Transcript Interferntial Current

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
minutes
– Burst mode typically
applied 3x a week in
30 minute bouts
• Precautions
– same as all electrical
currents
• Contraindications
– Pain of central origin
– Pain of unknown
origin
• Indications
– Acute pain
– Chronic pain
– 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
Long Duration
Sweep Fq
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.