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Electrical Stimulation Currents

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Title: Electrical Stimulation Currents


1
Electrical Stimulation Currents
  • Therapeutic Modalities
  • Chapter 5

2
Electricity is an element of PT. May be most
frightening and least understood.
  • Understanding the basic principles will later aid
    you in establishing treatment protocols.

3
Electromagnetic Radiations
  • Other Forms Of Radiation Other Than Visible Light
    May Be Produced When An Electrical Force Is
    Applied

4
Infrared
Spectrum
Red
Orange
Yellow
Green
Blue
Violet
Ultraviolet
5
Electromagnetic Radiations
  • In Addition, Other Forms Of Radiation Beyond
    Infrared And Ultraviolet Regions May Be Produced
    When An Electrical Force Is Applied
  • These Radiations Have Different Wavelengths And
    Frequencies Than Those In The Visible Light
    Spectrum

6
Collectively The Various Types Of Radiation Form
The Electromagnetic Spectrum

7

Electromagnetic Spectrum
Longest Wavelength
Lowest Frequency
Electrical Stimulating Currents
Commercial Radio and Television
Shortwave Diathermy
Microwave Diathermy
Infrared

LASER
Visible Light
Ultraviolet
Shortest Wavelength
Highest Frequency
Ionizing Radiation
8
Wavelength And Frequency
  • Wavelength-Distance Between Peak Of One Wave and
    Peak of the Next Wave
  • Frequency-Number Of Wave Oscillations Or
    Vibrations Per Second (Hz, CPS, PPS)
  • VelocityWavelngth X Frequency

9
Electromagnetic Radiations Share Similar Physical
Characteristics
  • Produced When Sufficient Electrical Or Chemical
    Forces Are Applied To Any Material
  • Travel Readily Through Space At An Equal Velocity
    (300,000,000 meters/sec)
  • Direction Of Travel Is Always In A Straight Line

10
Electromagnetic Radiations Share Similar Physical
Characteristics
  • When Contacting Biological Tissues May Be

11
Electromagnetic Radiations Share Similar Physical
Characteristics
  • When Contacting Biological Tissues May Be
  • Reflected

12
Electromagnetic Radiations Share Similar Physical
Characteristics
  • When Contacting Biological Tissues May Be
  • Reflected
  • Transmitted

13
Electromagnetic Radiations Share Similar Physical
Characteristics
  • When Contacting Biological Tissues May Be
  • Reflected
  • Transmitted
  • Refracted

14
Electromagnetic Radiations Share Similar Physical
Characteristics
  • When Contacting Biological Tissues May Be
  • Reflected
  • Transmitted
  • Refracted
  • Absorbed

15
Laws Governing The Effects of Electromagnetic
Radiations
  • Arndt-Schultz Principle
  • No Changes Or Reactions Can Occur In The Tissues
    Unless The Amount Of Energy Absorbed Is
    Sufficient To Stimulate The Absorbing Tissues

16
Laws Governing The Effects of Electromagnetic
Radiations
  • Law Of Grotthus-Draper
  • If The Energy Is Not Absorbed It Must Be
    Transmitted To The Deeper Tissues
  • The Greater The Amount Absorbed The Less
    Transmitted and Thus The Less Penetration

17
Laws Governing The Effects of Electromagnetic
Radiations
  • Cosine Law
  • The Smaller The Angle Between The Propagating
    Radiation And The Right Angle, The Less Radiation
    Reflected And The Greater The Absorption

Source
Source
18
Laws Governing The Effects of Electromagnetic
Radiations
  • Inverse Square Law
  • The Intensity Of The Radiation Striking A Surface
    Varies Inversely With The Square Of The Distance
    From The Source

Source
1 Inch
2 Inch
19
Electromagnetic Modalities
  • The Majority of Therapeutic Modalities Used By
    Athletic Trainers Emit A Type Of Energy With
    Wavelengths And Frequencies That Can Be
    Classified As Electromagnetic Radiations

20
Electromagnetic Modalities Include...
  • Electrical Stimulating Currents
  • Shortwave And Microwave Diathermy
  • Infrared Modalities
  • Thermotherapy
  • Cryotherapy
  • Ultraviolet Radiation Therapy
  • Low-Power Lasers
  • Magnet Therapy

21
(No Transcript)
22
General Therapeutic Uses of Electricity
  • Controlling acute and chronic pain
  • Edema reduction
  • Muscle spasm reduction
  • Reducing joint contractures
  • Minimizing disuse/ atrophy
  • Facilitating tissue healing
  • Strengthening muscle
  • Facilitating fracture healing

23
Contraindications of Electrotherapy
  • Cardiac disability
  • Pacemakers
  • Pregnancy
  • Menstruation (over abdomen, lumbar or pelvic
    region)
  • Cancerous lesions
  • Site of infection
  • Exposed metal implants
  • Nerve Sensitivity

24
Terms of electricity
  • Electrical current the flow of energy between
    two points
  • Needs
  • A driving force (voltage)
  • some material which will conduct the electricity
  • Amper unit of measurement, the amount of current
    (amp)
  • Conductors Materials and tissues which allow
    free flow of energy

