C H A PTE R 16

Electrical Stimulation for Wound Healing Carrie Sussman and Nallcy By!

INTRODUCTION

Electrical stimulat ion (ES) for wound healing has achieved acknowledgment by the medical community. resulting in morc referra ls. All ES procedures a re not alike. creating con­fusion about which one to use for wound healing. This chap­ter tries to stra ighten out some of the confusion. It begins wi th defi nitions and terminology used to discuss and distin­guish e lectrica l stimulation parameters. The second sec tion de tails the science and theory oCtile therapy and re lates back to the parameters. Clinica l decision making applies the sci­ence and theory by considering the indications for the therapy, reasons [or re ferra l. medica l history. and systems reviews that are pa rt of the diagnos tic process. Thi s section is fol­lowed by description o flh e equipment and accessories used, the ra tionale fo r se lection of pro tocols. the expected out ­comes, and the patient sc t-up. Since ES is a treatment inte r­vcntion that can be taught to patients or other caregivers, se lf-ca re teaching guidel incs arc included. Case studies ap­plying the fun ctional outcome report (FO R) to document the ra tionale for selection of e lectrical stimulation as the inte r­vcnt ion fo llowed by a discussion revealing the c linical deci­sion-making process and the actual outcomes conclude the chapter.' Chapter 2 describes the FOR.

DEFINITIONS AND TERM INOLOGY

Electrica l stimulation for wound hea ling is defined as the use of a capac it ive coupled e lectrical current to transfer en­ergy to a wound . The type o f e lectri ci ty that is transferred to the target tissue is cont ro lled by the e lectrica l source.2

Ca pacitive Cou pling

Capacitive ly coupled ES involves the transfer o f e lectric Clirrent through an appl ied surface e lectrode pad that is in wet (e lectro lytic) contact (capacitively coupled) with the exte rnal skin surface and/o r wound bed . When capacitively coupled ES is used, at least two e lectrodes are required to complete the e lectric circuit. Electrodes a re usually placed over wet conductive medium : ( I) in the wound bed or on the skin a di stance away from the wound- monopolar technique, or (2) straddling the wound- bipolar technique.

Am plitude a nd Voltage

Amplitude refers to e ither the voltage or the current in­tensity o f an e lectric current. Voltage is a measure of the force of the fl ow o f electrons and amperage is the measure o f the rate of fl ow of the current. When vo ltage is turned up, the current will also go up, and vice versa. Some stimulators provide a readout o f voltage and some a readout of current. The relationship between voltage and current is expressed as Ohm 's law. The formul a for th is is current times resis­tance equals voltagc [V = I R, where V is voltage, I is cur­rent , and R is res istance]. In genera l, low-voltage devices produce voltages o f ditTerent ranges from 60 to 100 V. High­voltage devices range from 100 to 500 V. Thcse arc pcak ranges.

357

Amperage

The unit o f current is the ampere (A), which is defin ed as the rate at which e lectrons move past a certain po int. A mil-

358 W OUND CARl

liampcre (mA) is onc thousandth oran ampere. and a micro­ampere (~IA) is onc millionth of an ampere. Microampcragc current is lIsually between 5 and 20 ~A of current ( less than 1.0 mAl.

C harge

Electrical charge is the excess or deficiency of electrons or ions. An electrically neutral substance that loses electrons becomes positively charged, and i f it gains electrons it be­comes negatively charged. The unit of mcasurc for charge is the coulomb. In bio logic systems the charges are small and ex pressed in microcoulombs (fl )] A typical high-voltage stimulator. for example, has a maximulll pulse charge of only 10 to 15 ~I C. which is very safc."'(pli5I The charge density is the electrical charge per cross-sectional area of the electrodes. The larger the size of the electrode the smaller the charge densi ty, and conversely.

I'olari ty

Polarity refers to the propcrty of having two poles that are oppositely charged . The positive po le is ca lied the anode and the negative pole the cathode. The positive pole lacks elec­trons and attmcts electrons from the negative pole , or ca th­ode. Polarity can be chosen or emphasized for biologic ef­Iccts.

\ \'avcfo rms

Different types o f current have diITerent characteristic waveforms. Waveforms are the graphic representations of a current on a current/ time or vo ltage/time pIOL) Waveforms arc classified by the direction of current flow. Current flow is e ithe r unidirectional o r bidirectional. Figures \6- \ lO

\6- 6 show examples of direct current. monophasic square wave pul sed currenl, twin peaked pulsed monophasic cur­rent, alternating current, and balanced biphasic and asym­mctric biphasic waveforms. Each waveform and related char­acteri stics a rc descri bed.

Direct C urrent

_ nidirectional current is also ca lled galvani c or direct currelll (Figure 16- 1). Direct current (DC) is continuous, uninterrupted, unidirec tiona l current. Direction of the flow is determined by the polarity selected . Direct current wave­forms may be subdivided into pulsatile currents (PC).

Time DIRECT CURRENT

•••

Figure 16-1 Graphic representation of the unidirectional now of charged part icles. Source: Reprinted wi th permission from ElecllVlherapelllic Terminology ill Physical Thempy, p. II. C' 1990. Section on Clinical Elect rophysiology and the American I)hysical Therapy Association.

Pulse (phase)

~ I I

•

•

Interphase Interval

•

Cvcle Time

I-- r--

• MONOPHAStC PULSED CURRENT WAVEFORM

Note: tn a monophasic waveform, phase and pulse are identical.

Figure 16--2 Graphic rcprescnlJtion of monophasic pulses. Source: Reprintcd with permission from Elecllvtherap(!wic Terminology i" PhYSical Therapy. p. 13. 1990, Scction on Clinical Elcc tro­physiology and the Americal I)bysical Therapy Association.

Mo noph asic Pulsed C ur rent

Pu lsed current is phasic. Monophasic pulsed current is defined as pu lsed direct current (PC) that deviates from baseline and relUrns to baseli ne after a designated timc pe­riod. The monophasic pul sed current waveform may be ei­ther a square wave or the traditional twin peaked pulsed wave of the high-voltage pulsed current. Monophasic pulses and phases arc identical (Figure 16 2). Monophas ic waves are such that at one electrode the polarity is positive and the other is negative. This s tays constant throughout the treat­ment unless changed by the clini cian. Pola rity appears to have specific eITects on biologic responses.

Fre'luency or Pulse Rate

A pu lse rate or frequency is the number of pulses dcl iv· cred per unit of time. TIle rate of the ofT and on cycle is defined as pu lses per second (pps). The mnge of pulses per second is usua lly from 0.1 l iz to 999 Hz.A pulse of 0. 1 Hz is on for 10 seconds and a pu lse of999 Hz is on fo r I mill isec­ond. The time between pu lses when no electrical activity occurs is the interpulse in terva l (Figure 16- 3). Pulsed elec­trica l sti mu lation (PES) has a trai n of pulses that are repeated at regu lar intervals and arc termed the pulse ratc or pul se frequency. Pulsed current can be ei ther unid irectional or bid irect ional.

Pulse Duration

The on time duri"-£ which curren t is fl owing is the pulse duration. Pulse dura tion arTccls biologic responses. For ex­ample. direct Clirrent has a continuous du ration and has the ability (0 raise tissue temperature and change the pH under the electrode. However. a short pulse duration, typical of high­voltage pulsed current , produces insigni fica nt changes in both tissue pH and tiss lie temperature:' 6 Such a current is therefore very safe but raises questions about the effect of

PUlS( CHAliCE

-1': ._ L _._ I ~ 'oooo~ .. c ~

Figure 16-3 Typical pulse characteristics of a high-voltage sti mu­lato r. Source: Rep rinted with permiss ion fr0111 A Ion G, Dc Domenico G. I-ligh ~vltage Stimlliatio,, : All Integrated Approach to Clil/ical Electrotherapy. 1st cd .. p. 62. 1987. Hixton. TN: The Chattanooga Group.

Electrical Stimlliatioll for WOlllld /-Iealillg 359

polarity when the pul se duration is so short. For purposes of muscle stimulation, the stimulation must be provided at an intensity and a duration that will stimulate a muscle contrac­tion. If the goal is to keep the sti mulati on tolerable, the am­plitude may be kept as low as possible, forc ing the dura tion of the st imulus to be longer. Muscle is most sensit ive to a stimulus from a negative electrode. When providi ng electri­cal stimulation to denervated muscle, some recommend that the st imulus beon for only I and 50 mi lli seconds. 7

•K Because

high-voltage pul sed monophasic current has a shorter pul se duration it cannot be used to stimul ate denerva ted muscle. For pain management and wound hea ling, the pulse duration and the amplitude of the current are variable. Some clin i­cians and researchers suggest that thi s current must be on for al least 1 second 10 produce strong polarity efTects of the tissue under the electrodes.

Duty Cycle

Thc on/otTratio is the rat io of the timc the cur rent is on to

the timc the current is off. A du ty cycle is the ratio of 011 time to the IOwl cycle time includ ing both the on and off time (Figure 16- 2). A rat io is used 10 express the relative propor­tion of the on and off time and can be expressed as a per­centage. For instance, if the total cycle is 60 microseconds, the on time is 20 microseconds, and the off time is 40 micro­seconds, there is a 1: 2 on/otT rat io and the du ty cyc le is a 1:3 ratio, or a 33% duty cycle.

Uigh-Voltage Pulsed C urrent

High-vo lt age pul sed curren t (HVPC) typ ica lly has a twin peaked monophasic waveform (Figure 16- 3). HVPC is a misnomer if ga lvanic is used with it. Th is current was named incorrectly by the manu fact ure rs. The acronym HVPC does not have galvanic in the acronym. The pul se rate 1110st fre­quently used for wound hea li ng is 50 to 120 pps (0.83 to 1.25 mill iseconds). Each peak or spi kc has an effective 5- to 20-microsecond phase duration. Vo ltage can be se lected with in tensity between 100 and 500 V. The ampl itude selected fo r wound healing is usually between 80 and 200 V, and the po­larity and pulse rate are varied. There is a long intcrpul se interval between pulses that makes a low average current. The high-voltage st imulat ion has a high peak current that means greater penetration into tissue, allowing fo r sti mu la­ti on of deep Illotor points:'II'P59 71) On the skin surface, alka­line/ac idity changes under the electrodes have not been mea­sured.s.6 Since HVpe is not galvanic, th is ex plains why there is no alkaline/acidity effects. Absence of chemica l changes under the electrodes has led to questions about how polarity efTects can be the factor that stimulates ce llular responses

360 W OUND CA"'

when the duration of the IIVP pulse is so short. However, multiple studies demonstrate different effects under the an­ode and cathode using I-IVP . Table 16- 1 lists errects re­ported by v~lrious rcse .. u chcrs using HVpe that nrc polarity depcndent. For instance, one study showed that fibroblasts were attracted to the cathode of an HVPC stimul ator, sug­gesting that there may be some cellular polarity effects un­der the electrode." Although multiple studi es show cellular crrects and responses to HVPC, each study shows something different: there fore. corroborating research is needed to sup­port the findin gs of these single studies.

Microcurrcnt Electrical Stimulation

A pul sed monophasic stimulus is referred to as monopha­sic low-voltage microcurrcnt electrical stimulation (MENS). This refers to a pulsed current at an intensity less than I mA ( I to 999 ~IA) and the voltagc is less than 100 V. MENS is delivered at amplitudes that have minimal detectable sensa­tion and are incapable of motor nerve stimulation . ME S typically has a si ngle modi fied monophasic square wave­form . The pu lse duration o f these devices ranges from 0. 1 to 999 liz, cq uiva lent to on timc of 10 seconds to I microsec­ond. The pulse duration is inverse ly related to the frequency. Microcurrent stimulation has a prolonged pulse duration at the lower frequencies. which will have a different tissue po­larity effectthall a shorter-dura tion pulse most typically used in high-voltage stimulation. For example. a low-vo ltage pul sed stimulus at 0.1 H/ is 0 11 for 10 seconds, whereas the high-vo ltage monophasic simulators arc used at 80 to 120 pps and arc on for only 0.83 to 1.25 milliseconds_ Thus. pu lsed low-voltage current of at least I pps can mai ntain the polarity effect delivered to the ti ssues under the electrode. The peak ampli tude is usually 600 ~IA/60 V. The average amplitude commonly used is 200 to 300 ~A for soft ti ssue' and 20 ~lA for bone hea ling in rabbits. HI ME current has been used in bone healing; howevcr. in thi s clinica l applica­tion. the amplitudc rccol11mended is 20 to 50 ~lA (bonc hea l­ing research). When pulsed slowly. there arc reported ccllu­la r and tissuc polari ty effccts under thc elcctrodcs. 11 Th is type of current may be used 10 restore the normal bioelectrical resting current or reversc the injury currcnt. II Therc is somc concern that the vo hagc may bc 100 low to push the current through thc resistance of the skin and the subeUlaneous ti s­sues. but no specific studies could be found to confirm this.

Alternating Current

Bidirectional waveforms me referred to as faradic or al­tcrnating as well as biphasic or bipolar. Brit ish literature uses the tcrm "faradic" for all alternat ing current. probably in reference to the scienti st Faraday. In the United States. fa-

radic is no longer design cd in ES units bccause it is very uncomfortable. Alternating current (AC) is unin terrupted bidirectional current now (Figure 16-4). The waveforms may be symmetric. where the shape of the waveform is always balanced . Both the shape and size are the same. A n asym­metric waveform can be balanced or unbalanced (see Fig­ures I 6-5 A and 16- 59 ). One of the most comlnon outputs from an electrical stimulator is balanced asymmetric. A bal­anced asymmetric waveform is typical of transcutaneous elec­trical ncrve st imulation used for pain modulation (Figure 16-5). Biphasic waves are such that the polarity is constantly changing. They are opposite at any moment in time. But the waveform can be biased so that one polarity is emphasized . Several studies using this type of current for wound healing have been reported in the Iiteraturc. The best wound healing effects seem to be achieved whcn a biphasic waveform is asymmetric and biased so that the polarity at one pole pre­dominates. The effects of stimulation with th is waveform on wound hca ling is di scussed further in fo llowing scctions.

Time

SYMMETRICAL ALTERNATING CURRENT

Figure 16--4 Symmetrica l ahernating (biphasic) waveform . Source: Reprinted with permission from £lel'rIVrherapeuric Terminology ill Physical Therapy, p. II. 0 1990. Section on Clinica l Electro· phys iology and the American Phys ical Therapy Association.

" " .~

f ~-L--4-----~r----L--+-----~----C ~ ~

o

Time BALANCED ASYMMETRICAL BIPHASIC WAVEFORM

Figure 16-5A Balanced asymmctrical altcrnating (biphasic) wave­form . Source: Reprinted Wi lh permission from Elecrf'Orherapeuric Termillology ill PhYSical Therapy. p. 12. 1990. Section on Clin i­cal Electrophys iology and the American Physical Therapy Asso­cia tion.

Time UNBALANCED ASYMMETRICAL BIPHASIC WAVEFORM

Figure 16- SIJ Unba la nced asymmet ri ca l b iphas ic wa\cforlll. Source: Reprinted wi th permission from Electrotherapeufic Ter­millology ill Physical rlleropy. p. 15. c 1990. Sect ion on Clinica l Electrophysio logy and thcAmcrican Phy~ic;] IThempy Association.

