title: Peripheral vasoconstriction influences thenar oxygen saturation as measured by near-infrared spectroscopy.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Eight healthy individuals (age 26 ± 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) before, during, and after skin cooling. Measurements also included heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), stroke volume (SV), capillary refill time (CRT), forearm-to-fingertip skin-temperature gradient (Tskin-diff), perfusion index (PI), and tissue hemoglobin index (THI).
  
  
  RESULTS
  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 1.0°C (-1.6-1.8) to 3.1°C (1.8-4.3) (P < 0.05), and from 10.0% (9.1-11.7) to 2.5% (2.0-3.8), respectively. The THI values did not change significantly.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Intensive Care Adults, Erasmus MC University Medical Centre Rotterdam, PO Box 2040, 3000 CA Rotterdam, The Netherlands. a.pintolima@erasmusmc.nl
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lima
authors.forename: Michel Egide
authors.initials: ME
authors.lastname: van Genderen
authors.forename: Eva
authors.initials: E
authors.lastname: Klijn
authors.forename: Jan
authors.initials: J
authors.lastname: Bakker
authors.forename: Jasper
authors.initials: J
authors.lastname: van Bommel
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D062186:Arterial Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D003080:Cold Temperature; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood*; D012881:Skin Temperature / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D013318:Stroke Volume / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology*
chemical_list: D006454:Hemoglobins; D010100:Oxygen