The influence of wavelength and probe configuration on findings of a skin vasoconstriction test when using laser Doppler perfusion devices.
The aim of this study was to establish the degree to which a standardized test based on laser Doppler blood flow measurement is dependent on the particular equipment set-up being used. For this purpose, we examined finger skin blood flow with laser Doppler instruments in 20 healthy subjects. In laser Doppler perfusion monitoring (LDPM), we used a custom-made probe with two detecting fibers placed 0.25 and 1.2 mm from the illuminating fiber, respectively, and two laser Doppler perfusion imagers (LDPI) with a wavelength of 632.8 nm and 780 nm, respectively. Warming of the hand was achieved with a Peltier element, and reflex vasoconstriction was induced by immersing the other hand for 3 min into a water bath kept at 15 degrees C. As a measure for the change in skin blood flow, a vasoconstriction index (VAC: cooling/before cooling) was calculated and used for the comparison of the different devices. VAC values gathered around 0.6 for all devices. However, LDPI with a wavelength of 632.8 nm showed a slightly higher VAC index, and the difference was significant. We conclude that using a standardized test is the most appropriate for monitoring changes in blood flow rather than recording and comparing discrete values in intermittent recordings. Although a difference was noted when comparing the devices, different fiber separations and wavelengths seem then to be of little consequence.
Freccero
Carolin
C
Department of Plastic and Reconstructive Surgery, Malmö University Hospital, University of Lund, SE-20502 Malmö, Sweden. carolin.freccero@plastsurg.mas.lu.se
Wollmer
Per
P
Sundkvist
Göran
G
Svensson
Henry
H
D000328:Adult; D005385:Fingers / Q000098:blood supply; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008991:Monitoring, Physiologic; D010477:Perfusion; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply* / Q000000981:diagnostic imaging*; D012881:Skin Temperature; D012882:Skin Tests; D013997:Time Factors; D014463:Ultrasonography; D014661:Vasoconstriction / Q000502:physiology*