Interferential TherapyInterferential Therapy

Interferential TherapyInterferential Therapy

Interferential therapy is a form of electrical Interferential therapy is a form of electrical treatment in which two medium-frequency treatment in which two medium-frequency currents are used to produce a low-frequency currents are used to produce a low-frequency effect. effect.

the transcutaneous application of the transcutaneous application of alternating medium-frequency electrical alternating medium-frequency electrical currents, which are slightly out of phase currents, which are slightly out of phase through the tissues, amplitude modulated through the tissues, amplitude modulated at low frequency for therapeutic purposes at low frequency for therapeutic purposes such as relief of pain, improve circulation such as relief of pain, improve circulation and enhances healing process.and enhances healing process.

Destructive Interference

Constructive Interference

Beat Frequency Cuurent

Carreir Currents

skin impedance is inversely proportional to skin impedance is inversely proportional to frequencyfrequency

ohmic resistanceohmic resistance - a material's opposition to the flow - a material's opposition to the flow of electric current; measured in ohmsof electric current; measured in ohms

Ohmic resistance is developed due to skin and Ohmic resistance is developed due to skin and depends on following factors: depends on following factors: Ohmic resistance is inversely proportional to the size of the Ohmic resistance is inversely proportional to the size of the

electrodes used. electrodes used. Ohmic resistance is directly proportional to the dryness of the Ohmic resistance is directly proportional to the dryness of the

skin. skin. Ohmic resistance is directly proportional to the hairy and oily Ohmic resistance is directly proportional to the hairy and oily

skin. skin.

Production of Interferential Production of Interferential CurrentCurrent

Interferential current is essentially a Interferential current is essentially a medium-frequency current that medium-frequency current that rhythmically increases and decreases in rhythmically increases and decreases in amplitude at low frequencyamplitude at low frequency

The principle upon which interferential The principle upon which interferential therapy is based is that which produces therapy is based is that which produces the interference effect where two medium the interference effect where two medium frequency currents cross in the patient’s frequency currents cross in the patient’s tissues. tissues.

Two medium frequency Two medium frequency currents are used to currents are used to produce the interferential produce the interferential current. current. They are known They are known as carrier waves as as carrier waves as they do not produce they do not produce muscle nerve muscle nerve stimulation and are just stimulation and are just used to get the greater used to get the greater depth of penetration depth of penetration and to produce the and to produce the interferential current.interferential current.

Interferential current is produced by mixing two Interferential current is produced by mixing two medium-frequency currents that are slightly out of medium-frequency currents that are slightly out of phase, either by applying them so that they interfere phase, either by applying them so that they interfere within the tissues, or alternatively by mixing them within the tissues, or alternatively by mixing them within the stimulator prior to application within the stimulator prior to application (premodulated current). (premodulated current).

Theoretically, the two currents summate or cancel Theoretically, the two currents summate or cancel each other out in a predictable manner, producing each other out in a predictable manner, producing the resultant amplitude-modulated interferential the resultant amplitude-modulated interferential current.current.

The frequency of the resultant current will be The frequency of the resultant current will be equal to the mean of the two original currents, equal to the mean of the two original currents, and will vary in amplitude at a frequency and will vary in amplitude at a frequency equal to the difference between these two equal to the difference between these two currents. This later frequency is known as the currents. This later frequency is known as the amplitude-modulated frequency (AMF) or beat amplitude-modulated frequency (AMF) or beat frequency.frequency.

Area of Interference:Area of Interference:

It is the area where interferential current is It is the area where interferential current is set-up. The pattern of the interferential set-up. The pattern of the interferential area may be static or dynamic. area may be static or dynamic.

Amplitude-Modulated Frequency (AMF) or Beat Amplitude-Modulated Frequency (AMF) or Beat

Frequency:Frequency:

AMF is defined as the difference between the AMF is defined as the difference between the frequencies of the two medium-frequency frequencies of the two medium-frequency currents, which is produced in the tissues at the currents, which is produced in the tissues at the point where the two currents cross. point where the two currents cross.

Amplitude of AMF is always higher than the Amplitude of AMF is always higher than the amplitude of the two medium-frequency currents. amplitude of the two medium-frequency currents.

Amplitude-Modulated Frequency (AMF) or Beat Amplitude-Modulated Frequency (AMF) or Beat Frequency:Frequency:

Most IF machines allow a constant AMF to Most IF machines allow a constant AMF to be selected, e.g. 10,50 or 100 Hzbe selected, e.g. 10,50 or 100 Hz

This is called Constant or Static mode.This is called Constant or Static mode. Some machines allow the AMF to change Some machines allow the AMF to change

automatically & regularly b/w some automatically & regularly b/w some presetpreset pair of frequencies over a specified time pair of frequencies over a specified time period. This is variously called a period. This is variously called a Frequency Modulation, swing or Sweep.Frequency Modulation, swing or Sweep.

Static AMFStatic AMF

INTERFERNTIAL CURRENTINTERFERNTIAL CURRENT

Clover leaf pattern is bacically the Clover leaf pattern is bacically the theoretical distribution of current in a theoretical distribution of current in a homogenous mediumhomogenous medium

In reality this neat uniformity cannot takes In reality this neat uniformity cannot takes place b/c of the heterogeneity of tissuesplace b/c of the heterogeneity of tissues

This represents the static pattern and called This represents the static pattern and called STATIC AMF.STATIC AMF.

