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Using High-Voltage Electrical Stimulation in the Treatment of Recalcitrant Pressure Ulcers: Results of a Randomized, Controlled Clinical Study
Abstract
The use of electrical stimulation has been studied in a variety of wounds emphasizing different variables with regard to provision of therapy. The purpose of this prospective, randomized, controlled clinical study was to evaluate the effect of high-voltage electrical stimulation (HVES) on nonhealing, lower-extremity, Stage II and Stage III pressure ulcers. Patients admitted for care and eligible to participate in the study received standard supportive care and topical treatments covered with wet-to-moist dressings. Patients assigned to the treatment arm of the study also received HVES (100 V; 100 µs; 100 Hz) continuously for 50 minutes once daily, five times per week. Patients were followed until healing for a maximum of 6 weeks. Wound tracings and measurements were obtained weekly. Over a 4-year period, 26 patients were enrolled in the treatment and 24 in the control group. Ulcers had existed for an average of 3.17 and 2.83 months in the treatment and control groups, respectively. Most were classified as Stage II (17 in the treatment and 16 in the control group) with an average baseline size of 4.54 cm2 and 3.97 cm2, respectively. Wound areas and linear measurements decreased significantly in both groups (P <0.05), but increases in granulation tissue were significant in the treatment group only (P = 0.006). Wound area, linear measurement, wound volume, and granulation tissue changes were statistically significantly greater in the treatment than in the control group starting in the second week of treatment. Week 6 surface area change was 88.9% (SD 14) in the treatment and 44.4% (SD 63.1) in the control group (P = 0.00003). Correlation coefficients between changes in wound surface area, longest length, and longest width were R = 0.96 and R = 0.98 in the treatment and R = 0.94 and R = 0.89 in the control group. HVES improved the healing rate of recalcitrant Stage II and Stage III pressure ulcers. Research to compare the effectiveness of using cathodic and anodal stimulation combined or alone and to determine the optimal duration of these two types of electrical stimulation is warranted.
Potential Conflicts of Interest: The authors have nothing to disclose. All research activities were funded by the Medical University of Silesia, Katowice, Poland.
Introduction
The treatment of pressure ulcers usually involves a wide range of interventions, including use of a support surface and application of moisture-retentive dressings.1,2 If the ulcer fails to respond to standard care, guidelines2 suggest direct contact (capacitive) electrical stimulation (ES) should be considered in the management of recalcitrant Stage II, Stage III, and Stage IV pressure ulcers. Other physical modalities that may be used for pressure ulcers not responding to appropriate moist wound care strategies include negative pressure wound therapy (for Stage III and Stage IV ulcers only), ultrasound, ultraviolet light, and electromagnetic therapy.2
Electricity and healing. Muscle and nerve conductivity and intercellular communication are enabled by bioelectric processes. An electric current necessary for a live cell to function flows because of the gradient of ion concentration in the cells and their different electric potentials. Weiss3 and Lampe4 reviewed the results of 32 and 85, preclinical and clinical studies, respectively, addressing the influence of electric current on tissue healing. It followed from the reviews that the surface of healthy human skin has a slightly negative electric potential (compared with the deeper layers of tissue), while wounds are characterized by a positive electric potential. This difference in potentials generates an electric current that stimulates wound healing. Voltage induced by ES amplifies the current usually present in wounds.
Electrically stimulating the wound surface has been shown to attract neutrocytes, leukocytes, macrophages, and fibroblasts.4 In vivo studies3 have shown that the application of electric current significantly increases synthesis of adenosine triphosphate (five-fold) and proteins (by 70%). The flow of an electric current also has been observed to increase adenosine triphosphate synthesis in human wounds and to accelerate the incorporation of amino acids into cell protein.4
Collagen synthesis. ES of fibroblasts improves collagen synthesis. Bourguignon’s5 in vitro study with human fibroblast cell cultures showed accelerated protein and DNA synthesis. The study used HVES utilizing monophasic, twin-spike pulses that had a fixed pulse duration of 100 µs. Protein and DNA synthesis was accelerated using 100-Hz pulses and a voltage ranging from 100 to 200 V. Reger6 conducted an in vivo study with 30 healthy young Hanford minipigs using direct current (0.6 mA; 0.2 mA/cm2) and an alternating current (40 Hz; 300 µs; 7-10 mA) and observed an increased density of collagen fibers in the treated compared to the control pressure ulcer area. In the study, the healing of wounds experimentally inflicted on Hanford minipigs was observed. In one group (n = 11), wounds were treated with alternating current (AC); in the second group (n = 9), direct current (DC) was applied; and the third group (n = 10) served as a control and was not treated. Using a 300- to 600-µA pulsed current of 0.8-Hz frequency, Wood et al’s7 in vivo study involving guinea pigs found increased membrane-associated thioredoxin reductase activity after skin biopsy from the electrically stimulated site; according to the authors, this may lead to the growth of fibroblasts and keratinocytes. 
