electrical stimulation currents
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Electrical Stimulation Currents. Therapeutic Modalities Chapter 5. 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. Electromagnetic Radiations. - PowerPoint PPT PresentationTRANSCRIPT
Electrical Stimulation Currents
Therapeutic ModalitiesChapter 5
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.
Electromagnetic Radiations
Other Forms Of Radiation Other Than Other Forms Of Radiation Other Than Visible Light May Be Produced When An Visible Light May Be Produced When An Electrical Force Is AppliedElectrical Force Is Applied
RedRed
OrangeOrange
YellowYellow
GreenGreen
BlueBlue
VioletViolet
InfraredInfrared
UltravioletUltraviolet
Electromagnetic Radiations
In Addition, Other Forms Of Radiation In Addition, Other Forms Of Radiation Beyond Infrared And Ultraviolet Regions Beyond Infrared And Ultraviolet Regions May Be Produced When An Electrical May Be Produced When An Electrical Force Is AppliedForce Is Applied
These Radiations Have Different These Radiations Have Different Wavelengths And Frequencies Than Wavelengths And Frequencies Than Those In The Visible Light SpectrumThose In The Visible Light Spectrum
Collectively The Various Collectively The Various Types Of Radiation Form The Types Of Radiation Form The
Electromagnetic SpectrumElectromagnetic Spectrum
Electrical Stimulating CurrentsElectrical Stimulating CurrentsCommercial Radio and TelevisionCommercial Radio and Television
Shortwave DiathermyShortwave DiathermyMicrowave DiathermyMicrowave Diathermy
InfraredInfraredLASERLASER Visible LightVisible Light
UltravioletUltravioletIonizing RadiationIonizing Radiation
{{
LongestLongestWavelengthWavelength
ShortestShortestWavelengthWavelength
LowestLowestFrequencyFrequency
HighestHighestFrequencyFrequency
Wavelength And FrequencyWavelength 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)
Velocity=Wavelngth X Frequency
Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsProduced 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
Electromagnetic Radiations Share Similar Physical CharacteristicsWhen Contacting Biological Tissues
May Be…
Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsWhen Contacting Biological Tissues
May Be…Reflected
Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsWhen Contacting Biological Tissues
May Be…ReflectedTransmitted
Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsWhen Contacting Biological Tissues
May Be…ReflectedTransmittedRefracted
Electromagnetic Radiations Share Electromagnetic Radiations Share Similar Physical CharacteristicsSimilar Physical CharacteristicsWhen Contacting Biological Tissues
May Be…ReflectedTransmittedRefractedAbsorbed
Laws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic RadiationsArndt-Schultz PrincipleArndt-Schultz Principle
No Changes Or Reactions Can Occur In The No Changes Or Reactions Can Occur In The Tissues Unless The Amount Of Energy Tissues Unless The Amount Of Energy Absorbed Is Sufficient To Stimulate The Absorbed Is Sufficient To Stimulate The Absorbing Tissues Absorbing Tissues
Laws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic RadiationsLaw Of Grotthus-DraperLaw Of Grotthus-Draper
If The Energy Is Not Absorbed It Must Be If The Energy Is Not Absorbed It Must Be Transmitted To The Deeper TissuesTransmitted To The Deeper Tissues
The Greater The Amount Absorbed The Less The Greater The Amount Absorbed The Less Transmitted and Thus The Less PenetrationTransmitted and Thus The Less Penetration
Laws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic RadiationsCosine LawCosine Law
The Smaller The Angle Between The The Smaller The Angle Between The Propagating Radiation And The Right Angle, Propagating Radiation And The Right Angle, The Less Radiation Reflected And The Greater The Less Radiation Reflected And The Greater The AbsorptionThe Absorption
Source Source
Laws Governing The Effects of Laws Governing The Effects of Electromagnetic RadiationsElectromagnetic Radiations
Inverse Square Inverse Square LawLawThe Intensity Of The Intensity Of
The Radiation The Radiation Striking A Surface Striking A Surface Varies Inversely Varies Inversely With The Square With The Square Of The Distance Of The Distance From The SourceFrom The Source
Source
1 Inch
2 Inch
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
Electromagnetic Modalities Include...Electromagnetic Modalities Include...Electrical Stimulating CurrentsShortwave And Microwave DiathermyInfrared Modalities
Thermotherapy Cryotherapy
Ultraviolet Radiation TherapyLow-Power LasersMagnet Therapy