25
Fundamentals of Electricity
  • Electricity is the force created by an imbalance
    in the number of electrons at two points
  • Negative pole an area of high electron
    concentration (Cathode)
  • Positive pole an area of low electron
    concentration (Anode)

26
Charge
  • An imbalance in energy. The charge of a solution
    has significance when attempting to drive
    medicinal drugs topically via iontophoresis and
    in attempting to artificially fire a denervated
    muscle

27
Charge Factors to understand
  • Coulombs Law Like charges repel, unlike charges
    attract
  • Like charges repel
  • allow the drug to be driven
  • Reduce edema/blood

28
Charge Factors
  • Membranes rest at a resting potential which is
    an electrical balance of charges. This balance
    must be disrupted to achieve muscle firing
  • Muscle depolarization is difficult to achieve
    with physical therapy modalities
  • Nerve depolarization occurs very easily with PT
    modalities

29
Terms of electricity
  • Insulators materials and tissues which deter the
    passage of energy
  • Semiconductors both insulators and conductors.
    These materials will conduct better in one
    direction than the other
  • Rate How fast the energy travels. This depends
    on two factors the voltage (the driving force)
    and the resistance.

30
Terms of electricity
  • Voltage electromotive force or potential
    difference between the two poles
  • Voltage an electromotive force, a driving force.
    Two modality classification are
  • Hi Volt greater than 100-150 V
  • Lo Volt less than 100-150 V

31
Terms of electricity
  • Resistance the opposition to flow of current.
    Factors affecting resistance
  • Material composition
  • Length (greater length yields greater resistance)
  • Temperature (increased temperature, increase
    resistance)

32
Clinical application of Electricity minimizing
the resistance
  • Reduce the skin-electrode resistance
  • Minimize air-electrode interface
  • Keep electrode clean of oils, etc.
  • Clean the skin of oils, etc.
  • Use the shortest pathway for energy flow
  • Use the largest electrode that will selectively
    stimulate the target tissues
  • If resistance increases, more voltage will be
    needed to get the same current flow

33
Clinical application of Electricity Temperature
  • Relationship
  • An increase in temperature increases resistance
    to current flow
  • Applicability
  • Preheating the tx area may increase the comfort
    of the tx but also increases resistance and need
    for higher output intensities

34
Clinical Application of Electricity Length of
Circuit
  • Relationship
  • Greater the cross-sectional area of a path the
    less resistance to current flow
  • Application
  • Nerves having a larger diameter are depolarized
    before nerves having smaller diameters

35
Clinical Application of Electricity Material of
Circuit
  • Not all of the bodys tissues conduct electrical
    current the same
  • Excitable Tissues
  • Nerves
  • Muscle fibers
  • blood cells
  • cell membranes
  • Non-excitable tissues
  • Bone
  • Cartilage
  • Tendons
  • Ligaments
  • Current prefers to travel along excitable tissues

36
Stimulation Parameter
  • Amplitude the intensity of the current, the
    magnitude of the charge. The amplitude is
    associated with the depth of penetration.
  • The deeper the penetration the more muscle fiber
    recruitment possible
  • remember the all or none response and the
    Arndt-Schultz Principle

37
Simulation Parameter
  • Pulse duration the length of time the electrical
    flow is on ( on vs off time) also known as the
    pulse width. It is the time of 1 cycle to take
    place (will be both phases in a biphasic
    current)
  • phase duration important factor in determining
    which tissue stimulated if too short there will
    be no action potential

38
Stimulation Parameter
  • Pulse rise time the time to peak intensity of
    the pulse (ramp)
  • rapid rising pulses cause nerve depolarization
  • Slow rise the nerve accommodates to stimulus and
    a action potential is not elicited
  • Good for muscle reeducation with assisted
    contraction - ramping (shock of current is
    reduced)

39
Stimulation Parameters
  • Pulse Frequency (PPSHertz) How many pulses
    occur in a unit of time
  • Do not assume the lower the frequency the longer
    the pulse duration
  • Low Frequency 1K Hz and below (MENS .1-1K Hz),
    muscle stim units)
  • Medium frequency 1K ot 100K Hz (Interferential,
    Russian stim LVGS)
  • High Frequency above 100K Hz (TENS, HVGS,
    diathermies)

40
Stimulation Parameter
  • Current types alternating or Direct Current (AC
    or DC)
  • AC indicates that the energy travels in a
    positive and negative direction. The wave form
    which occurs will be replicated on both sides of
    the isoelectric line
  • DC indicated that the energy travels only in the
    positive or on in the negative direction

DC
AC
41
Stimulation Parameter
  • Waveforms the path of the energy. May be smooth
    (sine) spiked, square,, continuous etc.
  • Method to direct current
  • Peaked - sharper
  • Sign - smoother

42
Stimulation Parameter
  • Duty cycles on-off time. May also be called
    inter-pulse interval which is the time between
    pulses. The more rest of off time, the less
    muscle fatigue will occur
  • 11 Raito fatigues muscle rapidly
  • 15 ratio less fatigue
  • 17 no fatigue (passive muscle exercise)

43
Stimulation Parameter
  • Average current (also called Root Mean Square)
  • the average intensity
  • Factors effecting the average current
  • pulse amplitude
  • pulse duration
  • waveform (DC has more net charge over time thus
    causing a thermal effect. AC has a zero net
    charge (ZNC). The DC may have long term adverse
    physiological effects)

44
Stimulation Parameter
  • Current Density
  • The amount of charge per unit area. This is
    usually relative to the size of the electrode.
    Density will be greater with a small electrode,
    but also the small electrode offers more
    resistance.

