indication and application of faradic current

Indication and Application of Faradic Current

PST 410

Adedokun O.E

Faradic current

•This is a short duration, interrupted direct current, with a pulsed duration of 0.1-1ms, and a frequency of 30-100Hz.

Indications

Facilitation of Muscle Contraction

• Stimulation is used therapeutically to initiate and facilitate voluntary contraction of muscle when contraction is inhibited or impossible due to pain or injury

• Faradic stimulation can be used to re-educate the quadriceps muscle, restore knee stability when it is inhibited by pain such as in patient with knee osteoarthritis or rheumatoid arthritis.

Indications

• In the above situations, faradic current is applied to assist in establishing voluntary muscle contraction which is inhibited by pain.

• The large anterior horn cells which are inhibited by pain, get free from the inhibition by the electrical stimulation of the afferent fibres, which influence the alpha motor neuron pool facilitating transmission to the extrafusal fibers and inhibiting the antagonist.

Indications

Re-education of muscle action

• In situations where muscle action is not readily under voluntary control such as disuse, faulty postural habits (long standing flat foot due to disuse of the intrinsic foot muscles), faradic current is applied to produce movement

Indications

Training a new muscle action• In situations where a new muscle action has to be

learned e.g following tendon transfer surgeries or other reconstructive procedure, the muscle is stimulated using faradic current to produce a new muscle action• Electrical stimulation is started 5 weeks after the

surgery to prevent tendon tear due to the brisk contraction of the muscles stimulated

Indications

Nerve injury

• In neuropraxia of motor nerve or following the re-innervations of an axonotmesis or repaired neurotmesis, faradic current is useful

• In case of severed motor nerve, degeneration of axons take place, after which there is no response to faradic current

Indications

Hysterical paralysis

• In such situations, it becomes necessary to show the patient that a particular movement is possible. This is done using faradic stimulation

• Strengthening weak muscles

• Electrical stimulation selectively recruits the large fast twitch type-II fibres than the slow twitch type-I fibres thereby achieving strength gain.

Indications

Prevention and loosening of adhesions

•When there is effusion in the tissue, adhesion are likely to form, this can be prevented by keeping the structures moving with respect to each other

•When active exercise is not possible due to pain, electrical stimulation may be used for this purpose.

•Uses: post traumatic elbow stiffness

Indications Deformity correction

•Deformities in joints due to tight muscle can be corrected using faradic current combined with stretching - faradism under tension

• Titanic contraction by surged current gradually pulls apart the shortened myofibrils with less pain

Faradism under tension

• Surged faradic current is used

• Surge duration – 3 sec

• Surge interval – 9 sec

• Intensity: enough to produce a visible contraction of the muscle

• Treatment time: 15 – 30 minutes

•Patient is encouraged to actively contract the muscles along with the current and relax during surge interval

• Faradic current can also be applied to the antagonist muscle which suffer stretch weakness, thereby increasing their strength and overcoming the muscle imbalance that cause the deformity

Indications

Improved venous and lymphatic drainage (Faradism under pressure)

• Increased venous and lymphatic return, is brought about by the pumping action of alternate muscle contraction and relaxation and on joint movement on the veins and lymphatics

• Electrical stimulation of the muscle that generally act as the muscle pump is combined with compression and elevation of the limb to increase venous and lymphatic return.

Faradism under pressure

Used in the management of oedema

• The passive electrode is placed is placed over a convenient area proximally and different active electrodes are placed over the muscle groups on the limb. The electrodes are maintained in place with the aid of straps.

• Elastic crepe bandage is applied on the limb with decreasing pressure from distal to proximal avoiding gaps between the turns of the bandage.

• The limb is kept elevated above the heart level by pillows and sandbags

• Faradic current is then applied sequentially stimulating the proximal muscle groups first, then moving distally.

• The typical timing will be 3 seconds of contraction followed by 5 seconds of rest

Indications of Use

• Functional electrical stimulation

• Functional electrical stimulation (FES) is the use of electrical stimulation to produce muscle contractions that have a functional purpose.

• FES involves the use of electrical stimulation to elicit a muscle contraction that translate into a functional activity

• It is the electrical stimulation of the intact lower motor neuron to initiate contraction of the paralyzed muscles to produce functional movements

•Commonly used in patient who have damaged CNS (SCI, Stroke, Multiple Sclerosis e.t.c)

Application of Faradic Current

General Assessment• History taking

• Check for general contraindications:

• Hyperpyrexia/Fever

• Anemia

• Severe renal and cardiac failure

• Deep X-ray and cobalt therapy

• Epileptic patients

• Non-cooperative patients

• Mentally-retarded patients

• Very poor general condition of the patient, etc.