General Therapeutic Uses of ElectricityControlling acute and chronic pain Edema reductionMuscle spasm reductionReducing joint contracturesMinimizing disuse/ atrophyFacilitating tissue healingStrengthening muscleFacilitating fracture healing
Contraindications of Electrotherapy
Cardiac disabilityPacemakersPregnancyMenstruation (over abdomen, lumbar or pelvic
region)Cancerous lesionsSite of infectionExposed metal implantsNerve Sensitivity
Terms of electricity
Electrical current: the flow of energy between two pointsNeeds
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 pointsNegative pole: an area of high electron
concentration (Cathode)Positive pole: an 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 iontophoresis and in attempting to artificially fire a denervated muscle
Charge: Factors to understand
Coulomb’s Law: Like charges repel, unlike charges attractLike 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 firingMuscle depolarization is difficult to achieve with
physical therapy modalitiesNerve 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 VLo Volt: less than 100-150 V
Terms of electricity
Resistance: the opposition to flow of current. Factors affecting resistance:Material compositionLength (greater length yields greater
resistance)Temperature (increased temperature, increase
resistance)
Clinical application of Electricity: minimizing the resistanceReduce the skin-electrode resistance
Minimize air-electrode interfaceKeep electrode clean of oils, etc.Clean the skin of oils, etc.
Use the shortest pathway for energy flowUse the largest electrode that will selectively
stimulate the target tissuesIf resistance increases, more voltage will be
needed to get the same current flow
Clinical application of Electricity: TemperatureRelationship
An increase in temperature increases resistance to current flow
ApplicabilityPreheating 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 CircuitRelationship:
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 CircuitNot all of the body’s
tissues conduct electrical current the same
Excitable TissuesNervesMuscle fibersblood cellscell membranes
Non-excitable tissuesBoneCartilageTendonsLigaments
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 ParameterPulse 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
Stimulation Parameter:
Pulse rise time: the time to peak intensity of the pulse (ramp)rapid rising pulses cause nerve
depolarizationSlow rise: the nerve accommodates to
stimulus and a action potential is not elicitedGood 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 timeDo not assume the lower the frequency the longer the
pulse durationLow 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)
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 currentPeaked - sharperSign - 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 occur1:1 Raito fatigues muscle rapidly1:5 ratio less fatigue1:7 no fatigue (passive muscle exercise)
Stimulation Parameter:
Average current (also called Root Mean Square)the “average” intensityFactors 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)
Stimulation Parameter:
Current DensityThe 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 durationThe higher the capacitance the longer before a
response. Body tissues have different capacitance. From least to most:Nerve (will fire first, if healthy)Muscle fiberMuscle 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 intensityThe 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 & Frequency
Are described according to the pulse width1 pps = twitch10 pps = summation25-30 pps = tetanus (most fibers will reach tetany by 50
pps)Frequency selection:
100Hz - pain relief50-60 Hz = muscle contraction1-50 Hz = increased circulationThe higher the frequency (Hz) the more quickly the
muscle will fatigue
Frequency selection:
100Hz - pain relief50-60 Hz = muscle contraction1-50 Hz = increased circulationThe 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 conductorMonophasic application requires one negative electrode
and one positive electrodeThe strongest stimulation is where the current exists the
bodyElectrodes 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
Other:E lectrode Spacing
Burst O ption, V oltage/Acc.Accupoint (1-5pps)
Tim e: 20-60 m in
PPS : 70-100Polarity: purpose & com fort
Hz: 100+Tens, HVG S, IFC
Pain
Other:E lectrode Spacing
Voltage/Acc.W ith m uscle cxn or pain reduction
Tim e: 20 m in
PPS : 120Polarity: negative
Hz: 100-150HVGS , IFC
Edem a
Other:E lectrode Spacing, surge
Burst O ption, V oltage/Acc.Accupoint (1-5pps)
Tim e: Fatigue (1-15 m in)
PP S: 1-20Polarity: purpose & com fort
Hz: 50-60Type: depends on purpose
Muscle Re-ed.
