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Authors

  1. Matas, Anna BSc
  2. Sowa, Michael G. PhD
  3. Taylor, Vern PT, MCPA
  4. Taylor, Geoff
  5. Schattka, Bernhard J. MSc
  6. Mantsch, Henry H. PhD, FRSC

ABSTRACT

OBJECTIVE: The high melanin concentration in dark skin prevents the observation of a blanch response to light finger pressure. The objective of this study was to determine the ability of visible and near-infrared spectroscopy (the technique used in pulse oximetry) to monitor a blanch response from in vivo spectra in individuals with light and dark skin, based on changes in blood volume.

 

DESIGN: A quasi-experimental repeated measures design was employed. A stepper motor with an attached spectrophotometer probe was used to deliver controlled pressure to the participants' forearms, mimicking the finger-blanching test. Visible and near-infrared spectra were acquired throughout the blanching cycle.

 

SETTING: The In Vivo Tissue Optics Lab at the Institute for Biodiagnostics, Winnipeg, Manitoba, Canada.

 

PARTICIPANTS: A convenience sample of 10 healthy light-skinned individuals and 10 healthy dark-skinned individuals.

 

RESULTS: Determined by analysis of the spectra, the 2 groups differed in pigmentation in both the visible (P<.01) and near-infrared (P<.01) regions of the absorbance spectrum. There was a significant difference in total hemoglobin at high and low pressure in both the visible (P<.01) and near-infrared (P<.05) regions.

 

CONCLUSIONS: The observation of a significant difference in total hemoglobin at high and low pressure in both light- and dark-skinned groups in this study demonstrates the ability of visible and near-infrared spectroscopy to monitor blood volume changes associated with a blanch response. These findings support the potential use of this technology as the basis of a clinically useful blanch response tool that is insensitive to skin color.