Measurements of skin temperature responses to cold exposure of foot and face in healthy individuals: variability and influencing factors.

Skin vasomotor responses to cold exposure (CE) have been measured widely and shown to be abnormal in some clinical conditions. Among other methods, monitoring of skin temperature (Tsk) changes has been applied for those purposes. We investigated such changes simultaneously in different skin areas of healthy young men during foot and facial CE. Tsk was measured using infrared thermography in the big toe and dorsum of the left foot and with a contact thermode in the fingertip. The relationship of Tsk responses within individuals and factors influencing them were examined using mixed model analysis. Tsk changes varied greatly between sessions, measured areas and individuals. Foot CE that was painful produced both stronger central circulatory and Tsk responses than facial CE. Tsk changes were prominent in the fingertip, moderate in the toe and weak or absent in the dorsal foot. The Tsk changes were related to the baseline levels and changes of blood pressure, heart rate, the baseline Tsk values and stimulus intensity. However, despite the different cold stimuli and measurement techniques, an intra-individual correlation of the Tsk responses was good. In the foot, the big toe area is applicable for studies of Tsk reactions when warm, and the modified Tsk gradient helps to evaluate the level of peripheral vasoconstriction. The cold-induced Tsk changes may be informative in the studies of the cutaneous vasoregulation but the individual character of the cold stress reactivity and numerous confusing factors should be considered when drawing conclusions on the basis of the recorded results.