Physiologic Response To Electrical Currents Lecture PDF

PHYSIOLOGIC RESPONSE TO ELECTRICAL CURRENTS Dr. Omar Mabrouk Lecturer of Basic sciences For Physiotherapy  My Regards for Prof /Sahar Adel Prof/ Ommima Ktabbi DR /Mohamed Yahia The Use of Electrop...

PHYSIOLOGIC RESPONSE TO ELECTRICAL CURRENTS Dr. Omar Mabrouk Lecturer of Basic sciences For Physiotherapy  My Regards for Prof /Sahar Adel Prof/ Ommima Ktabbi DR /Mohamed Yahia The Use of Electrophysical Agents EPAs indicates that their main use is for the treatment of human soft tissue pathologies that have an impact on a patient’s life. The role in the global therapeutic spectrum is to complement other physical, medical, and surgical therapeutic interventions. As a result, EPAs seldom are the sole therapeutic intervention in any given clinical case.  International Society for Electro physical Agents in Physical Therapy In 2011, the World Confederation for Physical Therapy (WCPT) admitted another sub-group in areas of interest to its organization: (the International Society for Electro physical agents) The ISEAPT defines the term electro physical agent as the use of electro physical and biophysical energies for the purposes of evaluation, treatment and prevention of impairments , activity limitations, and participation restrictions (www.wcpt.org/iseapt). Evaluative EPAs may include, but are not limited to, ultrasound imaging and electro neurophysiologic testing that can assist diagnosis, guide treatment procedures, and evaluate treatment outcomes Recommendations Do the right thing for the patient is to show effectiveness. Higher levels of clinical efficiency must be demonstrated to optimize patient care  PHYSIOLOGIC RESPONSE TO ELECTRICAL CURRENTS Structural level Therapeutic Effect physical Chemical Thermal 1. Electrophysical effects It’s the first effect of ES as it stimulate sensory , Motor & pain nerves through depolarization which cause tingling sensation then muscle contraction then pain sensation if intensity exceeded  Skin softening Skin Hardening Sclerolytic effect Sclerotic effect  3. Electro thermal effects Charged particles Kinetic move Heat energy through conductor  Skin irritation / Redness / Hot Spot Examination of patient after ES is needed Normally disappear within hours It may develop to burn Structural level A. Cellular level 1. Excitation of nerve cells 2. Change in cell membrane permeability 3. Protein synthesis 4. Stimulation of fibroblast and osteoclast 5. Alteration in microcirculation B. Tissue level 1. Skeletal muscle contraction 2. Smooth muscle contraction 3. Tissue regeneration  Is there difference in muscle contraction either voluntary or electrically stimulated?  Voluntary Contraction of Muscles is Non-synchronous firing of motor neurons resulting in a smooth physiological contraction. The force of a contraction is increased according to:: First: The number of motor unit recruited. Second: The frequency (firing rate) of nerve impulses. Type I MU (MOTOR) fire first, then Type IIa. Type IIb brought in last of all Motor Unit. Is a single somatic motor neuron and innervate group of muscle The higher the frequency of the action potential the more quickly the threshold may be exceeded Electrical Stimulation Pattern SYNCHRONOUS firing pattern (all MU’s fire together) Electrical stimulation can induce muscle contraction either by 1. Stimulation of motor nerves which results in contraction of the muscle supplied by that nerve (as innervated muscle). 2. Stimulation of the muscle directly (as denervated muscle). Type II neurons (sensory fibers )are LARGER (therefore have a lower threshold, therefore fire first -reverse of the natural sequence). reverse of the natural sequence Criteria necessary for successive stimulation Depolarization must occur as the stimulus should be : Sufficient Amplitude : strong enough Sufficient duration long enough Fast enough  Approximately linear relationship between CURRENT INTENSITY and FORCE OF CONTRACTION The greatest effects with least current intensity by using BIPHASIC PULSED or BURST AC currents. Tension related Frequency Maximum tension at 60-100 Hz BUT also get higher fatigue. 20 Hz stimulation will achieve about 65% force, BUT also much less fatigue. 1s TO CONCLUDE: c. At segmental level 1. change in Joint mobility 2. change in circulation & lymphatic activity which has a direct impact on edema & pain Can Electrical Stimulation gain Strengthening ? Appears to be possible to get an increase in strength with ES. The best effects are achieved if NMES is combined with active exercise BUT can get demonstrable effects with ES alone. Increase in ISOMETRIC strength, then CONCENTRIC. No change in ECCENTRIC  The strength gain by ES in normal muscle can be attributed to sever the neural mechanisms include; Increase sensitivity of synapses as a result of continuous stimulation of input fibers. Synchronization of motor unit firing patterns. The selective recruitment of large fast-twitch type II fibers over the slow-twitch-type I fibers could also be implicated. Increase activity of the spinal motor neuron pools, which regulate the force of muscle contraction due to stimulation of afferent neurons.  