High Voltage Pulsed Current Research Articles

High Voltage Pulsed Current Using Surface Electrodes: Effect on Acute Edema Formation after Hyperflexion Injury in Frogs

We have repeatedly demonstrated that high voltage pulsed current (HVPC) applied via immersion technique at 120 pps and 90% of visible motor threshold curbs posttraumatic edema formation in nonhuman vertebrates. Clinically, however, HVPC is frequently applied to patients via surface electrodes. The purpose of this study was to determine whether use of HVPC with surface electrodes would also result in curbing of edema formation in nonhuman vertebrates. Ankles of 20 anesthetized frogs were sprained bilaterally. One randomly selected limb of each frog received HVPC for 30 minutes immediately after trauma, while the other limb served as a control. Limb volumes were measured before and after trauma, after treatment, and at 1-hour intervals for 4 hours. Unlike three previous experiments with cathodal HVPC, a single 30-min HVPC treatment delivered via surface electrodes did not curb edema formation. These results suggest that electrode type or position or both may be critical factors in the efficacy of HVPC in the treatment of edema in frogs. J Orthop Sports Phys Ther 1992;16(3):140-144.

Influence of high voltage pulsed current on edema formation following impact injury in rats.

High voltage pulsed current (HVPC) has been shown to be effective in curbing posttraumatic edema formation in frogs. The purpose of this study was to establish the utility of HVPC in controlling edema formation in a mammalian model. Both feet of 20 anesthetized rats were traumatized following initial determination of hind-limb volumes. Four 30-minute cathodal HVPC treatments at 120 pulses per second and 90% of visible motor threshold interspersed with 30-minute rest periods were applied to one randomly selected hind limb of each rat via the immersion technique. The other hind limb served as a control. Limb volumes were measured after each treatment and rest period. All data were expressed as changes from pretrauma limb volumes in milliliters per kilogram of body weight; these data were analyzed by repeated-measures analyses of variance and post hoc paired t tests. Volumes of untreated limbs were significantly greater than volumes of treated limbs after the second treatment. Evidence of significant treatment effects in frogs, and now rats, provides a compelling rationale for initiating trials of efficacy of cathodal HVPC in inhibiting acute edema formation in humans.

Effects of low voltage pulsed current on edema formation in frog hind limbs following impact injury.

The purpose of this study was to test the effect of low voltage pulsed current (LVPC) on posttraumatic edema formation in frog hind limbs. Feet of 26 anesthetized bullfrogs were systematically injured by weight drop. One hind limb of each animal was randomly selected to receive continuous 100-pps LVPC at 90% of motor threshold; the opposite hind limb served as a control. A series of four 30-minute treatments (interrupted by 30-minute rests) was begun minutes after injury. Changes from pretrauma limb volumes were determined before and after each treatment and at 8, 17, 20, and 24 hours posttrauma. Analysis of variance revealed no significant treatment effect. Similar studies utilizing high voltage pulsed current (HVPC) at 90% of motor threshold revealed significant curbing of edema formation in frogs. Waveform (LVPC versus HVPC) seems to influence the efficacy of electrotherapy for edema control.

Effect of electrically induced muscle contractions on posttraumatic edema formation in frog hind limbs.

We tested the hypothesis that repeated muscle contractions induced by high voltage pulsed current (HVPC) would limit volume increases in traumatized frog hind limbs. Twelve frogs were anesthetized, and both hind limbs of each frog were traumatized by impact. Limb volumes were measured via water displacement over a 24-hour period. Four 30-minute treatments of continuous 1-pulse per second HVPC were applied to one limb selected randomly. Stimulation produced muscle contractions that resulted in minimal joint movements. Volume changes from pretrauma limb volumes (in milliliters per kilogram) were analyzed by an analysis of variance for repeated measures. Our hypothesis was rejected (ie, repeated muscle contractions, as induced in this study, did not limit posttraumatic edema formation in frogs). Further investigation of the relative influences of limb position and varying pulse rates, pulse durations, and intensities of HVPC on edema formation may provide valuable insights on effective treatment of edema in humans.

Effect of a Single 30-Minute Treatment of High Voltage Pulsed Current on Edema Formation in Frog Hind Limbs

The purpose of this study was to investigate the effect of a single treatment of high voltage pulsed current (HVPC) on edema formation. Twenty-four frogs were anesthetized, and both hind limbs of each frog were traumatized by impact. Limb volumes were measured by water displacement immediately before and after trauma and at predetermined intervals for 24.0 hours posttrauma. One limb of each frog was randomly selected to receive 30 minutes of continuous, 120-pulse per second, cathodal HVPC at voltages 10% less than motor threshold levels. Data were analyzed by an analysis of variance for repeated measures. Sources of significant differences were determined by paired t tests (probability values determined by Bonferroni adjustment). A single 30-minute application of HVPC significantly curbed edema formation for between 4.0 and 7.5 hours following treatment (ie, volumes of treated limbs were significantly less than those of untreated limbs). These results suggest that regimens currently applied to humans (ie, one treatment per day or three times per week) may be insufficiently aggressive to provide sustained treatment effects.