THEORY AND SCIENCE OF ELECTRICAL STIMULATION

BioeleClric~ll Systems

The body has its own bioelectrical system. Thi s system influences wound h~aling by allracting the ce lls of repair. changing cell mClllbrane permeability. enhanc ing cellular secret ion through cellmcmbrancs. and orient.ning cel l struc­tures.

Sodium Current of Injury

The iJ1lact skin surface maintains an average constant elec­tronegath e charge of approximately 23 mV with respect to

the deeper epidermal layers. The negative charge on the sur­fa ce is created by negati vely charged chloride ions (CI ). \\ hich stay on the surHlce aftcr positively charged sodium ions (Na ) arc pumped into the inner layers of the epidermis by the sodiulll ion pump. Thus. the sk in has electrica l poten­tia ls across it and it ac ts as a battery. When there is 1.1 break in the sk in surface. currelll can now between the parts of the sk in transmi tted through the ionic fluids of the tissues be­tween the outer and inner layers of the s kin l~ (see Figure 16 6). Regenerating tisslles show a dist inct pattern ofunidi­rcct ional current fl ow and po lari ty sw itching. As healing is completed. or arrested. these currents disappear. When ul­cers become dry. the vo ltage gradient is eliminated and the current di sappears. II Th is has been suggested as an ex plana­tion of why moist wounds hea l beller than dry wounds. One rationale for applying electrical sti mulation is that it mimics the natural current of injury and will jump-start or acceler­ate the wound healing processY

Galvanotaxis and Polarity

Unidirect ional electrical current fl ow in the tissues attracts the ce ll s of repair and is ca ll ed ga lvanotax is. The re is a signif'icant body of research that demonstrates that polarity

Electrical Stimulatioll /in' Wouud Ilealillg 361

Figure 16- 6 C urrent path in wounded sec tion of skin . Dis ruption in epidcrmis has provided a rcturn p::llh for currcnt dri ve n by transepithc lial pOlcntia!. Source: Reprintcd with permiss ion from Clinics ill Dermatology. Vol. 2. l.F. Jan"c :.md J.\V. Vnnablc. Elec­tri c Ficlds and Wound Ilealing. pp. 34 44, 1984. Elsevier Science. Inc.

Clinical Wisdom: Moist Wounds Promote the "Current of Injury"

Keeping a wound moist with normal (0.9%) saline (sodium chloride) maintains the optimal bioelectric charge because it simulates the electrolytic concen­tration of wound fluid , Dressings such as amorphous hydrogels and occlusive dressings help promote the body's "current of injury" by keeping the wound envi­ronment moist.

innuences hea ling in different ways at different phases. Table 16-1 summari les Ihe cellular e!Tects by phase of wound healing. Table 16- 2 summarizes the polarity efTects 011 other aspects o f'biologica l systems related to wound healing.

Neutrophi ls. lymphocytes. platelets. and l1l <lcrophagcs arc early responders to injury and start the innal11l11atory re­sponse. The neutrophil s arc attrac ted to the negative pole if the wound is infected to the posi ti ve pole ifnol infected.'" Lymphocytes and platelets are attracted to the negative pole .1} Macrophages arc attracted to the positi ve poleY These ce lls fight infection and produce chemotactic and growth-stimu­lating cytokines needed to repair or regenerate the tissue. Autolysis and phagocytosis are med iated by the l11acro­phages and ncutrophil s. Thus. a suggested clin ica l applica­tion of elect rical current that integrates these principles wou ld be as follows: for a wound that is necrotic. but 110t infected lise a pos itive electrode over the wound to promote autoly­sis. and put the negative electrode over the wound if it is infected. If) However, for the treatment of diabetic ulcers.A lon et al. Ll sed posi tive polarity with HVP throughout the course of care .l ~

Fibroblasts arc key ce lls in contraction and connective tis­sue formation . Fibroblasts arc attracted by the negat ive pole

362 WOUND C\RI

Table 16-1 Galvanotactic Effects on Cells by Phases of Healing

Effect

Inflammation: autolysis and phagocytosis

Proliferation: fibroplasia (collagen formation)

Wound contraction

Epithelialization

Cells

Macrophages H Neutrophils (± ) Mast cells (decreased) H

Fibroblasts (+)

Myofibroblasts (+)

Epidermal cells H

Pole

Anode Anode/cathode Anode

Cathode

Alternating

Anode

Table 16-2 Polarity Effects of Electrical Stimulation

Effect Pole Researcher

i Blood flow Negative Mohr et al.28

Politis et al.29

Pollack'" Gentzkow et al. 13

I Edema Negative Mendel and Fish" Reed" Ross and Segal"

Debridement Negative Sawyer"'"""

Thrombolysis Negative Sawyer"'-36

Thrombosis Positive Williams and Carey"

Oxygen Anode Byl et al.38

Oxygen Alternating Baker et al. 39

Wound contraction Alternating Stromberg ,g

Tendon repair Positive Owoeye et al.<Io

Bacteriostatic effects Both Barranco et al .. 41

Rowley et al. 42

Kincaid and Lavoie43

Szuminsky et ai"

Type of Current Researcher

DC Orida and Feldman's DC Fukushima et al. u;

Kloth " PES, 35 mA, 128 Weiss et al. 22;

pps Gentzkow and Miller12

HVPC, 50 V, 100 Bourguignon and pps Bourguignon23

DC, 1o-100~VI Canaday and Lee" ; cm Erickson and

Nuccitelli2S

DC, 1500 mV/cm Yang et al. '"

HVPC Stromberg"

DC. 50 mVlmm Cooper and Schliwa"

Type of Current

HVPC PES PES PES

HVPC HVPC HVPC

DC

DC

DC

MENS, 1 00 ~A low volt

Asymmetric biphasic

PES

HVPC

DC DC HVPC HVPC

to proliferate and synthesize co llagen and to contract the wound rapid ly.'" Protein and DNA synthesis are enhanced by negative stimulation. Under si milar parameters. ca lcium ion (Ca" ) or uptake by fibrobla st cells is incrcasc(L which im­mediately produces an increased exposure of insul in recep­tors on the fibroblast cell surface. If insu lin is avai lable to bind, the addi tional receptors on the fibroblasts will signifi­cantly increase protcin and DNA synthesis. If insu lin is added after exposure to HVpe stimulation, further increase in Ca2•

uptake occurs and a twofold increase in protein and DNA synthesis. Therefore. timing of insulin delivery and HVPC treatment to diabetic patients with wounds may have a dif­ferent outcome. Conversely, these samc receptors are inhib­ited by Ca" channel blocker medicati ons. ' Slower hea ling can be expected in wounds if the patient is taking C~12' chan­nel blocker medication. When the clinician is taking a medi­cal hi story. the pharmaceutical hi story should be reviewed with these factors in mind. Drug effects could change the prognosis for heal ing.

The use of electrical stimulation to enhance the benefits of an tibioti cs is being researched. IS Research to investigate timing of drug delivery and physical therapy modal ity treat­ment to enhance effects of both cou ld open a new approach to intcrvcnrions.

Research on rapid wound contrac tion can also provide clinical guidance for treatment selection. Stromberg '9 found that pulsed monophasic current . alternating polarity every 3 days, at 128 pps and amplitude at 35 mA, accelerated wound contraction during the first 4 weeks after injury. Conversely he found that constant polarity, either negative or posi tive, was less efTeetive. Thoughtfu l application should be consid­ered in areas where rapid wound contraction would not be desirable. such as in the hand or neck.

Epidermal cells have been reported as migrating toward the posi ti ve pole. Animal studies demonstrate that, in the early acute inflammatory phase of hea ling. the rate of epidermal cell migration in dermal wounds is enhanced by 3 days of stimulation with a negative pole, followed by stimulation with the positive pole for 4 days. Closure was achieved in 100% of the treatment group and only 87% of control group. Com­parison of tensile strength and mitotic activity between treated and control groups was comparablc,20.21 This corresponds to a 0- to 3-day inflammatory phase and a 4- to 7-day repair phase of healing.

The goal of wound healing is a sca r whose characteristics are most like the original skin. Mast cells regulate thi s proc­ess throughout the healing cycle. A large number of mast cells in the hea ling wound are associated with diseases of abnormal fibroti c healing such as keloid formation. After exposure to positive polarity current, a decrease in mast cells, decreased scar thickness, and better cosmetic results were observed in treated wounds.ll

Electrical Stimulatio" fo r Wound Healing 363

Refining the choice of polarity for specific effects has been the subject of many research studies (Tables 16 I and 16-2). There will always be a need for additional research to explain and validate the effi cacy of procedures and proto­co ls. Meanwhile, readi ng and interpreting the current litera­ture builds understanding and professional j udgment. The physical therapist is the best-trained practitioner to under­stand and interpret the research pertaining to electro­therapeutic modalities. As such. the phys ica l therapist has an obligation to understand the physiologic implications of each treatmcnt intervent ion selected and 10 be responsible for accurately predicting outcomes.

In practicc, the issues of polarity and wound hea ling arc appropriate when referring 10 continuolls or monophas ic pulsed current. Even though the electrodes are marked as positive and negative for units that deliver AC, the imbal­ance of the charge of the electrodes is very small and not enough to affect the movemcnt of the ions under the elec­trodes. When using continuous current, a change in polarity is a change in the direction of the current and a clulIlge in the flow of the ions under the electrode. The studies demonstrat­ing thesc polarity effects have been done wi th continuous and pulsed currents, usually with the current 0 11 for morc than I second. One of the concerns in wound hea ling re­search is whether the polarity effects of monophasic pulsed current predictably occur under the electrodes when the du­ration of the current is on for such a very short period of time. For exampl e, with high-voltage stimul ation. th e monophasic waveform is on for less than I second (80 to 120 pps), and no measurable changes occur relative to alka­linity (W ) or ac idity (O H ).' The question is whether some cell migration is still faci litated by the polarity of the elec­trodes at the wound si te or whether some other factors ex­plain the physiologic effectiveness of externally applied high­voltage, pulsed currents for healing wounds. More research is needed to show that high-voltage stimulation creates mea­surable polarity efTects, or that other physiologic processes of hea ling are faci litated.

Although the efTects of polarity and wound hea ling have focused primarily on the movement of ions under the elec­trodes, there are other issues about current flow that could facilitate healing. For example, Wolf 's law"" '" states lhat un­der conditions of repetitive stTCSS, collagen is remodeled. One type of stress on a ti ssue is a mechanica l force, such as weight bearing. This weight bearing faci litates the deposition of coll agen in soft tissue and bone along the lines o f the force on the ti ssue. Mechanical forces on the ti ssue can al so be created when other types of energy are delivered 10 the tis­sue, sllch as ultrasound or electricity. When a sound wave pul sates or an electrical current pulsates, a force is created on the ce ll and it expands and contracts, creating a piezo­electric effect. It has been suggested that this piezoelectric

364 W OUN\} CARl

effect accounts for the increased collagen deposition :I1•4S

Thus. in pulsed current. it is possible that wound healing repair (collagen depos ition) measurement is facilitated by this mechani sm independent of the polarity effects of the e lectrode. I f this is truc, then biphasic current should have a piezoelectric effect. However, al this lime. biphasic current is rarely used for wound healing. In the future. this may change g iven that recent results of several studies document significant healing effects with biphasic current.

Blood Flow and Edema

Several studies in the literat ure reported improved blood flow after trcallllCIlI with electrical stimulation . Treatment with HVpe with negative polarity induced greater blood flow in rats than did posi tive polarity. The blood Ilow volume was increased nearly instantaneously at the pul se rates tested : 2. 20,80. and 120 pps. In addition, blood now was enhanced by increasing the amplitude of the current (Lip to stimulating musc le cOlllraction). In a small number of cases, however. blood now volume increased without visible muscle con­traction . Blood now velocity remained elevated from 4 10 20 minutes after treatmcIlL11I Necros is of skin naps and free full-thickness skin gra fts arc a major problem following plas­tic surgery. Severa l skin nap studics showed greater blood now increases following e lectrical stimu lation with a cath­ode in the treated naps than that with untreated naps.29JO . .t'l

Alonand De Domenico" rcvicwed the literature on the ef­fects of electrical stimulation on venous circulation. As yet electrical stimulation is not used extensively for management o f venous c irculation problems, but merits inclusion in this sec tion for thoughtful application. There is no support for intervention in the acute phase of varicose hemorrhage or deep vein thrombosis, but electrical stimulation can efTec­tively treat chronic conditions includi ng deep vei n thrombo­sis and venous stasis. When musclc groups in the ca lf and posterior thigh arc st imulated to produce intenniuent tctanic muscle contraction . there is very efTective enhancement of venous return in cases of venous insufficiency or deep vein thrombosis. The required stimulation parameters are those needed to provide motor excitation leading to evoked inter­mittent tetanic musc le contraction. Augmentation of the venous return initiates a response of vasodilatation of the arterioles to bring blood flow to the muscles. Enhanced blood now to tissues will support ti ssue demands for inc reased oxygen and nutrients required for healing. In the case of the patient with venous illsuiTiciency. stimulation of enhanced blood flow wi ll need to be eva luated and may require after­care of compression to avoid pooling of blood at the ankles due to the incompetent valves (see Chapter 9). If the arteri­o les are severely occ luded the vasodi latation response may not occur and (hen electrica lly evoked musc le contraction mny not be desired. In fact, the muscle contraction may calise

severe pain by curtailing limited blood now to the area lead­ing to ischemia. There is ve ry limited clinical data to sup~ port specific protocols for this efTecl. Therefore, it is up to the physical therapist to eva luate the vascu lar impairments based on the diagnostic process and select a protocol to sup­port the desired effect. The section 011 protocols and proce~ dures provides an example for guidance.

Kaada'IBl reported a causal relationship between transcu­taneous electrical nerve stimulation (TENS) and mechanisms involved in widespread microvascular cutaneous vasodilata­tion. Results showed that a 15- to 3D-minute period of T ENS­induced vasodilatation produced a prolonged vascular re­sponse with a duration of several hours or longer. poten­tially indicating the release of a long~lasting neurohumoral substance or metabolite. Kaada attributed the effects to three possible modes of action: inhibition of the sympathetic fibers supplied to skin vesse ls. release of an active vasodilator sub­stance. vasoactive intestinal polypeptide (V IP). or a segmental axon renex responsib le for affecting local circulation. The Kaada studies included reports of clinical results wherein patients served as their own controls of stimulation-promoted hcaling in cases of chronic ulceration of various etio l ogies. ~ l

Edema reduction under the negative pole is attributed to a phenomenon called cataphoresis. l.l Cataphoresis is the move­ment of nondissocia ted colloid molecul es. such as droplets of fat , albumin, partic les of starch. blood cells, bacteria, and other single cells. all of which have an electrical charge due to the absorption of ions. under the innucncc ofa direct cur­rent toward the cathode. Ross and SegaJ ll claimed benefit in treating postope rative edema, hea ling, and pain with HVPC. Effects of direct current on cdema werc attributed to cata­phoresis based on the effects of direct current. They formu­lated a protoco l based on the usc of the cathode to reduce edema. Albumin is a colloidal protein found in blood and is nega tively charged and is repe lled by negat ive polarity. caus­ing a nuid shin and thereby a reduction of edema. Several attempts have been made to learn whether the same effect occurs with HVPCy·l~ Reed 'l reported reduction of post­traumatic edema in hamsters following HVPC and attrib­uted the effect to reduced microvesse l leakage. Post­traumatic edema was curbed in frogs treated with 1-IVpe when the cathode was used. There was no effect if the anode was applied. Treatment effect was significant from the end of the first treatment session until the end of data recording 17 hours later.lI A similar study using HVpe on rat hind paws found significant treatment effects aflcr the second 20-minute treat­ment with the cathode. 2lI More investigation is needed to verify this phenomenon in humans.

