Transcript Principles of Electrical Currents

Principles of Electrical Currents
Electricity is an element of PT
modalities most frightening and
least understood.
• Understanding the basis principles will later
aid you in establishing treatment protocols.
General Therapeutic Uses of
Electricity
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Controlling acute and chronic pain
Edema reduction
Muscle spasm reduction
Reducing joint contractures
Minimizing disuse/ atrophy
Facilitating tissue healing
Strengthening muscle
Facilitating fracture healing
Contraindications of
Electrotherapy
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Cardiac disability
Pacemakers
Pregnancy
Menstruation (over abdomen, lumbar or
pelvic region)
Cancerous lesions
Site of infection
Exposed metal implants
Nerve Sensitivity
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
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 and area of low electron
concentration (Anode)
Charge
• An imbalance in energy. The charge of a
solution has significance when attempting
to “drive” medicinal drugs topically via
inotophoresis and in attempting to
artificially fires a denervated muscle
Charge: Factors to understand
• Coulomb’s Law: Like charges repel, unlike
charges attract
– Like charges repel
• allow the drug to be “driven”
• Reduce edema/blood
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
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.
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
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)
Clinical application of
Electricity: minimizing the
resistance
• Reduce the skin-electrode resistance
– Minimize air-electrode interface
– Keep electrode clean of oils, etc.
– Clean the skill on 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
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
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
Clinical Application of
Electricity: Material of Circuit
• Not all of the body’s
tissues conduct
electrical current the
same
• Excitable Tissues
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Nerves
Muscle fibers
blood cells
cell membranes
• Non-excitable tissues
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Bone
Cartilage
Tendons
Ligaments
• Current prefers to
travel along excitable
tissues
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
Simulation Parameter
• Pulse duration: the length of time the
electrical flow is “on” 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
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)
Stimulation Parameters
• Pulse Frequency: (PPS=Hertz) 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 .11K Hz), muscle stim units)
– Medium frequency: 1K ot 100K Hz
(Interferential, Russian stim LVGS)
– High Frequency: above 100K Hz (TENS,
HVGS, diathermies)
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
Stimulation Parameter:
• Waveforms; the path of the energy. May be
smooth (sine) spiked, square,, continuous
etc.
• Method to direct current
– Peaked - sharper
– Sign - smoother
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
– 1:1 Raito fatigues muscle rapidly
– 1:5 ratio less fatigue
– 1:7 no fatigue (passive muscle exercise)
Stimulation Parameter:
– Average current (also called Root Mean
Square)
• the “average” intensity
• Factors effective 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)
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.
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
Capacitance:
• Increase intensity (with decrease pulse
duration) is needed to stimulate tissues with
a higher capacitance.
• Muscle membrane has 10x the capacitance
of nerve
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
Factors effecting the clinical
application of electricity
• An increase in the diameter of a nerve
decreased it’s 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
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.
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
Muscle Contractions
• 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:
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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
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
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
General E-Stim Parameters
Pain
Edema
Muscle Re-ed.
Tissue Healing
Hz: 100+
Tens, HVGS, IFC
Hz: 100-150
HVGS, IFC
Hz: 50-60
Type: depends on purpose
Hz: 100+ or 1(? inc. circ)
IFC, Ionto, Mens (?)
PPS: 70-100
Polarity: purpose & comfort
PPS: 120
Polarity: negative
PPS: 1-20
Polarity: purpose & comfort
PPS: vary but typically tens like
Polarity: purpose & comfort
Time: 20-60 min
Time: 20 min
Time: Fatigue (1-15 min)
Time: 20 min
Other:
Electrode Spacing
Burst Option, Voltage/Acc.
Accupoint (1-5pps)
Other:
Electrode Spacing
Voltage/Acc.
With muscle cxn or pain reduction
Other:
Electrode Spacing, surge
Burst Option, Voltage/Acc.
Accupoint (1-5pps)
Other:
Electrode Spacing
Voltage/Acc.