Blood flow and capillary density. Studies have shown that ES improves blood flow. Mohr’s8 in vivo experiment with rats showed that a high-voltage positive and negative current (40–60 V; 20 Hz; average current 35 µA) induced significant increases in blood flow in the rat hind limb (P <0.004 for negative current and P <0.003 for positive current).
In an open, prospective, pilot clinical study, Junger9 reported a mean increase of 43.3% in capillary density in the venous leg ulcers of 15 patients whose wounds had not improved after several months of standard care. They used a monophasic pulsed current for 30 minutes daily for a mean of 38 days (pulse duration 140 µs; average current 630 µA at frequency of 128 Hz and 315 µA at 64 Hz). For the first 14 days, 630 µA of negative current was delivered to the wounds. Then treatment electrode polarity was switched to positive for 3 to 10 days, and then the polarity was changed back to negative. When the wound had made significant clinical progress toward healing, the current amplitude was reduced to 315 µA. Capillary density (observed by light microscopy) improved from a prestimulation baseline of 8.05 capillaries/mm2 to 11.55 capillaries/mm2 after stimulation (P <0.039). The investigators also measured transcutaneous partial pressure of oxygen (TcPO2) in the periwound skin before and after ES. They found that TcPO2 increased from 13.5 to 24.7 mm Hg, respectively (normal is >400 mm Hg), and that skin perfusion increased as determined by laser Doppler fluximetry.
A positive effect of ES on neoangiogenesis also was found in Borba’s10 in vivo study involving rats. In the stimulation group, before the incision, the positive electrode was placed on the animals’ backs and a pulsed current was applied for 30 minutes, delivering a rectangular pulse current of 8 mA at a frequency of 7.7 Hz (the negative electrode was placed on the abdominal wall). After ES, an incision was made on the animal’s back. The animals in the control and stimulation groups were subdivided into two subgroups of 10 animals each on postoperative days 7 and 14. In both the control and stimulation groups, histomorphometric analysis was used to determine the number of newly formed vessels, using morphologic characteristics, such as the presence of endothelial walls thinner than those of other vessels. In the stimulation group, the number of blood vessels on postoperative day 7 was greater than that in the control group (P <0.0091). No significant differences (P <0.3375) were found in the number of blood vessels between the groups on postoperative day 14. The stimulation group also showed a greater number of fibroblasts on postoperative day 7 than the control group (P <0.0060), whereas on postoperative day 14, no significant differences (P <0.1267) were observed in the number of fibroblasts between the groups.
Chronic wound healing. Kloth’s11 1996 literature review justified the use of electric charges for wound healing. This conclusion is particularly relevant to chronic wounds, where the natural flow of electric currents that induce healing processes may be disturbed by tissue desiccation, residue from heavy metals (eg, iodine, silver), the repeated use of nonconductive petrolatum found in some impregnated dressings, and debriding enzymes. In those cases, ES can restore natural electric potentials and intensify healing processes. 
Electric stimulation factors in clinical studies (see Tables 1 and 2).
Types of electrical current. Clinical studies assessed the effectiveness of ES utilizing different types of electric current: microamperage direct current,12,13 microamperage alternating current,7,14 and low-voltage milliamperage current.15 In two studies, pressure ulcers were treated with HVES.16,17
Number of pressure ulcers treated. In several studies researched, the microamperage direct current was applied to 10012 and 1513 pressure ulcers, the microamperage alternating current was used to treat 437 and six14 pressure ulcers, and the effectiveness of the milliamperage pulsed current was evaluated following the treatment of 26 wounds.15 Small sample size was noted in HVES studies (eight17 and nine16 pressure ulcers).
Amperage and voltage. In some studies, amperage of current ranges between 200 and 800 µA.7,12-14 When HVES is used in soft tissue procedures, voltage typically ranges from 100 to 200 V (342–500 µC/s). The electric current amplitude used during HVES procedures (approximately 2.5 A) is approximately 25 times greater than that applied during low-voltage ES, but the average amperage is low, usually within 1.5–2.0 mA.16,17 Patients subjected to amperage used during low- and high-voltage stimulation felt a painless tingling sensation but no muscle contractions.15-17
Frequency. The frequency of the microamperage alternating current was between 0.5 and 0.8 Hz.7,14 Feedar15 used a milliamperage pulsed current, selecting its frequency depending on the stage of the pressure ulcer. Stage III and Stage IV pressure ulcers were treated with an electric current of 128 Hz, while the frequency applied to Stage II pressure ulcers was 64 Hz. Procedures involving HVES used pulses of 100 Hz17 and 105 Hz.16
Application protocol. In five clinical studies, the active electrode was placed on a moistened pad overlying the wound.
Type of electrical current. In three clinical studies12,13,15 with monophasic current, pressure ulcers were stimulated by both negative and positive currents, with cathodic stimulation being introduced early on in the treatment process. Kloth1617 used a different approach: Kloth applied anodal stimulation first and cathodic stimulation followed if healing progression was not observed; Griffin’s used cathodic stimulation throughout treatment period.
