Eliminating the issue of skin color in assessment of the blanch response.
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.


METHODS
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.


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


METHODS
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.
Matas
A
A
Institute for Biodiagnostics, National Research Council, Winnipeg, Manitoba, Canada.
Sowa
M G
MG
Taylor
V
V
Taylor
G
G
Schattka
B J
BJ
Mantsch
H H
HH
D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D003668:Pressure Ulcer / Q000175:diagnosis* / Q000503:physiopathology; D012867:Skin / Q000098:blood supply*; D012880:Skin Pigmentation; D019265:Spectroscopy, Near-Infrared