3...Medium frequencmnknkmy currents.pptx

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1. WELCOME

2. MEDIUM FREQUENCY CURRENTS After this lecture, participants will be able :

3. MEDIUM FREQUENCY CURRENTS Medium frequency currents are therapeutically used currents whose frequency is in the range of 1000 to 10,000 cycles per seconds. They are basically used to stimulate deeply situated muscles and nerves since it is difficult to stimulate these muscles and nerves by low frequency currents without the spread of current . USES for muscle re-education, to retard the rate of muscle atrophy, drainage of edema and for pain relief

4. Various currents in this category Interferential Therapy (I.F.T) Russian current

5. Historical background Intro. By Nemec in Vienna in the early 1950’s He wanted to overcome the problems of discomfort caused by low- frequency currents, while maintaining their claimed therapeutic effect. It disappeared until late 1960s and 1970s when work on pain mechanism by Melzak / wall showed that pain could be decreased by stimulating primary afferent neurons.

6. Interferential Therapy It is amplitude modulated AC Transcutaneous application of two alternating medium frequency electrical currents used to produce low frequency therapeutic effects.

7. Why need of IF current Faradic and sinusoidal (low frequency currents) —very high skin impedance . Medium frequency currents---- reduce skin impedance The principle of IFT is to pass two medium frequency alternating currents which are slightly out of phase, through the tissues, where the current intersect to produce a low frequency effect . The superimposition of one alternating current on the other is called interference.

8. Principles Of Wave Interference : Combined Effects & Constructive interference: Constructive interference: when two sinusoidal waves that are exactly in phase or one, two or three wavelengths out of phase, the waves supplement each other in constructive interference

9. Destructive interference W hen the two waves are different by 1/2 a wavelength (of any multiple) the result is cancellation of both waves Two waves slightly out of phase collide and form a single wave with progressively increasing and decreasing amplitude Continuous interference

10. Working One of the alternating currents has a fixed frequency of 4,000 Hz F requency of the other alternating current can be set between 4,000 and 4,250 Hz or less than 4000 (varying frequency). The frequency of the new medium frequency alternating current can be calculated as follows: Example: f1 = 4,000Hz f2 = 4,150 Hz f 1 - f2 = 4,000 - 4,150 = 150 Hz (AMF or treatment frequency, beat freq ) The AMF has a value of: AMF = Δf = f1 – f2

11. Variation in frequency Can be pre-selected on the machine Can be constant or rhythmic Constant Beat Frequency In the constant mode there is a constant difference between the frequencies of the two circuits Variable Beat Frequency The frequency between the two circuits varies within pre-selected range in variable beat mode .

12. Frequency swing A rhythmic mode indicates that the frequency is swinging continously from lower to higher value and back If rhythmical range of 0-100 Hz required, vary the freq of second circuit btw 3900-4000 Hz over a period of 5-10 second.

13. Physiological Effects This depends upon: Magnitude of current Type of mode used i.e. Rhythmic or constant The frequency range used Accuracy of electrode positioning

14. Physiological Effects Main clinical applications are : Pain relief stimulation of the descending pain suppression system at frequencies of 10-25 Hz Muscle stimulation Most effective motor nerve stimulation range is between 10-25Hz Increased local blood flow Experimentation demonstrated vascular changes at 10-25Hz . Reduction of edema 1-10Hz rhythmic Stress Incontinence weakining of pelvic floor muscle.

15. PAIN RELIEVE Increasing local area circulation- -------------By heat Tissue injury releases chemicals at the site that stimulates nociceptive nerve endings . Physiological Block -------------------------- TENS & IFT Nociceptive Stimulus-------- If a higher frequency of stimulation is applied, a physiological block to conduction might occur Pain Gate Theory ------------------------ Heat, TENS & IFT Activation of Descending Pain Suppression System ------ low TENS, Manipulation, Transverse Friction

16. Types of ELECTRODES 1: PLATE ELECTRODES: Attached to the patient by means of straps to assure a good contact and greater tolerance of treatment. Smaller electrodes are used for a localized effects but this effects is more superficial . Larger plates electrodes give more comfortable treatment and deeper effect Made of conducting rubber which are comfortable and long lasting.

17. 2: Vacuum Electrodes: Not indicated for treatment of the hairy areas because cant get an airtight seal. Excellent for treatment flat smooth areas for example back or a plump knee. Wet sponges are placed in the cups and moisten the adages of the cups for better adherence. Suction should not be constant because it can be uncomfortable and causes bruising .

18. Methods of Application QUADRIPOLAR

19. Quadripolar Technique . The four electrodes are positioned around the target treated area so that each channel runs perpendicular to the other and the current crosses at a midpoint. The interference effect branch off at 45° angles from the center of the treated area in the shape of a four leaf clover. Tissues within this area receive the maximal treatment effect .

20. CURRENT PATHWAY PATTERN

21. Therapeutic Uses of IFC

22. precautions Position suction electrode below the level of damage or discomfort. Over anterior chest wall Epileptic patients Patients with febrile conditions IFT apparatus must be at least 6 meters away from SWD machine

23. Contra-indications

24. JAZAK ALLAH