Duration of application. Depending on the type of current used, researchers also selected different ES durations. The direct current was applied for a relatively long time (4 to 6 hours a day, 20 to 42 hours/week).12,13 ES utilizing the milliamperage pulsed current was applied for a total of 7 hours a week (1 hour/day).15 HVES in Kloth’s16 study was found to be effective at 3.75 hours a week (45 minutes/day, five times a week), whereas Griffin17 treated patients with HVES 7 hours a week (1 hour/day; 7 days/week). Study duration also varied, ranging from 314,17 to between 7 and 8 weeks.7,16
Researchers have applied cathodic stimulation and anodal stimulation for different lengths of time. Gault12 applied cathodic stimulation until surface wound infection was resolved. Carley13 used negative current for 3 days, then used a positive current until the end of treatment. Feedar,15 using a milliamperage pulse current to treat Stage IV pressure ulcers, adopted a different method that involved switching electrode polarity: electrode polarity was reversed every 3 days until pressure ulcers looked like Stage II — ie, cathodic stimulation was applied for the first 3 days, replaced by anodal stimulation for another 3 days, and so on.
Electric stimulation and stage of healing. A series of in vivo experimental studies18-20 using HVES (100 µs; 80 Hz; 25-80 V) on full-thickness incisions has provided arguments for using cathodic stimulation in the early stage of wound healing (even right after tissue injury has been detected). Used during a later period, the cathode was found to inhibit healing.18
The literature review by Kloth11 concluded that pressure ulcer therapies should be selected in relation to the current stage of wound healing. In the early period, when inflammation and exudation appear, macrophages and polynuclear granulocytes remove the damaged tissue. Fibrin and the products of its degradation have chemotactic properties toward neutrophils and monocytes that phagocytose bacteria and necrotic tissue in the wound. Applying the negative electrode to a pressure ulcer at this stage helps attract positively polarized macrophages and neutrophil granulocytes to the wound, as well as stimulate bactericidal processes. The review also concluded that granulation tissue formation may be affected because endothelial cells forming the linings of blood vessels, keratinocytes, and fibroblasts migrate to the wound, attracted and stimulated by the cathode. Plus, the anode can be used to stimulate re-epithelialization to attract electronegative epidermal cells, which migrate from the deeply located hair follicles and sweat glands to form new epidermis.
Assessing healing. Outcomes usually are evaluated by recording changes in pressure ulcer surface area and linear dimensions. In some studies,7,12,15-17 percentage change in wound parameters measured before and after treatment are calculated and compared with the results obtained for the control groups; in two,15,16 average weekly changes in wound size were reported.
The recent recommendation2 that ES be considered in the management of recalcitrant Stage II, Stage III, and Stage IV pressure ulcers is based, in part, on a meta-analysis21 conducted to quantify the effect of ES on chronic wound healing. The meta-analysis included 216 pressure ulcers, of which 130 were treated with ES and 86 received a control treatment. The control groups received diverse therapies; placebo ES was applied or topical treatment with use of various types of moist dressings or antiseptics and whirlpool treatments. During the course of the study, pressure ulcer surface area treated with ES decreased an average by 16.63%, compared with 3.59% in the control groups. It was concluded that pressure ulcers treated with ES healed more expediently than control treated ulcers, although conclusions about which type of ES was most effective could not be made.
Specific soft tissue injuries. HVES was used to treat different types of soft tissue injuries in various studies. Alon22 evaluated the effectiveness of 80-Hz HVES in a controlled clinical study involving 15 patients with diabetes and foot ulcers (ages 42 to 85 years). Lesions were stimulated for 1 hour a day, 3 days a week. In 12 of the 15 patients, the ulcers healed completely within 2.6 months, whereas in 12 of 15 patients, pressure ulcers healed completely within 10.5 weeks (average healing rate during treatment was 80%). Unfortunately, the study did not have a control group.
Houghton’s23 randomized, double-blind, prospective clinical trial involved 27 patients;14 received HVES and 13 were in the control receiving sham HVES. In the treatment group, the average healing rate observed in the course of treatment (4 weeks) was 44.3% compared with 16.6% in the control sham group.
Franek24,25 conducted two randomized controlled clinical studies using HVES (100 V; 100 µs; 100 Hz) to treat venous leg ulcers. A 50-minute procedure was administered to 33 patients (average age 68.1 years)24 and 26 patients (average age 69.8 years)25 once a day, 6 days a week, for 6 weeks. Wounds decreased from an average of 22.7 cm2 to 9.3 cm2 (P <0.001), respectively,24 and an average of 55.26%.25
Because more controlled clinical studies to examine the effect of HVES on pressure ulcers are needed, the purpose of this study was to compare the effect of HVES to standard care in the management of wounds caused by various types of prolonged pressure against soft tissue.
