Skin-temperature variability indicates vascular sympathetic activity

Measurement of skin temperature in normal human subjects using high-resolution system revealed low amplitude temperature fluctuations (40/spl times/10/sup -3//spl deg/C) designated as ´Temperature Variability´ (TV). The raw signal was filtered to extract this oscillatory component. Spectral analysis of the filtered signal revealed that most of the energy was in the range 0.01-0.04 Hz. Power spectra of temperature variability and pulse pressure amplitude were compared. Both of the signals exhibited similar peak frequency and similar stress-related response. Stress-related changes of TV power spectrum were similar to changes of power in the spectrum of heart rate variability in the same frequency range. The TV signal showed greater sensitivity to stress than mean temperature that is the presently used variable. The TV phenomenon was attributed to vasomotor activity primarily mediated by sympathetic tone.