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 benefi cial impact of electrical stimulation with steady direct current on th e 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 mad e towards the optimization of steady direct current stimulation of wou nd healing with respect to the shape and positioning of stimulation el ectrodes. The effects of direct current stimulation on wound healing w ere studied in a double-blind clinical trial involving fifty patients with spinal cord injuries, suffering from pressure ulcers. The therape utic effect of electrical stimulation was found to depend on the posit ioning and shape of the electrodes. Healing of pressure ulcers was sig nificantly enhanced by direct current, with the positive stimulation e lectrode overlaying the wound surface and the negative electrode place d on intact skin around the wound. By contrast, stimulation by the sec ond type of electrode configuration-which assumed positioning of both stimulation electrodes on intact skin at the opposite sides of the wou nd-had only a non-significant effect on pressure ulcer healing. Numeri cal modelling showed that direct current stimulation using two types o f electrode arrangements induced different electric field distribution s in the stimulated tissue in the wound area. Endogenous electric cond itions in the skin were closely approached with external electrical st imulation when the wound surface was covered with the positive stimula tion electrode, while the negative electrode surrounded the wound. Wit h such stimulation, highly significant acceleration of wound healing w as observed in the clinical study, leading to the assumption that endo genous electrical phenomena in injured skin are not just side effects, but play an active role in healing. The agreement of the externally i nduced electric field with the endogenous electric field distribution in injured skin was adopted as the basis for optimization of direct cu rrent electrical stimulation for wound healing enhancement. (C) 1997 E lsevier Science S.A.