Aplicacion Clinica de Electroterapia

7/30/2019 Aplicacion Clinica de Electroterapia

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C l i n i c a l A p p l i c a t i o n o f [ J e c t r o t h e r a p yMICHAEL G. DOLAN, MA, ATC, CSCS Canisius CollegeFRANK C. MENDEL, PhD State University of New York at Buffalo

Sing electrotherapy in the ma nag em entof athletic injuries is standard practice formost athletic trainers and therapists. Electri-cal stimulation (ES) is applied to relieve pain,to elicit muscle contractions for strength

and reeducat ion af tertrauma or immobiliza-tion, in iontophoresis,and to manage edemaand chron ic wounds .Although use of ESis c o m m o n c l i n ic a lpract ice , and athlet ictraining students typi-cally receive extensiveinstruction in its appli-cat ion, there is l i t t lee v i d e n c e f ro m r a n -domized clinical trialsclear ly demonstrat ingp o s i t i v e " t r e a t m e n t "effects on funct ionaloutcomes or return toplay for athletes. Manyclinicians and educ atorsare firm proponents ofthe clinical benefits ofe lec t ro therapy in them a n a g e m e n t o f a t h -letic injuries, and theymight be justified, but

until more definitive research is completedES should be considered as just one c om po-nent of a comprehensive rehabilitation pro-gram . Like all modalities, ho wev er ES shouldnot be used in certain circumstances. Con-traindications include, but are not limited to,cardiac pacemakers, pregnancy, infections.

KEY POINTSA l t h o u g h e l e c tr ic a l s t im u l a t i n g c u r r e n tsa r e e v e r y d a y p r a c t ic e s a n d a t h l e t ic t r a i n in gs t u d e n t s t y p i c a l ly r e c e iv e e x t e n s i v e i n s t r u c -t i o n , l i t t l e e v i d e n c e f r o m r a n d o m i z e d c l in i c a lt r ia l s s u p p o r t s t h e e f fe c t iv e n e s s o f s o m e o ft h e s e " t r e a t m e n t s " o n f u n c t i o n a l o u t c o m e so r i n f l u e n c i n g r e t u r n t o p l a y f o r a t h l e t e s .H i g h - v o l t a g e p u l s e d c u r r e n t , i f a p p l i e di n fim e d i a t e ly a f te r t r a u m a , i s a s e f f e c t i v ea s s o m e f o r m s o f c r y o th e r a p y a n d n o n s t e -r o id a l a n t i - i n f l a m m a t o r y d r u g s in c u r b i n ge d e m a f o r m a t io n i n a n i m a l m o d e l s .H i g h - l e v e l e l e c t r ic a l s t im u l a t i o n i s e ff e c t iv ei n r e c o v e r in g g u a d r ic e p s s t re n g t h d u r i n ge a r l y r e h a b i li ta t i o n a f te r A C L r e c o n s t r u c t i o n .O f a i l th e p r o p o s e d i n d i c a t io n s o f e l e c tr ic a ls t i m u l a t io n , t h e i r u se in w o u n d m a n a g e -m e n t is s u p p o r t e d b y b a s i c s cie n c e a n dc o n t r o l l e d c l i n i c a l t r i a l s .K e y W o r d s : e le c t r ic a l s t im u l a t i o n , a t h l e t ici n j u r i e s , m o d a l i t i e s

neoplasms, and peripheral vascular disease.If in doubt, clinicians should err on the sideof caution and consult with the referringphysician before initiating treatment.

OverviewClinicians struggle with the terminology usedto describe electrotherapy For example, trans-cuta neo us electrical neural stim ulation (TENS)is an acronym familiar to all athletic trainersand therapists. When the term TENS is used,many clinicians envision a small, portableunit that evokes sensory-level stimulation tomanage pain. The electrical parameters of aTENS unit, such as waveform, pulse width,and duration, might be very comparable tothose of large ES units used in clinical set-tings, but som e clinicians would not co nsiderthe latter to be TENS units. Technically, anydevice that produces electrical current suf-ficient to produce sensory-level stimulationand transm its that current to patients via elec-trodes is conside red a TENS unit. Rather th anfocus on the name of the electrical stimulator,which is driven by m arketing strategies of theman ufacturers, clinicians should focus on thestage of the inflammatory or healing processand the desired treatment outcome. Then, ifapplicable, choose the appropriate electricalparam eters to achieve the treatmen t goal forthe individual patient.