General Assessment• Check for local contraindications:

• Open wounds

• Very recent fractures

• Skin grafts

• Severe oedema

• Hairy surface

• Acute inflammation

• Metallic implant

• Malignancy

• Hypersensitive skin

• Loss of sensation

Treatment tray• Mackintosh• Lint pads• Pad or plate electrodes and pen electrode• Leads• Straps• Cotton• Powder• Gel.• Soap, Cotton Wool, Vaseline, Towels

Treatment tray

•Preparation of treatment tray

•Mackintosh: The mackintosh is to be kept under the patient’s treatment part to prevent earth shock and to prevent dripping of water.

• Lint pad: The lint pad is made up of lint cloth and it is used to prevent accumulation of chemicals in the tissues formed during the treatment which if not prevented leads to burn.

Treatment tray

• Electrodes: Electrodes could be of pad or plate type or pen

type. Pad or plate electrodes are kept in between the lint

pads for even distribution of current.

• The edges of plate electrode should be blunt. It should be

smaller than the lint pad so that it cannot come in contact

with the skin. Pen electrode is used for smaller muscles or

for specific motor points.

Electrodes

• Polymer-based electrodes: the electrode consist of carbon-impregnated silicone rubber. The electrodes are reusable, can be cut to size and can be moulded to a skin surface that is not too irregular.

• Normally coupled to the skin through the use of an electrically conductive gel

• The electrode must be taped into place securely.

• Tin-plate or aluminium electrodes: These are coupled to the skin with saline water retained within a cotton pad or sponge

• The electrode is less malleable than the polymer-based type.

Electrode size

• The choice of electrode size depends on the size of the muscle to be

stimulated and the intensity of the contraction to be elicited.

• Small electrodes may be used to localise stimulation to small muscles

while larger electrodes are needed to stimulate larger muscles and

muscle groups.

• The larger the electrode, the lower is the intensity of current per unit

area.

Treatment tray

• Leads: Used to connect the electrodes with the stimulator.

• Straps: Usually rubber straps are used. It should be placed over the pad.

• Cotton: Used to prevent dripping of water and for cleaning the surface.

• Powder: Applied over the skin if there is any redness after the treatment.

• Gel: Used for pad electrodes where lint pads are not used. Gel aids proper contact of electrodes with the patient’s skin.

Treatment tray

• Soap: It is used for cleaning the part to be treated to remove

dirt, dust or sebum, etc. thus lowering the skin resistance

• Vaseline: It is applied over scar tissue. It prevents the

concentration of more current on the scar tissue.

• Towels: Towels are used for covering the body part. The

towel should be neat and clean.

Preparation of apparatus

• Check whether all the knobs are at zero.

• Check the pins of the plug and check whether the switch is turned off.

• Check the insulation of the wire.

• Check whether the switch in the stimulator is working.

• Check whether fuse is present in the apparatus; see that it is not blown out.

Positioning

Correct positioning of the patient:

• The patient should be placed in a comfortable position.

• Part to be treated must be exposed and should be at adequate distance from the modality.

Correct positioning of Physiotherapist:

• Position of Physiotherapist should also be comfortable.

• Position should be such that it provides maximum accessibility to both the treatment part and the modality.

Checking of apparatus:

• Self test.• Apparatus must be checked once in front of the patient.• Place the electrodes on yourself on palmar or dorsal as • Switch ‘on’ the apparatus and gradually increase the

current.• Explain the feel of the current to the patient • This will increase the confidence of the patient and will

reduce apprehension.

Skin preparation

• The skin should be washed with soap and water or alcohol-based wipe prior to treatment This is to remove skin debris, sweat and dirt

•Cleaning the skin facilitates good contact between the skin and reduces electrical resistance

Application of faradic current

Electrodes

• The electrode is selected based on the size of the muscle to be stimulated and area of placement of the electrode

• To prepare pad electrode, lint clothes of appropriate size of plate (aluminium or zinc) is cut

• There should be a gap of 1 cm between the plate and the margin of the lint pad and there should be a minimum of 8 layers of lint on each side


• The lint pads are soaked in 1% warm saline. Salt reduces resistance to the current flow and warmth is facilitatory.

• The corners of the plates should be rounded as pointed corners lead to concentration of current

• If carbon electrode is used, there is no need to use lint cloth, as the electrode is applied to the skin through electrode gel

• The electrodes are connected to the machine through the leads, i.e red or brown with the passive and black or blue with the active.

