Local Sweating Response To Intradermal Electrical Stimulation: A Comparison Of Continuous And Bursting Stimulation Patterns.

The local sweat rate response (LSR) to intradermal electrical stimulation generates a sigmodal stimulus-response curve with a peak sweat rate generated by a 30 s period of continuous stimuli at a frequency of 16 to 32 Hz. The in vivo firing pattern of the sudomotor nerve however resembles a bursting firing pattern. PURPOSE: To compare the LSR to a 30 s continuous intradermal electrical stimulation frequency to a 30 s bursting pattern with a similar number of stimuli. We hypothesize that there would be no difference in the LSR response between the two stimulus patterns. METHODS: Subjects (n = 11) were studied seated in a temperature-controlled room at 27 °C. The LSR was measured with a miniature sweat capsule with guide sleeves for holding the intradermal stimulating electrodes. The air flow through the capsules was set at 100 ml/min. The water content of the effluent air was calculated by measuring the relative humidity (RH) and air temperature. Ten continuous stimulus frequencies were 1, 2, 4, 6, 8, 10, 12, 16, 32, and 64 Hz. The bursting stimuli contained a similar total number of stimuli with a burst interval of 1.5 sec. The LSR was determined by the area under the sweat rate-time curve. RESULTS: The peak LSR response was similar for both stimulus conditions (0.396 ± 0.250 and 0.385 ± 0.241 ml • min). However, the sigmoidal shaped stimulus response curves were significantly different (p = 0.0006) with the LSR during continuous stimuli at 12, 16, and 32 Hz being greater than with a bursting stimulus pattern. CONCLUSION: These data do not support the concept that a bursting stimulus pattern will improve sweat gland output during electrical activation of the sudomotor nerve. Department Funding