Electr ical currents are c lass if ied asd i rec t cur ren t (DC), a l t e rn a t ing cur ren t( A C ) , or pulsed current (PC). DC, or gal-vanic curren t, is defined a s curr ent thatflows uninterrupted in one direction, DCis indicated for stimulating long-standing

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denervaced muscles, in iontophoresis, and, in somecases, for wound healing, AC. or faradic current, isalso continuous but alternates equally between thepositive and negative poles and therefore creates nonet charge. PC is interrup ted curren t tha t is on an d offfor specific periods. For exam ple, high-voltage pulsedcurrent is characterized by short monophasic twin-spiked pulses followed by long interpulse intervals.Clinicians choose either positive or negative polarityfor this type of electrical therapy, depending on thedesired outcom e. Because the duty cycle, which is cal-culated by dividing the time current is actually on bythe total treatment time, is so short (typically 1 -2 % ),

little to no skin irritation typically o ccurs. Converselydermal injuries are a concern when using DC, whichby definition has a duty cycle of 1 00% . Russian,biphasic, and interferential currents are classifiedas PC because they do not fit the strict definition ofeither DC or AC. The major applications of electro-therapy add resse d in this article are outlined in Table1. The information in the table should be viewedas suggested starting points, not as strict protocolsThese suggestions are based on current theory andclinical experiences but should b e m odihed accordingto specifications of the electrical generator and theindividual needs of the patient.

OutcomePain relief(gate control)Fain relief(opiate)

Musclestrengthening^

Long-standingdenervatedmuscleEdema controlIontophoresis^

Wound man-age mem'

T A B L E l . G E N E R A L S E T T I N G S F O R E L E C T R O T H E R A P YWavfformPC or AC

PC or AC

AC 2500 Hz; PC(Russian, HVPC.biphasic. Inferen-tial. NMES)DC

HVPC

DC

HVPC

P o l a r i t yNA

NA

NA

NA

NegativeBased oncharge ofmolecule tobe driven-1- to attractmacrophages,- to attractfibroblasts

PulseSettinqHigh (100-Kpps)Low (1-5 pps)for m uscle con-traction andacupuncture

Moderate (50-75 pps)

NA

120 ppsNA

100

ElectrodesElectrode overpainful areaSmall electrodesor probe overmotor point oracupuncturepointMotor points

Over muscle

Underwater orlarge surfaceOver targetedtissue

Active electrodein wound oradjacent towound edges

Output90% of visiblemotor thresholdor tingleMuscle contrac-tion or noxious

Maximal con-traction withinpatient tolerance;10 so n, 50 soffMotor threshold

90% of visiblemotor thresholdLow current

Tingle

Note. See references For specific set-up. PC = pulsed curren t: AC = alrernaiing curren t: pps = pulses/s: hfVPC = high-voltage pulsed curre nt. NMES = neuro muscular electrical sEimulation.

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Pain ManagementAcute pain management is often a goal for certifiedathletic trainers who use electrotherapy. Clinicians arekeenly aware that managing pain and swelling is anessential starting point in all rehabilitation programs.Unchecked pain leads to further inflammation anddelays implementation of exercise that restores rangeof motion, strength, balance, neuromuscular control,and functional activity. Electrotherapy is well estab-lished as a safe and effective m ethod of man aging mus-culoskeletal pain. Historically, Melczak and Wall's gate-control theory has served as the primary model for painrelief. Sensory but submotor ES is thought to influencepain perception by stimulating large-diameter afferentfibers, which in turn reduce pain by inhibiting trans-mission of pain stimuli to the brain. Exact parametersfor waveform, pulse rate, and phase duration have notbeen established experimentally, but most treatmentsbased on gate-control theory consist of sensory-levelstimulation (perceived as tingling) applied at high pulserates {IOO-F pulses/s) for extended periods of time(hours or days) via smail portable stimulators. MostTENS units produce biphasic waveforms and thereforeare classified as PC or AC stimulators .

Sensory-level TENS effectively redu ces mu scleinhibition after laboratory-induced knee effusion. 'TENS might reduce muscle inhibition by decreasingfunction of Ib-inhibitory interneurons or by stimulat-ing la-excitatory interneu rons, both of which might beplausible mechanisms for decreasing muscle inhibi-tion that accompanies joint swelling.