Goals of Electrical Stimulation Short Term : Decrease pain Stimulate muscle Longer Term (chronic) Improve function strengthen Electrotherapy in clinical practice  Muscle strengthening Injury or pain can inhibit voluntary muscle contractions and cause weakness. Facilitation of muscle control Stimulation is extensively used therapeutically to initiate and facilitate voluntary contraction of muscle, although it is not possible to distinguish this effect from the strengthening effect already considered.  Maintenance or increase of range of joint motion The motion may be limited by different tissues and from different causes. Electrical stimulation has been used in: Contractures of fibrous tissue or due to shortening of soft tissues on one side of the joint has been treated by electrical stimulation of the muscles that stretch the contracture.  Electrical stimulation has been applied as an alternative to / combined with manual passive movement to help prevent the loss of motion due to shortening of the opposing muscles. Pain modulation. Pain is modulated by ES currents through mechanisms a-Gate control theory b-Endogamous opiate theory Reduction of edema First, the muscle pumping action, in which intermittent muscle contraction mechanically compresses adjacent soft-walled venous and lymphatic vessels to increase the centripetal flow of their contents whatever the stage or cause.  Secondly, Application of current displaces the negatively charged plasma proteins of the interstitial fluid of a traumatized region. The increased mobility of albumin in particular should accelerate the normally lymphatic capillary up take ,so increasing the fluid return in the lymphatic system and reducing edema. A third is that the current acts to decrease the permeability of capillaries in someway, thus diminishing fluid and plasma protein loss to the interstitial space.  Accelerate the healing of wounds and bone. ES can increase in cell metabolism & microcirculation accelerate the healing of wounds and bone It has been indicated that monophasic currents can accelerate the healing of cutaneous wounds and bone. Stimulation of Denervated Muscle even partial or complete denervation Transplantation surgeries In circumstances in which a new muscle action has to be learned, for example where a muscle or a motor nerve has been transplanted.  For children with cerebral palsy, where electrical stimulation may enhance muscle contraction and provide sensation and control In hemiplegic patients Aim: to gain control of standing and walking Electrical stimulation for the control of spasticity: stimulation of antagonists to utilize the effect of reciprocal inhibition. Contra indication for electrical stimulation DVT  Electric shock Shock: Shock is stage of unconsciousness which could be due to so many causes. Examples are: hypovolemic, neurogenic, psychogenic and electric shock etc. Electric shock: Electric shock is a painful stimulation of sensory nerves caused by: 1. Sudden flow of current 2. Cessation or pause of flow of current 3. Variation of the current passing through the body measures  Causes of Electric Shock 1. Poorly designed electromedical apparatus 2. Improper insulation of equipment 3. Improper insulation of wires 4. Badly serviced medical equipment 5. Mis-handling of apparatus 6. Improper guidance to the patient 7. Lack of proper safety Types of Electric Shock 1. Minor electric shock: In minor electric shock the victim gets frightened and distressed. no loss of consciousness. 2. Major or severe electric shock: In major or severe electric shock there is a fall of blood followed by ventricular fibrillations and cardiac arrest. Treatment of Electric Shock 1. The current should be switched off immediately. 2. The victim to be disconnected from the source of supply. 3. If there is no switch in the circuit, the victim must be removed from contact with the conductor, but rescuer must take care not to receive a shock himself from touching the affected person, contact with whom should be made only through a thick layer of insulating material. 4. Following a minor shock the patient is to be reassured that everything is alright and allowed to rest. 5. Water may be given to drink, but hot drinks should be avoided as they may cause vasodilatation which facliltate hypotention. 6. Tight clothing should be loosened and plenty of air allowed. 7. If respiration has ceased, the airway must be cleared and artificial respiration is to be commenced immediately 9. Oxygen therapy may also be administered if required. 10. Patient must be shifted to the hospital after the primary care. Precautions to avoid electric shock 1. All apparatus should be tested before use. 2. Connections to be checked before application. 3. Controls should be checked to ensure that they are at zero before switching on. 4. Adequate warming up time should be allowed. 5. The current intensity should be increased with care.