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Interferential Current (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
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Interferential Current (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 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 AC? • Comfortable • With AC, higher freq = short phase width = lower impedance • Possibility of neural block
Production of IFC (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 uniform medium (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 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 ?? • 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 Guidelines • 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
Ant knee: IFC (left) vs Tens (right)Gastroc: IFC (right) vs Tens (left)