Debridement and Thrombosis

Review of the rcsearch is a guide for the clinician and provides cvidcnce to support a protoco l for wound healing

initiated wi th the negative pole at the wound site. Debride­ment is facilitated if the tissue is solubili zed or liquefied such as occurs with enlymat ic debriding agents or autolysis. For example, necrotic ti ssues arc made up of coalesced blood elements. E using ncgath c current can solubilize this clot­ted blood .14 III

Reperfu sion of tissues is rapidly followed by autolytic debridement Increased blood now, stimulated by electrica l stimulation at the negat ive pole. has been attributed to hav­ing this enecl. When the clinical studies are compare(~ it becomcs clear that the negative pole has been used to ini­tiate treatment in all reported control led cl inical studies. Many of the wou nds in the treatment groups inc luded necrotic wounds.

The positive electrode has been found to induce clumping of leukocytes and forming of th romboses in the small ves­sels. These clumping and thrombotic effects can be reversed with the negative electrode. I' This may explain a clinical ob­servation. where hematoma and hemorrhaging at the wound margin or on granulation ti ssue are di ssolved and reabsorbed following application of llVPC with the negative pole. Hem­orrhagic materia l goes on to necrosis if not dissolved and reabsorbed quickly. Perhaps continuous use of positive po­larity produces the clumping of leukocytes and also explains why a protocol of intermittently changing polarity restart s the heali ng process. These are cri tical issues that need to be researched.

Antibacterial Effects

Because infection is a contributing factor in chronic wound hcaling, mcthods to control infcction arc of cli nica l impor­tance. Bactericidal effects have been attributed to electrica l stimulation. Rescarch suggests Ihat there is evidencc to sup­port this theory. In vi tro and in vivo studi es applying direct currCIll have bOlh been shown to inhibit bacterial growth rates for organisms cOllllllonly found in chronic wounds at the cathode."I."! Passage of positive current (anode) through sil ­ver wi re electrodes was found to be bactericidal to gram­negative bacteria in wounds and inhibitory to gram-posit ive wound bacteria." At low levels of amplitude, 0.4 to 4 !tA. thcre were ncgli gible bactericidal effects." l Kincaid and Lavoie'" tested in vitro sti mulati on. lIsing HVPC at the cath­ode and anode, and Szuminsky et al. "" tested HVPC in vi tro at the cathode. Both studies found inhibition of Staphylo­coccus alirellS, Escherichia coli , and Pseudomonas aerugillosa. However. the amplitude of the stimu lation re­ported by Kincaid and Lavoie was at an amplitude of 250 V. and Szuminsky ct al. reported 500 V. Patients would likely find thi s voltage amplitude intolerable. Since there is incon­sistency in these findings and si nce there arc no chemical changes (ac idity or alkalinity) measured under the electrodes of high-voltage pul sed current. it is not clear whether the

Elect,.ical Stimulation lor If(mml /leali,,!: 365

antibacterial efTects are due 10 polarity or another mecha­nism. For example. increased subcutaneous oxygen was found under the anode when a microamperage current (0.3 I-Iz) was passed through the electrode. '" It is po>sible that the oxygen rather than the polarity is the variable that is rcspon­sible for the bactericidal efTects on pathogens.

Oxygen

Oxygen is critical for wound hea ling. Constalll delivery of oxygen is required to meet high metabolic demands of the tissues, ox idative killing of infectiolls organ isms, pro­tein and col lagen synthesis. and hydroxylation of proline to make useful collagen. Blood flow is the mechanism of oxy­gen transport to the tissues. Treatment interventions that in­crease blood flow consequent ly wi ll enhance oxygen deliv­ery to the tissues and improve healing. Electrical stimula­tion may be one way of enhancing oxygen and nutrient en­

richment to the tissues. Increasing oxygenation could be an important reason to use ES. Lack of adcquatc oxygen coul d be a partial explanation for difficulty in hea ling diabetic ul­cers. q Baker et a I. 5"}~ measured oxygen enrichment to the cells of wound repair in a study of age-matched older nor­mal adu lt s and diabetic subjects. Oximctry readi ngs of the partial pressure of transcutancolls oxygen (tcpO!) were taken 30 minutes prior to stimulation. during 30 minutes ofstimu­lat ion, and 30 minutes after stimulat ion. The electrical st imu­lation waveforms used were monophasic paired spikes wi th negative polarity and a compensated monophasic waveform. Both waveforms were introduced with the cathode over the wound. The older normal adults also showed higher tcpO! levels at the end of 30 minutes of stimulation regardless of waveform used. However. there were differences in response time for the diabetics. The normal adults showed increased oxygen levels ear lier in the treatment period than did the diabetics. Diabetic subjects showed measurable but not sig­nificant increases in tcp02 at the end of the 30 minutcs of stimulation but did show sign ifica nt increases 30 minutes after cessation of (he stimulat ion. Increases occurred with both waveforms. but no change occurred when submotor or trace muscle contraction was elicited with the compensated monophasic wave form. For some reason the trace musc le contract ion blunted the tcpO! response in the diabetics. The same effects were found for both waveforms and with stimu­lation by ei ther the positive or the negative pole.

In another study of diabetics, Baker et al. N compared the effects of a monophasic paired spike \\'3\efonn lIsing both negative and positive polarity with a symmetric biphasic waveform. Transcutaneous oxygen pressure from baseline 30 minutes prior to stimulation. during 30 minutes ofstim u­lation, and 30 minutes after treatment were compared. The findings showed that the tcpO! levels were significant ly in­creased rcgardless of waveform or polarity. Increases were

present at the end of the st imulation period and cont inued to rise during the next 30 minutes after stimu lation. Therefore. Baker et al. \II concluded that the mechanism of action of ES on increasing transcutaneous oxygen was unrelated to po­larity and did not require any net ion flow. Byl et al. 5b found that whcn supplell''ICnta l oxygen was given by mask prior to

and during microamperage stimulati on (1 00 ~lA for 45 min­utes). there were significant increases in subcutaneous oxy­gen measurcd . Maximal oxygen saturation may be neces­sary prior to and during ES in order to faci litate the di ssocia­tion of oxygen from the hemoglobin. ~b

In transferring technology from the lab bench to the bed the physical therapist could take the information from these three research stud ies and formulate and test a protocol for wound heal ing for diabetics. For examp le. nasal supplemen­tation of oxygen could be provided during ES treatment for patients with diabetcs to accclef3Lc the oxygcl1uptake.A trial to evaluate the differcnce in wound healing outcomes for diabetics treated with ES whi le brearhing room ai r or supple­mental oxygen could yield useful clinical data from these types of studies. The results would be development of a new clinical protocol for trearing diabetic wounds.

Noninvasive electrical stimu lators that stimulate sensory nerves can be classified as TENS." A large body of litera­ture supports the usc of TENS for both acute and chronic pain management. Techniques for pain modulation can be used along with the wound healing protocol s. For examp le. one electrode may bc placed 011 the painful area, which in­cludes the wound and adjacent Lissues. and the indifferent electrode over the related spinal nerve. The electrodes call al so be bracketed proximal and distal to the areas of pain arou nd the wou nd such as with a bipolar Lcchniqllc described later in th is chapte r. ~~ Pain management would be a good rcason to lise clectrodes of cqual size so that there would be suO'icicn t current density at the dispersive electrode.

Scar Formation

In anima l and human studies, naps and grafts treated wi th monophasic pulsed current electrical stimul ation heal with­out ischemia and result in natter, thinner scars than in COIl­

trols.l'Ul

CLINICAL STUDIES

Since the 19605 a series of clinical trials has been under­taken to eva luate the effect of electrica l stimulation on wound healing. The early studics arc classics in th is field .

Low Voltage Pulsed Microal1lpcragc Direct Current Studies

Direct current was lIsed in three clinical studies. Wolcott eL al. ~.l . Gault and GatensN

• and Carley and Wainapel !itl treated ischemic and indolent ulcers. In all three studies a positive (anode) polarity was lIsed after a period of3 or more days at the caLhode. The polarity was reverscd cvery day or every 3 days if wound healing did not progress. Rationale for cath­ode app lication was the sol ubilization of necrotic tissue'6 and bactericidal efTects .'41 .. u The first two studies used an ampli­tude of 200 to 800 flA and the latcr study 300 to 700 fiA. Duration of treatment was very long: 2 hours. two or three timcs per day. or 42 hours per week for the first two studies, and 20 hours per week for thc later study. A combined tOLal or 163 paticnts were trcated and 29 served as controls. In most cases the patient served as his or her own control. Mcan healing timcs reported were 9.6 wceks, 4.7 wceks, and 5.0. respectively. for the threc studies. The diflerencc in healing time between these three studies is not clear. Perhaps in the Wo\con eL al. study the wounds were more extensive.

Microcurrcnt stimulation has becn studied in animal mod­els in which current was appl ied on ly onc or two times per day for 30 minutcs for I LO 2 weeks; no significant clinical effects were demonstrated on wound healing.l~.6! In another study. there were significant increases in subclltaneous oxy­gen measurements when supplementa l oxygen was given by mask during the MENS stimulation.:'>b There was no accel­erat ion in healing.

Modified Biphasic Stimulation Study

Barron et al.b! reported a study of six patients with prcs­Sllre ulcers who wcre Lreatcd threc times a week for 3 weeks for a total of nine treatments with microcurrcnt stimulation. The waveform was a modified biphasic square wave. The treatment characteristics were 600 ~A. 50 V. and 0.5 Hl. The electrode probes were placcd 2 cm away from the edge of the ulcer and thcn moved circumferentially arOllnd the ulcer. Each successive placement of the probes was 2 cm from the prior placement. In this small study. two ulccrs healed 100%. three healed 99%, and onc decreased in siLe 55°0.

High-Voltage Pulsed Current Studies

Three controlled clinical studies have been rcported by Kloth and Fcedar.b-1 Griffin et al. .1>-1 and Unger et al.b~ In the st udy by Kloth and Fcedar.t'" wounds had a mean hea ling

timc of7.3 wceks. and 1000/0 of the treatment group healed.

Unger et al.M reported on a controlled study of nine subjects in the treatment group and eight controls. The average wound size in the trcatment group was 460 111m!. compared wi th the control group whose average wound size was I 18.5 mm2 .

Me~l11 healing time was 7.3 weeks for the treatment group, with 88.9% completely healed. GrifTin et al." had demon­strated an 80% reduction in si7c in 4 weeks, but ulcers were not treated until healed. UngerM reported an uncontrolled study using IIVpe treatment for 223 wounds. The mean heal­ing limes for the 223 wounds in the uncontrolled study was 10.9 weeks. In all studies. the treatment frequency was five to sevcn timcs pcr wcck for 45 to 60 minutes. All treatmcnt protocols began with negativc polarity. After the wounds were clean of infection. polarity was changed to positive cxcept in the study by GrirTin ct al..nJ whcre the polarity was kept at

negative for the 4-week study period (Table 16- 3). Tv.'o additiona l published uncontrolled studies included

30 patients. Alon ct al. 11 used positive po larity and stimu­lated wounds three times a week for I hour: 12 of the IS or SO% of the ulcers treated healed. One patient died. one did not respond and the ulcer in one decrcased significantly in size but did not hea l in 21.6 weeks. Akers and Gabrielsonh7

published a study that compared ( I ) Ilvrc direct app lica­tion to the wound: (2) application of Ilvrc using the whirl­poolas a large electrode: and (3) whirlpool alone. The di rect application of the active electrode to the wound site had the best outcome. followed by II vpe lIsing the wh irlpool as an electrode. Whirlpool alol1e was the least efTective.

Lo\\-Voltagc Pulsed Electrica l Current Studies

Two controlled clinical tria ls with low-voltage pu lsed cur­rent. labeled PES. were located in the litera ture. Gentzkow et al. l \ reported a study of40 ulcers in37 patients. Nineteen pressure ulcers were stimulated and 21 were sham stimu­lated. The triallastcd for 4 \leeks. The treated ulcers healed

Table 16-3 HVPC Clinical Studies

Researchers

Alon et al. 17

Kloth and Feedar"

Griffin et al.s. Unger" Unger et al."

No. of Patients

15 Treated, a controls (diabetic) 9 Treated, 7 controls, 3 crossovers

(mixed wound etiology) 8 Treated, 9 controls (pressure ulcers) 223 Treated , a controls 9 Treated , 8 controls (pressure ulcers)

Electrical Stimulation/iH' H'tJlIl1t1l1ealil1g 367

Clinical Wisdom: Best Method for Effective HVPC Treatment

Apply HVPC directly to the wound for best expected outcome. Conducting current to the tissues during whirlpool is not recommended because it is less ef­fective, and some clinicians report that stimulator leads have become entangled in the agitator. There have even been stories of stimulators falling into the water.

more than twice as much as the sham-stimulated ulcers (49.S% versus 23.4%). healing at a rate of 12.5% per week compared with 5.8% for the sham-stimulated group. Cross­over results for 15 of the 19 sham-treated ulcers showed a fourfold greater healing during the 4 weeks of stimulation compared to 4 weeks of sham treatment. This difference was statistica lly signi fieant. 1.1 Fcedar et al. fill publ ished a study on pressure ulcers. The 61 patients served as their own con­tro ls. The treatment phase of the study was preceded by a 4-wcek control phase of optimal nonelectrically stimu lated wound care. Only the stage II I or IV ulcers with need of surgical debridement, necrotic/purulent drainage. or exudate seropurulent drainage that did not improve during the con­trol phase went on to the trealmenl phase. After 4 weeks of treatment 58.8% of the wounds had improved. After an aver­age ofS.4 weeks, 23% completely healed and 82% improved significantly.