45
Capacitance
  • The ability of tissue (or other material) to
    store electricity. For a given current intensity
    and pulse duration
  • The higher the capacitance the longer before a
    response. Body tissues have different
    capacitance. From least to most
  • Nerve (will fire first, if healthy)
  • Muscle fiber
  • Muscle tissue

46
Capacitance
  • Increase intensity (with decrease pulse duration)
    is needed to stimulate tissues with a higher
    capacitance.
  • Muscle membrane has 10x the capacitance of nerve

47
Factors effecting the clinical application of
electricity
  • Factors effecting the clinical application of
    electricity Rise Time the time to peak intensity
  • The onset of stimulation must be rapid enough
    that tissue accommodation is prevented
  • The lower the capacitance the less the charge can
    be stored
  • If a stimulus is applied too slowly, it is
    dispersed

48
Factors effecting the clinical application of
electricity
  • An increase in the diameter of a nerve decreased
    its capacitance and it will respond more
    quickly. Thus, large nerves will respond more
    quickly than small nerves.
  • Denervated muscles will require a long rise time
    to allow accommodation of sensory nerves. Best
    source for denervated muscle stimulation is
    continuous current DC

49
Factors effecting the clinical application of
electricity
  • Ramp A group of waveforms may be ramped (surge
    function) which is an increase of intensity over
    time.
  • The rise time is of the specific waveform and is
    intrinsic to the machine.

50
Law of DuBois Reymond
  • The amplitude of the individual stimulus must be
    high enough so that depolarization of the
    membrane will occur.
  • The rate of change of voltage must be
    sufficiently rapid so that accommodation does not
    occur
  • The duration of the individual stimulus must be
    long enough so that the time course of the latent
    period (capacitance), action potential, and
    recovery can take place

51
Muscle Contractions Frequency
  • Are described according to the pulse width
  • 1 pps twitch
  • 10 pps summation
  • 25-30 pps tetanus (most fibers will reach
    tetany by 50 pps)
  • Frequency selection
  • 100Hz - pain relief
  • 50-60 Hz muscle contraction
  • 1-50 Hz increased circulation
  • The higher the frequency (Hz) the more quickly
    the muscle will fatigue

52
Frequency selection
  • 100Hz - pain relief
  • 50-60 Hz muscle contraction
  • 1-50 Hz increased circulation
  • The higher the frequency (Hz) the more quickly
    the muscle will fatigue

53
Electrodes used in clinical application of
current
  • Electrodes used in clinical application of
    current At least two electrodes are required to
    complete the circuit
  • The body becomes the conductor
  • Monophasic application requires one negative
    electrode and one positive electrode
  • The strongest stimulation is where the current
    exists the body
  • Electrodes placed close together will give a
    superficial stimulation and be of high density

54
Electrodes used in clinical application of
current
  • Electrodes spaced far apart will penetrate more
    deeply with less current density
  • Generally the larger the electrode the less
    density. If a large dispersive pad is creating
    muscle contractions there may be areas of high
    current concentration and other areas relatively
    inactive, thus functionally reducing the total
    size of the electrode
  • A multitude of placement techniques may be used
    to create the clinical and physiological effects
    you desire

55
General E-Stim Parameters
56
E-Stim for Pain Control typical Settings
57
High Volt Pulsed Stimulation
58
CURRENT CONCEPTS EVIDENCE BASED
  • ES increased 20 verses control (no activity)
    demonstrating that ES can alter the blood flow
    in muscle being stimulated Currier et all 1996
  • Currier et al 1988 Similar study but 15
  • Bettany et al 1990 Edema formation in frogs
    decreased with HVPC 10 minutes after the trauma

59
CURRENT CONCEPTS EVIDENCE BASED
  • Walker et al 1988 HVS at a pulse rate of 30 Hz
    and intensities to evoke 10 - 20 MVC did not
    increase blood flow to the popliteal artery. The
    exercise group demonstrated 30 increase
  • Von Schroeder et al 1991 Femoral venous flow
    shown to increase greatest with passive SLR
    elevation, then CPM, active ankle dorsiflexion,
    manual calf compression and passive dorsiflexion

60
HVPS
  • The application of monophasic current with a
    known polarity
  • typically a twin-peaked waveform
  • duration of 5 - 260 msec
  • Wide variety of uses
  • muscle reeducation (requires 150V)
  • nerve stimulation (requires 150V)
  • edema reduction
  • pain control

61
Clinical Application
  • Physiological response can be excitatory and
    non-excitatory
  • Excitatory
  • Peripheral nerve stimulation for pain modulation
    (sensory, motor and pain fibers)
  • Promote circulation inhibits sympathetic nervous
    system activity, muscle pumping and endogenous
    vasodilatation
  • Non-Excitatory (cellular level)
  • Protein synthesis
  • Mobilization of blood proteins
  • Bacteriocyte affects (by increased CT
    micro-circulation there is a reabsorption of the
    interstitial fluids)
  • Setting the ES with no twitch has purpose