Methods and Procedures
Study enrollment. All patients with a lower extremity pressure ulcer treated at the Janusz Daab Surgery Hospital in Piekary Slaskie, Poland, between January 1, 2005 and September 30, 2009 were eligible to participate in the study. Study eligibility was determined by the patient’s physician. The exclusion criteria were an ankle-brachial pressure index (ABPI) <0.9, diabetes mellitus, systemic sclerosis, a cancer diagnosis, pareses, and paralysis caused by injuries to the central or peripheral nervous system. Patients whose pressure ulcers required surgical intervention also were excluded from the study. After they agreed to participate in the study by providing informed consent, eligible patients were randomly allocated to the HVES intervention (treatment) or control group. The physician allocating patients to groups had 60 envelopes, each containing a piece of paper marked with either A (HVES group) or B (control group). The physician would draw and open an envelope in the presence of a physiotherapist to see the symbol and direct the patient to one of the comparative groups accordingly.
The study was approved by the Bioethics Commission of the Medical University of Silesia, Katowice.
Treatment. Measures to prevent the development of additional pressure ulcers were implemented for all patients. Pressure-redistribution surfaces and devices and pillows were used as needed. Patients also were instructed to change their positions frequently and to relieve pressure on the ulcer area as much as possible. Patients unable to move were repositioned by the physical therapist at least every 2 hours.
All wounds received standard topical care, including cleansing with potassium permanganate followed by covering the ulcer base with dressing. In both groups, dressings were tailored to meet the needs of each subject and to promote moist interactive healing. Wound dressings used in both groups included nonadherent gauze pads, dressings moistened with 0.9% sodium chloride, hydrogel, propolis extractum, and solcoseryl. If wound infection was suspected, desoxyribonucleasum plus fibrinolysinum, ethacridine lactate, and colistinum were additionally applied. Dressings suspected of adversely interacting with ES, such as topical agents with metal ions and petrolatum-based products, were not prescribed in ES group. Sharp debridement was performed in a relatively small number of subjects (four in HVES group and six in control group). Before ES was applied, pressure ulcers were thoroughly cleansed with 0.9% sodium chloride solution. As soon as the procedure was complete, dressings mentioned were applied. All immobilized patients received low-molecular-weight heparin (enoxaparin) as a standard therapy. Patients with elevated leukocyte levels were administered antibiotics based on culture and sensitivity testing of microbiological swabs taken from pressure ulcers.
Patients in group A additionally received HVES procedures. The device used for this purpose was the Ionoson (Physiomed, Germany). The voltage exceeded 100 V. Twin monophasic pulses lasting 100 µs in total and having a frequency of 100 Hz were applied as per previously published protocols.17,24-27
The amperage utilized during HVES procedures evoked a tingling sensation in the patients, but no motor effects were induced. The positive electrode and the negative electrode were made of conductive carbon rubber. Each patient had his/her own set of electrodes. The active electrode was placed on an aseptic gauze pad saturated with physiological saline overlying the wound site. The passive electrode (closing the electric circuit) was positioned at least 20 cm from the pressure ulcer (proximally or distally, depending on its location). After each procedure, the electrodes were sterilized in a disinfectant solution.
Patients received five 50-minute procedures per week (one procedure per day). Treatment continued until healing or for a maximum of 6 weeks. During the first 1 to 2 weeks, the HVES procedures utilized cathodic stimulation to facilitate granulation tissue formation, followed by anode stimulation for the rest of the treatment period.
Variables and measurements. Between January 1, 2005, and September 30, 2009, 57 patients were qualified to participate in the study. Five patients dropped out from the study during treatment (HVES = 3, control = 2). Three patients (HVES = 2, control = 1) had complications unrelated to treatment and were directed to other hospitals. One patient in the HVES group chose to discontinue treatment and withdrew from the study for personal reasons. One patient in the control group died.
Of the 50 patients who completed the study protocol, 22 were men, 28 were women with ages ranging from 14 to 88 years. Eleven participants were obese (seven in the HVES group and four in the control). Body mass of the other participants was within normal range. The patients were not addicted to either alcohol or drugs; 25 smoked cigarettes (11 in the HVES group and 14 in the control). Diabetes, renal or hepatic failure, tumors, and central or peripheral nervous system diseases were not diagnosed in any patient.
The participants had Stage II and Stage III pressure ulcers on lower extremities. Pressure ulcers were located on the legs (29, 58%), feet (14, 28%), lateral and medial ankles (5, 10%), and greater femoral trochanter (2, 4%). The disease had continued for 1 to 6 months before the study.
Demographic information on the patients enrolled in the study was obtained from standardized subject interviews, physical examinations, vascular flow examinations, as well as the results of additional examinations and the history of concomitant diseases found in participant’s medical documentation.