•Connect the input cable to the power plug


Preparation of the patient

• The patient should be placed comfortably in a chair or on a couch/plinth.

• The patient is examined for contraindications

• Skin sensation test is done

• The nature of the treatment and sensation to be experienced is explained to the patient


Stimulation of the motor point

• This is the point over the muscle where the main motor nerve enters

• It is the point over the surface of the muscle where great densities of terminal end plates are found

• These points are zones of low threshold excitability and the skin is more sensitive to faradic type current.

• The point generally lies at the junction of the upper one third and the lower two third of the fleshy belly of the muscle

• In deeply placed muscles, the motor point is at the emergence of the muscle from its superficial coverings.

Motor point for muscles supplied by the facial nerve


• The electrode connected to the negative terminal serves as the active electrode used to stimulate the motor point

• The electrode connected to the positive terminal serves as the passive electrode which is placed over the nerve trunk or plexus that supplies the muscle.

• The passive electrode should be larger than the active electrode this is to prevent unnecessary motor and sensory stimulation under the passive electrode by reducing the current density under it.


• Select the surge interval and duration while testing the machine

• The surge interval should be greater than the surge duration except when exercise is meant for enhancement of endurance , in this case the surge interval and duration are the same

• The intensity should be increased gradually to avoid electric shock

Electrode placement

In the upper limbs, the passive electrode is placed over

• the neck region to effect the roots for the brachial plexus,

• the radial groove to effect the muscles supplied by the radial nerve or the posterior interosseous nerve,

• cubital fossa for the median nerve and anterior interosseous nerve,

•posterior aspect of the medial humeral condyle for the ulnar nerve innervated muscles

Electrode placement

In the lower limbs, the passive electrode is place over

• the lumbrosacral region to effect roots of the femoral or sciatic nerve

• the popliteal region to effect the muscles in the posterior aspect of the leg and over the sole of the foot

• the region of the neck of the fibula to effect the muscles supplied by the common peroneal nerve

The active electrode is placed at the motor point for individual contraction.

• The intensity is gradually increased till a satisfactory muscle contraction is obtained.

• The electrodes are removed at the end of the treatment and the skin is inspected

•Appearance of mild erythema is normal.

Group stimulation

• This type of stimulation is used for re-educating muscle groups e.g the quadriceps, pelvic floor muscles and small muscles of the foot

• The passive electrode is placed over the nerve plexus where it is superficial.

• The active electrode is placed on the motor points of the different muscles in the group

Pelvic floor muscle stimulation

• Stimulation of the pelvic floor muscles may be required in cases of a early stage prolapse of uterus or for stress incontinence following childbirth in females or in cases of stress incontinence following prostactectomy in males

• The passive electrode is placed over the lumbrosacralregion

• The active electrode – a special type of electrode called vaginal of rectal electrode is used


• The electrodes should be adequately sterilized.

• The surge interval should be sufficiently long to allow adequate rest periods between contractions, this is because the pelvic floor muscles are small and they easily undergo fatigue.

• The patient should be told to contract muscles voluntarily, along with the electrical stimulus


Positioning

• The patient is placed in a side-lying position, with the pillows placed between the legs.

• A plastic sheet is placed under the patient

• The passive electrode is placed over the lumbrosacralregion

• The active electrode impregnated with sterilized electrode is introduced into the rectum or vagina

•When the rectal or vaginal electrode cannot be used, a small button electrode is placed over the urogenital (or anal region)

• The intensity of the stimulation should be small, and the duration of the treatment should be short.

• Surge duration of 1s and interval of 3s recommended

Faradic foot bath

•Because the foot has 4 layers of muscles it is not possible to stimulate the muscles by motor point or conventional group stimulation

• In this case, the muscles can be stimulated by faradic type currents through baths because water makes perfect contact with the tissues and it reduces the need for pads and the resistance offered by the skin is less due to water.

Faradic foot bath

• The patient is prepared and placed in high sitting on a chair with an insulated and non-metallic back support

•A porcelain tray filled with warm water is placed on a stool with a plastic cover

Faradic foot bath

• The patient’s foot is placed inside the tray/bath containing warm water to cover the toes

• The electrodes are arranged inside the tray for the different purpose • For the lumbricals, the passive electrode is placed

below the heel, and the active electrode at the region of metatarsophalangeal joint.• To stimulate plantar interrossei, the electrodes are

placed on each side of the foot at the level of the metatarsals

Advantages

•Lowered skin resistance

•Electrolytes formed under the electrodes are not concentrated on the skin

Disadvantages

•Current cannot be localized

•Chances of electric shock is higher

indication and application of faradic current

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