Peripheral vasoconstriction influences thenar oxygen saturation as measured by near-infrared spectroscopy

Near-infrared spectroscopy has been used as a noninvasive monitoring tool for tissue oxygen saturation (StO(2)) in acutely ill patients. This study aimed to investigate whether local vasoconstriction induced by body surface cooling significantly influences thenar StO(2) as measured by InSpectra model 650. Eight healthy individuals (age 26 +/- A 6 years) participated in the study. Using a cooling blanket, we aimed to cool the entire body surface to induce vasoconstriction in the skin without any changes in central temperature. Thenar StO(2) was noninvasively measured during a 3-min vascular occlusion test using InSpectra model 650 with a 15-mm probe. Measurements were analyzed for resting StO(2) values, rate of StO(2) desaturation (RdecStO(2), %/min), and rate of StO(2) recovery (RincStO(2), %/s) In all subjects MAP, CO, SV, and core temperature did not change during the procedure. Skin cooling resulted in a significant decrease in StO(2) from 82% (80-87) to 72% (70-77) (P < 0.05) and in RincStO(2) from 3.0%/s (2.8-3.3) to 1.7%/s (1.1-2.0) (P < 0.05). Similar changes in CRT, Tskin-diff, and PI were also observed: from 2.5 s (2.0-3.0) to 8.5 s (7.2-11.0) (P < 0.05), from 1.0A degrees C (-1.6-1.8) to 3.1A degrees C (1.8-4.3) (P < 0.05), and from 10.0% (9.1-11.7) to 2.5% (2.0-3.8), respecti Peripheral vasoconstriction due to body surface cooling could significantly influence noninvasive measurements of thenar StO(2) using InSpectra model 650 with 15-mm probe spacing.