Fingertip temperature as an indicator for sympathetic responses.

Changes of acral skin blood flow are a commonly used indicator for sympathetic reflex responses to various stimuli. The goal of the present study was to determine whether decreases in fingertip temperature are indicative for sympathetic induced changes in microcirculation. Infrared thermography demonstrated that various stimuli triggering the sympathetic nervous system induced decreases in cutaneous microcirculation, most prominently in fingertip skin. Various such stimuli induced almost immediate temporary vasoconstriction, measured by laser Doppler flux and photoplethysmography. With a lag phase of approximately 15 s, reduced microcirculation was also reflected by a transient decrease in fingertip temperature. Vasoconstrictions were easily demonstrable by fingertip temperature when the starting fingertip temperature was above 32 degrees C and vasoconstriction lasted at least 5 s. Temperature measurement offers the advantages of ease and simplicity of performance and analysis, compared with the more complex analyses of flux and pulse volume.