Other:E lectrode Spacing
Voltage/Acc.Accupoint
Tim e: 20 m in
PP S: vary but typically tens likePolarity: purpose & com fort
Hz: 100+ or 1(? inc. circ)IFC , Ionto, Mens (?)
Tissue Healing
E-Stim for Pain Control: typical Settings
E lectrode P lacem entB iopolar: D ista l & Proxim al to m uscle
Monopolar: O ver m otor po ints
Alternating Rate: Alternating
Po larity: + or -
P ulse R ate: <1535-50 for tonic contraction
Intensity: S tong & com fortab le
N eurom uscular S tim ulationH igh Volt Pulsed S tim
Electrode P lacem entD irectly over m otor points
Mode: continuous
P hase D uration < 100 usec
Pulse R ate: 60-100 pps
Intensity: S ensory
G ate C ontro l TheoryH igh-Volt P ulsed S tim
Electrode P lacem entD irectly over m otor po ints
Mode: C ontinuous
P hase D uration: 150-250 usec
P ulse R ate 2-4 pps
Intensity: M otor leve l
O piate R eleaseH igh-Vo lt P ulsed S tim
E lectrode P lacem entG rid Tech: d ista l & proxim al to site
Mode: 15-60 sec at each site
P hase D uration: 300-1000 usec
Pulse R ate: 120pps
Intensity: N oxiousType title here
B rief-Intense (P robe)H igh-Volt P ulsed S tim
High Volt Pulsed Stimulation
CURRENT 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
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
CURRENT CONCEPTSEVIDENCE BASED
HVPS
The application of monophasic current with a known polarity typically a twin-peaked waveformduration of 5 - 260 msec
Wide variety of uses:muscle reeducation (requires 150V)nerve stimulation (requires 150V)edema reductionpain control
Clinical Application:Physiological response
can be excitatory and non-excitatory
ExcitatoryPeripheral 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 synthesisMobilization of blood
proteinsBacteriocyte affects
(by increased CT micro-circulation there is a reabsorption of the interstitial fluids)
Setting the ES with no twitch has purpose
General Background
Early in history HVS was called EGS (electrical galvanic stimulation), then HVGS, then HVPS
Current qualifications to be considered HVSMust have twin peak monophasic currentMust have 100 or 150 volts (up to 500 V)
HVPS
PrecautionsStimulation 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
Treatment Duration
General - 15-30 minutes repeated as often as needed
Pain reduction - sensory 30 minutes with 30 minute rest between tx
Current Parameters
greater than 100-150 Vusually provides up to 500 Vhigh peak, low average currentstrength 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 TechniquesMonopolar: 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 areasProbes: one hand-held active lead
advantages: can locate and treat small triggersdisadvantages: one on one treatment requires full
attention of the trainer
Electrodes
Materialcarbon 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
Sizebased on size of target areacurrent density is important. The smaller the
electrode size the greater the density
Neuromuscular StimulationRoles:
re-educate a muscle how to contract after immobilization (does not produce strength augmentation but retards atrophy)
Parameter SettingIntensity Strong, comfortable
Pulsefrequency
Muscle cxn <15ppsTonic cxn 35-50 pps
Polarity + 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 Setting for Gate ControlMethod
Intensity Sensory
Pulsefrequency
60-100 pps
PhaseDuration
< 100sec
Mode Continuous
Placement Directly over pain site
Parameter Setting OpiateRelease
Intensity Motor Level 150VPhase
Duration150-250 msec
Pulsefrequency
2-4pps
Mode ContinuousPlacement Directly over pain site
Pain Control - Opiate Release Setting
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)
Control and Reduction of Edema
Roles:Sensory level used to limit acute edemaMotor-level stimulation used to reduce subacute or chronic inflammation
Parameter Setting Sensory Level Control
Intensity Sensory
Pulsefrequency
120 pps
Polarity -
PulseDuration
Maximum allowed by generator
Mode Continuous
Motor-Level Edema Reduction
Cell Metabolism: increased and may increase blood flowWound Healing: May increase collagnase levels and inhibit bacteria in infected wounds (for this effect 20 min - polarity followed by 40 min + polarity recommended)
Parameter SettingIntensity Strong, comfortable
Pulsefrequency
Low 2-4 pps
Polarity + or -Alternation Yes
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
T.E.N.S.
