The thermal effect on the blood flow response to electrical stimulation

Background:    Wounds, especially in the elderly, can be life threatening. One modality which allegedly increases blood flow (BF) as an aid to heal chronic wounds is electrical stimulation. This technique applies electrical current (ES) across wounds. However, while many studies show positive findings, others do not. The purpose of this investigation was to investigate some of this inconsistency in results by determining the effect of environmental temperature on the circulation of the skin which may negate the effects of electrical stimulation in a clinical setting.
    Material/Methods:    Ten people with no wounds, controls (C), and 12 people with wounds (W) were examined in a thermally neutral or cool room (20°C) and a warm room (34°C) to observe the effect of reducing sympathetic vasoconstrictor activity on the response to 5 and 15 mA sine wave biphasic ES delivered by 2×2 cm surface electrodes.
    Results:    C and W subjects showed a greater BF in the skin in a warm room. In group C, after 30 minutes of stimulation at a current of 15 milliamps, BF increased significantly (p<0.05) but by an average of only 4 flux in the cool room. In the warm environment, BF increased significantly (p<0.01) by 19.3±7 flux and increased further during the 60 minute recovery phase. In the W group, BF during ES increased much more during stimulation in a warm room compared to a cool room.
    Conclusions:    The results show that local vasoconstriction due to exposure to a warm global temperature greatly increases the response of the skin the ES.

Keywords: Blood Flow Velocity, Adult, Case-Control Studies, Skin - injuries, Temperature, Transcutaneous Electric Nerve Stimulation, Wound Healing, Wounds and Injuries - therapy