Interferentiai currents are also used to managepain, but no more effectively than traditional TENS.-Interferential-current stimulators produce two sinewaves that are slightly out of phase. These two wavessummda- and create a resultant wave, referred to as anamplitude-modulated wave. Theoretically, this resul-tant wave penetrates deeply into tissues. Electrodesare usually arrang ed in an X patte rn over the targetedtissue or pain site.

Clinicians can also choose from a variety of tech-niques collectivelv known as opiate-mediated paincontrol. Strong eh^ctrical stimulation of motor points,trigger points, aci ipuncture points, or painful tissue canalso be used to treat pain by inducing the release ofendo geno us op iates. Current theory suggests that painrelief is attributable to chemical inhibition of noxious

Fiqun I Application of noxious stimulation using a probe for opiatepain relief.

input at the dorsal horn of the spinal cord. Electricalcurrent is applied by a probe to a very small area,at low pulse rates (1-5 pulses/s), and at amplitudessufficient to elicit motor contractions. Alternatively,clinicians can apply focused stimulation over triggeror acupuncture points until the patient perceives anoxious effect for 30-60 s (see Figure 1). Athletesoften report significant pain reduction and a senseof mild anesthesia after treatment. The physiologicalmechanisms underlying such effects are elusive andnot fully understood. Enkephalins inhibit transmissionof painful stimuli along neural pathways, and thereis some evidence that ES, as just described, mightstimulate enkephalin production. Some clinicians useboth the gate-control and the opiate-mediated pain-control theory on the sam e patient at different stagesof the rehabilitation process. For example, duringearly stages of an injury when pain is intense andmuscle contractions are unwanted, clinicians mightchoose typical gate-control settings (i.e., amplitudesufficient to produce a strong tingle, high pulse rate.100 or greater, applied continuously for long periods).After acute pain has decreased they could implementopiate-based pain relief, which generally includesamplitudes that minimally cause muscle contractionor noxious sensation, typically at much lower pulserates ranging from 1 -80 pulses/s .

Electrically Induced Muscle ContractionsAthletic trainers and therapists have a long history ofusing ES to elicit muscle contractions. Pain, swelling.

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immobilization, and surgery common ly cause surround-ing musculature to "shut down." Improved surgicaltechniques, including more arthroscopic techniques,and a m ove me nt toward early mobilization after injuryhave reduced the need for electrically induced musclecontraction over the past 10-15 years. Even with theseadvances, however, patients still present with decreasedmuscle strength postsurgery. Specifically, pain, swell-ing, and immobilization after ACL-reconstructive sur-gery result in reduced strength of quadriceps muscle.Snyder-Mackler et al.-' establishe d that high-level electri-cal stimulation was effective in recovering quadricepsstreng th during early rehabilitation after ACL reconstruc-tion. Generally, the current is 2,500 Hz AC delivered at5 0 -7 5 pu lses/s for 10- to 15-s intervals, followed by arest cycle of 50 s. The stimulus intensity is sufficientto invoke muscle contraction and is increased up topatient tolerance.

Denervated MusckOccasionally, athletic trainers might treat patients whocanno t perform a volitional muscle contraction becaus eof denervation. Some forms of TENS that produce pulsesof exceptionally long duration can cause denervatedmu scle to con tract. M ost clinicians, however, choose DC,or galvanic, stimulation to invoke muscle contractionsfor these patients. Because the nerve is dam age d or notfunctioning. DC stimulators are designed to provide aconstant flow of current to directly depolarize muscle.

Edema ManagementEdema, a natural part of the inflammatory process,is initiated by virtually any trauma including athleticinjuries. Uncontrolled edema can increase pain, pro-long imm obilization, reduc e range of joint mo tion, an dinhibit ligament healing, all of which can extend timeto recovery. Swelling, or edema, is formed as inflamma-tory mediators released after injury cause gapping ofendoth elial cells lining the blood vessels. Such gap pingallows plasma proteins, leukocytes, and water to leaveblood vessels and move into intercellular space, causingede ma . Reed" dem onstra ted that one form of ES, high-voltage pulsed current (HVPC), limits permeability ofmicrovessels, thereby reducing th e amo unt of fluid thatescapes into tissue spaces. The mechanism of actionrem ains unk now n. Output from HVPC genera tors is

typically in the form of short (8-iO | A S ) monophas itwin peaks delivered at 10 0-1 20 pu lses/s. Such outpuis characterized by high peak voltage but low averagcurrent. High-voltage stimulators enable clinicians tchoose either positive or negative polarity, but becausof low average current and duty cycles, skin injuriecaused by changes in skin pH are unlikely.