Biphasic Stimulation Studies

There are reports in the literature by Kaad'-1. ~1 Lundeberg et al.,bQ Stefanovska et al. 70 and Baker ct a1. 71.7! of clinica l trials of wound healing with biphasic waveforms. Kaada ~1

and LUl1deberg el nl."" each used biphasic symmetric wave-

80% 100%

% Healed

80% Reduction in size 89.7% 88.9%

Mean Time to Heal

2.6 Months (10.4 weeks) 7.3 Weeks

4-Week treatment period 10.85 Weeks (54 .25 days) 7.3 Weeks (51.2 days)

368 W OUND J\RI

form s with significant improvement in both ulcer area and healed ulcers. Ka'lda" reported resuits ofT E Son 10 sub­jects, who served as the ir own cont ro ls, with recalc itrant ul ­ce rs o f di ffe re nt e tio log ies. Stimul a tio n was prov ided indirec tly over the web of the thumb da ily during three 30-minute sessions with rests o f 45 minutes between for a total o f I Y2 hours stimulation. Stimulation was below visible muscle contraction. LUlldeberg et al.69 performed a controlled study on 64 patients with chronic diabetic ulce rs due to venous stasis. All patients received standard treatment with pas te bandage in addit ion to the sham or T ENS treatment. Asymmetric biphas ic stimulation was determined to produce s igni f icant wound hea ling e lTects. whereas the other wave­fo rms did not inc rease the hea ling ra te. The study by Stefanovska et a l. 70 compared direct current and asymmetric biphas ic current. In another study. Baker et al. compared asyml1letric biphas ic. symmetric biphasic. and microcurrent (DC). The <lsYl1ll11etric biphas ic wave form has a potentia l for some po lar efTect that should not be di scounted. The po­lar efTcct may ex phl in why it was more effecti ve than the symmetric biphas ic waveform. However. another like ly ex­planation of the effects arc stimulation of neural mechanisms that e fTect hea ling.11 In a ll of the studies except Kaada, stimu­lation was de li vered to the skin at the wound perimeter rather than into the wound bed.An advantage of the perimeter stimu­lat ion was less di sruption o f the wound bed, less cross-con­tamination o f the wound, and less interference with the dress­ing. Benefits were found in patients with spinal cord inj ury who had pressure ulcers70·11 and patients with diabetic ulcers including those with pcripheralneuropathy12 and venous sta­sis."" Table 16- 5 shows protocols used in these studies.

Summary

Electrica l stimulation studies have va ried from continu­ous wave form appl icat ion with direct current to pulsed short­duratio n mo nophas ic pul ses to biphas ic pul ses. What is known and acknowledged is that electrica l stimulation seems to have positive e lTecls o n wound healing or on the compo­nents necessary for wound hea ling (eg. blood fl ow and oxy­gen uptake, DNA and protein synthesis). but there is still ambiguity about the type o f e lectrical stimulation character­istics that are Illost important or critical. For instance, polar­ity has played an important ro le in protocols used even though the li ke lihood of po lari ty efTects o r currents wi th pulses of very short duration is questionable. One possible reason for the wound healing e lTccts o f e lectrica l stimulation with any type of current may result from the effect o f low-l evel sen­sory stimulation on the peri phera l nerves. which is not wholly dependent on the po lar nature of e lectrica l current. Kaada ~u

describes e fTccts that include inhi bition of sympathetic in-

put to superficia l vessels. release of an active vasodilator. and axon-renex stimul ation.

CHOOSING AN INTERVENTION: C LINICAL REASONING

ApplyingTheory and Science to Clinical Decision Making

The prev ious sect ion eva luated the e fTi cacy o f elec trical stimulation on many components of hea ling. as well as clini­ca l tria ls o f wound hea ling. T he studies basica lly looked at four components:

I. Gal va notaxis and efTect at the ce llul ar leve l 2. Ci rculatoryefTects 3. EfTects on pai n 4. Effects on repai r, regeneration, and completeness of

hea ling

The clinician should consider these variables when select­ing ES intervent ion and choosing a protocol.

The specific medical diagnosis may not be a signi fica nt fac tor in sclecti ng ES for wound healing. The medical diag­nosis o f patients in the studies included burns. pressure ul ­cers. diabe tic ulcers (vascular and neuropa thic), vascular ul­cers. and vasculit ic ulce rs. The surgica l wounds incl uded in the studies were skin naps. donor sites. and dehiscence. Acute wounds were a lso inc luded . Electrica l stimulation had dem­onstrated cn' icacy for wound hea ling across diagnosis and pathogenesis. Reported effects were related to the stimula­ti on o rthe mechanisms of healing at the cellular. ti ssue, and! or systems leve l. Hea ling fo llows a pred ictable pa ttern re­gardl ess of etiology; what a ffects the outcome are the int rin­sic. extri nsic. and iatrogenic rac tors that a lter healing de­scribed in Chapter 2. The physica l therapist inte rvenes in wound management spec ifica lly to fac ilitate the functional mechanisms of hea ling. Electrica l stimulation is j ust one of the interventions that can be used.

Wound attributes that have positi vely responded to elec­trical stimulation were necrotic tissue, innammation. wound contrac tion. in fec tion. and wound resurfac ing. Wounds or a ll depths from part ia l thickness to full th ickness and deeper have been successfully treated with e lectrical stimulation (eg. stage II to stage IV pressurc ulcers). Wounds have tradition­ally been class ified by med ical diagnosis. by depth of ti ssue disruption. and/or by phase o f wound healing. Depth of ti s­sue disruption is a description o f the ti ss lie loss and runction that is broader and more gene ric than that in the medical di agnos is system. The depth o f ti ssue di sruption system can be used for wounds regardle s o rthe wound etiology. Class i­fica tion by phase o f wound healing is a lso independent of the medica l diagnosis. Change in wound phase is an out­come of the process of wound hea ling.

The Iypica l subj ecIs selecled for cli nica l !rials wilh elec­trica l st imulation had nonconforming wound healing with long chronici ty. The chronic wounds were the reason for re­fe rral for electrical stimulation. There is signi ficant sc ien­ti fic evidence to support that early intervent ion with exter­na lly applied e lec trical currents w ill a lso acce lerate hea ling for the aClIte healthy wound . Early intervention with electri ­cal stimulat ion could be a lI se fulm cthod to prevent chronic­ity and return the individua l earlier to a functiona l status. This is consistent w ith o ther areas of physical the rapy prac­tice, such as stroke and low back rehabilitat ion. where early intervention can reduce the development of costly chronic heallh problems.

In summary. selection of ES for wound healing is not de­pendent on the medical diagnosis. Select ES intervention and trea tment characteristics when there are impairments 10 the systems that interfe re with healing at one or more levels: cellular, tissue, or organ. Functional loss at any of these levels suggests that the wound will not or has not hea led wi th the current leve l of interventi on. The reason for referral 10 Ihe physical Iherapisl is for Ihe developmenl of anolher stra tegy to facilitate hea ling. The use of externally applied currents is one such stra tegy. Th e type of stimul ati on that has been most consistently evaluated clinically and found 10 be etTicac ious is high-vollage pul sed currel1l (see Table 16-4).

Table 16-4 Appropriate Wound Descriptors for High­Voltage Electrical Stimulation

Wound Classification

Level of ti ssue disruption

Etiologies/diagnostic groups

Wound phase diagnosis

Age

HVPC

Superficial, partial thick­ness, full thickness, subcutaneous and deep tissues

Burns, neuropathic ulcers, pressure ulcers, surgical wounds, vascular ulcers

Inflammation phase: acute, chronic, absent

Proliferation phase: acute, chronic, absent

Epithelial ization phase: acute, chronic, absent

Remodeling phase: collagen organization

Older than 3 years

Electrical Stimulation/or Wound !-Iealing 369

I'recautions

Signs of adverse efiects usi ng electrical st imulation for wound healing were eva luated in the va riolls cl inical trials. The only two adverse signs were some skin irri tation or tin­gling under the electrodes in a few cases and pain in some other cases. Patients with severe peripheral vascular occ lu­sive disease. parti cularly in the lower extremity, may ex peri­ence some increased pain with e lectrica l stimulations, usu­ally described as th robbing. An alternat ive acupuncture pro­tocol has been suggested in these cases: placing the ac tive electrode on the web space of the hand between the thumb and first finger instead of over the ulcer located 0 11 the leg. SO•51

Young children under the age of 3 years should not be con­sidered candidates for intervention with ES. Healing mecha­ni sms for this group are not we ll understood and, although there arc no known adverse effects, the benefits arc not de­f ined.

Contraindications

Contraindi cations for the use of electrical stimulati on as described arc fro m various sources and fa ll into the follow­ing categories: ( I) when stimulation of ce ll proliferation is eonlraindicaled (eg, malignancy); (2) where Ihere is evidence of osteomye litis; (3) where there are metal ions; (4) where the placement of electrodes for treatment with electrical stimulation could adversely affect a renex center: or (5) where electrical current could affect the function of an electronic implant.' 6.58 Carefull y eva luatc the medica l history and re­view body systems when considering candidates for use of this intervent ioll .

Presellce of Malig"''''cy

When there is a malignancy in the area to be treated elec­trica l stimul ation should not be lIsed (eg. malignant mela­noma. basa l cell carcinoma). Electrical stimul ation stimu­lales ce ll proliferal ion and could lead 10 lIlleonlro lied cell growth . If Ihe malignancy is distant from the wound (eg, breast cancer in a patient with a pressure ulcer on an ankle), however. local use of electrical st imulat ion would be a pre­caution, but not a cont raindicati on. although this is not con­sistent wi th required manufacturer labeling.

A(,tive 03·te()lIIyeliti.~

Stimulati on of tissue growth with electrical stimulation may cause superficial covering of an area of osteomyelitis. This could blind the site from observation. If the medical record documents a history o f a bone infection that should trigger an investigation of the current status of the infection. It is not unusual for the osteomyeliti s to be resolved but not to be noted in the medica l record.

370 WOUND CAR'

Clinical Wisdom: Identification of Osteomyelitis

If a wound penetrates to the bone, as determined by inserting a probe, it must be assumed that osteo­myelitis is present and the patient should not be treated with electrical stimulation. An immediate referral to a surgeon for evaluation13 must be initiated.

Topical S ubstances COJlllli"illg ,WeIll/loll .,'

Topical substances containing metal ions (cg. povidone­iodine, zinc. Mercurochrome, and silver sulfadiazine that may be used as part of the wound treatment regimen) should be removed before the application of ES. Direct-current elec­trical stimulation has the ability to transfer ions into the tis­sues by iOlllophorcscsis. i-I cavy metal ions may have toxic properties when introduced into the body. If rcmova l of the topical substance is not appropriate, however, electrical stimu­lation could be lIsed on other areas of the skin where the topical agcnt has not becn applied.

Electronic Imp/tlll ts

Dcmand type cardiac pacemakers and other electrica l im­plants raise concerns regarding the use of electrica l current. Electrical stimulation is contraindicated O\'er electrica l illl­plul1Is because the current and electromagnetic fields cou ld disrupt the runction orthe implant. Sare application or TENS in 10 patients with 20 different cardiac pacemakers at four sitcs (lumbar area. cervica l spinc, left leg. and lower arm area ipsilateral to the pacemaker) without ill effects was re­ported by Ra~l11u ssen et al. 74 Therefore. using electrical stimu­lation locally in an area away from the implant could be dOlle safely, since it is unlikely to transmit to the electronic im­plant.

NlItllrll/ Reflexes

There are areas or the body that are particularly sensitive to any stimulation (eg. carotid sinus. heart. parasympathetic nerves. ganglion. laryngeal muscles, phrenic nerve) . Sen­sory levels of e lectrical stimulation might create a vaso­spasm or some type of vasoconstriction that cou ld lead to a vasovagal response and other neural responses that cou ld interfere with the function of vital centers and be harmfu l to the patient. Thus, ES is contraindicated to run current through the upper chest and anterior neck .

Eq uipment

R egu/lItlJlJl Apprm'lI/

Under what is called premarket approval (PMA), manu­fltcturing companies are allowed to make claims of effec-

tiveness and safety about medical devices. PMA requires extensive clinical trial s, typically 2.000 to 3.000 cases ror approva l. "Off label" means treatment not approved by the Food and Drug Administration (FDA). 0 electrical stimu­lators have received PMA by the FDA ror wound healing. Externally applied currents for wound healing arc consid­ered as "ofT label " use at this time. OfT label usc ror medical devices is an accepted and comlllon practice in medicine as innovative therapy. as long as the participants are not closely associated with the manufacturer. 7~ For example. the lOon la­bel" uses for neuromuscular stimulators, such as 1-IVpe. in­clude app lication for increased circulation. relaxation of muscle spasms, and muscle reeducation . The on label use for TENS is pain management.

Expect to find an FDA-mandated instruction manual ac­companying each electrica l stimulator. Listed in the manual are labeled indications. contraindications, warnings, and pre­cautions (Exhibit 16- 1). The FDA indi ca tions and contra­indications do not exact ly match what is described in the previous text. The physical thempi st must be aware of these lim itations when selecting a protocol with electrical stimu­lation and lise thoughtful clinical judgment .

Ex hibit 16-1 FDA Indications and COlltraindi c:1 tions for Electrical Stimulat ion

FDA Indica lions for Eh.'c lric .. 1 St imuhtlion

• Relaxation of muscle spasms • Prcvention o r rctardation of disuse atrophy • Increas ing local blood circulation • Muscle reeduc:'lIion • Immediate pos tsurgica l s timulation of ca lf Illuscles to

prevent venous thrombosis • Maintaining o r increasing range of Illotion

• Pain

FDA Contra indications for Electric,, 1 Stimu lation

• Should not be used on patients with demand type cardiac pacemakers

• Should not be lIsed on pe rso ns known to havc cancerous lesions

• Should not be lIsed for symptomatic pa in rdief unless ctiology is established o r unless a pain syndrome has been diagnosed

• hould not be lIsed over pregnant uterus • Elect rode placcmelll s must be avoided that apply current

to the carot id s inus region (:'lI1tcrior neck) or trans­cerebrnlly (t hro ugh the head)

Devices

Electrical stim ulators have three basic components: a source of power, an oscillator c ircui t, and an Olltput ampli­fier. There are two size ranges: clinica l models and ponable models. The latte r may be as sma ll as a beeper. Two basic power sources are used: batteries and house line current. Batteries are used in portable st imulators. HOllse line cur­rent is usually used in the clinic setti ng. Batteries need to be fully charged to deliver the output ex pected. A spare battery shou ld be kept on hand. Rechargeable batteries may be more cost effect ive than single-lise types. House li ne current is usually available.

Many e lectrical stimul ators now use microprocessors with a choice of several waveforms and pulse rates and even in­clude preset protocols for wound treatment. The c lin ician should not assume that this is the "correct" protoco l for the wound. It is the cli ni cian's responsibility to know the ra­tionale for protocol characteristics and what the se tt ings are on the chosen stimulator. Most programs allow clinicians to override the preset programs.

Select a st imulator based on the available waveform , pulse characteristic, and abi lity to adjust intensity and polari ty. A desirable st imulator shou ld allow for nex ibility to set up and deliver a variety of protocols based on changes dictated by clinical tria ls and curren t concepts of physio logic rationa le. Manufacturers are an important source of he lpfu l informa­tion about the charac teristics of their devices.

