Electrical Stimulation Technologies for Wound Healing

Abstract

Objective: To discuss the physiological bases for using exogenously applied electric field (EF) energy to enhance wound healing with conductive electrical stimulation (ES) devices. Approach: To describe the types of electrical currents that have been reported to enhance chronic wound-healing rate and closure. Results: Commercial ES devices that generate direct current (DC), and mono and biphasic pulsed current waveforms represent the principal ES technologies which are reported to enhance wound healing. Innovation: Wafer-thin, disposable ES technologies (wound dressings) that utilize mini or micro-batteries to deliver low-level DC for wound healing and antibacterial wound-treatment purposes are commercially available. Microfluidic wound-healing chips are currently being used with greater accuracy to investigate the EF effects on cellular electrotaxis. Conclusion: Numerous clinical trials described in subsequent sections of this issue have demonstrated that ES used adjunctively with standard wound care (SWC), enhances wound healing rate faster than SWC alone.

Luther C. Kloth, MS, PT, FAPTA, CWS, FACCWS

Figure 1.

DC flows continuously and, therefore, has no waveform but has distinct positive or negative polarity. DC that flows for sufficiently high current levels for significant periods of time may cause electrochemical injury to the skin and wound tissues. At sufficiently low μA levels, exogenous DC current may be used to mimic the endogenous DC current of injury. DC, direct current. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound

Figure 2.

Pulsed electrical currents used in wound healing are either monophasic or biphasic. (A) Examples of monophasic pulses above (or below) the zero baseline. When they are above the baseline, they have positive polarity; when they are below the baseline, they have negative polarity. (B, C) Examples of biphasic pulses, one phase above and one phase below the zero baseline. Their shape may be asymmetric (B) and charge unbalanced with polarity or symmetric (C) and charge balanced without polarity. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound

Figure 3.

The PosiFect RD™ DC device (BioFisica™, Odiham, Hampshire, United Kingdom and Atlanta, GA), with anode ring and cathode tab. Shown with permission of Rafael Andino, President of Biofisica. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound

Figure 4.

Waveform of LVMPC used in several clinical trials^,,, that reported positive healing outcomes after treatment of chronic wounds in conjunction with standard care. LVMPC, low-voltage monophasic pulsed current.

Figure 5.

Waveform of high-voltage monophasic pulsed current. Clinical voltage levels used to deliver low levels of current to wound tissues (∼3.2 μC/pulse) will not cause tissue injury from electrochemical pH changes. (From Nelson and Currier, with permission.)

Figure 6.

Conductively coupled monopolar electrode placement with treatment electrode placed on a conductive saline, moist gauze or on a wafer hydrogel sheet dressing. The return electrode is applied to intact skin. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound

Figure 7.

Conductively coupled bipolar treatment electrodes of opposite polarity positioned on opposite sides of a wound. This electrode placement approach has been utilized to deliver LVBPC in six clinical studies.^,, LVBPC, low voltage biphasic pulsed current. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/wound

Figure 8.

The woundEL^® LVMPC device (Göteborg, Sweden) delivers the same signal previously used in clinical wound-healing studies performed in the United States and Germany that reported positive healing outcomes.^,,, Permission granted by Molnlycke Health Care.

Figure 9.

The antimicrobial Procellera™ DC device (Vomaris Innovations, Chandler, AZ) contains 25 micro-batteries and a silver formulary (permission granted by Vomaris Innovations): (A) Dry inactive dressing with zero mV measured. (B) Moist active dressing showing mV measured.