detx ss part 1.ppt - ciao seminars · 2009-04-09 · dispersive electrode proximal to it and larger...

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Dynamic Dynamic Modality UseModality Use

Confidently apply modalities in the older adult patient population

Part I: The Basics

ElectrotherapyElectrotherapy

Historical perspectiveHistorical perspective• Modalities, especially

electrotherapy, have been used for many years

• Very common in PT and OT ti t d

© 2006 Yorick Wijting, PT

practice today• Many misapplications and

missed applications

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NMESNMES• Neuromuscular Electrical Stimulation• Stimulation through intact peripheral motor

nerves• Treatment goals:


– Strengthening– Recovery motor

control

EMSEMS• Electrical Muscle Stimulation• Direct stimulation of membrane of

denervated muscle• Wide pulse duration, high intensity


• Treatment goals:– Retard muscle

atrophy– Improve local

blood flow

FESFES• Functional Electrical Stimulation• NMES to promote function• Stimulation delivered

in ‘timed’ manner


• Difficult to achieve well coordinated movement

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TENSTENS• Transcutaneous Electrical

Nerve Stimulation• Externally applied • Portable


• For pain management

CurrentCurrent• Flow of charged particles between

electrodes • Current flow is measured in mille-Amperes

(mA)• Neurons in path of current depolarize when


• Neurons in path of current depolarize when critical threshold is reached

• Mostly delivered as Pulsed Current

Key variables to considerKey variables to consider• Intensity• Resistance encountered• Pulse and phase duration• Frequency

Ch l i t ti


• Channel interaction

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Current intensity (amplitude)Current intensity (amplitude)• Increasing the intensity (current flow) will

increase the effect of the current– Increased depth of penetration– Increased number of neurons depolarized both

superficially and deeper


superficially and deeper

vs.

Resistance Resistance –– Ohm’s lawOhm’s law• Current flow (intensity/amplitude) changes

with changing resistance• Ohm’s law (I=V/R) governs relationship

between intensity and resistance


Resistance Resistance –– CC or CV?CC or CV?• Constant Current mode (CC)

– Machine keeps intensity constant by changing voltage to compensate for changing resistance

– Very constant stimulation– Possible discomfort with small electrode


• Constant Voltage mode (CV)– Machine keeps voltage constant regardless of

changing resistance– Intensity level (and therapeutic effect) will

fluctuate– Ideal for dynamic, high intensity applications

since risk of discomfort is low

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Pulse durationPulse duration• Isolated electrical event separated by a

finite time from the next event• Pulse duration usually measured in

microseconds (μs)


• Each pulse contains one or more phases• Phase duration determinates which size

neuron is stimulated

Pulse duration Pulse duration –– Size principleSize principle

• <150μs– Sensory (Aβ) – touch, vibration, proprioception– Large motor (Aα) – fast twitch contraction

• 150-250μs


– Small motor (Aα) – slow twitch contraction– Sensory (Aδ) – pinprick, intense heat or cold

• >250μs– Nociceptive (C) – noxious,

“slow” pain

FrequencyFrequency• Number of pulses per second• Expressed as pulses/sec (pps) or Hertz (Hz)• Determines which neurons are stimulated

most effectively


– Large neurons: 80-150Hz• Aβ sensory• Fast twitch motor

– Slow twitch motor neurons: 25-35Hz– Small myelinated Aδ sensory neurons: 1-10Hz

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Channel interactionChannel interaction• Single channel

– Use when single muscle group is target

• CoContract– Use when stabilization of single joint is desired


• Reciprocal– Use when simple alternating movements are

desired

• VMS FR (Fast Response)– Use to improve initiation and motor control of

more complex movements

VMS FRVMS FR


ContraindicationsContraindications• Do not allow current to flow through the

heart muscle– Could cause arrhythmia

• Do not apply current to anterior neck– Could trigger bradycardia through stimulation of


Could trigger bradycardia through stimulation of carotid sinus

– Could cause laryngospasm through stimulation of intrinsic laryngeal muscles

– Exception: VitalStim Therapy

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ContraindicationsContraindications• On or over neoplasm or infection

