DC electrical stimulation for chronic wound healing enhancement .1. Clinical study and determination of electrical field distribution in the numerical wound model

Notwithstanding several past clinical studies demonstrating the beneficial impact of electrical stimulation with steady direct current on the healing of chronic cutaneous wounds, the basic mechanisms underlying its effects on regenerative processes remain to be elucidated and the stimulation regime optimized. In the present study, an attempt is made towards the optimization of steady direct current stimulation of wound healing with respect to the shape and positioning of stimulation electrodes. The effects of direct current stimulation on wound healing were studied in a double-blind clinical trial involving fifty patients with spinal cord injuries, suffering from pressure ulcers. The therapeutic effect of electrical stimulation was found to depend on the positioning and shape of the electrodes. Healing of pressure ulcers was significantly enhanced by direct current, with the positive stimulation electrode overlaying the wound surface and the negative electrode placed on intact skin around the wound. By contrast, stimulation by the second type of electrode configuration-which assumed positioning of both stimulation electrodes on intact skin at the opposite sides of the wound-had only a non-significant effect on pressure ulcer healing. Numerical modelling showed that direct current stimulation using two types of electrode arrangements induced different electric field distributions in the stimulated tissue in the wound area. Endogenous electric conditions in the skin were closely approached with external electrical stimulation when the wound surface was covered with the positive stimulation electrode, while the negative electrode surrounded the wound. With such stimulation, highly significant acceleration of wound healing was observed in the clinical study, leading to the assumption that endogenous electrical phenomena in injured skin are not just side effects, but play an active role in healing. The agreement of the externally induced electric field with the endogenous electric field distribution in injured skin was adopted as the basis for optimization of direct current electrical stimulation for wound healing enhancement. (C) 1997 Elsevier Science S.A.