Therapeutic Currents
Introduction
Faradism is the use of an interrupted low-frequency direct current surged to induce alternate contraction and relaxation of the voluntary muscle. The frequency is 50 to 100 Hz while the pulse duration is 0.1 to 1 milliseconds. The stimulation of the muscle contraction is to maintain the health of paralysed muscles until regeneration or recovery in damaged motor nerves.
Galvanism is the therapeutic application of direct electric current, especially the electrical stimulation of nerves and muscles. It is a long duration current. The commonly used duration is 100MS and requires a frequency of 30 pulses per minute. Moreover, if the duration increases the frequency must be reduced. It is used in the treatment of various forms of paralysis for the patients.
Content
Faradic current:
Faradic current is a short duration interrupted surged direct current, with pulse duration ranging from 0.1 and 1 milliseconds, and a frequency of 50 to 100 Hz. Besides, faradic current stimulates the intact nerve by producing change in the permeability of the cell membrane by altering their resting potential. When the resting potential of the cell membrane reaches the excitatory level, which is -90mV, the muscle supplied by the nerve will contract.
Faradic currents are always surged for treatment purposes to produce a near normal tetanic-like contraction and relaxation of the muscle. Current surging means the gradual increase and decrease of the peak intensity. The process of giving relaxation to the tetanic contraction produced by faradic current is called surging.
The first surging is trapezoidal surging. The impulses increases and decreases gradually and forming trapezoidal shape. It is applied for the moderate injury innervated nerve.
Diagram: trapezoidal wave.
Next, in the triangular surging, the impulses increases and decreases forming triangular in shape. It is suitable for less injury nerve.
Diagram: Triangular wave.
Moreover, the impulses increase gradually but suddenly fall in the sawtooth wave. It is more aggressive and suitable for the nerve that is completely injured.
Diagram: Triangular wave.
Indications:
1) Re-education of muscle action. The current which rises or falls suddenly is more effective and initiating an impulse for the muscle which is prolonged disuse and inability to contract voluntarily.
2) Stimulation of nerve. When sensory nerve is stimulated, the upward travelling impulse is appreciated to reach the brain. When motor nerve is stimulated, the downward travelling impulse causes the contraction of muscles.
3) Training a new muscle action. After tendon transplantation surgery, faradic current stimulation is required.
4) Improvement in venous and lymphatic drainage. Contraction and relaxation of the muscles exert a pumping action on the veins and lymphatic vessels.
5) Neuropraxia of a motor nerve. When we stimulate the nerve below site of lesion, the impulses will easily pass to the muscle and cause the contraction.
Contraindications:
1) Skin lesions. Electric current will accumulate at the site of injury.
2) Thrombosis. This is because it will cause the breaking of the clot and interrupt the blood clotting.
3) Site of inflammation. It will interrupt the healing process and cause the muscle spasms.
4) Specialized tissue like eye and testis.
5) Marked loss of skin sensation. If the intensity of the current increase, it will break the skin tissues.
Galvanic current:
Galvanic current is an interrupted direct current, long duration modular pulsed currents and the flow of current is unidirectional. Direct current stimulation requires pulse duration greater than 1 millisecond, and more often uses even longer durations, up to 300MS or 600MS. It requires a frequency of 30 pulses per minute. If the duration increases the frequency must be reduced. Moreover, the interval duration between the impulses should never shorter than the impulses themselves.
Besides, galvanic current is used to activate the muscles directly, without activation of the peripheral nerve. Besides, the appropriate electrical stimulation can cause the denervated muscle to contract and the recovery time of the muscle can also be shortened.
There are different pulse shapes in the galvanic current. In the rectangular pulse, the currents gently go up, stay for one duration, and go down gently. In other words, the current turns on and off intensity abruptly.
Diagram: Rectangular wave.
Next, a slow rise and slow fall of intensity forming triangular shape is known as triangular pulse.
In the trapezoidal pulse, the current is raised slowly, plateaus for a short period and then gradually declines.
The last pulse is sawtooth. It is the gradual rise of current and the current falls abruptly.
Indications:
1) For the stimulation of denervated muscles, the impulse required is more than 1 millisecond.
2) Increasing local blood circulation to injured area and promoting fluid movement to and from treatment area.
3) Preventing or retarding muscle disuse atrophy by stimulating the muscles to contract and relax.
4) Managing chronic surgical pain conditions allowing patient to participate in their pain management program.
5) Oedema, swelling, and inflammation reduction. Contraction and relaxation of the muscles thus exert pumping action on the veins, blood vessels and lymphatic vessels.
Contraindications:
1) Do not use on the front of the neck, head or over the eyes or lungs.
2) Patient with epilepsy or seizures. It will stimulate more unwanted impulses.
3) Pregnancy. Especially on pelvic, low back and abdomen.
4) Patient who is in the hemorrhagic condition. This will cause more blood flow at the site of injury.
5) Patient with an active pacemaker around the chest wall.