Testillg Equipment

Meters are very useful to the clin ician to check 011 the current flow between two electrodes. Use the device meter if available; if no Illeter is available on the stimulator, go to other options. Patient sensat ion is always a good indicator, if the patient can give a report. The use of e lectrical st imula­tion for wound healing is lIsually done at a sensory level, but many of the patients are insensate or unable to comlllun i­cate. or the wounds are deep and below the leve l o f sensa­tion and the patient wi ll nOI be able to ind icate if the current is not felt. Another test method is to position the dispersive/ indifferent e lectrode over a muscle motor point to see whether there is a muscle twitch or tingling under the electrode. The e lectrode pads can be chcckcd by the physical therapist by plac ing a wet contact on both positive and negative elec­trodes and then resting the forearms on each e lectrode pad. Ask a colleague to turn up the device until a sensation of prickling is felt.

Electrical stimulation equipmelll shou ld have regu lar ca li­bration checks. I n between checks, a mult i meter can be used for periodic spot checking to see that the equ ipment is func­tioning properly. Multimeters, which are a combination of volt-ohm-rn itliammeter, have the ability to determine cur-

Electrical Stimulation for Wound /lealing 37 1

rent fl ow. They are inexpensive, easy to usc, and readily avail­able. A broken lead wire, weak battery. or resistan t e lectrode may not be apparent because the stimulation in the wound bed is below the level of sensa tion or the patient is insensate or cogn it ivc1y impaired and cannot report changes in sensa­tion. Checking for good electrica l conduct ion is the respon· sibility of the clin ician.

Electrodes

Electrode Nluteriul."

The e lectrode is the contact point between the electrical c ircuit and the body. The electrode must be a good conduc· tor and prov ide very little resistance 10 the cu rrent. All met­a ls are good conductors of elect ric ity. Aluminum foil is an excellent conductor to use for e lectrodes (Figures 16 7 A and 16-7B). It is nontoxic, inexpensive, disposable, and conform­able and can be sized as needed. Carbon-impregnated elec­trodes are sold to go with most e lectrotherapeutic devices. They are designed for multiple uses and arc relat ive ly inex­pensive, but they need to be di sin fected between usc even if restricted to a sing le patient. They a rc nonconformable and wi ll become resistive over time as they lose carbon and ac­cumulate body oi ls and c leaning products.

ElectrodeArrallgemellts

Size Qlul Shape of Elel:trodes. Size. shape, and arrange­ment of electrodes affect the current density and depth. Cur­rent density is the amount of currell! flow per unit area. Cur­rent density is a measure of the quantity of charged ions moving through a specifi c cross-sectiona l area of body ti s· sue. The unit of measurement is milliamperes per square centimeter. This measure will affect the reaction of the tis­sues being stimulated. In genera l, the g reater the current density the grea ter the eITect on the tissue biology. Two de­leflninants of current density are si:e of the e lectrode and the amplilllde of the curre ll! app lied. 76 Sma ll e lectrodes con­centrate the current for local effects more than larger e lec­trodes, which tend to disperse the charge. Also, the farther apart the electrodes, the deeper the current penetrates.

Active lIlId Dis(JerIive Electrode. The small electrode is commonly referred to as the active electrode and the large electrode as the di spersive e lectrode. If lhe two are nearly eq ual size or have equal current. the current will be divided between the two, with the currcnt density at the two treat­ment sites the same. If the two are not of equal size. the larger electrode will have less current density than the smaller elec­trode. A rule of thumb is that the combined area of tile act ive electrodes should not exceed the overall area of the d isper­sive electrode. Brown77 found that the effects of ES extends and affects events 2 to 3 cm beyond the edge of the elec-

372 W OUND CARl

A B

Figun.' 16-7 A and 8 , Aluminum foil electrode with alligator clip.

trades. Therefore. avoid placement of the active and disper­sive electrodes so thatthcy touch each other. Allow atl<ast4 to 5 em spacing between them 10 avoid the possibility that the wound is receiving stimulation from both poles (Figure 16 9A) .

In clinical practice. at times it is necessary to treat mul­tiple wound sites with a single electrical circuit using one or two bifurcated lead wires (Figure 16--8). The advantage of bifurcation is thall110re sites can be lr~1tcd simultaneously. A di sadvantage is that although the sa me current passes through all the bifurcated leads. the physiologic responses may vary significantly because the subliminal stimu lation is perceived under one electrode and the sensory stimulation under the 01 her. Another disadvantage is that if there is a difference in the lotal surface area of the clectrode(s) con­nected to one lead compared wilh the other. the stimulation will be stronger under the electrode with the smaller total surface area because there will be greater currellt density under that electrode. Often, the wound sites arc di fferent sizes. The depth and undermining may make the effective elec­trode silc of a small wound larger than the surface area ap­pears. The physica l therapist must consider these physical properties when planning treatment and correct them.At this timc it is not known what is the optima l current density or the best electrode sile to choose. 57 It may be prudent to usc a stimulalor with two channels or have two treatment sessions if there arc multip le wounds with a large di screpancy in wound sizes.

Dispeniil'e Pad Placement. Attcmpts have becn madc to apply sc ien tific findings to electrode placement. Most

Figure 16-8 Bifllrcated lcads.

stud ies use the active e lectrode for direct application (Fig­ure 16- 9A) to the s ite.o' t>6 but some lise the bipolar tech­nique (Figure 16 98). at the wound edges,"" 7:! The di sper­sive electrode placement has morc variation . For example. in two simi lar studies, the dispersive electrode was placed differently. In one study.61 it was placed cephalad on the neu­ral axis, while in the second study it was placed 30.5 cm from the wound.6~ One study 011 spina l cord injured patients

A

B

Figure 16- 9 A. Monopol:ir technique. B, Oipolar technique.

wi th pressure ulcers in the pelvic region used a protocol where the d ispe rs ive was a lways placed on the thigh. A not her method is to place the d ispe rsive proxi mal to the wound .C,5.Ml

Current thinki ng suggests that the d ispers ive should be moved around the wound to induce the current to enter the wound from dincrcnt sides. At this lime there is not an es tablished proven method that has been shown 10 change the elTeet o f the trea tment. All reported treatment methods had sta tist i­cally significant (reatment resuits.

Alonol'o/tII'Te(:/lIIiqlle

With the mona pa Jar technique. an e lectrode is placed to c011lro\ the po larity at the wound sile. Usually. one acti ve

elec trode is placed on a we t conductive medium in the wound bed and the dispe rsive e lectrode, in a we t conductive me­di um at a dista nce fro l11 the wound s ite, is placed on the in-

Electrical Srilllula rio" fbr 1I'01llld /-Iealillg 373

tact skin (Figure 16- 9A). Po lari ty for thc two e lec trodes will be opposite. Curre nt wi ll fl ow th rough the intervening ti s­sues between the two c lectrode poles. The c urrent under the active e lectrode is the po larity selected on the s timulato r. As stated be fore, the fa rther apart the two e lectrode po les the deepe r the current wi ll fl ow into the inte rvening ti ssues. Current w ill fl ow th ro llgh the ti ss llcs by fo llowing the path with the lowest res ista ncc. w hich is usuall y thro ugh the muscles a nd nerves and deepcr ti ssues. Inc reas ing the di s­tance betwcen the e lectrodes is a good pos ition choice if wounds arc deep and extend into underlying ti ssues, such as stage III and stage I V pressure ul cers, and/or having tunnel­ing and undermined spaces.

Thc e lec trodes can be ar ranged to targe t the stimulation to spec ific ti ssue sites. Remcmbe r to visua lize the path of the c urrent fl ow when plac ing the dispersive pad . The po les are usually set lip in para llc l fashion c nabl ing c urrent to flow between the positivc and negative e lectrodes no mail er how ma ny e lectrodes are used at e ither po le. Whe n the surface area o fth c c lectrodes is unequal , the c urre nt dens ity will not be {he same under the two s ites. Cur rent density may also vary accord ing to the impeda nce o f the intervening ti ssues and the s ize of the e lectrodes. Impedance is the opposition to current fl ow within {he ci rcuit . Different body ti ssues have different impedances to current fl ow. Skin. bone, and fat have high impedance and are poor e lectrical conductors. When there is a break in the sk in. however, the re is a s ignificant lowering o f the skin impedance to current. Techniques to reduce skin impedance inc lude abrasion o f the skin surface to remove the hard layers o f keratin on the SUrl~lCC, ti ssue warming. and hydrat ion. High-voltage curre nts o f approxi­mate ly 100 V have the demonstrated ability to cause sudde n. spontaneo us breakdown in skin impedance. 76 Because o f the fluid in muscles and blood vesse ls, these tissues me good e lectrical conductors, and it can be cx pected tha t current w ill fl ow directly th rough them with little impedance.

It is important to understa nd these princ ipl es o f ti ssue impedance and curre nt fl ow and the n apply them correctly to derive the optima l bene fits from treatment w ith e lec trical s timulation. For example, if the d ispers ive e lectrode is to be placed on the back, placc it helow the scapula to avoid the impedance to c ur rcnt fl ow by the bone . Patients w ith thic k laycrs o r callus on the feet will have high impedance to c ur­rent. Paring the ca llus should precede ES treatmcnt. or find ano the r placement where the e lectrode docs no t lie on cal­lus. A good placement for the dispers ive electrode when treat ­ing wounds o f the lower leg o r fOOl is the muscular ti ssue o r the thi gh. One suggestion is to sw itc h the di spe rs ive e lec­lrode fo r each trea tment so that the c urrent nows into the wound fro l11 each s ide o f the wound through d iffe rent sur­rounding ti ssues and through a different wound edge.77

,711 Not only the active e lectrodes can be bi furcated . The dispers ive

374 W OUND Ct\RI~

electrode can also be bifurcated. This allows use ofsmalJer electrode pads that can be made to conform to smaller body parts sllch as an arm or a lower leg (see Fi gure 16- 8).

Clinical Wisdom: Enlarging the Dispersive Electrode

If the dispersive electrode area size needs to be in­creased, this can be accomplished by using a wet washcloth wrapped around a limb or extending a wet washcloth out from the edges of the dispersive elec­trode to cover a larger skin area. If the wound area size is nearly as large as or larger than the skin area under the dispersive electrode, it will be more com­fortable for the patient but the intensity of the current or the treatment time may need to be increased to deliver the same total amount of current, but at a lower current density.

Bipolar Tech"ique

The definition of bipolar technique is the placement of the two leads with thei r respective electrodes on either side of the target area. This confines the stimulation to the area associated with the clinical problem. H For instance, the two electrodes with opposite polarity may both be placed on the intact skin adjacent to the wound site so that the current passes between the electrodes through the wound tissue. The closer together the more superficial the effect; this is a reasonable choice for superficial or partial-thickness wound disruptions. The bipolar technique is used with either monophasic or biphasic wave form s. An app lication of the bipolar technique is to place the electrodes on either side of the wound or place the treatment electrode in the wound and use four bifurcated dispersive leads connected to electrodes placed around the wou nd so that current will now through the wound from all sides at once. Finally. one act ive electrode cou ld be placed in the middle of the wound and a dispersive electrode fash­ioned like a donut, made from aluminum foil, slipped over the treatment electrode with an intervening space between so that st imulation wou ld now into the wound bed from all sides orthe wound edges simultaneously. The roi l electrode would connect to the dispersive lead with an alligator clip just like the active leads (sec Figure 16~9B).

WOUNI) HEALING I'ROTOCOL SELECTION FOR ELECTRICAL STIMULATION

Aspects

There are Illany different ES protocols for wound healing. This section first describes SOllle of the aspects of the proto-

cols described, including electrode polarity. rationale, rre­quency, and amplitude as described by the researchers.

Polarity

Polarity must be considered when using galvanic and monophasic pulsed current. Electrode polarity varies depend­ing on the protocol selected. Most researchers studying elec­trical stimulation for wound healing start their protocols with the negative pole as the active electrode and then change the polarity after a period of treatment. Griffin et a 1.&4 maintained negative polarity to the wound site throughout the assess­ment period of 4 weeks. The other resea rchers recommend using negative polarity ror 3 to 7 days and then changing polarity. Another recommendation is to use negative polar­ity until the wound is cleansed of necrotic ti ssue and drain­age is serosanguineous. then continue with the negative po­larity ror 3 additional days or change to the positive pole." '"' Some researchers suggest that the polarity should be changed back to negative ror 3 days when the wound plateaus. An­other method is to change the polarity every 3 days until the wound is hea led to a partial-thickness depth . Once that out­come is achieved. changc Ihe polarity by alternating daily until the wound is closed. Several animal studies demon­strate better healing when polarity is initiated at the ncgative pole and then switched to pos itive . 20...! ' .7~ See earlier sections on theory and sc ience for additional rationale for selecting polarity.

Rationale

Usually the negative electrode is used as the active elec­trode when infection is suspected. The polarity is often sw itched back and forth during the course of healing. Elec­trode polarity switching accommodates the variability in the skin battery potentials that occurs during the course of heal­ing. Thus. electrode polarity may need to be alternated dur­ing treatment to achieve an optimal rate of hea ling. Addi­tional research is needed to ascertain whether wound heal­ing with electrical stimulation is dependent on matching treat­ment electrode polarity with nuctuations in wound injury potentia l polarity.bJ So far, studies have not reported on this important issue. Still, the idea of polarity switching has somc demonstrated mcrit.

/JiplUisic Protocol.\·

Protocols demonstrating signi fi cant benefit for wound healing with biphasic current are now appearing regularly in the literature. ~9.f)9 7~ The five studies reported in thi s chapter have similar protocols, except that the two studies by the Baker et a1. 71

•n research group found that the best outcome was achieved when the biphasic waveform was asymmetric and biased toward the negat ive pole. Biphasic trcatment pro­tocols are shown in Table 165.

Electrical Still/li/lIIion/or Wound /-Iealing 375

Table 15-5 Biphasic Treatment Protocols

Parameters Kaadas, Lundeberg et al. 69 Stefanovska et al. 70 Baker et al. 1f.72

Phase duration Not reported 1 msec 0.25 100 ~sec

Pulse rate 100 Hz 80 Hz 40 Hz 50 Hz

Waveform Symmetrical Symmetrical Asymmetrical, charge Asymmetrical balanced

Amplilude 15-30 mA below 15-25 mA below Below contraction Below contraction contraction contraction

Frequency and Daily; three 30-min Twice daily for 20 min Daily for 2 hours Daily; three 30-min duration sessions (off 45 min sessions (off

between sessions) between sessions)

Location Web between 1 st and Wound edge Wound edge Less than 1 em from 2nd metacarpal edge; proximal bones and distal to ulcer

Patient population Multiple diagnoses Diabetics with venous Spinal cord injury wi th Spinal cord injury stasis ulcers pressure ulcers with pressure

Frequency

Frequency or pulse rale is another variable that varies from study to swdy without much explanation. Severa l studies uscd a pul se rate of 100 to 128 pps for treatment with HVPC.Ii.l,b-I One investigator starts treatment at 50 ppS.6M6

Sussman uses 30 pps. Rationale is based on the effect of HVPC on blood flow. In some research studies, lower pulse rates produced higher mean blood flow veloci ty after HVPC than higher pulse rates and had a longer mean recovery time following cessation of HVpe compared to contro l levels. 21f

Frequcncy switching is also not well understood. For ex­ample. in one study the rationale given for reducing the pulsc rate from 128 pps to 64 pps was "because we believed the higher pulse frequency might be harmful to the newly healed ti ssue."6S(pt.&8IThis concern is probably due to the higher pulse charge delivered to the ti ssue at the higher pulse rate.

