Title: Electrical Stimulation Currents
1Electrical Stimulation Currents
- Therapeutic Modalities
- Chapter 5
2Electricity is an element of PT. May be most
frightening and least understood.
- Understanding the basic principles will later aid
you in establishing treatment protocols.
3Electromagnetic Radiations
- Other Forms Of Radiation Other Than Visible Light
May Be Produced When An Electrical Force Is
Applied
4Infrared
Spectrum
Red
Orange
Yellow
Green
Blue
Violet
Ultraviolet
5Electromagnetic 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
6Collectively 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
8Wavelength 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
9Electromagnetic 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
10Electromagnetic Radiations Share Similar Physical
Characteristics
- When Contacting Biological Tissues May Be
11Electromagnetic Radiations Share Similar Physical
Characteristics
- When Contacting Biological Tissues May Be
- Reflected
12Electromagnetic Radiations Share Similar Physical
Characteristics
- When Contacting Biological Tissues May Be
- Reflected
- Transmitted
13Electromagnetic Radiations Share Similar Physical
Characteristics
- When Contacting Biological Tissues May Be
- Reflected
- Transmitted
- Refracted
14Electromagnetic Radiations Share Similar Physical
Characteristics
- When Contacting Biological Tissues May Be
- Reflected
- Transmitted
- Refracted
- Absorbed
15Laws 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
16Laws 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
17Laws 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
18Laws 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
19Electromagnetic 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
20Electromagnetic Modalities Include...
- Electrical Stimulating Currents
- Shortwave And Microwave Diathermy
- Infrared Modalities
- Thermotherapy
- Cryotherapy
- Ultraviolet Radiation Therapy
- Low-Power Lasers
- Magnet Therapy
21(No Transcript)
22General 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
23Contraindications of Electrotherapy
- Cardiac disability
- Pacemakers
- Pregnancy
- Menstruation (over abdomen, lumbar or pelvic
region) - Cancerous lesions
- Site of infection
- Exposed metal implants
- Nerve Sensitivity
24Terms 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
25Fundamentals 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)
26Charge
- 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
27Charge Factors to understand
- Coulombs Law Like charges repel, unlike charges
attract - Like charges repel
- allow the drug to be driven
- Reduce edema/blood
28Charge 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
29Terms 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.
30Terms 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
31Terms 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)
32Clinical 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
33Clinical 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
34Clinical 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
35Clinical 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
36Stimulation 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
37Simulation 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
38Stimulation 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)
39Stimulation 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)
40Stimulation 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
41Stimulation Parameter
- Waveforms the path of the energy. May be smooth
(sine) spiked, square,, continuous etc. - Method to direct current
- Peaked - sharper
- Sign - smoother
42Stimulation 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)
43Stimulation 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)
44Stimulation 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.
45Capacitance
- 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
46Capacitance
- Increase intensity (with decrease pulse duration)
is needed to stimulate tissues with a higher
capacitance. - Muscle membrane has 10x the capacitance of nerve
47Factors 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
48Factors 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
49Factors 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.
50Law 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
51Muscle 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
52Frequency 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
53Electrodes 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
54Electrodes 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
55General E-Stim Parameters
56E-Stim for Pain Control typical Settings
57High Volt Pulsed Stimulation
58CURRENT CONCEPTSEVIDENCE 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
59CURRENT CONCEPTSEVIDENCE 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
60HVPS
- 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
61Clinical 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
62General 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)
63HVPS
- 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
64Treatment Duration
- General - 15-30 minutes repeated as often as
needed - Pain reduction - sensory 30 minutes with 30
minute rest between tx
65Current 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
66Current 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
67Application 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
68Electrodes
- 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
69Electrodes
- Size
- based on size of target area
- current density is important. The smaller the
electrode size the greater the density
70Neuromuscular Stimulation
- Roles
- re-educate a muscle how to contract after
immobilization (does not produce strength
augmentation but retards atrophy)
71Pain Control
Roles Control acute or chronic pain both sensory
(gate control - 100-150 pps)) and motor level
(opiate release - through voltage)
72Pain Control - Opiate Release Setting
73Evidence 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)
74Control and Reduction of Edema
Roles Sensory level used to limit acute
edema Motor-level stimulation used to reduce
subacute or chronic inflammation
75Motor-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)
76Russian 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
77T.E.N.S.
78General 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)
79TENS
- 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)
80TENS may be
- high voltage
- interferential
- acuscope
- low voltage AC stimulator
- classical portable TENS unit
81Biophysical 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)
82Techniques 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
83Protocol for Various Methods of TENS
84Conventional 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
85Application 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
86Set 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)
87Low 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
88Burst 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
89Burst 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
90Brief, 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.
91Brief 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.
92Locus 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
93Modulated 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
94Electrode 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
95Contraindications
- Demand pacemakers
- over carotid sinuses
- Pregnancy
- Cerebral vascular disorders (stroke patients)
- Over the chest if patient has any cardiac
condition
96Interferential Current - IFC
97Interferential 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).
98Effects 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
99Positive 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.
100Evidence 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)
101Evidence 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
102Principles 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
103Principles 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
104Principles 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
105Amplitude-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
106IFC
- 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
107IFC 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
108Quad-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
109Bipolar 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
110Two-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
111Special 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.
112Special 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.
113Pain 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
114Neuromuscular Stimulation
- Beat frequency of approximately 15 HZ is used to
reduce edema - General Parameters
115IFC 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.
116Bone 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
117Bone 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.
119MENS or LIDC (low-intensity direct current)
120MENS
- 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)
121Biophysical 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
122MENS
- 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
123Electrode 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
124Application Techniques
- Standard electrical stimulation pads
- generator may have bells Whistles since MENS is
sub-sensory - Probe
125Bone 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.
126Microcurrent Electrical Stimulation
127Electrical 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
128Current 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 (-)
129Electrical 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
130Electrical Stimulation for Tissue Repair
- There is no evidence for the effectiveness of
sub-sensory-level stimulation for the healing of
open wound
131Electrical Stimulation for Bone Healing
- The current of injury theory for bone a
relative negativity of the injured tissue with
respect to the uninjured.
132Electrical 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)
133Electrical 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.
134Electrical Stimulation for Bone Healing
- 60 Hz sinusoidal AC, pulsed current, and
interference modulations of higher-frequency
alternating currents are also being used.
135Electrical Stimulation
136HVPS 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
137HVPS 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.
138HVPS 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
139HVPS 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
140HVPS 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 (-)
141HVPS 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
142IFS 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
143Premodulated 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