62
General Background
  • Early in history HVS was called EGS (electrical
    galvanic stimulation), then HVGS, then HVPS
  • Current qualifications to be considered HVS
  • Must have twin peak monophasic current
  • Must have 100 or 150 volts (up to 500 V)

63
HVPS
  • Precautions
  • Stimulation may cause unwanted tension on muscle
    fibers
  • Muscle fatigue if insufficient duty cycle
  • Improper electrodes can burn or irritate
  • Intense stim may result in muscle spasm or
    soreness
  • Contraindications
  • Cardiac disability
  • Pacemakers
  • Pregnancy
  • Menstruation
  • Cancerous lesion
  • Infection
  • Metal implants
  • Nerve sensitivity
  • Indications
  • past slide

64
Treatment Duration
  • General - 15-30 minutes repeated as often as
    needed
  • Pain reduction - sensory 30 minutes with 30
    minute rest between tx

65
Current Parameters
  • greater than 100-150 V
  • usually provides up to 500 V
  • high peak, low average current
  • strength duration curve short pulse duration
    required higher intensity for a response
  • high peak intensities (watts) allow a deeper
    penetration with less superficial stimulation

66
Current Parameters
  • Pulse Rate
  • ranges from 1-120 pps
  • varies according to the desire clinical
    application Current
  • Pulse Charge
  • related to an excess or deficiency of negatively
    charged particles
  • associated with the beneficial or harmful
    responses (thermal, chemical, physical)
  • Modulations
  • intrapulse spacing
  • duty cycle reciprocal mode usually 11 ratio
  • ramped or surged cycles
  • Clinical Considerations
  • always reset intensity after use (safety)
  • electrode arrangements may be mono or bipolar
  • units usually have a hand held probe for local
    (point) stimulation
  • most units have an intensity balance control

67
Application Techniques
  • Monopolar 2 unequal sized electrodes. Smaller
    is generally over the treatment site and the
    large serves as a dispersive pad, usually located
    proximal to the treatment area
  • Bipolar two electrodes of equal size, both are
    over or near the treatment site
  • Water immersion - used for irregularly shaped
    areas
  • Probes one hand-held active lead
  • advantages can locate and treat small triggers
  • disadvantages one on one treatment requires full
    attention of the trainer

68
Electrodes
  • Material
  • carbon impregnated silicone electrodes are
    recommended but will develop hot spots with
    repeated use
  • you want conductive durable and flexible material
  • tin with overlying sponge has a decreased
    conformity and reduced conductivity

69
Electrodes
  • Size
  • based on size of target area
  • current density is important. The smaller the
    electrode size the greater the density

70
Neuromuscular Stimulation
  • Roles
  • re-educate a muscle how to contract after
    immobilization (does not produce strength
    augmentation but retards atrophy)

71
Pain Control
Roles Control acute or chronic pain both sensory
(gate control - 100-150 pps)) and motor level
(opiate release - through voltage)
72
Pain Control - Opiate Release Setting
73
Evidence Based
  • Clinical Studies on HVPC and pain modulation is
    misleading pain associated with muscle spasm is
    decreased secondary to muscle fatigue/exhaustion
    (Belanger, 2003)
  • Studies on muscle strengthening have indicated no
    effect (Alon 1985, Mohr et al, 1985 Wong 1986)

74
Control and Reduction of Edema
Roles Sensory level used to limit acute
edema Motor-level stimulation used to reduce
subacute or chronic inflammation
75
Motor-Level Edema Reduction
Cell Metabolism increased and may increase blood
flow Wound Healing May increase collagnase
levels and inhibit bacteria in infected wounds
(for this effect 20 min - polarity followed by 40
min polarity recommended)
76
Russian Current
  • Continuous sine-wave modulation of 2,5000 pps and
    burst-modulated for fixed periods of 10 msec
    resulting in a frequency of 50 bursts per second.
  • Thought to depolarize both sensory and motor
    concomitantly (knots 1977). Thus simulating
    muscle training.
  • No North American has been able to duplicate
    Knots claims

77
T.E.N.S.
78
General Concepts
  • An Approach to pain control
  • Trancutaneous Electrical Nerve Stimulation
  • Any stimulation in which a current is applied
    across the skin to stimulate nerves
  • 1965 Gate Control Theory created a great
    popularity of TENS
  • TENS has 50-80 efficacy rate
  • TENS stimulates afferent sensory fibers to elicit
    production of neurohumneral substances such as
    endorphins, enkephalins and serotonin (i.e. gate
    theory)

79
TENS
  • Indications
  • Control Chronic Pain
  • Management post-surgical pain
  • Reduction of post-traumatic acute pain
  • Precautions
  • Can mask underlying pain
  • Burns or skin irritation
  • prolonged use may result in muscle spasm/soreness
  • caffeine intake may reduce effectiveness
  • Narcotics decrease effectiveness

Research is variable regarding the benefits of
TENS Therapy (see Table 2-2 Belanger, 2001)
80
TENS may be
  • high voltage
  • interferential
  • acuscope
  • low voltage AC stimulator
  • classical portable TENS unit