General Concepts:
An Approach to pain controlTrancutaneous Electrical Nerve Stimulation:Any stimulation in which a current is applied across
the skin to stimulate nerves1965 Gate Control Theory created a great popularity
of TENSTENS has 50-80% efficacy rateTENS stimulates afferent sensory fibers to elicit
production of neurohumneral substances such as endorphins, enkephalins and serotonin (i.e. gate theory)
TENS
IndicationsControl Chronic PainManagement post-
surgical painReduction 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)
TENS may be:
high voltageinterferentialacuscopelow voltage AC stimulatorclassical portable TENS unit
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 contractionsVarious 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: 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
Protocol for Various Methods of TENS
Parameter High TENS Low TENS Brief-IntenseTENS
Intensity Sensory Motor Noxious
Pulse Fq 60-100 pps 2-4 pps Variable
PulseDuration
60-100 sec 150-250 sec 300-1000sec
Mode Modulated ModulatedBurst
Modluated
Tx Duration As needed 30 min 15-30 min
Onset ofRelief
< 10 min 20-40 min <15 min
Conventional Tens/High Frequency TENSParesthesia is created without motor
responseA Beta filers are stimulated to SG
enkephlin interneuron (pure gate theory)Creates the fastest relief of all techniquesApplied 30 minutes to 24 hoursrelief 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
endorphinsLonger lasting pain relief but slower to
startApplication
pulse rate low 1-5ppx (below 10)Pulse width: 200-300 microSecIntensity: 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 TENSCarrier frequency of 70-100 Hz packaged in bursts
of about 7 bursts per secondPulses within burst can varyBurst frequency is 1-5 bursts per secondStrong contraction at lower frequenciesCombines efficacy of low rate TENS with the comfort
of conventional TENS
Burst Mode TENS - Application
Pulse width: high 100-200 microSecPulse rate: 70-100 pps modulated to 1-5
burst/secIntensity: strong but comfortabletreatment length: 20-60 minutes
Brief, Intense TENS: hyper-stimulation analgesia
Stimulates C fibers for level II pain control (PAG etc.)Similar to high frequency TENSHighest rate (100 Hz), 200 mSec pulse width intensity to
a very strong but tolerable levelTreatment time is only 15 minutes, if no relief then treat
again after 2-3 minutesMono or biphasic current give a “bee sting” sensationUtilize motor, trigger or acupuncture points.
Brief Intense TENS - Application
Pulse width: as high as possiblePulse rate: depends on the type of
stimulatorIntensity: as high as toleratedDuration: 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 sessionAuricular points are often utilized
Treat distal to proximalAllow three treatment trails before efficacy
is determinedUse 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:
Demand pacemakersover carotid sinusesPregnancyCerebral 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)
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).
Effects of IFC treatment:
Primary Physiological Effect: Capacity of IFC to depolarize Sensory and motor nerve fibers
Main Therapeutic EffectsSensory 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 managementMuscle 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.