AmplitlUle

Wound healing protocol s for amplitude are usually con­stant, repeated in either milliamperes or voltage. The HVpe protocols all report amplitudes of 100 to 200 V, the low-volt­age direct-current protocols call for a 35-mA amplitude, and the low-voltage microampcrage stimulation units have an amplitude less than I mAo The abi lity of the patient to toler­ate high-intcnsi ty current will depend on the sensory pcr-

ulcers Diabetic ulcers

ccption of the individual. For example, in superficial or par­tial-thickness tissue disruption iftherc is intact sensation, an amplitude above 100 V may be very uncomfortable. In deeper wounds or in cases of impaired sensation, these higher am­plitudes arc IVell tolerated. Adj ust the amplitude to patient comfort. It has been suggested to test the amplitude by stimu­lating until there is a visible musc lc contraction under the electrode. Thi s is not practical if the active electrode is lo­cated in a wound within a muscle because the scnsory nerves will not be st imulated. If the dispersive electrode is secure over a large body area, the intensity of the sti mularion re­quired to cause a muscle contract ion wi ll be very high and probably uncomfortable, and may not be vis ible to the physi­cal therapist.

COIlc/usio"

Clearly, morc invcstigation is needed to achieve an opti ­mal treatment protocol with clectrica l stimulation. In thc meantime, the protocols presented ill this chapter arc for usc with low- and high-voltage monophasic and biphasic wave forms, which represent these authors' interpretation of the literature and the application to clinical treatment. The au­thors have used these protocol s for several years with good clinical results. Protocols are listed for wound healing for the three phases of repair and for the Ireatment of an cdcma-

10US limb \\here the edema extends beyond the wound area. Protocols change for each phase of repair and have expected outcomcs for each. Expected outcomes arc based on the lit­cr::Hurc and clinical expenence.

Selecting the Device :.wd Treatment Protocol

rhe physical therapist is now ready to sclect the electrical stimulator for trcatment. Depending on the s timulator se­lected the protocol for trea tmcnt w ill vary. In some cases. the characteristics of electrical stimulation for di fTerent cur­rent type may not always be based on the wound healing phases. For examp le. asymmetric biphasic slIIllulation pa­rall1etl!rs arc not varied during the progression through the phases of healing."""

The most cOl11mon stimu la to r used for wound healing to­day is the hlgh-\oJtagc pu lsed current neuromuscular stimu­lator. This may change in the future. The protocols presented below arc based on lise of the high-voltage pulsed current

Table 16-6 Protocols for HVpe Treatment

-

stimulator. Since the protocol g iven mimics the studies done with low-voltage pul sed electrical current."~ the protocol would also be appropriate to lise wllh those stimulators. The protocols arc based initially ol1thc wound healing phase di­agnosis. and there are changes in polanty and pulse rate as the wounds progress through thc phases ofhea ling.

Sussman \\"ound I-It~a ling I)rotocol

Sussman usc!') a wound healing protoco l for HVPC based on the complcted diagnostic process (sec Chaptcr I ). Table 16 6 Itsts the Sussman Wound llealing Protocols for Il vpe for all fOllr phases of "ollnd healing and edema con­trol. In using this method the clinician inltiatcs an II VPC treatment protocol based on the assessed wound healing phase diagnosis. and predicts an expected outcome for that proto­col. Si nce the polarity or the healing ","ound changes during the phases of healing. (11 fTcrcnt tr(!atl11cnt charactcristlcs are lIsed as wound healing progresses. In the protocol given bc-

Venous Parameters Edema Inflammation Proliferation Epithelialization Remodelmg Return" ~

Polarity Negative Negative Alternate Alternate daily Alternate daily Not Critical; negative! adjust for positive patient every 3 comfort days

I-Pulse rate 30-50 pps 30 pps 100-128 pps 60-64 pps 60-64 pps 40-60 pps

(frequency)

Intensity 150 V or less 100-150 V 100-150 V 100-150 V 100-150 V Surge mode, depending on time, on patient 3-15 sec; tolerance off time,

9-40 sec (1 :3 on/off ratio) to motor excitation

~

Duration 60 min 60 min 60 min 60 min 60 min 5-10 min, progress to 20-30 min

Treatment 5-7 times! 5-7 times! 5-7 times! 3-5 times! 3 IImes!week, Daily; modify frequency week for week, once week, once week, once once daily to biweekly

first week, daily daily daily then 3 times/week for 1 week

L--

low, the stimulation selected for treatment is a monophasic current and monopolar technique used with HVPC. For wounds in the acute innall111lation phase. with an absence of innammat ion phase, or in a chronic innammation phase, the therapist would start treatment with characteri stics to stimu­late circulation and cellular responses to healing that are listed under the innammation phase. The protocol ca lls for change of characteristics as the wound healing phases progress. Like­wise, for a wound healing phase, diagnosis of the repair (pro­liferation) phase, and a wound in the remodeling phase, the therapist would start treatment using a difTerent set of char­acteristics as outlined.

Predic:tuble Outcom e,.,,' with S ussmun " 'OIUIl/ /Jellfillg Pr%col

Predictable outcomes a re expected for each protocol , wh ich are equiva lent to a change in the wound phase charac­teri stics. For example, if the wound healing phase diagnosis is aCl/te injlammatiol/ phase the expected olltcomes arc hem­orrhage free, necrosis free, erythema free, edema free, exu­date free , red gmnulation. and progression to the next phase­the proliferation phase. Jfthere is absence of inn am mati on or chronic innammation, an acute innal11 l11 ation phase needs to be initiated if possible. Expected outcomes would indi­cate change to an acute innam ll1ation phase, described as increased ery thema (change in skin color), edema , and warmth. The phase change outcome predicted is initiation a/acute il!{lammatioll phase. Each wound healing phase has its own diagnosis and expected outcomes that arc indepen­dent of wound etiology.

When the wound healing phase diagnosis is acllle pm/if­eratioll phase the expected outcomes are reduction in size (eg, open area, depth, underm ining/tunneling), rcd granula­tion ti ssue- filled wound bed minimal serous or serosanguin­eous wound exudate, odor free, adherence of wound edges, and at the end of the phase a change in wound healing phase to the cpithe lializalion phase, When the wound healing phase diagnosis is absence of or chronic proliferation. the predi cted outcome must be acu te proliferation : reduction in depth, re­duction in open area size. and closing of tunnels or under­mining, Chronic proliferation may be due to infection of the granulat ion ti ssue. There would be c linical signs of infec­tion. includ ing purulent exudate, malodor. and change in appearance of the granu lation tissue from beefy red to dull pink. The additional expected outcome for a chronic prolif­eration phase then would enable the wound to become infec­tion free and to restart the proliferation phase,

A wound hea ling phase diagnosis of acute epithelializa­tioll phase has the e.xpected outcome of resurfacing and a change in wound hea ling phase to remodeling. A wound in the remodeling phase has an immature scar formation that lacks optima l hea ling and could benefit from cont inued

Electrical Stimulation jor IIfJIIlld /-Iealillg 377

Clinical Wisdom: Ultraviolet Light Stimulation To Restart Epithelialization Phase

One method suggested to restart the epithelializa­tion phase is to use ultraviolet C light stimulation to create an erythema of the wound edges." By using a dosage that produces a second-degree burn, there is a burning back of the leading edge of the cells that have stopped migration. The erythema response to ultraviolet light may lead to shedding of the outer tayer of the skin, followed by a mild inflammatory response that includes vasodilatation and capillary permeabil­ity and reinit iates the epithelialization process. Ultra­violet light also has the benefit of being bacteric idal." Another approach is use of topical or oral vitamin A to stimulate an erythema in the tissues. Treatment with electrical stimulation should cease if a method to re­start the epithelialization process is not also attempted.

stimulation with e lect rica l stimulation to enhance the mi­gration of the epiderma l cells and the maturation of the vas­cular system of the scar ti ssue. Absence of an epithelializa­tion phase may result from a drying o ut of the wound ti ssues due to e ither H poor drcssing choice or an absence of dress­ing. Epiderma l cell s require a moist cllvironment to migrate across thc wo und su rface. Correc ti on of the inadcquate wound trea tment wou ld be a necessary part of the plan of care. Chron ic ep ithe lia li za ti on is associated with rolled wound edges that have become fibrotic and stuck wi thout resurfacing the wound. Olher adjunctive measures may be required to re in itia lc an inn ammatory respo nse in the wound edges that in turn will reinitiate the epithe liali7<11ion process.

Once c losure is achieved, the patienl is usually discharged from a treatment protoco l, including c lectrical stimulation. However, the remodeling phase is often overlooked as a point at which treatment with e lectrica l stimulation can be benefi ­cial in reducing the ri sk of immature scar breakdowll. The remodeling phase is the longest of a ll the phases of healing, lasting from 6 months to 2 years. A scar that is thicker, better vascula ri zed, softer, and natter is morc resistant to stress from shearing. friction. and pressure. a ll of which account for a high incidence of recurrence of ulceration on the seating surface or plantar surface of the foot. Elcctrica l stimulation enhances the remodeling of the scar. Of course, other meth ­ods also need to bc considered to protect the new scar ti ssue. including pressure- relief devices and drcss ings. The phys i­cal therapist a lso wou ld incl ude a program o f strctching. exercise, and soft ti ssue mobilization techniques to enhance the elasticity of the mature scar. C% r P/mes I to 6 illustrate a case taken through the four phases of hea ling with electri­cal stimulation.

378 W OUND ('/\It!

Procel/ll resjor Hig h-Vo/lilge Pll/.~·el/ Current

The proccdurc section of this chapter is outlined in a stepwise fashion to help the physical therapist (PT) and physi­cal therapist assistant deliver the treatment intervention with electrical stimulation in a systematic and time-efficient way for both the paticnt and the clinician. Unfortunately, treat­mcnt with clectrica l stimu lation requires a number of supply itcms and steps. First of all, consider having a physical thera­pist aidc set up the treatment station where the equipment and supplies are available (sec list of equipment and sup­plies needed). The same set of instructions would be useful to give to a palient or caregiver for home treatment. The PT aide can also be responsible to see that the supplies are or­dered and available in the department. Always have enough supplies on hand so that treatment is not delayed while some­onc is running around chasing down the needed equipment.

Protocol for WOll/ld Heali/lg

Eqllipmelll Needed:

• Normal sa line (O.9%) • Clean gloves • Irrigation syringe. 35-mL with 19-9auge needle or

angiocatheter • Clean gmll.;c pads • Aluminum foil electrode or carbon electrode • Alligator clips or electrode lead • Bandage tape • ylon stretch slrap • Wet washcloth • Dispersive pad • IIvpe machine leads • Infectious waste bag

InSlrucfions/i)r Palieltl lind Caregh'er:

I . Explain the procedure. the reason for treatment, and how long it will last. Explain that a mild tingling will be felt and where it wi ll be felt .

2. Advise the patient not LO handle, replace, or remove electrodes during the treatment. Patients who cannOI understand these directions or will not cooperate need to be monitored close ly.

3. Give patient a call light to use.

Selling Up fhe Patiellf jiJl' II VPC Hbulld Tremmelll:

I . I lave supplies ready before undress ing the wound. 2. Position the palient for ease of access by staff and for

the comfort of both. 3. Remove the dressing and place in infectious waste

bag (usually a red bag) .

Clinical Wisdom: Suggestions for Set-up To Maximize Treatment Effectiveness and Efficiency

• Assemble the setup supplies into kits before the start of the treatment day to make the delivery of service more time efficient.

• Precut and shape the aluminum foil electrodes. Size and shape should be close to the size of the wounds. Round is preferable to rectangular.

• To make an electrode, cut a strip of household alu­minum foil the width of the electrode. Fold the strip in half and turn in the edges to make a smooth pad.

• To make a packing strip from gauze, open a gauze pad and pull on the bias or diagonal and twist to make a spaghetti strip, or use stretch gauze strips.

• Warm saline or a package of amorphous hydrogel by placing bottle between a folded hot pack before use to avoid chilling the wound tissue and slowing mitotic activity. Check the temperature with a digi­tal thermometer. The temperature should not be greater than 100°F to avoid burns. Myer" reported keeping the wound care products, including a 16-oz bottle of saline, warm for 3 to 4 hours. She ob­served that warming of the wound care products before electrical stimulation treatment resulted in brighter redness of granulation tissue and contrib­uted to reduction of pain .s1

Clinical Wisdom: Irrigation Devices

Spray bottles and bulb syringes may not deliver enough pressure (2.0 psi or less) to cleanse wounds adequately. The Water Pik at middle to high settings may cause trauma to the wound tissue and drive bac­teria into wounds; it is not recommended for cleans­ing soft tissue wounds. Use a cleanser delivery de­vice such as syringe with a 19-9auge catheter to de­liver water at 4 to B psi. Warm the solution before ap­plication.82

Clinical Wisdom: Perform Sharp Debridement before HVPC Treatment

Complete sharp debridement procedure before set­ting the patient up for HVPC treatment so that the wound packing will act as a pressure dressing to con­trol any bleeding and so that the wound environment will not have to be disturbed again after HVPC treat­ment.

4. Cleansc wou nd thoroughly to rcmovc slough. exu­date. and any petrolatul1l products.

5. Sharply debride nccrOlic tissue, if required before IIVPC treatment.

6. Open gauze pads and fluff, then soak to moisten in normal sa li ne solution; sq ueeze ou t excess liquid before app lying.

7. Fillthc wound cavi ty with gauze, including any un­dermined/tunneled spaces. Ga uze pad can be opened to rull size Clnd then pulled diagonally to rorm a thill "spaghetti" strip. Insert into undermined/tunneled spaces like roller gauze. Pack gent ly.

8. Place electrode over the gauze packing; cover with a dry gauze pad and hold in place with bandage tape.

9. Con nect an alligator cl ip to the foil. I o. Con nect to the stimu lator lead and to output device. I I . Place the dispersive electrode.

a. The dispersive electrode is usually placed proxi­mal to the wound (see section on electrode place­ment for altcrnative locations).

b. Place over soft tissues; avoid bony prominences. c. Place a 1110ist washcloth over the dispersive elec­

trode. d. Place a washcloth against the skin and hold it in

good contact at all edges with a nylon elasticized strap. (Covering the wet dispersive set-up wi th a plastic sheet to separate it rr0111 the bed and the patient's clothing to keep them dry wi ll be appre­ciated by the patient and the nursing sta lT. )

e. Ifplaced on the back. the weight of the body plus the strap can be used to achieve good contact at the edges.

r. Dispersive pad should be larger than the sum of the areas of the active electrodes and wound pack­II1g.

g. The greater the separation between the active and di spersive electrode the deeper the current path . Use greater separation for deep and undermined wounds

h. Dispersive and active electrodes should be 4 to 5 elll apart and shou ld not louch. Current now will be shallow. Usc HVPC for shallow. partial-thick­ness wounds.