– Electricity causes a stimulation of metabolism which may stimulate these unwanted processes

• Directly over the abdomen of pregnant women


women– Unknown risk of adverse effects to fetus

• In or near field of shortwave diathermy– Electromagnetic field may interfere with current

delivery

PrecautionsPrecautions• Individuals who cannot give clear feedback

or over anesthetic skin– Patient can not indicate when current is hurting

• Over areas of peripheral vascular disease (PVD) th b hl biti


(PVD) or thrombophlebitis – Strong contractions may trigger the release

emboli

PrecautionsPrecautions• In patients with pacemakers or other

implanted electrodes– Electrical field may interfere with function of

implanted device– Extreme caution in patients with ICD


– Extreme caution in patients with ICD

• Over areas of excess adipose tissue– High intensity stimulation may be required to

overcome resistance of fat –may lead to adverse autonomic response

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PrecautionsPrecautions• In known seizure disorders

– Stimulation may trigger a seizure

• Over open wounds, unless specifically treating the wound


– Except for specialty electrodes, electrodes are usually not sterile

WaveformsWaveformsDemystifying the options

Interferential, RussianBiphasic, Microcurrent

High Volt, Direct current

Interferential currentInterferential current• Amplitude modulated medium-frequency

current (2,000-5,000 Hz)• Marketing made IFC very popular in Europe

since 50’ies, in USA since 80’ies


• Nemec (1950) claimed that high carrier frequency allows deeper and more comfortable penetration– Claim not substantiated in literature

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Interferential currentInterferential current• Sinusoidal waveform• Carrier frequency

2,000-5,000Hz• Amplitude modulation

frequency (or Beat

• Beat frequency can ‘sweep’ to prevent accommodation

• Vector scan (automatic intensity fluctuation)


q y (frequency) 1-250Hz increases treatment

area

Interferential currentInterferential current


Interferential currentInterferential current• Application

– Quadripolar• 4 electrodes• Treatment field where

currents cross


– Bipolar• ‘Premodulated’• Modulation in machine• Treatment field larger• Preferred method

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Interferential currentInterferential current• Compared to other waveforms

– High carrier frequency causes rapid fatigue of neurons – not best approach for strengthening

– Contraction force less compared to biphasic and Russian current


Russian current– High total current load: possible heating under

electrode

• Main application in the literature:– Pain control– Urinary incontinence

Russian currentRussian current• Burst-modulated medium frequency current

(2,500Hz)• Popular for muscle strengthening since

early 80’ies


• Kotz (’77) claimed that his current produced more force than voluntary contraction (30% more than MVC) and was more comfortable– Claims not substantiated in literature

Russian currentRussian current• Sinusoidal waveform• Frequency 2,500Hz• Bursts of 10ms each• Burst interval 10ms

• Burst frequency 50Hz• On:Off ratio 10:50 (10

secs on, 50 secs off)


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Russian currentRussian current• Compared to other waveforms

– Tissue reacts to each burst as if it were a single, long lasting pulse

– Muscle strengthening effects not better than regular biphasic current


regular biphasic current– Stimulation not more comfortable, actually less

comfortable at high intensities

• Literature support– Muscle strengthening

Biphasic currentBiphasic current• Pulsed waveform of brief pulse duration• Most frequently used waveform

– When used for pain inhibition: TENS (Transcutaneous Electrical Nerve Stimulation)Wh d f l t th i NMES


– When used for muscle strengthening: NMES (Neuromuscular Electrical Nerve Stimulation)

• TENS popularized since early 60’ies– Melzack and Wall’s gate control theory

Biphasic currentBiphasic current• Two phases per pulse• Symmetrical or

asymmetrical• Balanced or

unbalanced


• Frequency 0-250Hz• Different on:off ratios

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• Compared to other waveforms– Short pulse duration lowers skin resistance– Suitable for high intensity and/or long term

applications– Abundance of equipment available

Biphasic currentBiphasic current


– Abundance of equipment available

• Literature support– Muscle strengthening– Pain control– Edema management– Stimulation of circulation– Fracture healing