Wounds were classified based on the following criteria: partial-thickness loss of the dermis — Stage II ulcers, which were subdivided into Stage IIA (shallow lesions involving only the epidermis) and Stage IIB (ulcers with damaged dermis). Full-thickness tissue loss was classified as Stage III pressure ulcers and involved subcutaneous tissue and fascia. Pressure ulcers were photographed and size was recorded weekly by transferring their homothetic, congruent images onto transparent film sheets. The contours showed wound perimeters and granulation tissue areas and were also used to measure wound longest lengths and longest (perpendicular) widths with a centimeter ruler. Wound depth was measured using a digital caliper with a depth gauge (MIB-Messzeuge IP67 Germany) at the site where the wound was the deepest. The tip of the gauge had a soft, disposable, sterile cap that prevented the bed of the wound from being damaged. The site where depth was measured was also marked on the contour. The images then were measured with a planimeter. The electronic equipment measuring pressure ulcer area and volume consisted of a digitizer (Mutoh Kurta XGT, Altek, USA) wired to a personal computer with upgraded software (C-GEO v. 4.0 Nadowski, PL) for calculating and storing pressure ulcer area, perimeter, and volume measurements.
Data and statistical analysis. Distribution homogeneity of patients’ characteristics was investigated in both groups using the ML c2 test for independence and the Mann-Whitney U test.
Relative and percent change in wound area, volume, longest length and width, and granulation tissue area were calculated. The Gilman method28,29 (see Table 3) that estimates the wound size based on its surface area and the length of the perimeter was introduced in order to ensure precise evaluation and comparison of changes in the sizes of pressure ulcers having differently shaped contours.
Wound area measurement method errors for differently shaped wound areas (see Figure 1) and for calculating volume (see Figure 2) were calculated (see Table 4).
The Wilcoxon matched pairs test was used to compare average wound areas, volumes, lengths, and widths, as well as average relative granulation tissue areas before and after treatment within each group.
The Mann-Whitney U test was employed to compare average percentage change in wound areas, volumes, longest lengths and longest widths, and average percentage change in relative granulation tissue areas. Average wound areas and average relative granulation tissue areas were compared between groups A and B in successive weeks of treatment using the repeated measures ANOVA test and the Tukey’s post-hoc test for unequal sample sizes.
The correlations (R) between relative changes in wound areas, longest lengths, and longest widths were obtained from the Spearman test.
The level of significance accepted for all statistical tests performed during the study was P £0.05. 
Results
Fifty patients with Stage II and Stage III pressure ulcers were enrolled in the study. The treatment group consisted of 26 patients (eight women and 18 men), ages 19 to 87 years (average 59 years), whose body mass ranged from 55 to 112 kg (average 75.4 kg). Seven patients were obese (body mass index [BMI] >30). The body mass of each of the remaining patients was within the normal range. The ratio between smokers and nonsmokers was 11:15. Seventeen ulcers in the treatment group were classified as Stage II (of which five were Stage IIA). The control group consisted of 24 patients (14 women and 10 men), ages 14 to 88 years (average 56.2 years), whose body mass ranged from 45 to 96 kg (average 69.4 kg). Only the distribution of men and women was significantly different (P = 0.03) between the two treatment groups (see Table 5).
In the treatment group, six pressure ulcers occurred as a result of poorly fitting orthopedic aids (three cases of wrong orthopedic footwear and three prostheses). In six patients, the ulcers developed after mechanical injuries (pressure, abrasion, scratches), and in another five, temporary immobilization and forced positioning of the body due to surgical intervention (unconsciousness) or multi-organ injuries were considered the causative factors. In six patients, pressure ulcers formed beneath a cast, immobilizing splint, or traction device. Three persons had pressure ulcers because of prolonged inward pressure exerted by plates and screws used for internal bone stabilization.
Most (61.5%) ulcers were on the leg; 30.7% were on the feet and 7.7% on the lateral ankle or medial ankle. Patients in this group had their ulcers for 1 to 6 months (average 3.17 months) before physical treatment commenced.
In the control group, causative factors included immobilization due to postoperative positioning, multi-organ injuries or being unconscious; poorly fitting prosthetic limbs (three patients) or footwear (one patient); mechanical injury (three); and pressure exerted by plates and screws (three patients) or pressure from a plaster cast (one) or traction device (one). In three patients, pressure ulcers appeared under postoperative dressings.
Similar to the treatment group, more than half (54.2%) of the ulcers in the control group were on the leg. The other ulcers were located on the feet (25%), lateral or medial ankles (12.5%), and femoral trochanter (8.3%), with a duration of an average of 2.83 months (SD 1.97) before study enrollment.
A total of seven measurements were obtained during the study. On average, wound area and volume measurement error ranged from 2.7% to 37.9% for wound size and from 6.9% to 26.9% for wound volume. For both area and volume, error percentages were highest for smaller wounds (see Table 6).
After 6 weeks of treatment for both groups, a statistically significant decrease in ulcer size was observed in both treatment groups (see Table 7). A decrease in wound volume and an increase in granulation tissue from baseline also was observed in both treatment groups, but the difference was statistically significant in the treatment group only.
Statistically significant differences between the treatment and control group outcomes were observed for the following variables: decrease in wound area (P = 0.00003), linear dimensions (P = 0.0003 for length and P = 0.00008 for width), and volume (P = 0.008) (see Table 8). Change in the Gilman parameter was also significantly greater in the treatment than in the control group (P = 0.000003). Changes in percent granulation tissue area were not significantly different between the two groups (P = 0.18).
