High Voltage Pulse Stimulation

Electrotherapy

High Voltage Pulsatile Currents

OR

High Voltage Pulse Stimulation

• Introduction• Parameters of HVPC• Waveforms used in HVPC• Output Modulation• Treatment Time for HVPC• Electrode Configuration for HVPC• Indications• Uses• Precautions• Contraindications

Contents

• HVPC used in therapy for many years in many countries.

• It is highly popular in other countries

• HVPC delivers monophasic current so the polarity of each electrode is known

• It is a versatile form of electrical stimulation

• It has wide variety of uses (Muscle reeducation, nerve stimulation, Edema reduction, pain control)

Introduction

• HVPC generator produces:

• twin peaked waveform (pulses in duplets)

• OR

• a train of two single pulses having a short phase duration and long interpulse interval.

• Interpulse interval is much longer than pulse duration.

• Low pulse charge requires an output voltage of approx. 150 V or more to stimulate motor or sensory nerves i.e. high peaked voltage up to 500 V typically between 150-500 V

• Short phase duration allow activation of sensory and motor nerve at a low intensity without stimulating pain fibers.

• Current type: Monophasic

• Amplitude: 0-500 ma

• Voltage: 150-500 Volts

• Pulse Frequency : 1-120 Pulse/sec

• Pulse Duration: 13-100 ms

• Phase Duration: 13-100 ms

Parameters of HVPC

• Saw tooth

• M-wave

• Square Wave

Waveforms

• Duty cycle.

• Electrode Alternating rate.

• Electrode Balance (Bipolar/ Monopolar) . • Varying of intensity.

Output Modulation

Polarity(negative/ positive).

Probe electrode.

Surge /Ramp.

• Typical duration of HVPC is 15-30 min and the treatment may repeated as many time as day needed.

Treatment Duration

• HVPC is applied using either a monopolar or bipolar technique .

1. MONOPOLAR TECHNIQUE

Given over a wide area. In sensory level pain control.

Electrode Configuration

2. BIPOLAR TECHNIQUE

To produce specific muscle contraction. In motor level pain control.

• Peripheral nerve reeducation .

• Delay of denervation.

• Disuse atrophy by stimulating muscle contraction.

• Reduction of post-traumatic edema. • To increase local blood circulation

Indications

Restoring of range of motion.

Reduction of muscle spasm.

Inhibition of spasticity.

Re-education of partially denervated muscles.

Facilitation of voluntary motor function.

CHARACTERSTICS OF A PULSE

• The twin pulse wave form has almost instant rise with exponential fall.

• The pair of pulse(twin current) last only a few microsecond.

• the shape and duration are normally fixed.

• very high voltage is needed to provide a high enough current to stimulate nerve fibers

Such currents can easily pass through tissues as they are comfortable and brief.

They have wide discrimination between sensory motor and nociceptive nerve fibers.

Frequency, intensity and polarity can be altered by a mode switch.

Current is applied through flexible electrodes and sponges.

1. In continuous mode: The train of twin pulses are delivered continuously.

2. Reciprocate mode: Refers to the alternate application of train of pulses to one or other of two active pads and does not mean that current direction is reversed

3. Surge mode: Gives a train of pulses whose intensity is gradually increased.

A mode switch can change the patterns of current

1. Wound healing

2. Muscle Stimulation

3. Edema Reduction

4. Reduction of muscles spasm

5. Pain modulation

Uses

• This current is formed to cause healing of the wound and ulcer.

Induce human fibroblast

Increase rate of DNA and protein synthesis

Hence healing occurs

1. Wound Healing

Positive electrode is used as active electrode if wound healing is free from infection.

This is because of the biophysical effects on wound healing are polarity specific.

Blood clots /infection

pH acidic (+)

Hence cathode is used

• To account for the effects of polarity during the treatment of cutaneous wounds the application of 20 min of negative polarity by 14 min of positive polarity stimulation has been recommended .

• NOTE: depending upon the polarity of electrode leucocytes, epidermal cells, fibroblast are attracted to the area and level of collagenase increases.

• HVPS inhibits the growth of bacteria in infected wounds.

• No changes in Ph and temperature that could effect wound healing are not seen.

Negative polarity helps in dissolving blood clots and increases inflammatory byproducts, promoting healing of the tissues.

• The current is used for stimulation of innervated muscle as the pulses are very short(short pulses at high intensity are more selective in stimulating motor rather than pain nerves).

• HVPS is used both for strengthening as well as reduction of disuse atrophy.

• Frequency of 30 Hz has been used.

2. Muscle Stimulation

• Rhythmical muscle contraction and release due to the HVPS on motor nerve produces a pumping effect and increased blood flow in muscle and tissues and helps in draining in edema and direct effect on the ANS leads to local vasodilation, increase fluid exchange thereby reduces edema .

3. Edema Reduction

• Ability of HVPS to stimulate innervated muscle has leads to recommendation of this current in the treatment of muscle spasm and enhance joint mobility.

4. Reduction of Spasm

• Mechanism of pain relief brought about by this current is the same as involved in the gate control theory of pain.

• Since both the frequencies and intensities of HVPS can be controlled. It is possible to apply both the high frequency and low intensity stimulation for pain gate control and low frequency or high intensity stimulation for opiate release in descending pain suppression.

5. Pain Modulation

Parameters Gate Control Opiate Release

Output Intensity

Sensory Level Motor level

Pulse Frequency

60-100 pps 2-4 pps

Mode Continuous ContinuousElectrode arrangement

Monopolar/Bipolar Monopolar/Bipolar

Polarity Acute-PositiveChronic-Negative

Acute-PositiveChronic-Negative

Electrode Placement

Directly over painful site

• Painful site• Trigger Points• Acupuncture

points

• Stimulation of muscle can cause unwanted tension on the muscle fibers, tendons or bony insertions.

• If frequency is too high then muscle will fatigue rapidly.

• Improper use can cause electrode burns or irritation.

• Intense or prolonged stimulation may result in muscle soreness.

Precautions

• Pacemaker implants• Arterial Diseases• Uncontrolled hemorrhage• Blood Clots (DVT: Deep Vein Thrombosis)• Pregnancy• Cancerous Lesions• Exposed metal implants• History of Seizures• Sensory impairment• Unstable fractures

Contraindications