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Interferntial Current IFC

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					Interferential Current - IFC
         Interferential Current
• History: In 1950 Nemec used interference
  of electrical currents to achieve therapeutic
  benefits. Further research and refinements
  have led to the current IFC available today
  – Two AC are generated on separate channels
    (one channel produces a constant high
    frequency sine wave (4000-5000Hz) and the
    other a variable sine wave
  – The channels combine/interface to produce a
    frequency of 1-100 Hz (medium frequency)
      Effects of IFC treatment:
• Sensory nerve fibers - Pain reduction -
  receive a lower amplitude stimulation than
  the area of tissue affected by the vector,
  thus IFC is said to be more comfortable
  than equal amplitudes delivered by
  conventional means
• Muscle fatigue - muscle spasm - is reduced
  when using IFC versus HVS due to the
  asynchronous firing of the motor units
  being stimulated
 Positive effects of IFC include:
• reduction of pain and muscle discomfort
  following joint or muscle trauma
• these effects can be obtained with the of
  IFC and without associated muscle fatigue
  which may predispose the athlete to further
  injury.
    Principles of wave interference -
           Combined Effects
• Constructive, Destructive, & Continuous
• Constructive interference: when two
  sinusoidal waves that are exactly in phase or
  one, two, three or more wavelengths our of
  phase, the waves supplement each other in
  constructive interference

+                     =
    Principles of wave interference -
           Combined Effects
• Destructive interference: when the two
  waves are different by 1/2 a wavelength (of
  any multiple) the result is cancellation of
  both waves

+                    =
Principles of wave interference -
       Combined Effects
• Continuous Interference
    – Two waves slightly out of phase collide and
      form a single wave with progressively
      increasing and decreasing amplitude


+                      =
   Amplitude-Modulated Beats:
• Rate at which the resultant waveform (from
  continuous interference) changes
• When sine waves from two similar sources
  have different frequencies are out of phase
  and blend (heterodyne) to produce the
  interference beating effect
                              IFC
• Duration of tx 15-20          • Contraindications
  minutes                           – Pain of central origin
   – Burst mode typically           – Pain of unknown
     applied 3x a week in             origin
     30 minute bouts            • Indications
• Precautions                       – Acute pain
   – same as all electrical         – Chronic pain
     currents
                                    – Muscle spasm
   IFC Techniques of treatment:
• Almost exclusively IFC is delivered using
  the four-pad or quad-polar technique.
• Various electrode positioning techniques
  are employed:
  – Electrodes (Nemectrody: vacuum electrodes):
     • four independent pads allow specific placement of
       pads to achieve desired effect an understanding of
       the current interference is essential
     • four electrodes in one applicator allows IFC
       treatment to very small surface areas. The field
       vector is pre-determined by the equipment
       Quad-polar Technique
• Pads placed at 45º angles from center of tx
  area
• Can reduce inaccuracy of appropriate
  tissues by selecting rotation or scan


                  Channel B                 Channel B




                                Channel A
      Channel A                               SCAN
   Bipolar Electrode Placement
• The mix of two channels occurs in
  generator instead of tissues
• Biopolar does not penetrate tissues as
  deeply, but is more accurate
• When effects are targeted for one muscle or
  muscle group only one channel is used
          Two-circuit IFC:
– At other points along the time axes the wave
  amplitude will be zero because the positive
  phase from one circuit cancels the negative
  phase from the second circuit (destructive
  interference)
– The rhythmical rise and fall of the amplitude
  results in a beat frequency and is equal to the
  number of times each second that the current
  amplitude increases to its maximum value and
  then decreases to its minimum value
 Special Modulations of IFC:
– Constant beat frequencies (model): the
  difference between the frequencies of the two
  circuits is constant and the result is a constant
  beat frequency. That is, if the difference in
  frequency between the two circuits is 40 pps,
  the beat frequency will be constant at 40 bps.
 Special Modulations of IFC:
– Variable beat mode: the frequency between the
  two circuits varies within preselected ranges.
  The time taken to vary the beat frequency
  through any programmed range is usually fixed
  by the device at about 15 sec. IFC machines
  often allow the clinician to choose from a
  variety of beat frequency programs.
              Pain Control
– Similar to TENS - beat frequency 100Hz
     – Low beat frequencies when combined with motor level
       intensities (2-10Hz) initiate the release of opiates
     – 30 Hz frequencies affects the widest range of receptors

       Parameter                      Range

       Intensity                     Sensory

   Electrode Config                Quadpolar

        Beat Fq             High – Gate Control
                            Low – Opiate release
       Sweep Fq               Long Duration
    Neuromuscular Stimulation
• Beat frequency of approximately 15 HZ is
  used to reduce edema
            • General Parameters
         Parameter          Range

          Intensity       1-100mA

         Carrier Fq      2500-5000Hz

          Beat Fq          0-299 Hz

         Sweep Fq         10-500sec
IFC Technique of treatment:
– Electrode placement:
   • The resultant vector should be visualized in placing
     the electrodes for a treatment . The target tissue
     should be identified and the vector positioned to hit
     that area. Typically at 45º angles is most effective.
   • Segregation of the pin tips is essential in the proper
     electrode positioning for IFC. The electrodes may
     be of the same size or two different sizes (causing a
     shift in the intersecting vector). Treatment through a
     joint has also been advocated without adequate
     research to establish efficacy of the treatment
     technique.
  Bone Stimulating Current:
– Bone Stimulating Current:Bone Stimulating
  Current:IFC has been used (Laabs et al) studied
  the healing of a surgically induced fracture in
  the forelegs of sheep. Their study indicated an
  acceleration of healing in the sheep treated with
  IFC as compared to the control group
  Bone Stimulating Current:
– This study validated an earlier study by Gittler
  and Kleditzsch which showed similar results in
  callus formation in rabbits. Several other
  studies have shown an increase in the healing
  rate of fractures but the exact mechanism by
  which the healing occurs is not understood.
   Bone Stimulating Current:
– Some speculation is that an increased blood
  flow to the injured area is produced which
  allowed natural healing processes to occur more
  rapidly.
– In one study (mandible fractures ) the IFC
  caused very mild muscle contraction of the jaw
  and this muscle activity was thought to have
  been a potential accelerator of the healing.

				
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