Weekly differences in percent granulation tissue between the two groups were statistically significant during the week 5 assessment only (see Table 9), but differences in wound area became statistically significant after 2 weeks of care (see Table 9 and Figure 3). The Spearman test showed that ulcers were healing evenly in both groups, because changes in wound areas and in their longest lengths and longest widths were correlated. In the treatment group, correlation coefficients between changes in wound surface area, longest length, and longest width were R = 0.96 and R = 0.98, respectively.
The coefficient values as calculated for the control group were R = 0.94 and R = 0.89, respectively. In both groups the coefficients were statistically significantly different (P <0.000001) from zero.
Discussion
The treatment results achieved showed that therapies were effective in both comparative groups; however, the decrease in wound surface areas was significantly greater in the HVES treatment than in the control group. Weekly changes in wound areas indicated that in the ES treatment group, wounds healed evenly, whereas average wound areas in the control group were greater after 2 weeks of treatment than at the beginning.
Wound dimensions. The results of this research confirm previous studies7,14,15,17 showing that HVES is effective in treating Stage II and Stage III pressure ulcers. In the treatment group, the average wound area at baseline was 4.54 cm2 and decreased by 88.9% after 6 weeks. Similarly, Kloth16 applied HVES to pressure ulcers with an average baseline surface area of 4.03 cm2 and observed complete healing within 7.3 weeks, and Griffin17 applied HVES to pressure ulcers and observed an 80% decrease in ulcer size during 20 successive days of treatment. 
Treatment-induced linear changes in wound dimensions also were recorded in the current study. Wound lengths decreased in groups A and B by 74% and 36.1%, and widths by 79% and 36.3%, respectively. Linear changes in both groups were correlated with changes in total wound areas and wound volumes, suggesting an even healing process. In other studies undertaken to identify electrotherapy effects on pressure ulcer healing, the percentage of granulation tissue area in total wound area was not calculated. This means recent results are comparable only to those obtained by Franek,27 who assessed HVES influence on pressure ulcer healing and found an increased proportion of granulation tissue in total wound area following ES. Based on his findings, authors of the current study assumed that granulation tissue would grow steadily. However, the percentage of granulation tissue increased consistently in the treatment group only. In the control group it changed irregularly, increasing or decreasing from week to week. Figures 4 and 5 demonstrate pressure ulcer appearance before and after treatment with HVES.
Location. In the current study, HVES therapy was applied to Stage II and Stage III pressure ulcers located on the lower extremities. Kloth16 treated Stage IV pressure ulcers (his study does not specify their location); Griffin17 treated pelvic region Stage II through Stage IV pressure ulcers.
Treatment duration. Patients in the current study received 50-minute HVES procedures once a day, 5 days a week, so the total treatment time was 4.16 hours in a week. Kloth16 used similar durations, applying HVES for 45 minutes a day for 5 days in a week (3.75 hours a week). Griffin17 administered HVES to pressure ulcers for 1 hour a day for 20 successive days.
Electricity parameters. The electric current parameters selected for this study (100–150 V; 100 µs; 100 Hz) were similar to those used by Kloth16 (100–175 V; 100 µs; 105 Hz) and Griffin17 (200 V; 100 Hz). In all three studies, twin peak monophasic pulses were used. Feedar15 applied a milliamperage pulsed current (132 µs; 128 Hz and 64 Hz; 29.2 mA) to 26 patients with Stage II through Stage IV pressure ulcers for 4 weeks, 7 hours a week, achieving a 56% (statistically significant) healing rate. The pressure ulcers were located on lower extremities, and their average surface area before treatment was 14.65 cm2. In the control (placebo) group, pressure ulcers decreased by 33% on average. The average weekly healing rates in the HVES group and the control group were 14% and 8.25%, respectively.
These observations and current study findings show that pulsed currents can be an effective method for treating pressure ulcers, requiring from 4 to 7 hours of stimulation a week. A microamperage direct current has been found to improve pressure ulcer healing with stimulation applied for 20 hours13 and 42 hours12 a week. However, more research is necessary to 1) establish whether a shorter duration stimulation procedure utilizing a pulsed current would be as or more effective than a procedure employing a microamperage direct current, and 2) determine the minimal duration for the maximum effect of electrical stimulation in the treatment of pressure ulcers.
Ulcer duration. Before study enrollment, ulcers had been present for 3.17 months (HVES group) and 2.83 months (control group). Pressure ulcers in Barron’s study14 were of similar duration (average 13.5 weeks), but Barron used a microamperage biphasic current.
Electricity parameters/tissue defect considerations. The available literature does not specify what therapeutic current parameters should be selected to treat particular types of soft tissue defects. However, voltages of 100–150 V, as used in this study, seem to work well in this as well as other pressure ulcer16,17 and venous ulcer23-27 studies.
In the current study, 100 µs pulses at 100 Hz were used, similar to the settings used by other researchers performing clinical16,7,23-27 and animal studies18-20,30; in the latter, where HVES was used to treat soft tissue defects, twin-spike pulses were applied. Following the methodology described by other researchers,15-17 the amperage applied induced only sensory sensations in the patients.