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)
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
Principles of wave interference - Combined EffectsConstructive, Destructive, & ContinuousConstructive 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 EffectsDestructive 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 EffectsContinuous 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 minutesBurst mode typically
applied 3x a week in 30 minute bouts
Precautionssame as all electrical
currents
ContraindicationsPain of central originPain of unknown origin
IndicationsAcute painChronic painMuscle 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 A
Channel B
Channel A
Channel B
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 ControlSimilar 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 receptorsParameter Range
Intensity Sensory
Electrode Config Quadpolar
Beat Fq High – Gate ControlLow – Opiate release
Sweep Fq Long Duration
Neuromuscular Stimulation
Beat frequency of approximately 15 HZ is used to reduce edema
General ParametersParameter Range
Intensity 1-100mA
Carrier Fq 2500-5000Hz
Beat Fq 0-299 Hz
Sweep Fq 10-500sec
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 or LIDC (low-intensity direct current)
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 levelcurrent less than 1000A (approx 1/1000 amp
of TENS)Theorized that this is the current of injury
(Becker et al 1967, Becker & Seldon, 1987)
Biophysical Effects
Theory:Currents below 500A increases the level of ATP
(high Amp decreases ATP levels)Increase in ATP encourages amino acid transport
and increased protein synthesisMENS reestablishes the body’s 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
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
Electrode Placement
Electrodes should be placed in a like that transects the target tissuesRemember 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
Application Techniques
Standard electrical stimulation padsgenerator may have bells & Whistles since
MENS is sub-sensoryProbe
Bone Stimulating Current:
MENSHas 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.
Microcurrent Electrical Stimulation
Tissue & Bone Healing
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
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 (-)
Electrical Stimulation for Tissue RepairWound healing is also impeded by
infectionElectrical 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
Electrical Stimulation for Tissue RepairThere is no evidence for the effectiveness
of sub-sensory-level stimulation for the healing of open wound
Electrical Stimulation for Bone HealingThe “current of injury” theory for bone: a
relative negativity of the injured tissue with respect to the uninjured.
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)
Electrical Stimulation for Bone HealingPEMFs 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.
Electrical Stimulation for Bone Healing60 Hz sinusoidal AC, pulsed current, and
interference modulations of higher-frequency alternating currents are also being used.
Electrical Stimulation
Treatment Strategies
HVPS: Neuromuscular Stimulation Output Intensity
Strong, intense, comfortable contractions. Pulse frequency
If duty cycle cannot be adjusted: Low for individual muscle contractions (<15 pps).Adjustable duty cycle: Moderate for tonic contractions (>50 pps).
Duty CycleInitial treatments should begin with a low (e.g, 20%) duty cycle and be increased as the muscle responds.
Electrode placementBipolar: 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
HVPS: Sensory-level Pain ControlOutput Intensity Sensory levelPulse frequency 60 to 100 ppsPhase duration <100 µsec*Mode ContinuousElectrode arrangement Monopolar or bipolarPolarity Acute: Positive
Chronic: NegativeElectrode placement Directly over or
surrounding the painfulsite
* Not adjustable on most HVPS units.
HVPS: Motor-level Pain Control
Output Intensity Motor levelPulse rate 2–4 ppsPhase duration 150–250 µsecMode ContinuousElectrode arrangement Monopolar or bipolarPolarity Acute: positive
Chronic: NegativeElectrode placement Directly over the painful
site, distal to the spinalnerve root origin, triggerpoints, or acupuncture
points
HVPS: Brief-Intense Pain Control ProtocolOutput Intensity NoxiousPulse rate >120 ppsPhase duration 300 to 1000 µsecMode Probe
15 to 60 sec at each siteElectrode arrangement Monopolar (probe)Polarity Acute: Positive
Chronic: NegativeProbe placement Gridding technique,
stimulating hypersensitiveareas working from distal
to proximal
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. Cathode (-)
Anode (+)
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
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
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: 10:50 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