MicrocurrentMicrocurrent• Continuous or pulsed monophasic

waveform of very low amplitude (<1mA)• Becker (‘67) proposed model of tissue

healing based on studies revealing a ‘ t f i j ’


‘current of injury’– Normal healing tissue, unlike non-healing tissue,

contains characteristic, very low intensity electrical current

– Externally applied current may theoretically stimulate healing

MicrocurrentMicrocurrent• Monophasic• Pulsed or continuous

• Intensity <1,000μA• Polarity reversal

optional


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MicrocurrentMicrocurrent• Application

– One electrode on/in lesioned tissue, one electrode close to it

– Polarity reversal recommended– Frequency <1Hz for wound healing


– Frequency <1Hz for wound healing

• Literature support– Wound healing– Trigger points– Tendonitis

High VoltHigh Volt• Monophasic waveform, ‘twin peak’, very

short pulse duration, high voltage• Developed during 40’ies (Bell labs)• High voltage and short pulse result in low


impedance– Deeper penetration– More comfortable– More effective

High VoltHigh Volt• Monophasic, twin-peak• Pulsed: 1-200 pps• Pulse duration: 100μs

• Voltage: 150-500V• Intensity: high


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High VoltHigh Volt• Application

– Usually one smaller active electrode and one dispersive electrode proximal to it

– Polarity reversal recommended

• Literature support


• Literature support– Wound healing– Edema control– Spasticity control

Direct currentDirect current• Continuous (Galvanic) or interrupted

(Interrupted Galvanic) unidirectional current• First accounts of medical use of electrical

currents go back hundreds of years


• Primary use is iontophoresis– Using electromotive force to move electrically

charged particles

Direct currentDirect current• Monophasic• Continuous or pulsed

(interrupted)

• Intensity very low• Cathode: negative• Anode: positive


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Direct currentDirect current• Application

– Active electrode of same polarity as medication

– Dispersive electrode


Dispersive electrode proximal to it and larger

• Literature support– Iontophoresis

Shortwave DiathermyShortwave Diathermy

Diathermy = “To Heat Through”

History of Shortwave DiathermyHistory of Shortwave Diathermy

• 1920’S – 1st used clinically in Germany• Popularity of the treatment approach has

waxed and waned through the years• Problems with early SWD devices


• Rationale for more recent resurgence of SWD

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Shortwave DiathermyShortwave Diathermy• Electromagnetic energy which can be used

to deliver thermal or subthermal treatments• Can be used in pulsed or continuous mode• Effective heating of deep (>5 cm) and large


Draper et al. JOSPT 1999;29(1):13-22

areas– Ultrasound is limited to a treatment area of

approximately 2x’s the size of the sound head– SWD diathermy matches 1 MHz ultrasound’s

depth of penetration and heating rate

Physical properties of SWDPhysical properties of SWD• Frequency: 27.12 MHz• Triggers ion acceleration

– Produces kinetic energy within tissue (molecular vibration)

– Energy is converted to heat


gy• Electromagnetic radiation does not require

coupling medium– Unlike ultrasound energy, electromagnetic

radiation can travel through air – minimal/non-contact application

• Maximized by using Continuous Mode– Increase extensibility of deep collagen rich

tissue (must apply stretch to increase ROM)– Decrease joint stiffness– Relieve deep pain and muscle spasm

SWD: Thermal EffectsSWD: Thermal Effects


– Relieve deep pain and muscle spasm– Increase blood flow

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SWD: NonSWD: Non--thermal effectsthermal effects• Maximized by using Pulsed Mode

– Increased local microcirculation– Increased local tissue oxygenation– Increase phagocytosis

D d i


– Decreased pain– Possible changes in cell membrane function and

cellular activity – Increased protein synthesis– Increased ATP production

SWD: Capacitive fieldSWD: Capacitive field• Electromagnetic field generated by 2 plates