Physiological effects
The physiological effects of the faradic and galvanic currents are almost identical. The only difference between faradic and galvanic currents is faradic current stimulates innervated nerve while galvanic current stimulates denervated nerve.
In faradic current, it stimulates the motor nerves and causes the muscles supplied by the nerve to contract. In the galvanic current, stimulation of the muscles produces brisk muscles twitch followed by immediate relaxation. Moreover, contraction and relaxation of the denervated muscles are sluggish when the motor nerve is stimulated. Sensory stimulation can cause a reflex vasodilatation of the superficial blood vessels and erythema of the skin.
Besides, they can manage and reduce the pain. This is because when the electrical stimulation is applied to the area of pain, it causes the blood vessels to dilate and the deposited waste products in the blood vessels to be washed away. Galvanic current affects neural endings responsible for transferring of pain so that the pain can be diminished or removed completely. Cathodes enhance stimulativeness and conduciveness of the nerves whereas anodes will diminish them.
The next effect is helping with blood flow and improving circulation. Contraction and relaxation of the muscles will exert pumping action on the blood vessels which results in increasing blood flow thus increasing blood circulation. It will also exert pumping action on the veins and lymphatic vessels, which results that there is a net venous and lymphatic return. The currents also help to improve the effectiveness of delivering prescription drugs through electromotive drug administration which is known as iontophoresis.
In the aspect of chemical effects of the faradic current, it does not allow considerable amount of collection of chemicals under the electrodes. This is because it will give rise to a serious danger of burns due to its short duration of impulses.
Therapeutic effects
The therapeutic effects of faradic and galvanic currents are electrical stimulation allow the muscles to contract similar to the normal muscle voluntary contraction. In consequence, it will help the muscles to maintain strength and muscle tone during the period while the nerve is regenerating. The degenerative changes progress until the muscle is reinnervated by axons regenerating across the site of the lesion.
Besides, the contraction and relaxation of the muscle prevent it atrophy or wasting from disuse. This is because it will produce pumping action on the blood vessels which increases metabolism by consequent increase in demand for oxygen and foodstuffs of the muscle, and an increased output of waste products. Next, metabolites cause dilatation of the blood capillaries and arterioles and will result in increasing the blood supply to the muscle.
Moreover, electrical stimulation will train a new muscle action after the tendon transplantation. The patient has to observe the new action and try after sometime to perform the new action voluntarily along with the electrical stimulation. Electrical stimulation allows contractions that mimic the ways the body moves during exercise thereby increasing the range of motion. The reduced range of motion may caused by muscle pain or weakness.
Electrical stimulation can limit oedema and venous stasis, thus slowing down the muscle fiber undergoing fibrosis and degeneration. When the muscle contracts, it will has pressure acting over the blood vessels. In consequence, there is an opening of the drainage system and the swelling which is collection of fluid will reduce.
In the therapeutic effects of faradic current, it can prevent and loosen of adhesions in the blood vessels. When there is effusion into the tissues, adhesions are liable to form in the vessels, which can restrict blood flow and result in reduce the activity of the muscle and the range of motion of the joint. Contraction and relaxation of muscle can lose the adhesions of unwanted waste products by keeping the substances moving with respect to each other.
Methods of application of Faradic current and Galvanic current
In the faradic current, 30 muscle contractions are applied for the multiple motor points and repeat it successively. In addition, 90 contractions are applied for individual muscles. 90 contractions are regarded as the minimum for effective treatment, provided the muscle do not fatigue. The intensity given must be based on the patient’s tolerance. This is because the sensation of the current stimulation is different from person to person. If patients can feel or see the muscles contract, we can duplicate this muscular response. Most importantly, the pulses per second should be between 35 to 55 pulses per second. Higher pulse rates may produce more fatigue to the muscles. Besides, current intensity must be adequate for muscle contraction but it is comfortable for the patient. The pulse duration is ranging from 300 to 600MS.
In the galvanic current, it is divided into two methods of application. Firstly, one pad may be fixed over the origin of the muscle group but it is not fixed directly on the bony prominence and each muscle is stimulated with active pen electrode. Secondly, there are two pad electrodes, one pad electrode is fixed over the origin of the muscle and the other one is fixed over the distal end of the muscle bulk. Iontophoresis is one of the examples by using galvanic current. It is a therapeutic technique of introducing ions into the body tissues by means of electric stimulation.
Diagram: Equipment for electrotherapy
Conclusion
In conclusion, faradic current stimulates innervated nerve while galvanic current stimulates denervated nerve. Faradic currents have higher intensity and it is suitable for firming and toning of body muscles. As the current passes through the conductive pads, it stimulates the motor points of the muscle and triggering a visible muscle contraction. Faradic current is a better option for trunk stimulation. However, galvanic currents are used primarily for facial muscles. A galvanic current uses mild electric currents that consist of positive and negative ions to stimulate the local muscles. Thus, the outcome of a galvanic current is maintaining the physiology of muscle.
