SkBF and Temperature
Regional cutaneous blood flow during exercise was estimated
by laser Doppler flowmetry (LDF).24,d The laser Doppler
incorporates a low-power solid-state infrared laser diode as a
source of coherent light. Variables of frequency and power of
the reflected photons are analyzed to yield estimates of blood
volume and flow velocity. The probe head was applied to the
skin over the right upper back. The subject was then asked to
take deep breaths to verify stability of the signal and to ensure
that movement artifacts did not influence the readings.25 Cutaneous
vascular conductance was calculated as MAP divided by
LDF and expressed as the blood perfusion unit (BPU) per
millimeters of mercury. Skin temperature was measured using
a thermistore taped to the upper back.