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 uses to applying deeper tissues.
PRINCIPLES:
Beat frequency
Skin resistance depends on frequency. Resistence inversely
Z = I/2FC
Z – skin resistance
F – frequency
C – capacity of the skin
Interference effect:
- Two medium frequency currents interefered 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.
VARIATIONS OF INTERFERENCE:
Scale:
- 1 -100Hz constrant
- 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)
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.
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.
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
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
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
1-10Hz constant-
- Effects on muscular contraction
- Less sensory stimulation
- Greater depth of muscle stimulation
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)
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
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
CONTRAINDICATIONS
- Arterial disese
- DVT or thrombo-phlebitis
- Infective conditions
- Pregnancy
- Danger of haemorrhage
- Malignant tumours
- Artificial pacemaker
- During menstruation
- Febile condtion
- Large size open wound
- Unreliable patients
- Dermatological conditions
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
Frequency and duration:
Analgesic –
- 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
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
Stimulation of weak muscles with
innervated:
- 1-10Hz rhythmic, high dose, 5-15mins
Posterior root ganglior irritation:
- 90-100Hz rhythmic, low dose, 10-15mins
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
METHODS OF APPLICATION:
- Metal plate electrode and pads
- Quadripolar plate electrode
- Suction cup electrodes
- Quadripolar suction cup electrodes
- Quadripolar probe electrode
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 theTreatment 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.
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.
ADVANTAGES:
- Large doses won’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 effectlvely treated.
THOSE ABOVE ARE COLLECTED FROM SOME BOOKS AND
WEBSITES..
THANK YOU,
SRIKUMARAN
PHYSIOTHERAPY CLINIC & FITNESS CENTER
Comments