Accupoint
E-Stim for Pain Control: typical
Settings
Neuromuscular Stimulation
High Volt Pulsed Stim
Gate Control Theory
High-Volt Pulsed Stim
Opiate Release
High-Volt Pulsed Stim
Brief-Intense (Probe)
High-Volt Pulsed Stim
Intensity: Stong & comfortable
Intensity: Sensory
Intensity: Motor level
Intensity: Noxious
Type title here
Pulse Rate: <15
35-50 for tonic contraction
Pulse Rate: 60-100 pps
Pulse Rate 2-4 pps
Pulse Rate: 120pps
Polarity: + or -
Phase Duration < 100 usec
Phase Duration: 150-250 usec
Phase Duration: 300-1000 usec
Alternating Rate: Alternating
Mode: continuous
Mode: Continuous
Mode: 15-60 sec at each site
Electrode Placement
Biopolar: Distal & Proximal to muscle
Monopolar: Over motor points
Electrode Placement
Directly over motor points
Electrode Placement
Directly over motor points
Electrode Placement
Grid Tech: distal & proximal to site
High Volt Pulsed Stimulation
HVPS
• The application of monophasic current with a
known polarity
– typically a twin-peaked waveform
– duration of 5 - 260 msec
• Wide variety of uses:
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muscle reeducation (requires 150V)
nerve stimulation (requires 150V)
edema reduction
pain control
Clinical Application:
• Physiological response
can be excitatory and nonexcitatory
• 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 microcirculation there is a
reabsorption of the
interstitial fluids)
General Background
• Early in history HVS was called EGS, 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)
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
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Cardiac disability
Pacemakers
Pregnancy
Menstruation
Cancerous lesion
Infection
Metal implants
Nerve sensitivity
• Indications
– past slide
Treatment Duration
• General - 15-30 minutes repeated as often
as needed
• Pain reduction - sensory 30 minutes with 30
minute rest between tx
Current Parameters
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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
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 1:1 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
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
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
Electrodes
• Size
– based on size of target area
– current density is important. The smaller the
electrode size the greater the density
Neuromuscular Stimulation
• Roles:
– re-educate a muscle how to contract after
immobilization (does not produce strength
augmentation but retards atrophy)
Parameter
Setting
Intensity
Strong, comfortable
Pulse
frequency
Polarity
Muscle cxn <15pps
Tonic cxn 35-50 pps
+ or -
Alternation
Yes
Pain Control
• Roles:
– Control acute or chronic pain both sensory
(gate control - 100-150 pps)) and motor level
(opiate release - through voltage)
Parameter
Intensity
Setting for Gate Control
Method
Sensory
Pulse
frequency
Phase
Duration
Mode
60-100 pps
Continuous
Placement
Directly over pain site
< 100sec
Pain Control - Opiate Release Setting
Parameter
Intensity
Phase
Duration
Pulse
frequency
Mode
Setting Opiate
Release
Motor Level 150V
150-250 msec
2-4pps
Continuous
Placement Directly over pain site
Control and Reduction of Edema
• Roles:
– Sensory level used to limit acute edema
– Motor-level stimulation used to recude
subacute or chronic inflammation
Parameter
Setting Sensory Level Control
Intensity
Sensory
Pulse
frequency
Polarity
120 pps
Pulse
Duration
Mode
Maximum allowed by generator
-
Continuous
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)
Parameter
Setting
Intensity
Strong, comfortable
Pulse
frequency
Polarity
Low 2-4 pps
Alternation
Yes
+ or -
T.E.N.S.
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)
TENS
• Indications
– Control Chronic Pain
– Management postsurgical pain
– Reduction of posttraumatic & 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
TENS may be:
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high voltage
interferential
acuscope
low voltage AC stimulator
classical portable TENS unit
Biophysical Effects
• Primary use is to control pain through Gate
Control Theory
• 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)
Techniques of TENS application:
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Conventional or High Frequency
Acupuncture or Low Frequency
Brief Intense
Burst Mode
Modulated
Protocol for Various Methods of
TENS
Parameter
High TENS
Low TENS
Intensity
Sensory
Motor
Brief-Intense
TENS
Noxious
Pulse Fq
60-100 pps
2-4 pps
Variable
Pulse
Duration
Mode
60-100 sec 150-250 sec
Modulated
Tx Duration
As needed
Modulated
Burst
30 min
Onset of
Relief
< 10 min
20-40 min
300-1000sec
Modluated
<15 min
15-30 min
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
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
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 deeper=good, if stronger...use
shorter width)
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 patient’s tolerance
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
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
Brief, Intense TENS: hyperstimulation 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.
Brief Intense TENS - Application
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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.
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
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
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
Contraindications:
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Demand pacemakers
over carotid sinuses
Pregnancy
Cerebral vascular disorders (stroke patients)
Over the chest if patient has any cardiac
condition
Interferential Current - IFC
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)
Effects of IFC treatment:
• 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
• Muscle fatigue - muscle spasm - is reduced when
using IFC versus HVS due to the asynchronous
firing of the motor units being stimulated
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.
