Faradic current is the short duration interrupted direct current with a pulse duration in 0.1 to1 ms. The frequency is between 50-100Hz. This type of current is produced by an induction coil and also called as faradic coil. It is consists of two unequal phases, the first one is the low intensity but in long duration. The second one is the high intensity but in short duration. The modern stimulators produces short duration interrupted direct current with varying duration of impulses and the intervals between them.
Galvanic current is the direct current ,which is also the current that moves in only in one direct.Galvanic current is a direct current or an interrupted direct current. It is also called long duration current with having more than 1 ms up to 300 ms or 600 ms. But the commonly used duration is 100 ms duration requires a frequency of 30 pulses/ min. If the duration increases the frequency must be reduced.
The galvanic electric stimulation used to stimulate any muscle that is denervated or lacking proper nerve function. The causes of muscle denervation including trauma or injury, surgery, nerve entrapment, infections, and autoimmune disorders. Direct current stimulation is very useful in treating muscle weakness or muscle atrophy by stimulating the specific motor points on the skin where underlying muscle is situated. The motor point overlies the innervation zone of a muscle.
Content: Faradic current
Faradic machines produce an alternating current which is used to cause nerve and muscle stimulation. An electrical circuit must completed so it can pass the current to the client’s muscle. In order to do this, an electrodes pads are used. They are placed over or near the motor point of the muscle which is placed near the origin and insertion of the muscle. The motor point of the muscle is where the motor nerve enters the belly of the muscle in order to get the best contraction the pads are. The origin of a muscle is the joint to which the muscle is attached that does not move. The insertion is the joint to which the muscle is attached that does move. When the current is applied to the muscle, it will stimulates the motor point and causes muscle contraction as long as the curent is given sufficient intensity.
The modification of faradic current for interruption and surging.
The faradic current made by interruted at regular intervals to avoid the fatigue muscle. Surged faradic current is the modification characterized by slowly rise in the intensity such a manner that each impulse reaches to higher intensity than the preceding one and after peak level it either falls suddenly or gradually. The other name known as ramping.
Motor nerves-faradic current stimulate the motor nerve/muscle, causes contraction of the muscles. Because the stimuli repeated 50 times (50Hz) or more, the contraction is titanic. To avoid muscle fatigue secondary to this contraction the current become
Faradic current is a short-duration interrupted current, and the pulse duration ranging from 0.1 and 1 msec. The frequency of faradic current is 50 to 100 Hz. Faradic currents are always surged for treatment purposes to produce a near normal tetanic-like contraction and relaxation of muscle. Current surging means the gradual increase and decrease of the peak intensity.
Physiological effects of faradic current:
Stimulation of sensory nerves:
Applying the faradic current, there is having a mild pricking sensation. And there is also leading mild erythema(redness)of the skin due to vasodilation of superficial vessel. This vasodilation will only occur in superficial tissue.
Stimulation of the motor nerves:
Faradic current stimulate motor nerve if the sufficient intensity there will occur muscle contraction. As stimulation and thereby contraction repeated 50 times per second there occurs a tetanic type of contraction. If it is continued more than a short period of time , the concerned muscle will be fatigued. That is why the current is surged or interrupted give rest or relaxation to the muscle.
Effect on muscle contraction
When muscle contact, result of electrical stimulation. The changes taking place within the muscle are similar to those asociated with voluntary contraction. There occurs increased metabolism with consequence increase the demand for O2 and foodstuff associated with increased output of waste materials. As the muscle contract and relax, it exerts a pumping action on vein and lymphatic vessel lying within and around them.
Stimulation of the nerve is due to producing a change in the semi-permeability of the cell membrane:
This is achieved by altering the resting membrane potential. When it reaches a critical excitatory level, the muscle supplied by this nerve is activated to contract.
Effect on denervated muscles
For the stimulation of denervated muscles, the impulse required is more than 1 ms. So, faradic current is short duration current which cannot stimulate the denervated muscles.
Reduce swelling and pain:
Due to alteration of the permeability of the cell membrane, leading to acceleration of fluid movement in the swollen tissue and arterial dilatation. So, it leads to increase metabolism and get rid of waste products.
The ions move one way during one phase of the current; and in the reverse direction during the other phase of the current if it is alternating. If the two phases are equal, the chemicals formed during one phase are neutralized during the next phase. In faradic current, chemical formation should not be great enough to give rise to a serious danger of burns because of the short duration of impulses.
Therapeutic effects of faradic currrent:
Facilitation of muscle contraction and inhibited by pain:
Stimulation must be stopped when good voluntary contraction is obtained.