Recent work has established that cathodal HVPCdelivered at 120 pulses/s at 90% of visible motothreshold curbs edema formation as effectively asome forms of cryotherapy' ' or nonsteroicial antiinflammatory drugs (M.G. Dolan et a!., unpublisheddata, 2004). Clinicians should be aware of two keyfactors: (a) Electrical stimulation and other interventions should be applied as soon as practically possible because it appears that acute edema formationcan be curbed but, once formed, cannot be reducedand (b) duration of treatment is critical. It seems thathese treatments are effective only while the currenis actively applied. This suggests that near-co ntinuo utreatmen t is neede d throughout the acute inflammatory response." If so, the common clinical practice foacute athletic injuries might need revision. Currentlywe are applying electrical stimulation as a primarfirst-aid treatment to athletes who have sustaineinversion ankle sprains. This is in addition to the traditional ice, com press ion, and elevation. ES is appliedvia sock electrodes and small portable electrical stimulators, which allow near-continuous treatment (23+hr/day) while the inflammatory process is ongoin(see Figure 2).

Figure I Use of electrode sock and portable stimulator for continuouapplication of high-voltage pulsed current for edema managemenafter an acute ankle sprain.

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IontophoresisIontophoresis uses bipolar electric fields to propelmolecules through intact skin and into underlyingtissue. Analgesics and anti-inflammatory medicationare "driven" into tissue using electrical charges deliv-ered by DC gen erato rs specifically man ufactured foriontophoresis. For example, dexamethasone, a nega-tively charged anti-inflammatory medication, is placedunder the cathode, which is placed over the targetedtissue. Because like charges repel, the cathode forces(repels) the negatively charged medication into thetissue- Iontophoresis is sometimes considered "injec-tion without a needle." but its clinical efficacy rem ainsin doubt. Evans et a!.' reported that iontophoresis oflidocaine into myofascial trigger po ints was statisticallysignificant. Small effect size, however, which indicatesthe clinical meaningfulness of the treatment, suggeststhat iontophoresis had little clinical effect. Depth ofpenetration and the ability of electrical generators todeliver appropriate dosages of medication are com-monly debated among clinicians and researchers.Recent work in this area suggests that diffusion, notthe m agnitude of the repelling current, determines thedepth oF penetration of the drug molecules.^

Augmenting W ound Managementof all the proposed applications of ES, none is bettersupported by basic science and controlled clinicaltrials than its use in chronic-wound management."Most athletic trainers have limited clinical experi-ence in managing wounds such as decubitus ulcersor wounds caused by systemic diseases such as diabe-tes or peripheral v ascular d isease. As athletic trainersexpand their practice into nontraditional settings suchas hospitals and clinics, however, they will encounterthese clinical conditions.The transepiderm al electrical po tential, or epider-mal battery, is an electrical potential that normallyexists between the epidermis and deep er body fluids.Wounds in skin allow current to flow from inside tooutside damag ed tissue as long as the woun ds remainopen and moist. The "wound current" is what isthought to "inform" inflammatory cells to migrateto or alter their behavior to effect wound healing.For reasons still unknown, this wound current failsto materialize in some wounds, and, presumably as

a consequence, these wounds fail to heal. By induc-ing "artificial wound currents" with low-current ESsystem s, many researchers and clinicians have closedwounds that had remained open for months or years.Note that wound closure and wound healing are oftenused as synonym ous phrases. In the context of chronicwounds, wound closure might not mean full healing ofdeep er tissues, but in som e instances, it can m ean thedifference between amputation and sparing a limb.

Kloth'" suggests two methods of applying HVPCfor wound management. Using sterile techniques,one electrode is placed directly in a wound and theother is placed nearby on healthy tissue. The secondtechnique involves placing two electrodes of thesame polarity adjacent to wound edges and a dis-persive electrode on nearby skin. In either case, theactive electrodes (in or adjacent to wound) are set topositive to attract negatively charged neutrophils andmacrophages. To facilitate wound closure, the activeelectrodes are negative to attract positively chargedfibroblasts. HVPC is delivered at 100 pulses/s at sub-motor levels 1 hr/day until the skin closes. ES shouldbe considered an adjunct to moist-wound healingand should be performed by health-care profession-als with specialized training and clinical experiencein this area.