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
+
=
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
+
=
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
+
=
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
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
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
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
Channel A
SCAN
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
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
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.
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.
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
Parameter
Range
Intensity
Sensory
Electrode Config
Quadpolar
Beat Fq
High – Gate Control
Low – Opiate release
Long Duration
Sweep Fq
Neuromuscular Stimulation
• Beat frequency of approximately 15 HZ is
used to reduce edema
• General Parameters
Parameter
Range
Intensity
1-100mA
Carrier Fq
2500-5000Hz
Beat Fq
0-299 Hz
Sweep Fq
10-500sec
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.
Bone Stimulating Current:
– Bone Stimulating Current:Bone Stimulating
Current:IFC 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
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.
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.
MENS and IONTOPHORESIS
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)
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 body’s natural
electrical balance allowing metabolic energy for
healing without shocking the system (other
types of e-stim)
MENS
• Duration
– 30 min to 2 hours up to
4x a day
• Precautions
– Dehydrated patients
– on Scar tissue (too
much impedance)
• Contraindications
– Pain of unknown
origin
– Osteomyelitis
• Indications
–
–
–
–
–
–
–
–
–
Acute & Chronic Pain
Acute & Chronic Inflammation
Edema reduction
sprains & Strains
Contusion
TMJ dysfunction
Neuropathies
Superficial wound healing
Carpal Tunnel Syndrome
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.
TARGET
Application Techniques
• Standard electrical stimulation pads
– generator may have bells & Whistles since
MENS is subsensory
• Probe
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
Iontophoresis
Iontophoresis:
• The transfer of ions across the skin
(transdermal)by use of continuous direct current
– Iontophoresis is based on the principle that an
electrically charged electrode will repel a similarly
charged ion (first reported by LeDuc in 1903).
– Delivers a low-volt High-amp DC current
– Local blood flow is increased for 1 hour post tx
Iontophoresis
• Duration of Tx:
– Based on intensity desired
usually every other day for
3 weeks
• Indications
–
–
–
–
–
Acute or Chronic Inflam
Arthritis
Myositis
Myofacial Pain Syndromes
Invasive method for
delivering drugs
• Contraindications
– Hypersensitivity to
electrical currents
– Contraindications to meds.
– Pain of unknown origin
• Precautions
–
–
–
–
Prescription
Dosage
Do not reuse electrode
Burns if intensity to great
Iontophoresis
– Effects of treatment depends on the ion(s) delivered
• musculoskeletal inflammatory conditions (tendonitis, bursitis)
have been successfully treated:
• Using desamethosone sodium phosphate (decadron) and
Xylocaine
• Reduction of edema has been achieved by driving
hyaluronidase
• Transitory (5min) local anesthesia has been produced by
delivering lidocaine to the tissues. The anesthesia was better
than that achieved by topical application but less effective than
infiltration of the area with lidocaine.
Medication Dosage
• Medication dose delivered during tx is
measured in mA based on relationship of
amperage, tx duration
– Current Amp (mA) x Tx Duration - mA/min
• Iontophoresors are dose-oriented - where
user indicated desired tx does and generator
calculated duration and intensity
Biophysical Effects
• Dependant on Medication
• See following chart
Sample Medications
Meds
Pathology
Dose
Polarity
Acetic Acid
Myositis
80mA/min
+
Dexamethasone Inflammation 41mA/min
& Lidocain & Pain control & 40 mA
-
Lidocain &
Epinphrine
Pain Control
30mA/min
+
Lidocain &
Epinphrine
Pain Control 20 mA/min
+
Dexamethasone Inflammation 41mA/min
-
Electrode Placement
• Delivery Electrode (drug electrode)
– placed over target tissue
• Active electrode (dispersive electrode)
– place 4-6 inches from drug electrode
Side Effects: Tissue “burning”
– An alkaline reaction occurs under the cathode
(negative electrode) which is much more
caustic to the skin than the acidic reaction
occurring at the anode. The cathode may be
increased in size to attempt to decrease this
caustic reaction
Side Effects: Tissue “burning”
– Continuous unidirectional current (as needed for
iontophoresis) tends to cause tissue irritation because
skin will not tolerate current density greater than
1mA/sq.cm. Thin tissue areas, areas of skin abrasion
and areas of scarring are certain areas to avoid. This
potential for burn is exacerbated by the fact that there is
an anesthetic effect of DC under the electrode. Thus
tissue irritation may develop without the patient’s
realization
– Don’t need to drive every day 1-2x a week