Electrode placement. As in other studies,12,13,15-17 in this study the sterilized active electrode was placed over the pressure ulcer. Both active electrode and passive electrode were isolated from tissue with sterile gauze pads saturated with physiological saline to enable the electric flow and to provide the wound with adequate humidity.
A method previously employed in venous24-27 and pressure ulcers12,13 was used to plan the current study — cathodic stimulation was applied for 2 weeks to facilitate granulation tissue formation, followed by anodal stimulation to stimulate reepithelialization for the rest of the treatment time. In vivo study results18 seem to support this approach. However, Kloth16 treated pressure ulcers first with HVES based on anodal stimulation, and introduced cathodic stimulation if wound healing progression was not observed; whereas, others used cathodic stimulation throughout the entire treatment period.17,23 These differences suggest that more research is necessary in order to determine the effectiveness and optimal use of cathodic and anodal stimulation in wound treatment.
Adverse events. No adverse events were observed in this or other studies, indicating that HVES is safe. The treatment does not cause pain and can be used in all patient care environments, providing the patient and/or caregivers receive appropriate education and instructions, medical personnel assistance is available, and the treatment is monitored.
Summary. The effectiveness of HVES applied to assist pressure ulcer healing should encourage more studies into the influence of ES on other soft tissue defects. Other aspects that require further in-depth investigations are the usefulness of ES in treating infected wounds, the effectiveness of cathodic and anodal stimulation, and the necessary, minimal daily/weekly durations of ES applied to pressure ulcers. The types of electric currents (microamperage or milliamperage current; low- or high-voltage current; monophasic or biphasic current) that are most appropriate for treating soft tissue defects also need to be determined.
Study Limitations
The study length (4 years) could have introduced some variability in methods and procedures. At the same time, the authors were unable to follow patients for a sufficient amount of time to observe healing. Although study outcomes were consistent in each treatment group, the absence of blinding and use of placebo ES in the control group is a limitation of this study that may affect the generalizability of the findings.
Conclusion
The results of this study show that recalcitrant lower extremity Stage II and Stage III pressure ulcers treated with HVES (100–150 V; 100 µs; 100 Hz) applied for 50 minutes a day, five times a week over 6 weeks, exhibit significantly larger reductions in wound surface area and volume than ulcers treated with standard care only. Decreases in wound surface area, length, and width were highly correlated, suggesting continuous healing.
The results of this study confirm previously published clinical study results detailing the effectiveness of HVES. Future studies should follow patients until healing, and randomized controlled clinical studies are needed to compare the efficacy of using cathodic and anodal stimulation combined or alone and to determine the optimal duration of these two types of electrical stimulation.
Prof. Franek is a Professor of Medical Sciences and Head of the Department of Biophysics, Medical University of Silesia, Katowice, Poland. Dr. Kostur is Head of the Department of Physiotherapy, Janusz Daab Orthopedic and Trauma Surgery Hospital, Piekary Slaskie, Poland. Dr. Polak is an Assistant Professor, Chair of Physiotherapy, Academy of Physical Education, Katowice; and an Assistant Professor, Institute of Medical Science, Katowice School of Economics. Dr. Taradaj is an Assistant Professor, Chair of Physiotherapy, Academy of Physical Education, Katowice; and an Assistant Professor, Department of Biophysics, Medical University of Silesia. Dr. Szlachta is Head, Wound Treatment Department, Janusz Daab Orthopedic and Trauma Surgery Hospital, Piekary Slaskie. Prof. Blaszczak is a statistical analyst and Professor, Department of Biophysics, Medical University of Silesia. Dr. Patrycja Dolibog is an Assistant Professor, Department of Biophysics, Medical University of Silesia. Dr. Pawel Doliberg is an assistant, Department of Biophysics, Medical University of Silesia. Dr. Koczy is Director of the Janusz Daab Orthopedic and Trauma Surgery Hopsital, Piekary Slaskie. Prof. Kucio is head of Internal Medicine, Specialist Hospital, Jaworzno; and Head of the Chair of Physiotherapy, Academy of Physical Education, Katowice. Please address correspondence to: Anna Polak, PhD, PT, Faculty of Physiotherapy, Academy of Physical Education, Mikolowska 72A, 40-065 Katowice, Poland; email: a.polak@awf.katowice.pl.
1. Consortium for Spinal Cord Medicine Clinical Practice Guidelines. Pressure ulcer prevention and treatment following spinal cord injury: a clinical practice guideline for health-care professionals. J Spinal Cord Med. 2001; 24(Suppl 1):40–101.
2. National Pressure Ulcer Advisory Panel and European Pressure Ulcer Advisory Panel. Prevention and treatment of pressure ulcers: clinical practice guideline. Washington DC: National Pressure Ulcer Advisory Panel 2009.
