High Voltage Pulsed Current (HVPC) Mohammed Taher Ahmed Associate professor of PT E-Mail: MOMARAR@KSU.EDU.SA Mobile phone : 0542115404

History of HVPC In 1940 this current originally developed by Haslip in USA, and known as Dyna-wave. In 1970s this current become popular and known as HVPC. The first published paper on use of this current was by Young 1966, on edema reduction. High voltage developed in the 1940s and became commercially available in the mid‐1970s • The name of the device has changed and is now more commonly called high voltage pulsed current • HVPC is an electrical current with a monophasic waveform • There is a misconception that the current is called “Interrupted Galvanic”, or “Interrupted Direct Current”, because the waveform pulsed galvanic stimulators wereis monophasic

What is HVPC ? 1-Waveforme 1.1.Twin-peak monophasic pulse: Each pulse is made of a pair of monophasic (+/-) spike like waveforms that rising and falling rapidly, that reach maximum of 300-400mA. 1.2-Pulse duration: very short (5-200µS), usually 50-120µS 1.3.Very long inter-pulse duration of 9900µS 2-High voltage device: current voltage ranged from (0-500V), maximum voltages (150V). 3-Pulse frequency: 1-200Hz. Usually (1-120Hz) The HPVC waveform allows for a high peak voltage but a low average voltage, meaning the overall amount of current the patient receives is very low • The “high” in high voltage pulse current can be in the order of 500 volts, but the average amount of current is significantly less (measured in milliAmps [mA] and turned up to patient tolerance)

Very Short Pulse Duration (5-200 µSec) 3 No chemical effects Stimulation is safe and comfortable than Faradic current Maintained for longer periods of time (60minutes). 2 selectively stimulate motor rather than sensory nerves, so used for reduction of disuse atrophy. . 1 Not stimulate dennervated muscles as it can not depolarized membrane . The pulse or phase duration is quite narrow, usually varying 50 – 200 μsec • The interpulse interval is large, helping to decrease the overall amount of current flow into the tissues HVPC penetrates deeper than that of low-voltage currents.

Physiological effects Wound Healing Edema reduction Pain Modulation 1. Decrease in pain 2. Decrease in swelling/inflammation/ Increase in local circulation 4. Facilitation of wound healing 5. Facilitation of muscle contraction Muscles stimulations

Positive Polarity Negative Polarity Increases macrophages Vascularity Stimulation of fibroblastic growth Collagen production Epidermal cell migration Inhibits bacterial growth . Increases macrophages Promotes epithelial growth Facilitation of tissue healing – change in endogenous voltage of tissues with monophasic waveform, which involves migration of cells toward the anode or cathode – re‐establishing normal electric potential of the wound – migration of neutrophils, macrophages, lymphocytes and platelets enhances the inflammatory phase of healing Migration of fibroblasts enhances the proliferative phase of healing – Local increase in circulation, bringing more oxygen and foodstuffs, and removing debris and waste products

Edema Reduction Muscle pump Repeated muscle contraction (motor level stimulation) increase venous return & blood flow . Fluid Repulsion Theory Repulsion of protein rich fluid through microvascular exchanges (negative polarity). Edema Control: 5-20 Hz (muscle twitch) Decrease in swelling/oedema – Removal of vasoactive agents, debris and waste products from the injured area – Increase in cell membrane permeability allowing more extracellular fluid to be resorbed – Activation of motor nerves will bring about muscle contraction, thus enhancing the muscle pump effect What makes HVPC more effective for edema management? The net effects of these two mechanisms are to decrease edema

Pain modulation Improve circulation supra spinal Gate control theory supra spinal stimulation Improve circulation High frequency (80-120Hz) Low intensity HVPC C-TENS Low frequency (10-20Hz) High intensity HVPC AL-TENS Increase blood flow Removal of waist product Reduction of inflammatory process, Decrease in pain – Activation of pain‐gating mechanisms – Stimulation of release of endogenous opiates – Stimulation of descending pain suppression mechanism – Removal of pain metabolites and vasoactive agents from injured area

THERAPEUTIC USES AND INDICATIONS OF HVPC 1-Wound healing Pressure ulcer Diabetic foot ulcer Burn wound 2-Posttraumatic Edema (fracture, burn). Sprains & Strain 3-Musculoskeletal Pain Chronic low back pain. Osteoarthritis,

1. Be cautious when using HVPC over an area with: CONTRAINDICATIONS and PRECAUTIONS Over neoplasic lesion. Over area of extreme edema, Over hemorrhagic area. Over osteomyleities Over anterior cervical area. Over transcranial area. Over electronic implants. 1. Be cautious when using HVPC over an area with: a. Impaired sensation b. Extensive torn tissue c. Hemorrhagic area 2. Patients with epilepsy should be monitored during treatment.