81
Biophysical Effects
  • Primary use is to control pain through Gate
    Control Theory
  • (between 0-100 can be placebo effect
    (Thorsteinsson et al., 1978, Wall,1994)
  • Opiate pain relief through stimulation of
    naloxone (antagonist to endogenous opiates)
  • May produce muscle contractions
  • Various methods
  • High TENS (Activate A-delta fibers)
  • Low TENS (release of ??-endorphins from
    pituitary)
  • Brief-Intense TENS (noxious stimulation to active
    C fibers)

82
Techniques of TENS application
  • Conventional or High Frequency
  • Short Duration , high frequency and low to
    comfortable current amplitude
  • Only modulation that uses the Gate Control Theory
    (opiate all others)
  • Acupuncture or Low Frequency
  • Long pulse duration, Low frequency and low to
    comfortable current amplitude
  • Brief Intense
  • Long pulse duration, high frequency, comfortable
    to tolerable amplitude
  • Burst Mode
  • Burst not individual pulses, modulated current
    amplitude
  • Modulated
  • Random electronic modulation of pulse duration,
    frequency and current amplitude

83
Protocol for Various Methods of TENS
84
Conventional Tens/High Frequency TENS
  • Paresthesia is created without motor response
  • A Beta filers are stimulated to SG enkephlin
    interneuron (pure gate theory)
  • Creates the fastest relief of all techniques
  • Applied 30 minutes to 24 hours
  • relief is short lives (45 sec 1/2 life)
  • May stop the pain-spasms cycle

85
Application of High TENS
  • Pulse rate high 75-100 Hz (generally 80),
    constant
  • Pulse width narrow, less than 300 mSec generally
    60 microSec
  • Intensity comfortable to tolerance

86
Set up
  • 2 to 4 electrodes, often will be placed on
    post-op. Readjust parameters after response has
    been established. Turn on the intensity to a
    strong stimulation. Increase the pulse width and
    ask if the stimulation is getting wider (if
    deepergood, if stronger...use shorter width)

87
Low Frequency/Acupuncture-like TENS
  • Level III pain relief, A delta fibers get Beta
    endorphins
  • Longer lasting pain relief but slower to start
  • Application
  • pulse rate low 1-5ppx (below 10)
  • Pulse width 200-300 microSec
  • Intensity strong you want rhythmical
    contractions within the patients tolerance

88
Burst Mode TENS
  • Carrier frequency is at a certain rate with a
    built in duty cycle
  • Similar to low frequency TENS
  • Carrier frequency of 70-100 Hz packaged in bursts
    of about 7 bursts per second
  • Pulses within burst can vary
  • Burst frequency is 1-5 bursts per second
  • Strong contraction at lower frequencies
  • Combines efficacy of low rate TENS with the
    comfort of conventional TENS

89
Burst Mode TENS - Application
  • Pulse width high 100-200 microSec
  • Pulse rate 70-100 pps modulated to 1-5 burst/sec
  • Intensity strong but comfortable
  • treatment length 20-60 minutes

90
Brief, Intense TENS hyper-stimulation analgesia
  • Stimulates C fibers for level II pain control
    (PAG etc.)
  • Similar to high frequency TENS
  • Highest rate (100 Hz), 200 mSec pulse width
    intensity to a very strong but tolerable level
  • Treatment time is only 15 minutes, if no relief
    then treat again after 2-3 minutes
  • Mono or biphasic current give a bee sting
    sensation
  • Utilize motor, trigger or acupuncture points.

91
Brief Intense TENS - Application
  • Pulse width as high as possible
  • Pulse rate depends on the type of stimulator
  • Intensity as high as tolerated
  • Duration 15 minutes with conventional TENS unit.
    Locus stimulator is advocated for this treatment
    type, treatment time is 30 seconds per point.

92
Locus point stimulator
  • Locus (point) stimulators treatment occurs once
    per day generally 8 points per session
  • Auricular points are often utilized
  • Treat distal to proximal
  • Allow three treatment trails before efficacy is
    determined
  • Use first then try other modalities

93
Modulated Stimulation
  • Keeps tissues reactive so no accommodation occurs
  • Simultaneous modulation of amplitude and pulse
    width
  • As amplitude is decreased, pulse width is
    automatically increased to deliver more
    consistent energy per pulse
  • Rate can also be modulated

94
Electrode Placement
  • May be over the painful sites, dermatomes,
    myotomes, trigger points, acupuncture points or
    spinal nerve roots.
  • May be crossed or uncrossed (horizontal or
    vertical

95
Contraindications
  • Demand pacemakers
  • over carotid sinuses
  • Pregnancy
  • Cerebral vascular disorders (stroke patients)
  • Over the chest if patient has any cardiac
    condition

96
Interferential Current - IFC
97
Interferential Current
  • History In 1950 Nemec used interference of
    electrical currents to achieve therapeutic
    benefits. Further research and refinements have
    led to the current IFC available today
  • Two AC are generated on separate channels (one
    channel produces a constant high frequency sine
    wave (4000-5000Hz) and the other a variable sine
    wave
  • The channels combine/interface to produce a
    frequency of 1-100 Hz (medium frequency)
  • Evidence Based Although IFC has been used for 40
    years, only a few clinical studies have been
    published regarding use (DeDomenico, 1981,1987
    Savage, 1984 Nikolova, 1987).

