Interferential Current Interferential Current (IFC)(IFC) A unique use of kilohertz AC waveform “endogenous production of the IFC” Emphasis on use for pain control & some

limited NMES applications Anecdotal support - tissue healing & increase

circulation via autonomic stimulation Hx - Dr. Hans Nemec 1950s in Austria;

popularized in US in late 70s / early 80s; remains popular

IFC Waveform PrecursorsIFC Waveform Precursors

2 electrical circuits (channels) of AC– Medium Frequency AC (1,000 - 10,000 Hz)– One Carrier (fixed) frequency AC– One Variable frequency AC– Example: 5000 Hz / 5100 Hz. Diff = Beat Freq

Why Medium Frequency Why Medium Frequency AC?AC?Comfortable–With AC, higher freq = short phase

width = lower impedancePossibility of neural block

Production of IFC Production of IFC (theoretical, endogenous current)(theoretical, endogenous current)

Interference of 2 MFACs within the tissues results in the endogenous IFC

Beat Frequency: Variable freq – Carrier freq = Beat Waveform interaction (on an oscilloscope);

Benefit: IFC can be 2X amp of MFACs but doesn’t have to penetrate skin

IFC production - in a IFC production - in a uniform medium uniform medium (think 3-D)(think 3-D)

Clover-leaf Pattern of IFC Each circuit equal amplitude at a 90

degree angle to each other. Vector addition

Parameters to be usedParameters to be used

Beat Frequency & Amplitude. Options with Beat Freq:– Fixed vs Scanning Freq. (WHY?)

Vectoring / Sweeping of IFC “oscillation

of the cloverleaf”– Purpose– Physics

IFC in the Tissues: Reality IFC in the Tissues: Reality ????

Clover-Leaf pattern not realistic in human tissue Valid theoretical concept in uniform medium IFC technology is complex, but the mechanisms

of pain control are largely the same as TENS. Potentially better pain control– increased depth of current– comfort with stimulation– typically a clinical Rx only (PT applied & supervised,

combined w/ heat or cold).

Application & Rx Application & Rx GuidelinesGuidelines Treatment of an area of pain (joint OR soft tissue)

with IFC. Quadpolar setup, X marks the spot.– Acute Pain: High Freq (>50), Sensory to Low Motor

Amp– Chronic Pain: Low Freq (<10), Motor to Noxious Amp

Premodulated IFC (Bipolar)– IFC produced in the unit & delivered thru 1 channel, not

as comfortable but can put on & over; convenient

IFC – sample applicationsIFC – sample applications

Ant knee: Ant knee: IFC (left) vs Tens IFC (left) vs Tens (right)(right)Gastroc: Gastroc: IFC (right) vs Tens IFC (right) vs Tens (left)(left)

Hamstring: Hamstring: IFC (right) vs Tens IFC (right) vs Tens (left)(left)

Lateral Elbow: Lateral Elbow: IFC (left) vs Tens IFC (left) vs Tens (right)(right)