Considerations for HVPC Application Intensity ( motor and / or sensory) Frequency (pulse rate); high or low pulse frequency. Modes (continuously, reciprocal). Polarity (positive, negative). Electrodes Placement (monopolar/bipolar) Treatment time ( 10-60 minutes) Frequency of treatment (daily /3 time per week) HVPC requires the use of 2 electrical circuits in order to conduct current to the patient • The primary (active) circuit has positive or negative electrodes in a 1, 2 or 4 electrode formation • The secondary circuit is the dispersive circuit, where the density of current is reduced in order that the active circuit “feels stronger” We need to address the issue of polarity when applying HVPC to a patient. We will be using active electrodes and a dispersive electrode – Active electrodes will all be one polarity (‐ve or +ve) – The dispersive electrode will be the opposite polarity • HVPC must always use the dispersive electrode outlet in order to complete the electrical circuit Frequency • Intensity of current • Accurate localization of lesion/injury • Accurate placement of electrodes • Patency of circulation • Intact neurological sensation • Knowledge of underlying pathophysiology in relation to desired outcome of treatment • Contraindications and precautions to treatment

HVPC Application for Wound Healing Cleaned and debrided the wound before application of HVPC. Cover the wound with several layer of sterile gauze soaked in saline. Active electrodes soaked in antiseptic solution Active electrodes will be applied either Directly over the wound Directly in the wound periphery . Dispersive electrodes are placed proximal to active electrode so that the current passes through the wound.

HVPC Application for Wound Healing IF wound is infected used Negative electrodes (Cathode) Daily treatment (30-60minutes) IF wound is clean used Positive electrodes (anode) Day per day treatment (30-60minutes) Before TTT During TTT After TTT

HVPC Application for Wound Healing TREATMENT PARAMETER GUIDELINES • Pulse frequency: 100 pps • Pulse duration: about 100 μsecs • Treatment intensity: 150 ‐ 200 V • Treatment duration: 30 – 60 minutes; 3 ‐ 5 times/week Before TTT During TTT After TTT

HVPC Application for Hand Edema Reduction Technique 2 One active electrodes (negative polarity) were placed over the median nerve in the wrist crises, while another electrodes over dorsum of the hand, after being soaked in sterile 0.9% Na Cl, while the dispersive electrodes was placed over forearm area. Technique 1 One active electrodes (negative polarity) were placed over the median nerve in the anticubital foss, while another electrodes over the ulnar nerve, at medial epicondyle, after being soaked in sterile 0.9% Na Cl, while the dispersive electrodes was placed over forearm area.

HVPC TREATMENT PARAMETER GUIDELINES pain relief, most studies suggest the following: • Place the cathode (‐ve) electrode(s) on or near the painful site (switch polarity if patient uncomfortable or pain is not diminished after 2‐3 treatments) • Pulse frequency: between 80‐120 pps • Pulse duration: about 100 μsecs • Intensity: comfortable buzzing • Treatment duration: 20 – 30 minutes

Self Questioning? Describe the waveform characteristics of HVPC What are the 4 main indications for HVPC? Describe the parameters for targeting pain control What makes HVPC more effective for edema management? How does the sensation of HVPC compare to TENS? Pulse duration for HVPC How is HVPC beneficial for wound healing?

HVPC FOR SWELLING I EDEMA TREATMENT PARAMETER GUIDELINES • Place the cathode (‐ve) electrode surrounding the edema are • Pulse frequency: 120 pps • Pulse duration: about 5 ‐ 20 μsecs • Treatment intensity: strong buzzing (90% of visible muscle contraction) • Treatment duration: 30 – 60 minutes; 3 times/week