(capacitive applicators)• High frequency electrical field oscillates

between plates 27 million times/sec


• Energy is mostly absorbed in tissues with high electrical impedance

• Best suited for treating superficial soft tissue of high electrical resistance (tendon, skin, fat, joint)

SWD: Inductive fieldSWD: Inductive field• Electromagnetic field generated by

alternating current flowing through a coil housed in a drum or sleeve

• Produce a strong magnetic field in the t t ti


target tissue• Creates oscillating “eddy” currents in tissue

around the field lines• Preferentially heats low

impedance tissues (i.e. skeletal muscle, blood, synovial fluid)

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Pulse width Frequency Treatment

time

Acute 65 µsec 400 Hz 30 min

Dosimetry guidelinesDosimetry guidelines


Acute 65 µsec 400 Hz 30 min

Subacute 200 µsec 400 Hz 20-30 min

Chronic 400 µsec Continuous 20 min

Qualitative dosimetryQualitative dosimetry

• 4 dosage levels (I-IV)1. Athermal: Just below any heat sensation2. Mild thermal: Mild perception of heat3. Moderate thermal: Comfortable perception of


p pheat

4. High thermal: Vigorous heating without pain or burning

Temp increases and indicationsTemp increases and indications

Dose Indication

Non-thermal Acute injury

Mild thermal Sub-acute injury


Mild thermal Sub acute injury

Moderate thermal Chronic inflammation, pain, trigger points

Vigorous heating Stretch collagen

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Application ConsiderationsApplication Considerations• Make sure no metal is in the treatment area• Explain desired sensation to patient• Place towel applicators and skin• Maintain applicator parallel to treatment


pp parea

• Monitor patient• Remember: patient feedback overrules all

dosage calculations

SWD: ContraindicationsSWD: Contraindications• Over active neoplasm or infection• Over the abdomen and pelvic area of the

pregnant female• Over surface or implanted metal


• Over hemorrhage/acute injury (CSWD)• Cardiac pacemakers and other types of

electronic implants – Two case reports of patients with brain

stimulators suffering severe and permanent brain damage

SWD: ContraindicationsSWD: Contraindications• Over eyes, ears, genitalia• Over moist wound dressings• Hemophilia• Febrile patients


p• Over growth plates

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SWD: PrecautionsSWD: Precautions• Over ischemic area/vascular compromise

(thermal)• Over areas with impaired sensation• Over womb during menstruation


• Obesity (if using capacitive method to deliver thermal treatment)

UltrasoundUltrasound

Ultrasound Ultrasound • Sinusoidal wave• Thermal agent• Mechanical agent• Does not fall on electromagnetic spectrum


g p• Acoustical spectrum (above 20,000 HZ)• Human ear hears sound btwn 16,000-

20,000

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FrequencyFrequency• Depth of Penetration

– 1 MHz: Deep (up to 5 cm)– 3 MHz: Superficial (≤ 2.5 cm)

• Efficiency of heating


– 3 MHz heats approx 3 x faster than 1 MHz

Hayes et al JAT 2004;39(3):230-234; Draper et al. JOSPT 1995;22:142-150

Pulsed US Pulsed US • Periodic interruption of US wave• Duty cycle describes the percentage of time

that US energy is being delivered– e.g. 20% duty cycle = on 2 ms, off 8ms


• Minimizes unwanted heating effects at a given intensity proportional to the selected duty cycle

• Myth: selecting PUS eliminates all heating effects at all intensities

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NonNon--thermal effects (pulsed)thermal effects (pulsed)• Increased macrophage responsiveness• Increased intracellular calcium synthesis• Increased skin and cell membrane

permeability (greater than continuous US)


• Increased early fibroblastic activity leading to accelerated tissue healing

Thermal effects (continuous)Thermal effects (continuous)• Mild (1º C) to vigorous heating (≥4º C) is

achievable• Extent of heat build up depends on:

