INTERFERENTIAL THERAPY

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1. INTERFENETIAL THERAPY
Prof. Dr. M. Rajesh, PT, M.P.T(cardio), BCRC
TRINITY MISSION AND MEDICAL FOUNDATION
MADURAI

2. INTRODUCTION
Interferential therapy is a form of electrical treatment in which
two medium frequency currents are used to produce a low
frequency effects.
Medium frequency currents of around 4000Hz, while able to
stimulate motor and sensory nerves, encounter a much lower
skin-impedence.
IFT used to applying deeper tissues.

3. PRINCIPLES
Beat frequency
Skin resistance depends on frequency.
Résistance inversely proportional to
frequency
Z = I/2FC
Z –skin resistance in ohms
F –frequency in Hz
C –capacitance of the skin in
microfarads

4. Interference effect
Two medium frequency currents interfered in heterodyned to
make beat frequency
The beat frequency can modulate
Principle of IFT effect
Frequency range is limiting values, by changing one channel
frequency in IFT.

5. VARIATIONS OF INTERFERENCE
Scale
1 -100Hz constant
1 -10Hz rhythmic
90 -100Hz rhythmic
[ 10 sec –go up; 5 sec –come down]
Frequency swing by two control knobs
1-100Hz (Bosch)
0 –150Hz (Endomed)

6. Skin current compensations
It is achieved by electrode placements.
Electrodes close together –resistance is decreased
Interferential vector system
The vector mode advantage is specific area at any depth, it can
be treated with pulse low frequency stimulation.

7. Electrokinesy
It is one of the IFT application technique, which is using a glove
type electrode worn by physiotherapist. It is apply with 4000Hz,
carrying in low frequency modulation(50Hz) applied with glove
electrode.
Surge
It has varying surged upto 2-12 mins.

8. IFT with Galvanism(DC)
The IFT is combine with DC and select suitable pole.
Stereodynamic IFT
In this technique, IFT applied with three pair of electrode or
STAR electrode

9. PHYSIOLOGICAL EFFECTS OF
IFT
The effects depends on
Selection frequency range
Rhythmic or constant frequency swings
Intensity
Accuracy of electrode placement
Circulation and neurological functions
Underlying pathophysiology

10. 100Hz constant-
It is produce fine vibrations on sensory nerve endings –used of
analgesic effect
Tingling sensation –decrease pain (applied for upto 10-15
mins)
Direct stimulation –inhibition of the sympathetic system(use to
treat causalgic pain, reflex sympathetic dystrophy)
Increase vasodilation

11. 1-10Hz constant-
Effects on muscular contraction
Less sensory stimulation
Greater depth of muscle stimulation

12. 1-100Hz rhythmic-
Fine vibrations of the ions leads to facilitate the ion movments
through cell membrane.
It made increase venous return and lymphatic flow.
90-100Hz rhythmic
Analgesic effect –especially neuralgic pain (e.g. Brachial
neuralgia)

13. 1-10Hz rhythmic-
Stimulatory effect on motor and underlying tissues
Increase vasodilatory effect
Vigorous pumping effect (help to start absorbtion of exudates)
Electrokinesy (50Hz with 4000Hz current)
Useful in pain and muscle spasm conditions with application 2-3
mins

14. INDICATIONS
Pain
Muscle spasm
Oedema
Haematoma(on first 24 hours used with ice packs)
Chronic ligamentous lesions
Trigger spots in myofascial syndrome
Stress incontinence (treat wih vaccum electrodes; 1-100Hz
rhythmic with 15 mins application; electrode positioned in lower
abdomen just above pubis and inside of thigh on upper
posterior medial side)
Delayed union and Sudek’s atrophy –apply with 15-20 mins/day
for 2-3 weeks

15. CONTRAINDICATIONS
Arterial disease
DVT or thrombo-phlebitis
Infective conditions
Pregnancy
Danger of haemorrhage
Malignant tumours
Artificial pacemaker
During menstruation
Febile condition
Large size open wound
Unreliable patients
Dermatological conditions

16. DOSAGE
Intensity (Depends on size of electrode)
Low doses –not noticeable
Medium doses –just noticeable
High doses –clearly experienced, vigorous, pleasant sensation
Very high does –strong, vigorous, unpleasant sensation

17. Frequency and duration
Analgesic effect
Acute pain –90-100Hz rhythmic, medium doses, 10 mins
application
Chronic pain –100Hz constant, medium doses, 10 mins
application
Oedema
100Hz constant, medium dose, 10 mins
1-100Hz rhythmic, medium dose, 10 mins


18. Tenacious exudates
1-100Hz rhythmic, high dose, 10mins
1-10Hz rhythmic, high dose, 10mins
Pain due to sympathetic dysfunction
100Hz constant, medium dose, 10mins
90-100Hz rhythmic, medium dose, 10mins

19. Stimulation of weak muscles with innervated
1-10Hz rhythmic, high dose, 5-15mins
Posterior root ganglion irritation
90-100Hz rhythmic, low dose, 10-15mins

20. Parametritis (pelvic inflammation)
100Hz constant, medium dose, 15mins
1-100Hz rhythmic, medium dose, 10mins
Phatom pain
100Hz constant or 90-100Hz rhythmic, high dose, 10mins

21. METHODS OF APPLICATION
IFT applied with different type of electrodes
Metal plate electrode and pads
Quadripolar plate electrode
Suction cup electrodes
Quadripolar suction cup electrodes
Quadripolar probe electrode

24. TECHNIQUES OF APPLIATION
Patient should be comfortable position
Skin is prepared as for low frequency stimulation(thoroughly
washed and apply petroleum jelly if any skin lesions)
Site of treatment area is accurately located
Patient should be instructed about treatment, type current,
sensation and effects
Set treatment frequency
Rise intensity
Get the patient verbal feedback about the sensation and rise the
intensity with regular interval
After the completion of the session, get feedback about the
treatment
Maintain patients record and fix next appointment.

25. DANGERS
Burns –due to bare metal electrode, electrode close together,
increase intensity, and decrease moisture in the pads
Haematoma (commonly seen in suction cup electrodes)
Poor results –due to faulty position, incorrect frequency and
dose.

26. ADVANTAGES
Large doses doesn’t produce chemical burns
Decreased sensation is not a contraindication
Metal implant is not a contraindication(IFT is apply with caution
in this case)
Treatment with referred pain is effectively treated.

27. THANK YOU
Prof. Dr. M. RAJESH, PT,M.P.T(cardio),B.C.R.C
TRINITY MISSIOIN AND MEDICAL FOUNDATION
MADURAI.
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