98
Effects of IFC treatment
  • Primary Physiological Effect Capacity of IFC to
    depolarize Sensory and motor nerve fibers
  • Main Therapeutic Effects
  • Sensory nerve fibers - Pain reduction - receive
    a lower amplitude stimulation than the area of
    tissue affected by the vector, thus IFC is said
    to be more comfortable than equal amplitudes
    delivered by conventional means
  • Blood flow/edema management
  • Muscle fatigue - muscle spasm - is reduced when
    using IFC versus HVS due to the asynchronous
    firing of the motor units being stimulated

99
Positive effects of IFC include
  • reduction of pain and muscle discomfort following
    joint or muscle trauma
  • these effects can be obtained with the of IFC and
    without associated muscle fatigue which may
    predispose the athlete to further injury.

100
Evidence Based Research
  • Low frequency
  • This has been claimed as the key to IFC (Savage,
    1984, Nikolova, 1987)
  • Palmer, 1999 IFC unlikely to produce
    physiological and therapeutic effects different
    from those achieved by TENS
  • Alon, 1999 states that IFC simply provides a more
    expensive, different, least effective and
    somewhat redundant approach to achieving the same
    effects as other electrical stimulation
    parameters/waveforms
  • Pain sensation Although the physiological
    changes are not different with IFC, Pain
    perception is decreased with IFC (Palmer, 1999)

101
Evidence Based Literature
  • IFC does not lower skin impedance (Alon, 1999
    Gerleman et al, 1999)
  • Any pulsed biphasic current, regardless of
    waveform, having a medium frequency are capable
    of a deeper stimulating effect (Alon, 1999
    Hayes, 2000 Kloth, 1991) Snyder-Mackler, et al
    1989)
  • Increased Circulation is an anecdotal claim and
    has not been recreated in studies (Bersglien et
    al, 1988 Indergand et al.k 1995 Johnson, 1999
    Nusswbaum et al., 1990 Olson et al., 1999)
  • Analgesic Effect Similar not superior to other
    stimulations (TENS) (DeDomenico, 1982, 1987
    Nikolova, 1987 Savage, 1984)
  • Stephenson et al., 1995 Superior to a control
    group with ice/pain
  • Cramp et al., 2000 Failed to demonstrate any
    effective pain relief with IFC

102
Principles of wave interference - Combined Effects
  • Constructive, Destructive, Continuous
  • Constructive interference when two sinusoidal
    waves that are exactly in phase or one, two,
    three or more wavelengths our of phase, the waves
    supplement each other in constructive interference



103
Principles of wave interference - Combined Effects
  • Destructive interference when the two waves are
    different by 1/2 a wavelength (of any multiple)
    the result is cancellation of both waves



104
Principles of wave interference - Combined Effects
  • Continuous Interference
  • Two waves slightly out of phase collide and form
    a single wave with progressively increasing and
    decreasing amplitude



105
Amplitude-Modulated Beats
  • Rate at which the resultant waveform (from
    continuous interference) changes
  • When sine waves from two similar sources have
    different frequencies are out of phase and blend
    (heterodyne) to produce the interference beating
    effect

106
IFC
  • Duration of tx 15-20 minutes
  • Burst mode typically applied 3x a week in 30
    minute bouts
  • Precautions
  • same as all electrical currents
  • Contraindications
  • Pain of central origin
  • Pain of unknown origin
  • Indications
  • Acute pain
  • Chronic pain
  • Muscle spasm

107
IFC Techniques of treatment
  • Almost exclusively IFC is delivered using the
    four-pad or quad-polar technique.
  • Various electrode positioning techniques are
    employed
  • Electrodes (Nemectrody vacuum electrodes)
  • four independent pads allow specific placement of
    pads to achieve desired effect an understanding
    of the current interference is essential
  • four electrodes in one applicator allows IFC
    treatment to very small surface areas. The field
    vector is pre-determined by the equipment

108
Quad-polar Technique
  • Pads placed at 45º angles from center of tx area
  • Can reduce inaccuracy of appropriate tissues by
    selecting rotation or scan

Channel B
Channel B
Channel A
SCAN
Channel A
109
Bipolar Electrode Placement
  • The mix of two channels occurs in generator
    instead of tissues
  • Biopolar does not penetrate tissues as deeply,
    but is more accurate
  • When effects are targeted for one muscle or
    muscle group only one channel is used

110
Two-circuit IFC
  • At other points along the time axes the wave
    amplitude will be zero because the positive phase
    from one circuit cancels the negative phase from
    the second circuit (destructive interference)
  • The rhythmical rise and fall of the amplitude
    results in a beat frequency and is equal to the
    number of times each second that the current
    amplitude increases to its maximum value and then
    decreases to its minimum value

111
Special Modulations of IFC
  • Constant beat frequencies (model) the difference
    between the frequencies of the two circuits is
    constant and the result is a constant beat
    frequency. That is, if the difference in
    frequency between the two circuits is 40 pps, the
    beat frequency will be constant at 40 bps.

112
Special Modulations of IFC
  • Variable beat mode the frequency between the two
    circuits varies within preselected ranges. The
    time taken to vary the beat frequency through any
    programmed range is usually fixed by the device
    at about 15 sec. IFC machines often allow the
    clinician to choose from a variety of beat
    frequency programs.