Addif;ulIlIl Treafmelll Alethods:

• Up to rour wounds can be set up with a single-channel stimulator lIsing double bi rurca tcd leads rrom the stimu­lator to the electrodes. However, this will flot provide maximum current density at the treatment sites. For a patient with multiple wounds, it is not practica l to run several series ortreHtI11cnts. An alrernative is to usc two IIVPC stimulators. ifavailablc. Electrode placement wi ll

Electrical Slil1l11/atiollfor Wouud Healing 379

require careful planning so that the currcnt nows through target tissues. For example, if there is a wound on the right hip, coccyx, left rOOL and right heel, the disper­sive electrode should be placed on ei ther the right or left th igh. The thigh has a good blood supply and good conductiv ity. Thi s set lip will send the current flowing through the deep ti ssues to the feet. the hip. and the coccyx.

• Alternate placement orthe dispersive electrode ror each treatment , if possible. to direct current now to opposi te s ides of the wound has been suggcsted.7X This will be more difficult when wounds are located in the fee1.

• Ifa limb is involved the circumference may be too smail 10 wrap wi th the large dispersive electrode and main­tai n good contact. An alternative is to use birurcated Icads, which are avai lable 10 lise with the dispersive cable for some stimulators. When using this set-up. attach two round carbon-impregnated electrodes to make the sur­face area orlhe dispersive electrode larger than the ac­tive electrodc. Place the electrodes on either side oflhe limb. It is easier to conrorm the two pads to a small lilnb segment than the large rectangular dispersive electrode standard wi th most stimulators. Usc wei g<IUZC under the electrodes: ira greater conductive surrace is required extend the wet gauze out from the edges of the elec­trode over the surrounding skin. Hold the dispersive elec­trode in place wi th nylon e lasticized straps. If the patient complains of excessive tingling under the dis­persive set-up. check for good contact and see whether the size can be increased rurther. (See Figure 16 8. which shows birurca ted leads spread out on a washcloth for dispersive electrode.)

A /tern ath'e Met /rods of COll i/littillg Currellt t f) tir e JYO Il Ill/. Alternative methods or conducting cllrrent to the wound lIsing dressi ng products have been of interest ror a number or years. A recent study of conductivity or different wound dressings reported that: ( I ) transparent films are poor conductors. (2) fully saturated hydrocolloids will conduct cur rent. and (3) hydrogel amorpholls gels and sheet rorms arc good conductors because or their high water contenL HJ

An anima l study usi ng pigs wi th burn wounds demonstrated that usc of a hydrogel dressi ng with pulsed electri ca l stimu­lation delivered th rough the dressing increased the leve ls or collagenase during the cri tica l period ofepithc liali,wtion ini­tiation . Collagcnase enhancement may be one mechanism by which the electrical stimu lation acce leratcd the wound healing or these burns .1I4 See Chapter 10 ror a descri pt ion of amorphous and sheet hydroge l characteristics.

Use an amorphous hydrogel- impregnated gauze to con­duct current. Thi s type of dressing is used for partial-thi ck­ness, full-thickness, and subcutaneous lesions extend ing into deep tisslle wOllnds. Hydrogcls can be left in the wou nd ror

380 WOUN" CARl

lip to 3 days. This product class can benefit the wound man­agement by:

• Conducting electrical current when covered with an elec-trode.

• Promoting the "sodium current of injury:' • Absorbing light to moderate wound exudate. • Maintaining a moi st wound environment. • Graciuu lly absorbing wound moisture and is also a Inois­

lure dOllor to the wound. • Retaining the ce ll growth factors in the wound bed. • Reducing trauma and cooling orthe wound through less

handling. • Reducing product and labor costs by serving a dual pur­

pose.

Il ydrogcl sheets also have high waler content and can also be used to conduct currell! when placed under the electrode. lll

They have benefits similar to the amorphous hydrogels ex­cept that they should not be left on an infected wound. They are used for lightly eXlld3ting wounds and are best used for superficial partial-thickness wounds such as donor sites af­ler sk in grafting.

Amorphous hydrogel impregnated gauze or a hydrogel sheet can be used as the wet contact coupler under an elec~ trode. Although manufacturers say that all that is required is to clip the alligator clips to the dressing to conduct current, Alon "~ cxp lained that this will focus the cu rrent at one sma ll arca of the dress ing and not disperse it throughout the wound area unless the entire dressing surface is covered with an electrode. Follow the setup steps described above, but sub­stitute the salinc~soaked gauze with the amorphous hydro~ gcl impregnated gmlLe or hydrogel sheet. Dressings Illay be letl in plaee for up to 3 days. The amorphous hydrogel should be warmed before application, but be carefu l not to overheat the product and calise burns. Check temperature with a digi~ tal thermometer. Temperature should not be greater than 100° F. I f wound conditions permit. cover with a moisturel vapor~Jlerl11cab l c transparent film or another dressing to re~ tain moisture witholltmaceration and maintain body warmth. For amorphous hydroge l impregnated gauze. on the second day, li ft the secondary dressing and slip an al uminum foil electrode underneath; connect an alligator clip lead to the

Clinical Wisdom: Remove Petrolatum before Stimulation

All petrolatum products, including enzymatic debrid­ing agents such as collagenase (Santyl), and fibrinol­ysin (Elase), which are petrolatum-based products, must be removed before treatment or current will not be conducted into the wound tissues.

dressing and the stimulator. Replace secondary dressing. Repeat on the third day. The same approach "ou ld apply to the hydrogel sheet.

Protocol for Trelllment of Edema

Soft ti ssue trauma and a closed or minimally open wound would benefit from electrical stimulation to control. elimi­nate, or reduce edema formation. EdeJ1l3 sti mul3tes pain re­ccptors because of the tension in the tissues. blocks ofT cir­cu lation innow to the tissues. and impairs mobility. Edema eliminated controlled or reduced would be the expected outcome from this intcrvention. Table 16 6 show~ a protocol for trcatment for edcma rcduction u~ing high-voltage pulsed current stimulation. There are limited reports and no clinica l trials to support this treatment. \I l~

Se((ing Up (he PatiellfJor Treatmel1l (~lEdema:

I. Use the method for setting up the wound described undcr protocol for wound healing.

2. Elcvate the limb and support it on a pillow or foam wedge. above the hean if possible.

3. Use three or four electrodes. 4. Place onc clectrode over the wound and arrange the

other clectrodes over the v<-Iscul ar areas of the limb. a. Ifthc wound is in lower leg. pluee the second elec­

trode over the media l aspect of the loot and the third 0\ er the popliteal arca.

b. If the edema is in the foot diMal to the wound. a "foot sandwich" can be made by surrounding the foot with a foil electrode that wraps around the top and bottom of the foot.

NOle: Apply the same clinical reasoning for the upper extremity.

Protocol for Infection COlltrolmul Disinfection

A clean technique is recommcnded for treatment of chron ic wounds. The usc of aluminulll foi l electrodes is a good method of controlling infection and eliminates the need for disinfection of the electrode pads. If carbon electrodes or electrodes with sponges are used over the ' .... ound they need to be disinfccted betwecn cach use c,cn if used for a single patient. A cold disinfection solution. such as Cydex+. will disinfect for all organisms within 10 minutes according to

the material data sheet. Cydex+ comcs with an acthating solution that is added to the main solution when the bottle is opcned. The activated so lution can be rcusable for up to 28 days. The product is available in quan and ga llon si7es. Un­less large quantities of electrodes arc going to be di sinfected at one time. thc quart solution has been found to be most cost cfTect ivc .!\tI

Another cold disinfectant. Milkro-Quat , at the dilution of 18.6 g (% oz) in 3.8 L ( I gal) of water, has been tested for disinfection of electrodes and electrode sponges after (rCal­

mcnt of colonized wounds. The electrodes and sponges were soaked in the disinfecting so lution for 20 minutes and then tested for bacterial counts. Both the cfTicacy of the disinfec­tant and the protocol for disinfection were evaluated. Samples taken from 92% of the post-treatment electrode sponges af­ter they were di sinfected contained no bacterial growth . The remaining 8% comaincd two or fewer colonies. The results were the same for samples cultured anaerobically.ss The di s­persive pad, which is placed on intact ski n, should be cleaned between uses with soap and water or wiped with an alcohol­soaked pad. Alligator clips that come in contact with wound contaminants shou ld be disinfected between uses. One com­pany furnishes alligator clips with packs of hydroge l-imp reg­nated gauze that can be kept for si ngle patient use. Over time, the carbon electrodes wi ll absorb oil and detergent products and become resistant to current fl ow. A periodic check (eg, every 30 days) o f the conducti vi ty of the electrodes is highly recommended.

Clinical Wisdom: Benefits of Aluminum Foil Electrodes

Aluminum foil electrodes are very cost effective and time efficient for treatment of open wounds. They are easily made, are good conductors, can be molded to fit the body part, can be sized for maximum current density to the wound, and are disposable. Saline­soaked gauze packed in the wound and covered with an electrode is also cost efficient and is particularly good on deep lesions.

Ajterc:tlre. A ftcr the electrical stimulation treatment is complete, slip the electrode out from between the wct and dry gauze. The wound can be left undi sturbed . If sal ine­soaked gauze is the conductive medium , it should be changed before it dries or be covered with an occlusive dressing. If addi tional top ical treatments are required, such as enzymmic debriding agents or antibiotics, the packing will need to be removed. Frequent dressing changes are being discouraged because it disturbs the wound healing environment by re­movi ng important substanccs in wound exudate and cooling the wound. It takes 3 hours for a chi lled \vound to rcwarm and slows leukocytic and mitotic activity.87.ss

Protocol for Treat",ent of Chronic Venous Illsufficiency or Chronic Deep Vein Thrombosis

This protocol from Alon and De Domenico"(ppISS 1&0) is based on usi ng HVpe to elicit the pumping action of skel-

Electrical Stimulation Jor Wound Healing 38 1

etalmusc les (see Table 16- 6 showing I-I VPC protocols). The best muscle-pumping action is achieved from act ive exer­cise. but for some pati ents this is nO[ an option or is inad­equate to facilitate the venous pump mechani sms. Therefore, electrica l stimulation can be used as an il1lCrtllittel1l method for st imulation of muscle pump action. Patients wi th chronic lymphedema may also benefit.

Selling Up lhe Patie11l:

I . A bipolar technique is usually used. 2. Place both electrodes over the plantarnexors, one

proximal and one over the muscle bellies. 3. Use a surge or interrupted mode with an on time of3

to 15 seconds and an off time of 9 to 40 seconds. This 1:3 on/off ratio is essential to avoid musc le fa­tigue.

4. Begin with shorter oniofTtime and then increase the stimulation time as patient accommodates.

5. Polarity is not cri tical and can be adjusted for paticl1I comfort.

6. Pul se rate is between 40 and 60 pps and ean be ad­justcd for patient comfort.

7. Intensity that will produce intermittent, moderate te­tani<: muscle contraction is required. Increase inten­sity gradually for pati ent comfort and compliance.

8. Expect that a few treatment sessions wi ll be required to reach the desi rcd Icvel of muscle cOl1lraction.

9. Treatment time is pathology dependent. a. Chronie thrombophlebitis: 30 to 60 minutes bi ­

weekly b. Venous stasis: commence 5 to 10 minutes daily;

progress to 20 to 30 minutes biweekly 10. Precaution: Plantarflexors have a tendency to cramp;

proceed slowly to avoid cramping. Such cramping must be avoided. To avo id cramping, place the feel against a footboard that limits full range of plantar nexion .

I I. Expected outcome: enhanced venous return measured by reduced edcma. May facilitate hea ling of venous ulceration.

Selectillg tire Cundit/ute for Self-Care. HVPC stimula­tion and TENS are very safe and easy-to-apply treatments that a patient or caregiver can be taught for self-treatmcnt at home. HVPC stimulators, as describe(L arc ava ilable as por­table. battery-pack units. Some units come with compliance meters. TENS are also portable. Th is is a simple treatment, but it requires severa l steps and clear instructions. Rev iew the procedures with the person who will deliver the care to ensure that adequate care will be given to achievc the pre­dicted outcomes. I f the physical therapist does not believe that the person is able to be taught safe, appropriate proce­dures, th is should be documented and may be a rationa le for skilled services or anothcr intcrvcntion.

382 WULND CARr

To achieve success in a self-care program. psychosocial concerns need to be addressed before establishing the pro­gram. Select the patient andlor caregiver who is alert, moti­vated, and able to learn the directions ror application. It will require clinician support and encouragement to convince the paticn licarcgiver to accept the responsib il ity for self-care. Patients and caregivers are accustomed to receiving medical care al the clini c or by a home care practi tioner rather than doing selr-ea re. The concept orsharing the problem between patient and clinician is new to many people. It takes a step­by-step process to gai n patient cooperation. Begin in the clinic or al the home visit by encouraging and teaching the patient and/or the caregiver to participate in the setup process. Many people arc repulsed by the sight ora dirt y, smelly, ugly wound. That is oftcn the first hurdle. Takc it slowly. with patience and understanding of these feelings. Explain in simple lan­guage why the wound is dirty, smelly, and ugly and how the treatment wi ll improve the problem. Wound measurements and pictures can be used as moti vation to encourage contin­ued participation. Before-a nd-afler pictures of other cases treated this way are particularly effective ways of showing the patient/caregiver how other wounds improved. Move the patient or caregiver increasingly into the ro le of treatment provider as soon as possible. Observe, instruct, and offer words of support and praise.

Illstruction.'i, Independencc in the treatment routine mllst be established before dismiss ing the patient with an electri­cal stimulator for self-care at home. While it may seem over­whelming to give five steps of instructions for a single treat­ment protocol. understanding the five steps of instructions listed here wi ll ensure that the patient or caregiver is able to achieve the goal of independence in the treatment routine. Keep instructions as simple as possible so the responsible party will not be overwhelmed. Because of the number of steps required, prepared instruction sheets listing the five steps would be helprul. Stick-rigure drawings can be helprul in teaching the proper placement of the electrodes. DOl1't assume that the patient wi ll know where to place the elec­trodes or how to put on the dressing when he or she arrives home. Two or three visits with the physical therapist may be necessary to complete the instruction. Schedule regular fol­low-up assessments.

rile FiI'e Steps of Illstruction Are As fiJI/OlliS:

I. The list of needed supplies: Make sure thal the patient can acquire all the necessary items or help make ar­rangcment s to acquirc thosc that arc needed (eg. a por-

table HYPC stimulator with dispersive pad and nylon stretch strap).

2. Set-up of the patient and the wound for treatment. in­cluding all the steps listed: Review what is on paper and then do a demonstration (md rcturn demonstralion to confirm understanding.

3. The trcatment protocol: Review the treatmcnt proto­col by dialing in the characteristics ror the selected protocols on the stimulator to be used . The dials can be lel1 at the correct setting to help the paticnt , but they may be moved and should be rechecked at each treatment session. Give (Jllly the treatment protocol for the current wound healing phase. Tell the patient or caregiver what outcomes to expect and what findings should be reported promptly. Change instructions as the wound heals.

