2010

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Author:
jessiekate22
ID:
158948
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2010
Updated:
2012-06-16 07:00:25
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Interferential
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Exam
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  1. What is the principle of IF?
    • - the passing of two medium frequency alternating currents which are slightly out of phase through the tissue
    • - medium frequency currents pass more easily through the skin than low frequency currents because there is lower impedance to very short eletrical pulses
    • -  IF currents will stimulate nerves because of the amplitude modulation in the same manner as lower frequency currents
    • - exictable and non excitable tissue can respond to electrical stimulation within a certain frequency range
    • - this range is based on the frequency range of naturally occuring bio- eletric currents and these fall within 0.1- 200 Hz 
    • - A beta and C fibres fire at very slow rates, less than 1Hz
    • - The largest sensory fibres are capable of firing at frequencies at the larger frequencies 
  2. Medium frequencies
    • - the spread of medium frequency currents in the tissues is more uniform than low frequency currents. This allows the effects of medium frequency currents to occur deeper into tissues.
    • - treat deeper tissues with lower frequency 
  3. How are IF currents produced?
    • - sinusoidal currents with a carrier medium frequency range 3000-5000Hz
    • - amplitude or intensity of the resultant current wil rise and fall 
    • - the two IF curents cross over. Summation and resultant wave form- making the wave form smaller and chaning the intensity or current wave form
    • - machines are programmed to deliver beats or envelopes of current at a low frequency range of approximately 1-20 beats per sec
    • - the beat frequency is the difference in  frequency between the two medium frequency curents
    • - beat frequency relates soley to the number of times per second that the intensity rises and falls
    • - resultant frequency of the cross over is the difference between the two, the beating that is the IF effects eg 500 and 5050= 50
    • - IF can be applied in a static mode which allows a constant beat frequency to be selected
    • - can also be set to allow the beat frequency to change automatically and regularly between a preset pair of frequencies over a specified time period, eg 80-140bps. THis is know as a sweep. Believed to prevent nerve habituation and may extend the range of nerve types that can be stimulated.
  4. What frequencies stimulate what?
    • - lower frequency current stimlates the motor nerve fibres
    • - higher frequencies- over 80 stimulate sensory fibres
    • - IF can be used to create a sweep change the beat frequency two frequencies over a time period 
    • You can move the frequency and stimulate a range of nerve types 
  5. What is the theoretical and the true distribution of IF?
    • - theoretical- in a medium is a clover leaf shape
    • - due to current amplitudes and their directions needing to be summated ie vector addition-doesnt hapen in humans due to all the different tissue
  6. Clover leaf
    • - using a sweep, it is a possible to move the clover leaf pattern back and forth through 45*, giving a more uniform total distribution of the IF current through the tissues
    • - increases the area of effective treatment
    • - clover leaf can be swung back and forth 
  7. How are the currents applied?
    • - metal or carbon rubber electrodes with water soaked sponges
    • - suction units can also be connected to the IF machine with cups 
    • - electrodes are placed so that the currents cros on another in the target tissue 
  8. Methods of delivery
    • - bipolar method: two medium frequency currents are produced    resulting in an amplitude modulated IF current with a fixed beat frequency
    • - shape of field will be oval shaped 
  9. What is the quadripolar method 
    • - uses four electrodes with each pair of electrods connected to a respetive channel
    • - IF occurs outside at the level of the treated area where the two currents  interfere with each other in the target tissue
    • - try and get the electrode to cross in the area u r trying to treat. Maximum summation occurs when the currents cross
    •  
  10. Quadripolar with automatic vector scan method
    • - used to enlarge the IF field 
    • - 4 electrodes are used and two unmodulated  medium frequency currents applied
    • - one circuit is allowed to vary slowly between 50% and 100% of the  maximum set value- creates a rotating vector field 
    • - big area- bigger range of fibre types you can stimulate 
  11. Stereodynamic method of IF
    • - created by adding a third medium frequency circuit 
    • - produces a 3 dimensional effects within the tissues 
    • - 6 electrodes are necessary  
  12. Physiological effects of IF currents
  13. What are the contraindications of IF?
    • - trans thoracic applications
    • - in 3m of operating short wave diathermy equipment- cause IF surge
    • - uterus of pregnant woman 
    • - inbuilt stimulator eg pacemaker
    • - circulatory in or deep venous thrombosis  
  14. What are the precautions of IF?
    • - application over broken skin
    • - risk of dissemination eg acute infections, osteomyelitis, tumour  (benign or malignant) TB 
  15. What is the sensation test for IF?
    - sharp/ blunt test
  16. What is the pt warning for IF?
    • When having electrical stimulation you should feel … [a ‘tingling’ sensation for sensory stimulation and/or muscle contraction if motor level stimulation is used]. If you feel anything other than this, or any pain or discomfort, you must call me immediately. Otherwise, you may risk skin and other tissue damage under the electrodes. 
    • Please do not move or touch the equipment during treatment. If you become uncomfortable, call me. 
    • Do you understand what I have said? Do you have any questions? Are you happy for me to proceed?
  17. What are the dangers of IF?
    • - burns- electrical or chemical
    • - haematoma from the vacuum pump
  18. What are the indications for IF?
    • - pain
    • - oedema
    • - mm spasm
    • - mm stimulation
    • - urinary and anorectal incontinence disorder
    •  
  19. Therapeutic dosages
    • 100 constant- to selective stimulate sensory nerve. Pain relief. Increase vasodilation
    • 1- 10 constant- motor fibres are targeted
    • 1- 100 rhythmic- sweep- exciting and relaxing fibres- stimulating tissue not just nerves. Increase venous and lymphatic flow and tissue tone
    •  90 – 10 sweep- over 15 seconds- sensory- why use this instead of 100 constant- less nerve stimulation of the nerve
    • 1 – 10 rhythmic- sweep- motor nerves, increase vasodilation, more pumping action- help shift chronic swelling.
  20. LOOK AT NOTES FOR THE DOSAGES! DO NOT BE LAZY!
  21. Pt warnings for IF?
    • - When having electrical stimulation you should feel a tingling sensation for sensory stimulation or a muscle contraction if motor level stimulation is used. If you feel anything other than this or any pain or discomfort you must call me immediately. Otherwise you may risk skin and other tissue damage under the electrodes.
    • Please do not touch the equipment during treatment. If you become uncomfortable call me.
    • Do you understand what I have said? Do you have any questions? Are you happy for me to proceed?

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