Faradic Stimulation

Original Editor - Abdallah Ahmed Mohamed

Top Contributors - Abdallah Ahmed Mohamed, Kim Jackson and Aminat Abolade  

Introduction

Faradic current is a short duration interrupted direct current with a pulse duration ranging from 0.1 to 1 ms with frequency of 50 to 100 Hz. Faradic current are surged to produce tetanic contraction and relaxation of muscle. treatment with faradic current usually called faradism.

Difference between farradic and galvanic current

Faradic current

is interrupted direct current has frequency 50:100Hz with pulse duration from 0.1-1MS. this current can make contraction and relaxation in innervated muscle that mean muscle has nerve intact and not used for denervated muscle which need to short pulse duration.When applying faradic stimulation,it stimulate sensory nerve and the patient feel pricking sensation because short duration of pulse. the stimulated nerve is accompained by motor stimulation make contraction of the muscle.

Types of Faradic waveform

Trapezoidal surging: in this type of wave the impulse increase gradually and decrease gradually used in mild to moderate injury.

Triangular surging: this type as trapezoidal surging.

Saw tooth surging : in this type of wave the impulse increase gradually but sudden fall used in sever injury.

Galvanic current

is interrupted direct current has frequency 30 Hz with pulse duration 1Ms and more.This type of current used for muscle not have the nerve because of injury of the nerve.When applying galvanic,the denervated muscle respond to this stimulus because long pulse duration.The denervated muscle not respond to faradic because pulse duration is short.The patient with faradic feel of burning sensation

Types of galvanic waveform

Rectangular surging: the current turn on and off intensity abruptly.

Trapezoidal surging: it slow rise and slow fall.

Triangular surging: it raise slowly, plateau’s and then falls slowly.

Saw tooth surging: the gradual rise of current and abruptly falls.

Physiological Effect

• The physiological effect of farradic and galvanic almostly the same except faradic for innervated muscle and galvanic for denervated muscle.
• Both current increase blood flow to the area treated that make the area slight redness due to vasodilatation. Also both current make contraction the muscle similar to voluntary muscle contraction. To prevent fatigue the faradic allow the muscle to relax after contraction.
• The faradic and galvanic current increase metabolism and remove waste product and bring more blood supply and nutrients to muscle thus increase demand of oxygen and nutrients to muscle.
• Electrical stimulation will re-educate of muscle action.
• The electrical stimulation can help in minimize the extent of muscle atrophy.

Indication

1. facilitation of muscle contraction when inhibited by Pain.
2. Muscle re-education:muscle contraction is needed to restore the sense of movement.In cases of flat foot or in muscle transplantation.the brain appreciate movement not muscle actions so crrent should be applied to restore normal movement.
3. training of new muscle action.
4. Improved venous and lymphatic drainage as edema and gravitational ulcer by pumping action of muscle contraction and relaxation.
5. Prevention and loosening of adhesion.
6. Painful knee syndrome.

Contraindication

1. certain dermatological condition as psoriasis,tin ea and eczema.
2. Infection
3. Inflammation
4. Thrombosis
5. Loss of sensation
6. Cancer
7. Cardiac pacemakers

Practical Guidelines

• The patient is positioned so that the part to be treated is comfortably supported with the muscles to be stimulated in a shortened position although this may be modified with movement produced e.g,slight knee flexion allowing quadriceps stimulation to cause extension.
• The skin surface must be examined for any cuts or abrasions, treatment area should be washed to remove sebum and epithelial cells using hot water to lower resistance.
• Size of active electrode is chosen to considering size of treatment area.
• The electrode should be smaller than the pad to prevent the edge of the electrode being bent down on the skin.
• the pads should be soaked in warm tap water,saline or sodium bicarbonate solution before applied to the skin.
• Fixation is achieved with rubber strap or by body weight.
• explain to the patient sensation.
• when muscle is to be stimulated the active electrode is placed over motor point and small current is applied.The current may need to be increased and then decreased as the motor point found and good contraction obtain with less currnt.
• when muscle group is to be stimulated the active electrode placed at end of muscle group so current spread through the whole group.

Resources

Electrotherapy on the web

Difference between faradic and galvanic

Electrical muscle stimulator