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PTHER 555 - Therapeutic Modalities > Interferential Current (IFC) (WEEK 10) > Flashcards

Interferential Current (IFC) (WEEK 10) Flashcards

1
Q

IFC: how does it work/goal

A

electrical current delivered to the surface of the skin to stimulate nerves to fire (sensory, motor, nociceptors) to manage pain control

pain control**

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2
Q

IFC vs TENS: mechanism

A

IFC: transcutaneous application of two alternating media,-frequency electrical currents

TENS: one alternating current at a low frequency

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3
Q

IFC carrier frequency range

A

3000-5000Hz

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4
Q

IFC: Therapeutic Effects

A

main therapeutic benefit: PAIN MODULATION

pain modulation by

  1. pain gate mechanism
  2. DEOS
  3. endogenous opioid release at the level of the spinal cord
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5
Q

IFC: other therapeutic effects

A
  • oedema control

- muscle retraining

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6
Q

IFC vs. TENS

  • frequency
  • comfort
  • depth
A
  • frequency
    IFC: Medium
    TENS: low
  • comfort
    high frequency IFC is more comfortable
  • depth
    IFC penetrates deeper into tissue and therefore can stimulate deeper nerves
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7
Q

IFC: depth

A

IFC uses 2 oscillating currents and when the currents and crossed and synchronized they superimpose on one another and we get summation of their amplitudes

  • current travels from one electrode to another in an arched path, the further apart the electrodes the deeper the arc.
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8
Q

IFC: currents cancel out

A

If two oscillating currents are a half cycle out of sync then they cancel each other out completely - 100%

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9
Q

IFC: currents slightly out of sync

A

When two oscillating waves are slightly out of sync (5000Hz and 5100Hz), the resulting wave pattern is a series of “BEATS”

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10
Q

IFC: Beats

A

currents slightly out of sync
1. Perfect summation: every few beats circuit 1 and 2 are in sync and summate

  1. Perfect cancelation: every few beats circus 1 and 2 are half cycle out of sync and cancel out
  2. Partial summation or cancellation: majority of the time the beats partially summate or cancel
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11
Q

Beat frequency - what is it?

A
  • beats per second, also known as amplitude modulated frequency (AMF)
  • equal to the frequency difference between the two carrier frequency of oscillating waves. For example:
  • Circuit 1: carrier frequency = 5100Hz
  • Circuit 2: carrier frequency = 5000Hz
    when circuit 1 and 2 cross we get beat frequency (AMF) of 100Hz
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12
Q

Beat frequency - significance

A

Amplitude of the beats has a stronger amplitude than the original currents

  • stronger beat deep in tissue
  • at the location where the currents cross, we get our beat frequency which is of a stronger intensity than the carrier frequency
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13
Q

IFC pattern

A

clover-leaf pattern of current

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14
Q

True IFC: how does this work?

A
  • cross-fire arrangement of 4 electrodes to create 2 separate currents
  • interference of two currents occurs within the tissue
  • stimulation: superficial and deeper tissue
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15
Q

Pre-modulated ICF

A
  • 2 currents are mixed within the machine so that the frequency is delivered by a single circuit
  • no crossing and summation of currents within tissue, therefore we are not creating a stronger beat deeper in the tissue
  • beat frequency pattern is delivered to the surface of the skin
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16
Q

Pre-modulated ICF: stimulation location

A

most of the nerve stimulation occurs directly under the electrodes as we do with tens but since we are using a medium frequency then it may be more comfortable than TENS

17
Q

True vs. Pre-modulated ICF

A
  • no difference own clinical outcome when it comes to stimulating sensory, motor, or pain thresholds
  • True: more effective at targeting deeper tissues
  • pre-mod: more comfortable
18
Q

ICF vs. TENS: Beat frequency/AMF

A

when setting frequency we do not consider pulse width directly, rather we are setting the beat frequency

19
Q

Beat frequency/AMF
- sensory

  • motor
  • pain
A
  • sensory: 50-80Hz
  • motor: <10Hz
  • pain: >120Hz
20
Q

Intensity:
- sensory

  • motor
  • pain
A
  • sensory: comfortable
  • motor: less comfortable
  • pain: uncomfortable/painful
21
Q

Proposed mechanism

A
  • sensory: pain gate
  • motor: DEOS, opioid release at SC
  • pain: DEOS, opioid release at SCI
22
Q

Onset/Duration of pain relief

A
  • sensory: fast and short
  • motor: slow and long
  • pain: fast and long
23
Q

Treatment times

A
  • sensory: 15-20 mins
  • motor: at least 30 mins to stimulate opioid release
  • pain: depends on pt tolerance (15-30 mins)
24
Q

AMF: frequency - beat relationship

A
  • high beat frequency, we get shorter beats (shorter “pulse duration”)
  • lower beat frequency, we get longer beats
  • increase frequency, decrease pulse duration
25
Q

AMF - strength duration curves

A

lower beat frequency would move us to the right of the graph (just as longer pulse duration would)

26
Q

AMF parameter

A

changing AMF does not differentially stimulate different nerves and tissues

  • change to pain threshold were similar with AMF settings 0-100Hz
  • sensory threshold unaffected with varying AMF
  • True IFC frequencies showed similar deep stimulation
  • Similar + effects on pain when applying AMF frequency on Knee OA
27
Q

AMF relevance

A
  • behaviour in tissue is unpredictable because perhaps
  • currents not crossing gat all
  • no AMF is being created
28
Q

True and pre-modulated ICF predicability

A

Pre-modulated: ICF highest voltage in line with one circuit

True ICF: lowest was in the middle of the 4 electrodes, highest was recorded outside (5cm) the electrodes

29
Q

Comfort (Frequency)

A
  • higher AMF setting (50-100Hz) more comfortable than low frequency (1-10Hz)
30
Q

Modulation setting (sweep, modulated)

A
  • decrease habituation/accomodation of the target nerve

- fluctuating AMF may reduce habituation of nerve due to repetitive stimuli

31
Q

ICF and TENS: experimental pain

A

effective in treating various forms of experimental pain

  • Mechanical pain
  • Cold pain
  • Heat pain
  • Ischaemic pain
  • Chemical pain
32
Q

IFC: LBP

A
  • effective for pain and disability in chronic LBP
33
Q

IFC: OA

A
  • reduced pain and increased function; better with exercise

- no significant additional effects over exercise alone

34
Q

Adjunct treatment (acute/chronic LBP, frozen shoulder, knee OA)

A
  • more effective than control at discharge

- more effect than placebo at 3 months follow up

35
Q

IFC Alone (chronic LBP, knee OA, jaw pain)

A

not significantly better than placebo or therapies

PTHER 555 - Therapeutic Modalities (7 decks)

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