4. The aftercare procedures: Aftercare procedure instruc­tions should include how to apply the prescribed dress­ing product and disposa l orthe disposable waste prod­ucts from the treatment in the home setti ng (see Chap­ter 10). It is important to make sure that the patient or carcgiver understands the proper usc of the prescribed aftercare dressing products. Damage to the wound and failure to achieve predicted outcomes can be avoided by instruction in lise of products. Again. practice and a return demonstration (Ire proven methods of teaching new techniques.

5. A list of expected signs and symptoms: The patient and the caregiver need to be aware of the importance of any expected changes in signs and symptoms re­lated to the treatment and know when to report any undesirable results.

DOCUMENTATION

Docllmentation validates the treatment intervention . Docu­mentation is required to show treatment characteristics. and to track responses to treatment such as described in Chapter 4. Wound Measurements. and Chapter 5, Tools To Measure Wound Hea ling. Following are two case studies using the documentation methodology described in the functional out­comes report. The functional outcomes report explains the physical therapist 's rationale for selecting the intervention based on the patient eva luation and wound diagnosis, and the target outcomes expected from the intervention as shown in Chapter I, The Diagnostic Process. Data obtained during documcntation about trcatment outcomes should be done in a systematic manner; they can then be entered into a data­base to evaluate the program in the clinic. report success of the therapy, and predict outcomes and management costs.

Electrical Stimulation/or Wound Healing 383

Case Study 1: Pressure Ulcer Treated with ES

Patient ID: A.S. Age: 85 Onset: May

Initial Assessment: Brief Medical History and Systems Review

Reason for Referral

The patient has developed pressure ulceration along the lateral border of her left foot. She is not a candidate for surgical intervention because of multiple comorbidities.

Medical History

The patient is an 85-year-old woman who is unrespon­sive, with fetal posture and fixed contractures of all four extremities. She has a history of multiple cerebrovascu­lar accidents. She does not reposition herself in bed and cannot sit up in a wheelchair. She is on nasogastric tube feeding for nutrition; a Foley catheter is in place to con­trol incontinence of urine. The wound onset was 2 weeks prior to referral to physical therapy. The wound has dete­riorated and become necrotized. The nursing staff has been using enzymatic and autolytic debridement meth­ods.

Systems Review

Circulatory System. The patient has systemically im­paired circulation due to arteriosclerotic vascular disease. The circulation to the lower extremity is further impaired as a result of contractu res of the hips and knees.

Respiratory System. The patient has shallow, impaired respiration due to inactivity and her bed-bound status.

Musculoskeletal System. The patient has impaired joint mobility due to contractu res, resulting in severe dis­ability of the musculoskeletal system.

Neuromuscular System. The patient lacks the ability to respond to the need for self-repositioning and is cognitively unaware.

Examinations Indicated and Derived Data

Vascular Examination

Palpation of pulses indicates a weak dorsal pedal pulse. Determination of the ankle-brachial index is not possible

due to contractures at the elbow. Pulse oximetry of the great toe shows an oxygen saturation of 96%.

Musculoskeletal Examination

There is limited passive range of motion (less than 90· at either the hips, knees, or elbows). There is no active motor movement.

Integumentary Examination

The surrounding skin is erythematous, seen as red glow under darkly pigmented skin. The tissue is edematous. The temperature of the wound is elevated compared with surrounding tissues. There are hemorrhagic areas along the wound margin , and necrotic tissue covers the wound surface.

Evaluation of the Examination Findings and Relationship to Function

The specific dysfunction that generated a referral for the services of the physical therapist is loss of wound healing capacity. The patient's loss of function is due to generalized impairments (circulatory, cardiopulmonary, musculoskeletal, and neuromuscular). Limited bed mo­bility and limited cognitive ability further complicate the ability to heal wi thout physical therapy intervention for integumentary management.

Diagnosis

Musculoskeletal Disability

Impaired flexibility and strength leads to increased sus­ceptibility to pressure ulceration of the feet.

Neuromuscular Disability

The patient has neuromuscular disability associated with insensitivity and inability to reposition and make needs known.

Wound Healing Impairment

The signs and symptoms identified by the wound as­sessment, including edema, erythema, heat, and the pres-

continues

384 WOLND C ,.,

Case Study 1 continued

ence of necrotic tissue, indicate that the wound healing phase diagnosis is a chronic inflammation phase of heal­ing and impaired wound healing associated with a chroni­cally inflamed wound .

Functional Diagnosis

• Undue susceptibility to pressure ulceration on the feet

• Impaired wound healing • Chronic inflammation phase • Insensitivity to need for position change

Need for Skilled Services: The Therapy Problem

The patient has failed to respond to interventions with dressing changes for the last 2 weeks. She now requires the following four interventions:

1. Debridement of the necrotic tissue from the wound bed to determine level of tissue impairment and to initiate the healing process

2. HVPC to enhance circulation to the foot, facilitate debridement, and restart the process of repair

3 . Therapeutic positioning to remove pressure trauma on the foot

4. Range-ot-motion exercises to all four extremities to maintain tissue extensibility and increase circula­tion

Prognosis

Healing is not expected without intervention; however, the prognosis is good for a clean , stable wound . Initia­tion of the acute inflammation phase with electrical stimu­lation is expected in 2 weeks with progression to a prolif­eration phase in 4 weeks, and a clean , stable wound in 6 weeks.

Treatment Plan

• Instruction will be given to nurses' aides in range­of-motion needs of the patient; it will include initial and follow-up for two different shifts (four visits).

• Instruction will be given to the nursing staff in thera­peutic positioning; it will include initial instruction and follow-up for two different shifts (three visits).

• HVPC parameters: 1. The active electrode will be placed on the wound

site.

2. The dispersive electrode will be placed on the thigh.

3. Polarity initially will be negative, then alternated between positive and negative, as described under the Sussman Wound Healing Protocol , as the wound changes phases.

4. The pulse rate will be changed from 30 pps to 120 pps to 64 pps as phases change.

5. The current intensity will be set at 150 V through­out.

6. HVPC will be of a 60-minute duration, seven times a week.

• Debridement will be achieved by HVPC, enzymes, and sharp instruments daily as needed to remove necrotic tissue.

Interventions

Passive Range-ot-Motion Exercises

Passive range-of-motion exercises will be performed to all four extremities, ranged twice daily by the restor­ative nurses' aide as instructed by the physical therapist.

Targeted Outcome. The nurses' aide will be able to provide the optimal amount of range of motion for all four extremities; increase tissue extensibility at elbows, hips, and knees; and increase perfusion to the lower extremi­ties; due date: 2 weeks.

Healing Pressure Relief

Therapeutic positioning with adaptive equipment will be used to keep feet off the bed, and a pressure-relief mattress replacement will be provided.

Targeted Outcome. The nursing staff will be able to use therapeutic positions to reduce the risk of pressure ulcer formation on the feet, including elimination of pres­sure on the lateral border of the foot with pressure ulcer; due date: 1 week.

Electrical Stimulation with HVPC 7 Days per Week

Targeted Outcome. The intervention will stimulate per­fusion and cellular responses of the inflammatory phase, and wound debridement wi ll progress to the acute in­flammation phase followed by progression to the prolif­eration phase; due date: 6 weeks.

continues

Case Study 1 continued

Debridement

Sharp debridement will be used for nonviable tis­sue; enzymatic debridement wi ll be used to solubilize the necrotic tissue between sharp debridement ses­sions.

Targeted Outcome. The wound will be necrosis free: due date: 4 weeks.

Elec trical Stimulation/i)r lIf-mlid lIea /ing 385

Discharge Outcome

Within 4 weeks the wound was clean , granulating wound edges were contracting. and epithelialization was starting. Because it was now evident that there was po­tential for wound closure, the prognosis was changed to healed wound from clean and stable; HVPC treatment was continued, and at 12 weeks the wound was fully epi­thelialized and closed.

Case Study 2: Vascular Ulcer Treated with ES

Patient: C.Z. Age: 80 (Color photos of the case are Color Plates 55 and 56.)

Initial Assessment

Reason for Referral

The patient came to the physical therapist because a vascular ulcer on the posterior right calf would not heal. The patient and his wife reported that they had been car­ing for the ulcer for more than 6 months, and they wanted it to heal so they could resume their usual activities in the community.

Medical History

The patient has a history of severe arterial vascular oc­clusive disease of the lower extremities. Old World War II burn scarring covered the surrounding area of the calf, with hyperketotic scarring that kept breaking down. The recurrent skin breakdown on his leg resulted in protracted periods of healing (eg, more than 1 year). One ulcer had healed in 6 months after a course of care using electrical stimulation (HVPC). The previous ulcer took more than a year and did not heal. The patient was ambulatory and alert , with mild confusion. His wife reported that any moisture left on the surrounding skin caused maceration and skin breakdown. A femoral angioplasty had been done the week before the patient was seen in the outpa­tient clinic.

Functional Diagnosis and Targeted Outcomes

Integumentary Examination

Adjacent Skin. Hyperketotic; scar tissue; flaky, friable, dry skin; and pallor are present.

Functional Diagnosis. The patient has loss of func­tional mObility due to integumentary impairment.

Targeted Outcome. The patient will have improved skin texture and integrity; due date: 6 weeks.

Wound Tissue Examination

The wound edges are poorly defined. There is necrotic tissue along the margins. There is a small island of skin in the middle of the wound bed. The wound has partial­thickness skin loss with moderate exudate. The wound is about 200 cm' .

Functional Diagnosis. There is absence of an inflam­mation phase.

Targeted Outcome : Acute intlammation will be achieved; due date: 2 weeks.

Associated Impairment. Necrotic tissue is present. Targeted Outcome: A clean wound bed will be

achieved; due date: 4 weeks.

Functional Diagnosis. There is absence of a prolifera­tion phase.

Targeted Outcome: The wound will exhibit granula­tion tissue and be ready for grafting; due date: 6 weeks.

Vascular Examination

Medical Diagnosis. The patient has severe arterial vas­cular occlusive disease, status postangioplasty.

Functional Diagnosis. The patient has vascular im­pairment contributing to impaired healing.

Targeted Outcome: Perfusion will be enhanced; due date: 2 weeks.

continues

386 W OUND CARE

Case Study 2 continued

The patient's loss of function in these systems is re­sponsible for the undue susceptibility to skin breakdown on the legs and inability to heal without integumentary intervention. The patient has improvement potential. The wound will heal partially, and the wound bed will be pre­pared for grafting following intervention.

Need for Skilled Services

The patient has failed to respond to treatment with wound dressings and conservative management of the leg ulcer. It requires debridement of necrotic tissue to ini­tiate the healing process and HVPC to initiate the healing phases and to enhance perfusion so that the wound bed is prepared for grafting.

Treatment Plan

• The patient and wife will be instructed to perform HVPC as a daily home treatment program with a portable HVPC rental unit.

• Wound debridement will be performed to remove necrotic tissues; methods will include autolysis, sharp debridement, and enhanced perfusion with the use of HVPC.

• The wife will be instructed in wound dressing changes with alginate to absorb moderate exudate, including how to cut the dressing to fit the wound to avoid maceration.

REFERENCES

I. Swanson O. Functional outcomes report : the next generation in physical therapy reponing. In : Stewart DL. Abeln SH. cds. DocII­mel/ling FUllctional Oil/comes ill Physic(I/ Therapy. S, Louis. MO: Mosby-Year Book: 1993.

2. Bergstrom N. Bennett MA, Carlson CEo ct aL Tre(lfment of Pres­\'lin' Ulcers. Clinica l Practice Guideline No. 15 . AJ-ICPR Publica­tion No. 95-0652. Rockville. MD; Agency for Health Care Po licy and Research. U.S. Department of Ilealth and Iluman Services; De· cember 1994.

3. Kloth L. et al. Elecirorherapelilic Terminology in Physical Therapy. Alexandria. VA: eel ion on Clinical Electrophysiology. American Physical Therapy Association: 1990.

4 . Alon G. De Domenico O. J-Jigh 1'tJlwge Stimllimion : All Integrated Approtlch to Clinic," Electrotheropy. llixton. TN: The Chananooga Group: 1987.

5. Newton RA. Karsellis TC. Skin pH fo llowing high voltage pulsed galvanic stimulation. Phys Tiler . 1983:63:1593- 1596 .

6. Newton RA . I~ igh·vohage pu lsed current: theoretical bases and clinical applications. In : Nelson R, Currier D. cds. CliniclIl £Iec· rtrJlherapy. Norwalk. CT: Appleton & Lange; /99/:201 - 220.

7. Gersh M. Microcurrent electrical s timu lation: putting it in perspcc· tive. elin Manage. 1989:9(4) :5 1-54.

Discharge Outcomes

• The patient started care in mid-Oecember. • The wound was necrosis free. • The wound phase changed to both prOliferation and

epithelialization. The wound size was reduced to less than half the original area.

• The wound was grafted at the end of February. • The wound graft was successful. A smaller graft was

needed than originally expected because of the epi­thelialization. Surrounding integumentary integrity was improved: the skin was softer and smoother, and no new hyperkeratosis developed in the scar tissue area.

General Comments

The patient and his wife were very compliant with the home treatment regimen. The femoral angioplasty appar­ently opened the vessels enough to permit the enhanced perfusion from the HVPC to reach the tissues. Grafting was the best option for this couple because it provided faster closure and allowed them to live more functional lives without having wound care duties. It also provided a better covering with healthier skin from the opposite thigh to cover the open area. New scar tissue was better­quality tissue than that surrounding older scars, possibly due to the improved collagen organization and vascular­ization associated with the HVPC.

8. Nelson R, Nestor O. Electrophysiological evaluation: an overview. In: Nelson R. Currier D. cds. Clinical Electrotherol)Y. Norwalk. CT: Appleton & Lange; 1991 :331 - 360.

9 . Bourguignon CJ. Bourguignon LVW, Electric stimulation of hu· man fibroblasts causes an increase in Cll l' and the exposure of ad­ditional insulin receptors. J Cell PII),siol. 1989: 140:379 385.

10. Friedenberg ZB. Andrews ET. et III. Bone reaction to varying amoun ts of dircci current. Slirg Gynecol Obslf't. 1970: 131 :894-899.

II. Jaffe LS. Va nable JW. Electric fields and wound healing. Clin

DernllllOI. 1984:3 :34.

12. Gentzkow G, Miller K. ElectriC:11 stimul ation for dermal ..... ound healing. eli" Podiarr Med SlIrg. 1991 :8:827-841 .

13 . Genlzkow GO. Po llack Sv, et al. Improved healing of pressure ul· ccrs using Dermapulsc. a new electrical stimuilltion device . HOllnds. 1991 :3: 158- 160.

14. Fukushima K. Sends . et al. Studies of galvantotaxis of leuko· cytes. Med J OSllka U,.;v. 1953 :4: 195- 208.

15. Orida N, Feldman J. Directional protrusive pseudopodia I activity and motility in macrophages induced by extnlcellular electric fields. Cdl MVli/. 1982:2:243- 255 .

16. Kloth LC. Electrica l s timulation in tissue repair. In : McCulloch J. Kloth L. Feedar J. cds. WOllflt! Healing Alt('rll(lfi\'e.~ in Manage· ment. 2nd cd. Philadelphia: EA. Davis: 1995:275 310.