SummaryElectrical modalities are integral components of ath-letic training education and clinical practice. Electro-therapy will continue to evolve, we hope, based onits efficacy and cost effectiveness, and not on testi-monials and claims by clinicians and manufacturers.As athletic trainers continue to strive for recognitionas more autonomous health-care professionals, wemust insist that our clinical practices and educationbe guided by sound research. I

References1 Hopk ins JT, Ingersoll CD. Edw ards j , Klootwyk TE. Cryothera py

and i ranscutaneous elect r ic neuromuscular st imulat ion decreasearthrogenic muscie inhibition of the vastus medialis after knee jointeffus\or\. J Athletic Train. 2002:37:25-31 .

2. John son Ml. Tabasam G. An investigation into the analgesic effects ofinterferential currents and transcutaneous electrical nerve stimula-tion on experimentally Induced ischemic pain in otherwise pain-freevolunteers. Phys Ther. 2003:83:208-223.

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3. Snyder-Mackler L, Delilto A, Bailey SL, Stralka SW. Strength of the quad-riceps Femoris muscle and functional recovery after reconstruction ofthe anterior cruciate ligament, a prospective, ran dom ized clinical trialof electrical stimu lation.y Bon eJoin rSur^/4 m. 199 5:77:1166-1173.

4 . ReedBV. Effectof high voltage pulsed electrical stimulation on micro-vascular permeability to plasma proteins, a possible mechanism inminimizing edem a. Phys Ther. 1988:68:491-495 .

5. Dolan MC. Mychaskiw AM, Mendel FC. Cool-water immersions andhigh-voltage electrical stimulation curb ed em a form ation in rats, yAthletic Train. 2003:38-225-230.

6. Dolan MC, MychasKiw AM, Mattacola CC, Mendel FC. Effects ofcool water immersion and high-voltage electrical stimulation for 3cont inuous hours on acuie edema in raxs. J Athletic Train. 2003:38:325-329 .

7. Evans TA, KunklejR. Zinz KM, Walter JL, Denegar CR. The immedi-ate effects of lidocaine iontophoresis on trigger-point pain.7 SportRehabil 2001:10:287-297,

8. Anderson CR. Morris RL, Boeh SD, Panus PC, Semb rowich WL. Effectof iontophoresis current magnitude and duration on dexamethasonedeposition and localized drug retention. Phys Ther. 2003:83:161-170

9. Cardner SE, Frantz RA, Schmidt FL. Effect of electrical stimulationon chronic wound heal ing: ameta-analysis. Wound Repair Regen1999 :7(6) :495-503.

10. Kloth LC. How to use electrical stimu lation for wou nd healing. Nursing. 2OO2:32(12):]7.

Michael Dolan i s the Peter Canisius Dist inguished Te aching Professorin t he Depar tm ent of Spor t s Medic ine , Health d Hum an Per formanceat Canisius Col lege in Buffalo. NY, His resea rch interests include acu tet r auma ma nag eme nt , f oot or thot i cdevices . and eff icacy of anklebrac ingFrank Mendel i s an asso ci a t e professor and v i ce chai rm an of t heDepar tment of Pa thology and Anatomica l Sc i ences a t t he S t a t e University of New York at Buffalo, His research interests include efficacyof var ious t r ea tment s for spr a ins and contus ions .

UPCOMNGTHEMESNovember Appl i ed Cl in i ca l ResearchThomas W. Kaminski. PhD. ATC/R. University of Delaware

January 2005 S p o r t s -M e d i c in e P h a r m a c o l o gyGary L. Harrelson, EdD, ATC, DCH Regional M edical Center, Tascaloosa, AMarch E m ergen cy Care i n Athl e t ic Tra in ingMarisa A. Colston, PhD. ATC/L, University of Tenn essee at Chattanoo gaMay

SeptemberNovember

E m e r g e n c y P r e p a r e d n e s sKatie Walsh, EdD. ATC-L. East Carolina UniversityCore Stabi l izat ionGary L. Harrelson. EdD, ATC. DCH Regional M edical Center. Tascaloosa. AM a n a g e m e n t o f L u m b ar S p i n e D y s f u n c t io nMarisa A. Colston, PhD, ATC/L . University of Ten nessee at ChattanoogaPro f e s s i ona l Work Sat i s f ac t i onfiary L. Harrelson. EdD, ATC. DCH Regional Medical Center, Tascaloosa. A

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Aplicacion Clinica de Electroterapia

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