3. Weiss DS, Kirsner R, Eaglstein WH. Electrical stimulation and wound healing. Arch Dermatol. 1990;126:222–225.
4. Lampe K. Electrotherapy in tissue repair. J Hand Ther. 1998;12(11):131–139.
5. Bourguignon GJ, Bourguignon LY. Electric stimulation of protein and DNA synthesis in human fibroblasts. FASEB J. 1987;1:398–402.
6. Reger S, Hyodo A, Negami S, Kambic H, Sahgal V. Experimental wound healing with electrical stimulation. Artif Organs. 1999;23(5):460–462.
7. Wood J, Evans P, Schallreuter K, Jacobson WE, Sufit R, Newman J, White C, Jacobson M. A multicenter study on the use of pulsed low-intensity direct current for healing chronic stage II and stage III decubitus ulcers. Arch Dermatol. 1993;129(8):999–1009.
8. Mohr T, Akers TK, Wessman HC. Effect of high voltage stimulation on blood flow in the rat hind limb. Phys Ther. 1987;67(4):526–533.
9. Junger M, Zuder D, Steins A, Hahn M, Klyscz T. Treatment of venous ulcers with low frequency pulsed current (Dermapulse): effects on cutaneous microcirculation. Hautartz. 1997;48:879–903.
10. Borba GC, Hochman B, Liebano RE, Enokihara MM, Ferreira LM. Does preoperative electrical stimulation of skin alter the healing process? J Surg Res. 2011;166(2):324–329.
11. Kloth L, McCulloch J. Promotion of wound healing with electrical stimulation. Adv Wound Care. 1996;9(5):42–45.
12. Gault W, Gatens P. Use of low intensity direct current in management of ischemic skin ulcers. Phys Ther. 1976;56(3):265–269.
13. Carley P, Wainapel S. Electrotherapy for acceleration of wound healing: low intensity direct current. Arch Phys Med Rehabil. 1985;66(7):443–446.
14. Barron J, Jacobson W, Tidd G. Treatment of decubitus ulcers. A new approach. Minn Med. 1985;68(2):103–106.
15. Feedar J, Kloth L, Gentzkow G. Chronic dermal ulcer healing enhanced with monophasic pulsed electrical stimulation. Phys Ther. 1991;9(10):639–649.
16. Kloth L, Feedar J. Acceleration of wound healing with high voltage, monophasic, pulsed current. Phys Ther. 1988;68(4):503–508.
17. Griffin J, Tooms R, Mendius R, Clifft J, Vander-Zwaag R, el-Zeky F. Efficacy of high voltage pulsed current for healing of pressure ulcers in patients with spinal cord injury. Phys Ther. 1991;71(6):433–442.
18. Brown M, Gogia PP. Effects of high voltage stimulation on cutaneous wound healing in rabbits. Phys Ther. 1987;67:662–667.
19. Brown M, McDonnell MK, Menton DN. Electrical stimulation effects on cutaneous wound healing in rabbits. A follow-up study. Phys Ther. 1988;68;6:955–960.
20. Brown M, Gogia PP, Sinacore DR, Menton DN. High-voltage galvanic stimulation on wound healing in guinea pigs: longer-term effects. Arch Phys Med Rehabil. 1995;76:1134–1137.
21. Gardner S, Frantz R, Schmidt F. Effect of electrical stimulation on chronic wound healing: a meta-analysis. Wound Repair Regen. 1999;7(6):495–503.
22. Alon G, Azaria M, Stein H. Diabetic ulcer healing using high voltage TENS. Phys Ther. 1986;6(66):775–780.
23. Houghton P, Kincaid C, Lovell M, Keast D, Harris K. Effect of electrical stimulation on chronic leg ulcer size and appearance. Phys Ther. 2003; 83(1): 17–28.
24. Franek A, Polak A, Kucharzewski M. Modern application of high voltage stimulation for enhanced healing of venous crural ulceration. Med Eng Phys. 2000;22(9):647–655.
25. Franek A, Krol P, Chmielewska D, Blaszczak E, Polak A, Kucharzewski M, Taradaj J. The venous ulcer therapy in use of the selected physical methods (Part 2) — The comparison analysis. Pol Merkur Lekacski. 2006:20(120):691–695.
26. Polak A, Franek A, Hunka-Zurawinska W, Bendkowski W, Kucharzewski M, Swist D. High voltage electrical stimulation in leg ulcer’s treatment. Wiad Lek. 2000;53(7-8):417–426.
27. Franek A, Taradaj J, Polak A, Cierpka L, Blaszczak E. Efficacy of high voltage stimulation for healing of venous leg ulcers in surgically and conservatively treated patients. Phlebologie. 2006;34:255–261.
28. Gilman TH, Margolis D. Comparing healing rates across studies is the vision, but first, a correct equation please! Ostomy Wound Manage. 1995;41:6–7.
29. Gilman TH. Parameter for measurement of wound closure. WOUNDS. 1990;3:95–101.
30. Cruz N, Bayron F, Suarez A. Accelerated healing of full-thickness burns by the use of high-voltage pulsed galvanic stimulation in the pig. Ann Plast Surg. 1989;23(1):49–55.