Effect of Anodal High Voltage Pulsed Current on Edema Formation in Frog Hind Limbs

We have recently demonstrated that some forms of cathodal high voltage pulsed current (HVPC) curb posttraumatic edema formation in frog hind limbs. The purpose of this study was to determine, by assessing the capacity of anodal HVPC to curb posttraumatic edema formation, whether polarity is an important variable. Fourteen anesthetized bullfrogs were placed on large dispersive electrodes lining body slings that maintained the frogs' limbs in a dependent position throughout data collection. The frogs' feet were traumatized by impact following initial measurement of limb volumes. At the commencement of each of four 30-minute treatments, hind limbs were immersed in separate beakers and briefly stimulated until motor threshold was determined. One limb, randomly selected, received anodal HVPC at 90% of motor threshold and 120 pulses per second; the other limb served as a control. Treatments were followed by 30-minute rests. Limb volumes were measured by water displacement immediately after trauma and following each treatment and rest period. Data were expressed as changes from pretrauma volumes in milliliters per kilogram of body weight. A repeated-measures analysis of variance was used to test for treatment effect. Despite an aggressive series of treatments, virtually symmetrical bilateral edema occurred; therefore, no treatment effect was evident. This result contrasts with treatment effects previously reported for cathodal HVPC.

Author Response

We thank Dr Alon for his commentary, and we appreciate this opportunity to engage in further discussion of the theoretical rationale for high voltage pulsed current (HVPC) as a means of minimizing edema and edema formation. First, we admit to being in error in using the term “iontophoresis” in the “Discussion” section of our article. We should have used the term “ionophoresis” when we stated that “iontophoretic (electrical-field) effects may be immeasurably small during application of HVPC….” We incorrectly thought that iontophoresis and ionophoresis were synonymous. Indeed, they are quite similar, as both refer to movement of charged particles in an electrical field; they differ in that iontophoresis refers to movement of charged drug particles in an electrical field. Even in light of our improved diction, however, we continue to believe that both ionophoretic and iontophoretic effects are properly categorized as “electrophysical.”

Reduction of Chronic Posttraumatic Hand Edema: A Comparison of High Voltage Pulsed Current, Intermittent Pneumatic Compression, and Placebo Treatments

The purpose of this study was to compare the efficacy of intermittent pneumatic compression (IPC) and high voltage pulsed current (HVPC) in reducing chronic posttraumatic hand edema. Thirty patients with posttraumatic hand edema were randomly assigned to IPC, HVPC, or placebo-HVPC groups (10 patients in each group). Patients received a single application of the respective treatment for 30 minutes. Measurements were made before and after a 10-minute rest period and after the 30-minute treatment. A volumetric method was used to quantify edema reduction. Reduction in hand edema was significant between the IPC and placebo-HVPC groups (p = .01). Differences in edema reduction between the HVPC and placebo-HVPC groups did not reach statistical significance (p = .04), but were considered clinically significant. There was no significant difference between the IPC and HVPC groups. A single 30-minute administration of IPC produced a significant reduction in hand edema. Additional clinical studies are needed to delineate maximally effective treatment protocols for reduction of chronic posttraumatic hand edema. [Griffin JW, Newsome LS, Stralka SW, et al: Reduction of chronic posttraumatic hand edema: A comparison of high voltage pulsed current, intermittent pneumatic compression, and placebo treatments.

Inhibition of Bacterial Growth In Vitro Following Stimulation with High Voltage, Monophasic, Pulsed Current

Low-intensity direct current has been reported to be effective in promoting healing of infected wounds, and these results have been assumed to apply to stimulation of wound tissue with monophasic high voltage pulsed current (HVPC). The purpose of this study was to determine whether HVPC has an inhibitory effect on growth in vitro of three bacterial species--Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa--commonly isolated from open wounds. Following exposure to HVPC, the measured zone of inhibition of bacterial growth was not significantly different between bacterial species. Inhibition at the anode (positive pole) occurred secondary to build-up of toxic end products, and inhibition at the cathode (negative pole) resulted from exposure to HVPC. Duration of exposure and voltage showed a highly significant linear relationship. Exposure to more than 250 V of HVPC for at least two hours resulted in some degree of inhibition of growth in all three bacterial species.