– Frequency


– Intensity– Duration of treatment– Tissue composition

Temp increases and indicationsTemp increases and indications

Dose Indication

Non-thermal Acute injury

Mild thermal (1° C) Sub-acute injury


Mild thermal (1 C) Sub acute injury

Moderate thermal (2-3° C) Chronic inflammation, pain, trigger points

Vigorous heating (≥4° C) Stretch collagen

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Dosimetry: Thermal USDosimetry: Thermal US• Vigorous heating of Deep Muscle tissue

(3-5 cm deep)– Duty Cycle: 100% (continuous)– Frequency: 1 MHz

Intensit 1 5 W/ m2


– Intensity: 1.5 W/cm2

– Heating Rate: 0.3º C/min – Time: 13 min (13 min x .3° C/min = 3.9°C)

Dosimetry: Thermal USDosimetry: Thermal US• Vigorous heating of Superficial Muscle

tissue (≤2.5 cm deep)– Duty Cycle: 100% (continuous)– Frequency: 3 MHz

Intensit 0 5 1 0 W/ m2


– Intensity: 0.5-1.0 W/cm2

– Heating Rate: 0.3-0.6º C/min – Time:

• 13 min at 0.5-1.0 W/cm2 (0.3 x 13 = 3.9º C)• 7 min at 1.0 W/cm2 (0.6 x 7 = 4.2º C)

Dosimetry: Thermal USDosimetry: Thermal US• Vigorous heating of Deep

Tendon/Ligament tissue (3-5 cm deep)– Duty Cycle: 100% (continuous)– Frequency: 1 MHz

Intensit 1 5 W/ m2


– Intensity: 1.5 W/cm2

– Time: 10 min

– Rationale: Collagen rich tissue such as tendon heats 3.45 x faster than muscle. However, some US is absorbed in superficial tissue prior to reaching deep tissue.

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Dosimetry: Thermal USDosimetry: Thermal US• Vigorous heating of Superficial

Tendon/Ligament tissue (≤2.5 cm deep)– Duty Cycle: 100% (continuous)– Frequency: 3 MHz

Intensit 0 5 1 0 W/ m2


– Intensity: 0.5-1.0 W/cm2

– Time:• 7 min at 0.5 W/cm2

• 4-5 min at 1.0 W/cm2

Dosimetry: NonDosimetry: Non--thermal USthermal US• Pulsed US of Superficial tissue (≤2.5 cm

deep)– Duty Cycle: 20% (continuous)– Frequency: 3 MHz

Intensit ≤0 5 W/ m2


– Intensity: ≤0.5 W/cm2

– Time: 7 min

Dosimetry: NonDosimetry: Non--thermal USthermal US• Pulsed US of Deep tissue (≥3 cm deep)

– Duty Cycle: 20% (continuous)– Frequency: 1 MHz– Intensity: ≤0.5 W/cm2

Ti 7 i


– Time: 7 min

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ContraindicationsContraindications• Over active neoplasm or infection1,2,3,4,5

• Acute injury or hemorrhage (thermal)1,5

• Circulatory insufficiency (thermal)1,3,5

• Over areas of decreased sensation (thermal)1,3,5

• Over methylmethacrylate (cemented joint


• Over methylmethacrylate (cemented joint replacements)2,4

• Over plastic implants1,2

• Over electronic implants1,2,3,4,5

1=Belanger, 2=Cameron, 3=Michlovitz 4= Denegar, 5 = Starkey

ContraindicationsContraindications• Over the heart3,4,5

• Over skin that has been exposed to radiation therapy1

• Over the abdomen low back, or pelvic area during pregnancy1,2,3,4,5

O th b ti (th b hl biti /DVT)1 2 3 5


• Over thrombotic areas (thrombophlebitis/DVT)1,2,3,5

• Over the eyes1,2,3,4,5

• Over the reproductive organs1,2,3,4,5

• Directly over the spinal cord after laminectomy1,2,4

1=Belanger, 2=Cameron, 3=Michlovitz 4= Denegar, 5 = Starkey

Thank you!Thank you!

detx ss part 1.ppt - ciao seminars · 2009-04-09 · dispersive electrode proximal to it and larger...

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