Superimposed Current PDF

SUPERIMPOSED CURRENT DR. SYEDA SAMEERA HASHMI LECTURER JCRS SUPERIMPOSED CURRENT/ SUPER IMPOSED ELECTRICAL STIMULATION  SUPERIMPOSED CURRENT  It is a neuromuscular stimulator which has a short duration (microsecond), microamperage current driven by a high voltage current (up to 300...

SUPERIMPOSED CURRENT DR. SYEDA SAMEERA HASHMI LECTURER JCRS SUPERIMPOSED CURRENT/ SUPER IMPOSED ELECTRICAL STIMULATION  SUPERIMPOSED CURRENT  It is a neuromuscular stimulator which has a short duration (microsecond), microamperage current driven by a high voltage current (up to 300 volts) that is delivered as a twin- peak monophasic waveform of fixed duration (100 microseconds).  This direct current can produce both a mechanical contraction and a chemical change within the body.  The superimposition of Electrical stimulation(ES) onto Voluntary muscular contraction can theoretically activate more motor units than VOC performed alone, which can procreate an increase of the contraction force Superimposed technique: Application of an electrical stimulus during a voluntary muscle action Type : Low frequency modified direct current Duration : less than 10ms USES The two superimposed techniques can be used To evaluate the ability to fully activate a muscle. (evaluation of CAF-central activation failure). Functional electrical stimulation (FES) They can thus be employed to distinguish the central or peripheral nature of fatigue after exhausting exercise. In general, whatever the technique employed, the superimposition of ES onto volitional exercise does not recruit more MU than VOL, except with eccentric actions. Nevertheless, in a therapeutic context, training programmes using ES superimposition compensate volume and muscle strength deficit with more efficiency than programmes using VOL or ES separately.  TECHNIQUE OF SUPERIMPOSED CURRENT  TWO TECHNIQUES:  Two superimposed techniques can be used:  (i) the twitch interpolation technique (ITT) it consists of interjecting an electrical stimulus onto the muscle nerve.  (ii) the percutaneous superimposed electrical stimulation technique (PST) the stimulation is applied to the muscle belly. Both of these superimposed techniques can be used to evaluate the ability to fully activate a muscle.  METHOD OF  APPLICATION Functional electrical stimulation (FES) involves the electrical activation of voluntary muscles to help individuals with central nervous system impairments to produce functional movements. During FES, an electrically elicited muscle contraction is commonly superimposed over a voluntary contraction to increase force generation by a weak muscle.  Superimposition of electrical stimulation during voluntary contractions also can be used to evaluate an individual's ability to activate a skeletal muscle , to characterize the nature of fatigue , or to improve muscle strength during postsurgical rehabilitation and in individuals with muscle weakness due to upper motor neuron injuries  For accurate generation of targeted joint motions during FES applications, it is crucial that the appropriate amount of joint torque be generated by the combination of electrical and volitional contraction forces.  The manner in which volitional force production is augmented by electrical stimulation may depend on a variety of biophysical factors such as 1. Differences in the order 2. Rate of fiber recruitment between electrically and volitionally induced contractions 3. Distance of electrodes and electric field from target nerve fibers 4. Tissue conductivity PERCUTANEOUS SUPERIMPOSED ELECTRICAL STIMULATION TECHNIUE (PST)  it is applied to determine strength or activation of muscle and also in determining of CAF(central activation failure).  Method: in a measurement session of a maximal voluntary isometric contraction (MVIC) of the quadriceps femoris muscle with a burst superimposition technique.  A patient is seated in an electromechanical dynamometer with the hip flexed to 90 degrees and the knee flexed to 75 degrees  The axis of the dynamometer was positioned at the axis of rotation of the knee joint, and the distal edge of the shin attachment was placed 2 in (5.08 cm) proximal to the lateral malleolus of the test leg. A waist and a trunk strap were used for stabilization. Two self- adhesive electrodes were placed over the quadriceps femoris muscle at the motor point of the vastus medialis and proximal rectus femoris muscles. Subject performed 2 submaximal contractions and 1 MVIC lasting 2 to 3 seconds each in order to warm up the muscle and to familiarize the patient with the testing procedure  After 5 minutes of rest, patient was instructed to contract his quadrciep muscle to maximum extent for maximally contract the quadriceps femoris muscle for about 4 seconds.  Verbal command and visual output of their force were used to encourage the patient to produce MVIC. Approximately 3 seconds into the contraction, the stimulator delivered a supramaximal electrical stimulus of monophasic rectangular waves at a rate of 100 pulses per second for 100 milliseconds at 135 V. The knee extension force was measured and recorded using custom-written software with a 200-Hz sampling rate.  Five minutes of rest was provided between contractions in an effort to minimize muscular or neuromuscular fatigue. A maximum of 3 trials was recorded. The highest volitional force achieved during the 3 attempts was used for analysis. A weight correction was performed automatically by the computer program by adding the baseline force while the patient was relaxed to the force measurement.  PHYSIOLOGICAL/ THERAPEUTIC EFFECTS  Stimulation of partially denervated muscles  Stimulation of innervated muscles  Re-education of muscle action  Training new muscle action  Increase venous and lymphatic drainage  Prevention from adhesion  Detection of central activation failure(CAF)  Maintaining or increasing range of motion.  Edema/swelling/inflammation reduction.  Reducing motor spasticity.  Increasing local blood circulation to injured area and promoting fluid movement to and from treatment area.  Preventing or retarding muscle disuse atrophy.  Managing chronic/post-traumatic/post- surgical pain conditions allowing patient to participate in their pain management program.  Stimulation and acceleration of wound healing Contraindications Skin lesions high graded fever Infections Cardiac pace makers Open skin wounds Pregnancy Precautions take care in case of open skin wound do not apply over pregnant uterus do not apply in the vicinity of cardiac pace maker educate the patient before the application of current patient should be mentally relaxed. Dangers electric shock hypovolemia burns