (FMD). The purpose of this study was to examine the intraday and interday reliability of the reperfusion slope of StO2 (slope 2 StO2) and compare it to FMD Ultrasound-derived FMD was quantified following 5 min of distal cuff occlusion of the popliteal artery in nine healthy young men (26 ± 3 years). An FMD test was performed each of 4 days, with a fifth involving three tests. FMD was calculated as the greatest percent change in diameter from baseline (%FMD). StO2 was measured using NIRS throughout each test, with slope 2 StO2 being calculated as the upslope of 10-sec following cuff release. Reliability was determined using repeatability, intraclass correlation coefficients (ICC), and coefficient of variation (CV). Repeatability of slope 2 StO2 was better than %FMD for both intraday (0.43 and 5.65, respectively) and interday (0.48 and 4.82, respectively) comparisons; approximately 30% of mean values for slope 2 StO2 could be attributed to measurement error, whereas 100% of mean FMD could be for both intraday and interday comparisons. Similarly, ICC and CV values indicated stronger reliability of slope 2 StO2 compared to %FMD for both intraday (ICC 0.92 and 0.36, respectively; CV 9 ± 4% and 44 ± 24%, respectively) and interday (ICC 0.94 and 0.25, respectively; CV 14 ± 5% and 40 ± 22%, respectively) comparisons. In conclusion, NIRS-derived slope 2 StO2 can be used as a reliable measure of vascular reactivity.
authors.affiliation: Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Kaitlin M
authors.initials: KM
authors.lastname: McLay
authors.affiliation: Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Josh P
authors.initials: JP
authors.lastname: Nederveen
authors.affiliation: Department of Neurological and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pogliaghi
authors.affiliation: Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Donald H
authors.initials: DH
authors.lastname: Paterson
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, Ontario, Canada Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada jmmurias@ucalgary.ca.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Murias
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D011150:Popliteal Artery / Q000378:metabolism*; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared / Q000379:methods / Q000592:standards*; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult
keywords: Day‐to‐day reliability; endothelial function; oxygen saturation; reactive hyperemia; test‐to‐test reliability; vasodilation