HIGH-VOLTAGE PULSED GALVANIC STIMULATION (HVPGS)

• recognized by many different names, including – high volt pulsed galvanic (HVPG), – high voltage stimulation (HVS) and – direct current stimulation (DC)

• The high volt pulsed galvanic stimulator (HVPGS), a type of neuromuscular stimulator is a short duration (microsecond) microamperage current driven by a high voltage current (up to 300 volts) that is delivered as a twin-peak monophasic waveform of fixed duration (100 microseconds).

• Electrical currents are also used to produce chemical effects.

• Most biologic tissue contains negatively and positively charged ions.

• A direct current flow will cause migration of these charged particles toward the pole of opposite polarity.

• At the positive pole the negatively charged particles cause an acid reaction in which there is coagulation of protein and hardening of the tissues.

• At the negative pole the positively charged particles produce an alkaline reaction, liquefying protein, and causing softening of the tissues.

• According to Robert Becker M.D. ‘the current of injury’ when the body is injured has a negative charge.

• Placing a negative electrode over the injured body part perhaps creates a repelling and movement of ions

General Indications For Use Of A Galvanic Stimulator:

• Pain Control

• Edema Reduction

• Wound Healing

• Disuse Atrophy

• Muscle Spasm

• Post-Operative

Electrical Stimulation Characteristics of High

Voltage Pulsed Current

• Wave form: paired monophasic with instantaneous rise and exponential fall of current.

• Modulation: continuous, surged or interrupted.

Physiological effects Wound Healing Higher Frequency (80 to 120 PPS) • Stimulates increases in numbers of fibroblasts. These are the cells

responsible for collagen (component of soft tissue responsible for wound closure) synthesis.

• Inhibition of bacterial growth (staph aureus) • Increased blood supply by blockade of sympathetic nervous system

activity. Increased blood supply results in increased oxygen and nutrient delivery to the tissue.

Pain Reduction Higher Frequency (80 to 120 PPS) • Causes blockade of pain nerve fiber conduction. • Causes the release of the body’s national pain reducing endorphins and

enkephalins. • Causes reduction/blockade of pain where the source of pain is an

inflamed nerve (Neuritis), the edema associated with the inflammatory process and it’s subsequent exacerbation of the neuritis is blocked.

Edema Reduction Higher Frequency (80 to 120 PPS) • Causes blockade of the microvascular permeability to fluids.

This is an event that occurs with tissue trauma. The subsequent edema formed after an injury/surgery is secondary to microvascular leakage of fluid from the blood vessels into the surrounding tissues. Thus edema/swelling formation is reduced result.

Lower Frequency (5 to 20 PPS) • This is produced with a muscular contraction that is promoted

by moving fluid away from the injured area by the pumping action/muscle contraction stimulating the lymphatic system resulting in fluid movement.

Disuse Atrophy/Muscle Strengthening Lower Frequency (5 to 20 Hz) • The muscle contraction stimulation at this frequency allows for

the retardation of muscles weakening from disuse and/or promotes/stimulates muscle strengthening/re-education by stimulating muscle contraction.

Wound healing concept:

a. Intact skin surface negative with respect to deeper epidermal layers.

b. Injury to skin develops positive potentials initially and negative potentials during healing process.

c. Absent or insufficient positive potentials retard tissue regeneration.

d. Addition of positive potentials, initially through anode, may promote or accelerate healing.

Wound healing parameters.

a. Amplitude: comfortable tingling sensation, paresthesia, no muscle response.

b. Pulse rate: 50-200 pps.

c. Pulse duration: 20-100 μsec.

d. Duration of treatment: 20-60 min.

Wound healing procedures.

a. Inspect wound area.

b. Position patient and support treatment area.

c. Clean and debride wound site. Pack with sterile saline soaked gauze.

d. Place active electrode over gauze.

e. For bactericidal effect, active electrode should have negative polarity. For culture-free wound, active electrode should be positive.

f. Turn the intensity up slowly to selected level.

g. At conclusion of treatment, turn intensity down slowly to zero.