Muscle contraction is needed to restore the sense of movement in cases of prolonged disuse or incorrect use; and in muscle transplantation. The brain appreciates movement not muscle actions, so the current should be applied to the movement that the patient is unable to perform voluntarily.
Training a new muscle action:
After tendon transplantation, muscle may be required to perform a vary action. With stimulation by the faradic current, patient must concentrate with the new action and assist with voluntary contraction.
Improvement of venous and lymphatic drainage:
In edema and gravitational ulcers, the venous and lymphatic return should be encouraged by the pumping action of the alternate muscle contraction and relaxation.
Prevention and reducing of adhesions:
After effusion, adhesions are liable to form, it can be prevented by keeping structures moving with respect to each other. Formed adhesions may be stretched and loosened by muscle contraction.
Content: Galvanic current
Galvanic current is the interrupted direct current. This interruption is the modification of direct current. The flow of current commence and cease at the regular interval. The rise and fall of the intensity will be in sudden (rectangular) or gradual (trapezoidal, triangular, saw-tooth). Interrupted direct current usually used to stimulate denervated muscle and for the electrodiagnosis purpose. The impulse duration and frequency can be adjusted, the duration of 100 msec is commonly used. Impulse duration ranges between 0.01 to 300 msec. The frequencies of impulse vary as per pulse duration and the interval selected between them. The instance duration of 100 msec need frequency about 30 per minutes. The production of interrupted direct current for the treatment can be help from modern stimulators using transistors and timing devices.
Physiological effects of galvanic current:
Sensory nerve stimulation
Once the interruted direct current applied to the body, you will feel the stabbing or burning sensatio on the surface. the erythema or redness on the skin is the turn of reflex vasodilation of superficial blood vessel.
Motor nerve stimulation
Interruped direct current is stimulate motor nerve. As the stimuli are frequently repeated each one produce a brisk muscle twist followed by immediate relaxation. Threfore the beneficial effect is vey slow.
Therapeutic effects of galvanic current:
The purpose of this current is to maintain the muscles in healthy state and to prevent the complication by electrically artificial contraction. Skeletal muscles have greater power of regeneration. When the muscles are denervated the following changes will occur such as loss of voluntary contraction and reflex activities, atrophy causing resulting in fibrosis, and the fibrillization with Spontaneous contraction.
In 1987 Spieloloz concluded that it will retard the muscle atrophy and degeneration but can not prevent it completely. In 1983 Devis provide evidences that all the denervated muscle fibers must be activated to produce isometric contractions. An isometric contractions are more effective than isotonic contractions and the regular contraction should commence (start or begin or cause to start) as soon as possible.
In short number of electrical stimulation for denervated muscle is not proven and its application to gain muscle power may be small benefits but not justified. If some of the motor units (motor end plate + motor nerve + muscle fibers) are intact galvanic current is the choice of treatment.
Interrupted direct current is recommended for the treatment of Axonotmesis and Neurotmesis nerve repair is to be taken.
Faradic current application:
Faradic current can be applied by methods like motor point stimulation, nerve conduction method or bath method.
Motor point stimulation involves individual muscle.the electrode is placed at the origin of the muscle and the active electrode is placed on the motor point. Usually motor point is situated at the junction of upper 1/3 and lower 2/3rd of the muscle belly. But exceptions and variations are there. Slight adjustment of active electrode gives the required result.
In the nerve conduction method, the indifferent electrode is placed on convenient area on the muscle to be stimulated and the active electrode at a point where the nerve trunk is superficial.
In bath method, electrical current is passed in a tubor tray with water onside. In this method is used where it is not possible to stimulate individual muscle like small muscle of hand or foot. Bath method can be bipolar with two electrodes inside the tray or uni-polar with one electrode inside the tray and the other one at a suitable place over the part to be treated.
Galvanic current application:
To stimulate a denervated muscle, it should be noted that the current must pass through all muscle fibers. One pad or electrode(Anode) is fixed over the origin of muscle groups that serves as an active electrode and another electrode(Cathode)is held over the lower end of the fleshy belly of the muscle
It is the technique in which medically useful ions are driven through the patient’s skin into the tissues by interrupted direct current. It is also known as ion tranfer. Based on the principle that an electrically charged electrode will repel a similarly charged ion like negative ion is applied unde the cathode or the reverse. If a machine is an ionic form then it can be made to pass to the body tissue through the skin under the influence of interrupted direct current. Ions may eventually becomes chemically active int the tissue which they pass. The active electrode is placed at the area to be treated. Iontophoresis is particularly effective in the treatment of hyper hydrosis using glycopyronium bromide. It is also used in other skin condition.