This pattern is used for treating smaller This pattern is used for treating smaller areasareas

INTERFERENTIAL CURRENTINTERFERENTIAL CURRENT

By varying the current intensity in the two By varying the current intensity in the two circuits with respect to each other, it is circuits with respect to each other, it is possible to move the clover leaf pattern to possible to move the clover leaf pattern to and fro through 45 degrees, this gives a and fro through 45 degrees, this gives a more uniform total distribution of the IFC in more uniform total distribution of the IFC in the tissuesthe tissues

This pattern is used for the treatment of This pattern is used for the treatment of larger areas.larger areas.

Methods of applicationMethods of application

Quadripolar / Bipolar ApplicationQuadripolar / Bipolar Application

Interferential currents may be produced Interferential currents may be produced either by applying the two medium either by applying the two medium frequency currents via four electrodes frequency currents via four electrodes (quadripolar method) so that they intersect (quadripolar method) so that they intersect in the tissues, or alternatively by mixing in the tissues, or alternatively by mixing the two currents in the stimulator prior to the two currents in the stimulator prior to application via two electrodes application via two electrodes (premodulated or bipolar method).(premodulated or bipolar method).

QuadripolarQuadripolar

A quadripolar application of interferential A quadripolar application of interferential current produces modulated current in a clove current produces modulated current in a clove leaf pattern, with leaves set up at right angles leaf pattern, with leaves set up at right angles to the two medium frequency currents.to the two medium frequency currents.

Quadripolar interferential current is produced Quadripolar interferential current is produced deep inside the tissues (AMF is produced deep inside the tissues (AMF is produced endogenously); hence there is lowered skin endogenously); hence there is lowered skin impedance. Thus it is used to treat larger impedance. Thus it is used to treat larger areas.areas.

Bipolar ApplicationBipolar Application Bipolar interferential current will be distributed Bipolar interferential current will be distributed

similarly to conventional electrical stimulation, similarly to conventional electrical stimulation, with maximal current intensities underneath the with maximal current intensities underneath the electrodes, progressively decreasing with electrodes, progressively decreasing with distance.distance.

Bipolar interferential current is produced inside Bipolar interferential current is produced inside the machine (AMF is produced exogenously); the machine (AMF is produced exogenously); hence there is increased skin impedance. Thus it hence there is increased skin impedance. Thus it is used to treat localized area or smaller areas.is used to treat localized area or smaller areas.

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INTERFERENTIAL THERAPYINTERFERENTIAL THERAPYPHYSIOLOGICAL PHYSIOLOGICAL

OBJECTIVESOBJECTIVES Pain relief both acute and chronicPain relief both acute and chronic Reduction of edemaReduction of edema re-education and strengthening of re-education and strengthening of

muscle.muscle. Stimulation and improvement of Stimulation and improvement of

circulationcirculation General facilitation of healing General facilitation of healing

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INTERFERENTIAL THERAPYINTERFERENTIAL THERAPY

The generally accepted range of The generally accepted range of frequency is 0 to 150 Hz, with a low frequency is 0 to 150 Hz, with a low range from 0 to 10 Hz, commonly range from 0 to 10 Hz, commonly accepted as the appropriate accepted as the appropriate treatment for increasing local blood treatment for increasing local blood circulation; and a high range from 80 circulation; and a high range from 80 to 150 Hz which is used for pain to 150 Hz which is used for pain relief.relief.

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INTERFERENTIAL THERAPYINTERFERENTIAL THERAPYCONTRAINDICATIONSCONTRAINDICATIONS

PacemakersPacemakers ThrombosisThrombosis Cardiac ConditionsCardiac Conditions Bacterial InfectionsBacterial Infections MalignancyMalignancy

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INTERFERENTIAL THERAPYINTERFERENTIAL THERAPYWARNINGSWARNINGS

PregnancyPregnancy Implants of any electrical natureImplants of any electrical nature TranscerebrallyTranscerebrally Skin diseasesSkin diseases

Application in Different Application in Different ConditionsConditions

OR

How is IFC different than a TENS unit in relation to pain reduction?

TENS (Transcutaneous (through the skin) Nerve Stimulation) is strictly a non-invasive (any procedure that does not penetrate the skin or a cavity) pain management tool. TENS stimulates peripheral nerves (the nerves which supply the musculoskeletal system and surrounding tissues) producing a tingling sensation that interferes with pain. TENS masks pain by blocking nerve impulses on the sensory nerve (nerves that convey impulses to the brain and spinal cord) (Gate Control Theory (the hypothesis that painful stimuli may be prevented from reaching higher levels of the central nervous system (spinal cord and/or brain) by stimulation of larger sensory nerves which will block or prevent the sensory nerves from sending pain signals effectively to the brain).

TENS, has no other physiological (the normal process of the body as opposed to abnormal or pathological functions) effect. TENS delivers nerve stimulation transcutaneously. The increased sensory activity activates cells in the dorsal (pertaining to the back or lower part of an organ) horn of the spinal cord , closing the gate to pain transmission along the fibers that send pain response’s to the brain. Accommodation (dependency on a device) and habituation (becoming used to something) with reduced or eventual noneffectiveness are concerns when TENS is used for an extended period of time. Since the stimulation parameters (settings or guidelines) are limited or kept constant, the patient can/will adapt to minimally changing or unchanging stimulus (anything which excites functional activity in an organ

or body part). When this happens the TENS unit will no longer be as effective for the patient, and TENS has no long term curative value.