2. Introduction
• Developed by Dr. Hans Nemec
• The disadvantage of direct currents and low
frequency alternating current(<1KHz) applied to
body where high electrical resistance is offered
by the outer layers of skin is overcomed by
application of medium frequency alternating
currents(>1KHz to <10KHz).
• The medium frequency alternating current meet
little skin resistance and penetrate the tissue
easily.
3. • It is the waveform produced by the
interference of two medium frequency
currents(1000 to 10000 Hz).
• These two medium frequency currents are set
up in a way so that they intersect each other
and produces beat frequency.
• The beat frequency is equal to the difference
between the frequencies of the two original
ACs.
5. • Interferential current therapy maximizes the
current permitting the tissues, while reducing
to a minimum unwanted stimulation of
cutaneous nerves.
• Z= 1/2πfC (Z= impedence, f= frequency,
C= capacitance of the skin)
• As the frequency increases, the impendance
offered by the skin decreases.
6. • Due to the amplitude modulation,
interferential currents are thought to produce
deeper effects.
7. • When two medium frequency alternating
currents, which are slightly out of phase
interfere, due to catch up of one wave peak
with other there occurs constructive
interference for waves which are in phase and
destructive interference in waves, which are
out of phase.
• Constructive interference causes an increase in
the amplitude of the resultant wave.
8.
9. Physical principles of interferential
current-
• The beat frequency current flows maximally in
the region of maximum interference that
develops along diagonals extending at 45⁰ to
the direct path between the two sets of
electrodes.
• A clover leaf pattern of the field is created,
because one current flows laterally from its
direct path to interact with the adjacent
current.
10.
11. Modes: Amplitude modulation
frequency
• medium frequency components simply act as
carrier currents, bringing the low frequency
current into the tissues, which is amplitude
modulated.
12. SWEEP
• The beat frequency changes automatically and
regularly between some preset pair of
frequency over a specified time period.
• such sweep prevents accomodation of nerves.
15. Vector scan
• This produces a scanning movement of the
interferential field, so that all parts of the field
are subjected to maximum interferential effect
can be made.
16.
17. • Quadripolar / Bipolar application – the
quadripolar application is claimed to produce
a deeper effect with in the tissues, whereas
the bipolar application produces a current
flow in the manner as the electrical
stimulation, with maximal current intensities
under the electrodes.
19. Static interference
• Here the area in which
IFT is set up remains
stationary.
• This area of static
interference gives an
appearance of clover
leaf
• It lies to 45⁰ angles to
the perpendicular lines
from each other.
20. Dynamic interference
• This is moving the area of
interference current in a
to and fro manner
through 45⁰.
• It is obtained by varying
the current intensity from
50 to 100%.
• The dynamic area of
interference is also called
as vector sweep, vector
scan, rotating vector, etc.
21. Bipolar interference
• Here pre-modulated IFT
are applied through 2
surface electrodes.
• IFT is generated inside
the equipment and is
delivered to the patient
through 2 electrodes.
• Useful for smaller areas.
22. 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
24. Pain relief
• Achieved by stimulation of the reticular
formation at frequencies of 10-25Hz or by
blocking C fiber transmission at >50Hz.
25. Muscle stimulation
• For patients who can not generate useful
voluntry contraction, IFT may be beneficial.
• Most effective motor nerve stimulation range
is between 10-25Hz.
26. Blood flow
• IFT improves circulation.
• When applied to dorsal root or spinal segment of
origin of a peripheral nerve, causes peripheral
vasodilation.
• Frequency of 100Hz is used to promote
vasodilation.
• Frequency of 10 Hz which activates the
musculoskeletal pump is used to promote venous
and lymphatic return and reduces the edema.
27. Indications-
• Pain relief – use of high AMF(70-150Hz)for acute
pain and frequency below 50Hz for chronic and
subacute conditions.
• Edema relief – AMF of 1-10Hz rhythmic is used.
• Stress incontinence – 4 pole method is used.
Electrodes are placed over lower abdomen and
inner thighs..
• Relief of muscle spasm by increasing the blood
flow.
• Duration – 10 to 20 min.
31. Plate electrodes
• Made of conducting rubber which are
comfortable and long lasting.
• Larger plates electrodes give more
comfortable treatment and deeper effect
• Attached to the patient by means os straps to
assure a good contact and greater tolerance of
treatment
32. Vacuum electrodes
• Made from a vacuum unit plug into a rubber
suction cup connected to a machine capable
of producing a vacuum.
• Suction should not be constant because it can
be uncomfortable and causes bruising
• Excellent for using flat smooth areas.
• Not indicated for treatment of the hairy areas
because cant get an airtight seal.
33. Researches
• Effect of interferential current in patients with
fibromyalgia: a systematic review,
• Journal- fisioter pesqui,2018.
• Author – Mayara Tavares da Silva
• Methodology – The selection consisted only of
controlled RCTs, IFT frequency- 100hz, four
sessions during night
• result- interferential therapy is beneficial to treat
fibromyalgia and improves sleep quality.
34. • Effect of interferential current in the
management of musculoskeletal pain: a
systematic review,
• Journal -physical therapy research symposium,
2018.
• Author- Ginny Skipper
• out of 10, 9 studies have shown reduction in
pain
35. cont
• Interferential electrical stimulation for improved
bladder management following spinal cord injury,
• Journal - Biomedical reports, 2018.
• Author- Cristina Daia
• Methodology- frequency-0 – 100 Hz.
- silicone rubber electrodes 10×10 were used
- 2 electrodes were applied for each circuit
- duration 10 min with 10 sec interval.
• Result – patient with preserved sensations are best
beneficiaries of interferential current electrical
stimulation therapy.