113
Pain Control
  • Similar to TENS - beat frequency 100Hz
  • Low beat frequencies when combined with motor
    level intensities (2-10Hz) initiate the release
    of opiates
  • 30 Hz frequencies affects the widest range of
    receptors

114
Neuromuscular Stimulation
  • Beat frequency of approximately 15 HZ is used to
    reduce edema
  • General Parameters

115
IFC Technique of treatment
  • Electrode placement
  • The resultant vector should be visualized in
    placing the electrodes for a treatment . The
    target tissue should be identified and the vector
    positioned to hit that area. Typically at 45º
    angles is most effective.
  • Segregation of the pin tips is essential in the
    proper electrode positioning for IFC. The
    electrodes may be of the same size or two
    different sizes (causing a shift in the
    intersecting vector). Treatment through a joint
    has also been advocated without adequate research
    to establish efficacy of the treatment technique.

116
Bone Stimulating Current
  • Bone Stimulating CurrentBone Stimulating
    CurrentIFC has been used (Laabs et al) studied
    the healing of a surgically induced fracture in
    the forelegs of sheep. Their study indicated an
    acceleration of healing in the sheep treated with
    IFC as compared to the control group

117
Bone Stimulating Current
  • This study validated an earlier study by Gittler
    and Kleditzsch which showed similar results in
    callus formation in rabbits. Several other
    studies have shown an increase in the healing
    rate of fractures but the exact mechanism by
    which the healing occurs is not understood.

118
Bone Stimulating Current
  • Some speculation is that an increased blood flow
    to the injured area is produced which allowed
    natural healing processes to occur more rapidly.
  • In one study (mandible fractures ) the IFC caused
    very mild muscle contraction of the jaw and this
    muscle activity was thought to have been a
    potential accelerator of the healing.

119
MENS or LIDC (low-intensity direct current)
120
MENS
  • No universally accepted definition or protocol
    has yet to be substantiated
  • This form of modality is at the sub-sensory or
    very low sensory level
  • current less than 1000?A (approx 1/1000 amp of
    TENS)
  • Theorized that this is the current of injury
    (Becker et al 1967, Becker Seldon, 1987)

121
Biophysical Effects
  • Theory
  • Currents below 500?A increases the level of ATP
    (high Amp decreases ATP levels)
  • Increase in ATP encourages amino acid transport
    and increased protein synthesis
  • MENS reestablishes the bodys natural electrical
    balance allowing metabolic energy for healing
    without shocking the system (other types of
    e-stim)
  • Studies conducted indicate no difference from
    control group for wound healing

122
MENS
  • Duration
  • 30 min to 2 hours up to 4x a day
  • Research suggests high degree of variability on
    tx protocols
  • Precautions
  • Dehydrated patients
  • on Scar tissue (too much impedance)
  • Contraindications
  • Pain of unknown origin
  • Osteomyelitis
  • Inconclusive Data
  • DOMS as an indication (Allen et al 1999, Weber et
    al 1994)
  • Indications
  • Acute Chronic Pain
  • Acute Chronic Inflammation
  • Edema reduction
  • sprains Strains
  • Contusion
  • TMJ dysfunction
  • Neuropathies
  • Superficial wound healing
  • Carpal Tunnel Syndrome

123
Electrode Placement
  • Electrodes should be placed in a like that
    transects the target tissues
  • Remember that electrical current travels in path
    of least resistance, thus it is not always a
    straight line.
  • Either the or electrode can be placed on the
    injured tissue (Research is inconclusive Lampe
    1998, Sussmen et al 1999)
  • Suggest alternating and - electrode

TARGET
124
Application Techniques
  • Standard electrical stimulation pads
  • generator may have bells Whistles since MENS is
    sub-sensory
  • Probe

125
Bone Stimulating Current
  • MENS
  • Has been advocated in the healing of bone, using
    implanted electrodes and delivering a DC current
    with the negative pole at the fracture site.
    Further use of MENS has allowed increased rate
    of fracture healing using surface electrodes in a
    non-invasive technique. Theories on the
    physiology behind the healing focus on the
    electrical charge present in the normal tissue as
    compared to the electrical charge found with the
    injured tissue. MENS is said to allow an
    induction of an electrical charge to return to he
    tissues to a better healing environment
  • Research on bone stimulating current is
    inconclusive.

126
Microcurrent Electrical Stimulation
  • Tissue Bone Healing

127
Electrical Stimulation
  • Physiological effect of electrical currents on
    nonexcitable tissue for tissue repair in its
    various forms
  • (a) improvement of vascular status,
  • (b) edema control,
  • (c) wound healing,
  • (d) osteogenesis

128
Current of Injury (Theory)
  • Wounds are initially positive with respect to
    surrounding tissue
  • This positive polarity triggers the onset of
    repair processes
  • Maintaining this positive polarity would
    potentiate healing
  • Anode over the wound was suggested by most of
    the previous studies
  • Anode () Cathode (-)

129
Electrical Stimulation for Tissue Repair
  • Wound healing is also impeded by infection
  • Electrical stimulation using the negative lead of
    a DC generator has been shown in culture and in
    vivo either to be bacteriostatic or to retard the
    growth of common gram and gram- microorganisms

130
Electrical Stimulation for Tissue Repair
  • There is no evidence for the effectiveness of
    sub-sensory-level stimulation for the healing of
    open wound

131
Electrical Stimulation for Bone Healing
  • The current of injury theory for bone a
    relative negativity of the injured tissue with
    respect to the uninjured.

