Diabetic angiopathy

ORIGINAL INVESTIGATION

ABSTRACT

OBJECTIVE: To retrospectively evaluate the ability of high voltage pulsed current (HVPC) to increase microcirculation in critically ischemic wounds (transcutaneous oxygen[TcPO^sub 2^] less than 10 mm Hg) and, as a result, to improve wound healing. DESIGN AND METHODS: Clinical case series with successive adult diabetic subjects (3 men and 3 women) with nonsurgical ischemic malleolar or inframalleolar skin lesions, each subject serving as his or her own control.Wound area and TcPO^sub 2^ were measured periodically. Presence of distal arteriosclerosis was assessed on 5 patients by 2-dimensional, time-of-flight magnetic resonance angiography. End point was either complete wound closure or leg amputation.

RESULTS: Maximum mean TcPO^sub 2^ was 2 +/- 2 mm Hg at the wound edge before the start of electrotherapy. After electrotherapy began, maximum TcPO^sub 2^ was 33 +/- 18 mm Hg (N=6; P

CONCLUSION: The results of this clinical case series suggest that electrotherapy can improve periwound microcirculation of ischemic inframalleolar skin lesions.

Lower extremity amputation is an expensive complication of diabetes mellitus.1 Risk factors such as peripheral neuropathy and angiopathy can lead to distal lower extremity ischemic skin lesions and can possibly result in amputation. If feasible, ischemic ulcers are treated by surgical revascularization. A patient is not an operative candidate, however, if he or she has critical occlusive disease but no suitable outflow vessel for the bypass conduit or if the patient has a profound comorbidity that makes anesthesia a high risk. Unfortunately, numerous patients with peripheral vascular disease and diabetes have these impediments to surgery. Too often, the end result is a lower extremity amputation.

High voltage pulsed current (HVPC; also known as electrical stimulation) has been employed by health care practitioners to augment the healing rate of chronic wounds with few adverse events, according to prospective, randomized, blinded clinical trials2-5 and a recent meta-analysis.6 The salutary effect reported for HVPC has been attributed, at least in part, to increased blood flow to wounds. Increased blood flow to tissue from electrotherapy is reported by many clinical and in vitro studies.7-12

Cutaneous microcirculation consists of nutritional capillaries of the papillary dermis and nonnutritional arteriovenous plexuses of the subpapillary dermis and subdermis.13 Skin blood flow is quantified by laser blood flow, skin temperature, and transcutaneous oxygen (TcPO^sub 2^). TcPO^sub 2^ is an absolute measure of oxygen in units of partial pressure in the dermis.14 In prospective trials, TcPO^sub 2^ is an independent predictor of future lower extremity amputation. A TcPO^sub 2^ measurement less than 50 mm Hg carries a 3-fold increased risk for amputation.15 In addition, TcPO^sub 2^ predicts the healing success of residuum incisions for amputation at a transtibial level. A below-knee TcPO^sub 2^ measurement greater than 40 mm Hg carries a good prognosis; a TcPO^sub 2^ measurement less than 20 has a poor prognosis.14,16,17

For intact limbs, TcPO^sub 2^ predicts healing of infrapopliteal wounds in diabetic subjects better than segmental volume plethysmographyis or toe segment pressures.19 In addition, TcPO^sub 2^ may have sensitivity and specificity approaching 80% in the ability to infer flow of underlying macrovessels of the leg and foot.21 Normal perilesion TcPO^sub 2^ measurement is greater than 50 mm Hg; less than 20 mm Hg is ischemic, and less than 10 mm Hg is critically ischemic. Critically ischemic wounds have a guarded prognosis for complete closure. For the present study, critical ischemia was defined as a periwound TcPO^sub 2^ measurement less than 10 mm Hg.

CONCLUSIONS

HVPC improves microperfusion in the vicinity of inframalleolar ischemic skin lesions and tends to promote healing if microperfusion improves sufficiently to reach near-normal physiologic levels. A controlled clinical trial is needed to confirm these speculative positive clinical findings.

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Robert J. Goldman, MD; Barbara I. Brewley, RN; and Michael A. Golden, MD

Robert J. Goldman, MD, is an assistant professor and Barbara I. Brewley, RN, is a rehabilitation nurse in the Department of Rehabilitation Medicine; and Michael A. Golden, MD, is an associate professor in the Department of Surgery, Division of Vascular Surgery, University of Pennsylvania, Philadelphia, PA. Submitted October 11, 2000; accepted in revised form June 11, 2001.

Acknowledgments

Alan H. Stolpin, MD, PhD; Mark Rosen, MD, PhD; and David A. Roberts, MD, PhD, of the Department of Radiology, University of Pennsylvania, for interpretation of magnetic resonance angiograms. Andrew J. Cucchiara, PhD, of the General Clinical Research Center, University of Pennsylvania, for statistical analysis. Joseph Cavorsi, MD, and Pam Unger, PT, of the Institute for Advanced Wound Healing, St Joseph's Hospital Medical Center, Reading, PA, for expertise on wound healing and electrotherapy. Funding and equipment for this research was provided by the University of Pennsylvania Research Foundation; University of Pennsylvania Pilot Grant for Patient-Oriented Research; National Heart, Lung, and Blood Institute, Lung and Blood 1R41HL61983-01; Chattanooga Group, Hixson, TN; and Universal Technology Systems, Jacksonville, FL.

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