Electrotherapy Promotes Healing and Microcirculation of Infrapopliteal Ischemic Wounds: A Prospective Pilot Study

Advances in Skin & Wound Care, Jul/Aug 2004 by Goldman, Robert, Rosen, Mark, Brewley, Barbara, Golden, Michael

ABSTRACT

OBJECTIVE: To determine if high-voltage pulsed current (HVPC) electrotherapy augments ischemic wound healing and increases periwound microcirculation.

DESIGN: A prospective, randomized, single-blinded, sham-controlled clinical trial was conducted on a homogenous subset of quasistable ischemic wounds.

INTERVENTION: Active HVPC or sham HVPC was applied to wounds for a 14-week period.

MAIN OUTCOME MEASURE: Wounds were monitored every 4 weeks, except 2 weeks between weeks 12 and 14, for wound area, wound appearance, and microcirculation, which was measured by transcutaneous oxygen (TcPO^sub 2^) levels and laser Doppler flow.

RESULTS: Ischemic wounds treated with active HVPC decreased in size, contrary to the expected increase in ischemic wound size that was observed in wounds in the control group (P

CONCLUSION: The results of this study demonstrate that HVPC decreased the area of ischemic wounds, reversing the expected increase in wound size, and improved microcirculation. The promising results of this pilot study require a larger Phase II study to confirm and generalize these findings.

CLINICAL RELEVANCE: Electrotherapy may prove to be a relatively safe and effective complement to surgical revascularization to improve the odds of healing ischemic wounds and promoting limb salvage.

ADV SKIN WOUND CARE 2004;17:284-90, 292-4.

Prevalence of dysvascular amputations is reported to have increased 27% between 1988 to 1996.1 With an average of 133,325 limb-loss hospital discharges per year1 and a cost of $100,000 per amputation (considering surgical hospitalization and rehabilitation costs2), the direct yearly cost of dysvascular amputations in the United States is $13 billion.

A common precursor of dysvascular amputation is an ischemic wound. Electrotherapy has been proposed as an effective, straightforward, adjunctive treatment for ischemic wounds. Electrotherapy is intended to supplement surgical revascularization, which is the standard care for ischemic wounds. However, when vascular bypass is associated with minor amputation, such as with digits or at the transmetatarsal level, necrosis may still occur along the suture line, even with distal pulses present. Distal necrosis is more challenging to treat when a patient is a poor surgical candidate due to failing health or limited outflow arteries.

High-voltage pulsed current (HVPC) promotes microcirculation3,4 and healing4 of ischemic wounds. Improved ischemic wound healing was reported in a retrospective study of patients who were treated with HVPC therapy.4 In the study, 22 patients were evenly divided between the treatment group, which received HVPC plus standard care, and the control group, which received standard care alone. Patients were evenly matched for age, sex, and percentage with diabetes mellitus. The proportion of healed wounds 1 year after starting treatment was higher in the treatment group (90% healed) compared with the control group (30% healed). This difference was significant (P

HVPC consists of direct-coupled continuous trains of pulses, each a submicrosccond doublet of high peak amplitude (> 10 ma). This signal and the electrotherapy device have been sanctioned by the Food and Drug Administration (FDA) through its 510(k) mechanism and have been in use for decades to improve local blood flow.

Although the precise nature of the increased blood flow induced by HVPC is not well understood, it may improve microcirculation.5-7 Flow through arterioles in the subdermis and through capillaries in the nutritional and papillary dermis is collectively defined as skin microcirculation. The microcirculation consists histologically of subcutaneous paired arterioles and venules less than 0.1 mm in diameter that perforate muscle and fat layers and a horizontal plexus through the deep dermis.8 From the horizontal plexus, microvascular units perfuse the superficial dermis, with each unit resembling 3 dimensions of an umbrella arising from a stem. The stem of the umbrella consists of vertical ascending paired arterioles and venules (1.5 to 7 mm apart) that arborize into superficial horizontal plexuses of terminal arterioles and venules within the papillary dermis. Terminal arterioles give rise to capillaries that ascend through dermal papillae, form hairpin curves, and descend into terminal venules within the superficial dermal plexuses. The bulk of the skin microvasculature is contained in the papilary dermis 1 to 2 mm below the surface. The vascular islands, supplied by ascending arterioles, and intervening avascular spaces may form the classical livedo pattern in the presence of proximal ischemia.8

Microcirculation can be quantified in several ways. TcPO^sub 2^ can measure the absolute oxygen partial pressure of the dermis and subdermis, and laser Doppler flow can measure the velocity of red blood cells through the most external 1 mm of dermis, which primarily includes the horizontal papillary plexus and capillary loops. Additional methods of measuring microcirculation include vidcomicroscopy,9 which is a direct visualization technique, and skin surface temperature,10 which is an indirect measure of capillary flow. Although all of these methods are noninvasive, TcPO^sub 2^ and laser Doppler flow were selected for this study because of the supporting literature and ease of measurement.5-11-19