132
Electrical Stimulation for Bone Healing
  • The three best-studied and most commonly used
    techniques are
  • (a) Cathodal placement in the fracture site and
    anodal placement on the skin at some distance.
  • (b) Implantation of the entire system
  • (c) The use of pulsed electromagnetic fields
    (PEMFs)

133
Electrical Stimulation for Bone Healing
  • PEMFs is the use of inductive coils to the skin
    or cast to deliver an asymmetrical, biphasic
    pulse at a frequency of about 15 pps.
  • Semiinvasive DC, totally invasive DC, and PEMF
    were the only FDA-approved (and physician
    administered) osteogenic means.

134
Electrical Stimulation for Bone Healing
  • 60 Hz sinusoidal AC, pulsed current, and
    interference modulations of higher-frequency
    alternating currents are also being used.

135
Electrical Stimulation
  • Treatment Strategies

136
HVPS Neuromuscular Stimulation
  • Output Intensity
  • Strong, intense, comfortable contractions.
  • Pulse frequency If duty cycle cannot be
    adjusted Low for individual muscle contractions
    (lt15 pps).
  • Adjustable duty cycle Moderate for tonic
    contractions (gt50 pps).
  • Duty Cycle
  • Initial treatments should begin with a low (e.g,
    20) duty cycle and be increased as the muscle
    responds.
  • Electrode placement
  • Bipolar Proximal and distal to the muscle (or
    muscle group) to be stimulated. This method
    offers the most direct method of stimulating
    specific areas.
  • Monopolar Over motor points or muscle belly.
    Place the cathode over motor points

Bipolar electrode arrangement
137
HVPS Sensory-level Pain Control
  • Output Intensity Sensory level
  • Pulse frequency 60 to 100 pps
  • Phase duration lt100 µsec
  • Mode Continuous
  • Electrode arrangement Monopolar or bipolar
  • Polarity Acute Positive
  • Chronic Negative
  • Electrode placement Directly over or
    surrounding the painful site
  • Not adjustable on most HVPS units.

138
HVPS Motor-level Pain Control
  • Output Intensity Motor level
  • Pulse rate 24 pps
  • Phase duration 150250 µsec
  • Mode Continuous
  • Electrode arrangement Monopolar or bipolar
  • Polarity Acute positive
  • Chronic Negative
  • Electrode placement Directly over the
    painful site, distal to the spinal nerve root
    origin, trigger points, or acupuncture points

139
HVPS Brief-Intense Pain Control Protocol
  • Output Intensity Noxious
  • Pulse rate gt120 pps
  • Phase duration 300 to 1000 µsec
  • Mode Probe 15 to 60 sec at each site
  • Electrode arrangement Monopolar (probe)
  • Polarity Acute Positive Chronic Negative
  • Probe placement Gridding technique, stimulating
    hypersensitive areas working from distal to
    proximal

140
HVPS Sensory-level Edema Control
  • Intensity Sensory level
  • Pulse duration Maximum possible duration
  • Pulse frequency 120 pps.
  • Polarity Negative electrodes over injured
    tissues
  • Mode Continuous
  • Electrode placement The immersion method should
    be used when possible, or the active electrodes
    should be grouped over and around the target
    tissues.
  • Treatment duration
  • Four 30-minute treatments, followed by 60-minute
    rest periods
  • or
  • Four 30-minute treatments, each followed by
    30-minute rest periods.
  • Comments
  • Start treatment as soon as possible after the
    trauma.
  • The body part should be wrapped and elevated
    between sessions.
  • This treatment regimen should not performed if
    gross swelling is present.

Anode ()
Cathode (-)
141
HVPS Edema Reduction
  • Intensity Strong, yet comfortable muscle
    contraction
  • Avoid contraindicated joint motio
  • Pulse frequency Low
  • Polarity Positive or negative.
  • Mode Alternating.
  • Electrode placement
  • Bipolar Proximal and distal ends of the muscle
    group proximal to the edematous area.
  • Monopolar Active electrodes follow the course of
    the venous return system.
  • Comment Ice may be applied to the injured area,
    but this could impede venous return by increasing
    the viscosity of fluids in the area

142
IFS Sensory-level Pain Control
  • Carrier Frequency Based on patient comfort
  • Burst Frequency 80 to 150 Hz
  • Sweep Fast
  • Electrode Arrangement Quadripolar
  • Electrode Placement Around the periphery of the
    target area
  • Output Intensity Strong sensory level
  • Treatment Duration 20 to 30 minutes

143
Premodulated Neuromuscular Stimulation
  • Carrier Frequency 2500 Hz
  • Burst Frequency 30 to 60 bps
  • Burst Duty Cycle 10 percent
  • Cycle Duration 400 µsec
  • On/off Duty Cycle 1050 sec
  • Ramp 2 sec
  • Electrode Placement Bipolar Proximal and distal
    ends of the muscle
  • Output Intensity Strong muscle contraction.
    Discomfort may be experienced
  • Treatment Duration 10 cycles or until fatigue
    occurs
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