HVPGS - HIGH VOLTAGE PULSED GALVANIC STIMULATION

 

HVPGS

High voltage Galvanic stimulation or high voltage pulsed Galvanic stimulation: This form of currents was originally developed in the USA and given this name. That twin pulse waveform has almost instantaneous arises with exponential Falls.  HVPGS PARAMETERS: The pair of pulses last for only 0.1 millisecond and each peak lasts for only few microseconds; the shape and duration are normally fixed.  The frequency of the double pulse can be varied usually from 2 - 100Hz. With search shorts peaks very high voltages are needed to provide enough currents to stimulate nerve fibers.  Peak currents of 2 - 2.5A maybe generated during the few microseconds of peak voltage, but of course the total average current is very low at around 1.2 to 1.5 milliamp.   Such pulsed current will pass easily through the tissues, because they are so brief and will be relatively comfortable due to their wide discrimination between sensory, motor and nociceptor nerve fibers.   HVPGS GENERATOR: As well as the frequency the intensity can be varies 0 to 500 volts and the polarity altered.  The pattern of currents can be changed by mode switch. In continuous mode the train of Twin pulses is delivered continuously.  Reciprocate mode refers to the alternate application of trains of pulses to one or other of to active pads and does not mean that's the current direction is reversed.  Surge mode gives a train of pulses. A meter to indicate peak currents may be provided. On some machines the interval between the two peaks may be altered; this is called the interpulse interval.  The current is applied by flexible electrodes and sponges. The electrodes are usually small and are sometimes mounted on a handle. Various special electrodes are available.   Uses of HVPGS:   Wound healing: Since a direct current albeit of very low total intensity is being applied. There seems to be e evidence that low-intensity currents lead to tissue healing.   Muscle stimulation: HVPGS is used for the stimulation of innervated muscle and due to the short pulses and hence good transmission in the tissues it is an efficient way of doing so.  Consider the strength duration curve which shows that short pulses at high intensities will be more selective insulating motor, rather than pain nerves. HVPGS has therefore been used for muscle strengthening and the reduction of disuse atrophy of innervated muscle.  Frequency of around 30 Hz has been suggested with long intervals between bouts of tetanic contraction as the optimum schedule.   Pain modulation: How pain may controlled by electrical stimulation already been discussed since both the frequency and intensity of HVPGS can be controlled it is possible to apply both high frequency, low frequency stimulation for pain gate control and low frequency high frequency stimulation for encephalin type pain control.  HVPGS has been recommended for controlling all kinds of pain success acute chronic neurogenic and pain from many sources.   Other uses: Effects on vascular system are claimed in that rhythmical muscle contraction and relaxation due to HVPGS of motor nerves will have a pumping effects, increasing blood flow in muscle and surrounding tissues as considered earlier.  This effects can aid in the relation of tissue edema. Fish et al found that anodal high voltage pulsed current did not curb edema formation in frog Hind Limbs.  This contrast markedly with significant treatment effects found with cathodal HVPGS. Direct effects on autonomic nerve leading to local vasodilation increasing fluid exchange in the tissues and other beneficial effects have been claimed.  Consequent upon its ability to stimulate innervated muscle HVPGS has been recommended in the treatment of muscle spasm and to increase joint mobility.  Some uncertainty exist over the advantages of the Twin peaks waveform which is what makes this current unique. It has been suggested that's a single pulse could be just as effective. THOSE ABOVE ARE COLLECTED FROM SOME BOOKS AND WEBSITES.. THANK YOU, SRIKUMARAN PHYSIOTHERAPY CLINIC & FITNESS CENTER