IONTOPHORESIS EQUIPMENT
CHAPTER 6 Iontophoresis 171
It has been recommended that the maximum current intensity be determined by the size of the active electrode ( Figure 6–3 a ). 65 Current amplitude is usually set so that the current density falls between 0.1 and 0.5 mA/cm 2 of the active electrode sur-face 17 (Figure 6–3 b).
Treatment Duration
Recommended treatment durations range between 10 and 20 minutes, with 15 minutes being an average. 2 During this 15-minute treatment, the pa-tient should be comfortable with no reported or vis-ible signs of pain or burning. The athletic trainer should check the patient’s skin every 3–5 minutes during treatment, looking for signs of skin irritation.
Since skin impedance usually decreases during the treatment, it may be necessary to decrease current intensity to avoid pain or burning.
It should be added that the medicated electrode can be left in place for 12–24 hours to enhance the initial treatment. 2
Dosage of Medication
An iontophoresis dose of medication delivered dur-ing treatment is expressed in milliampere-minutes (mA-min). An mA-min is a function of current and
time. The total drug dose delivered (mA-min) = current × treatment time. For example:
40 mA-min dose = 4.0 mA current ë 10 minutes treatment time
OR
30 mA-min dose = 2.0 mA current ë 15 minutes treatment time A typical iontophoretic drug delivery dose is 40 mA-min but can vary from 0 to 80 mA-min depending on the medication.
Electrodes
The continuous direct electrical current must be de-livered to the patient through some type of electrode.
Many different electrodes are available to the ath-letic trainer, ranging from those “borrowed” from other electrical stimulators to commercially manu-factured, ready-to-use, disposable electrodes made specifically for iontophoresis. 8 , 40
The more traditional electrodes are made of tin, copper, lead, aluminum, or platinum backed by rub-ber and completely covered by a sponge, towel, or gauze that is in contact with the skin. The absorbent material is soaked with the ionized solution to be driven into the tissues. If the ions are contained in an ointment, it should be rubbed into the skin over Figure 6–3 (a) The maximum current intensity should be determined by the size of the active electrode. (b) Current amplitude is usually set so that the current density falls between 0.1 and 0.5 mA/cm2 of the active electrode surface.
100 0 30
20
10
200 300
Square centimeters
Milliamps
400 500
(a) (b)
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the target zone and covered by some absorbent material soaked in water or saline before the elec-trode is applied.
The commercially produced electrodes are sold with most iontophoresis systems. These electrodes have a small chamber, in which the ionized solution is housed, that is covered by some type of semiper-meable membrane. The electrode self-adheres to the skin ( Figure 6–4 ). This type of electrode has elimi-nated the “mess and hassles” that have been associ-ated with electrode preparation for iontophoresis in
the past. Some electrodes are available with the ion-ized solutions already inside. Other electrodes still need to have the medication injected into an elec-trode cavity ( Figure 6–5 ).
Regardless of the type of electrode used, to ensure maximum contact of the electrodes the skin should be shaved and cleaned prior to attachment of the electrodes. Care should be taken not to exces-sively abrade the skin during cleaning because dam-aged skin has a lower resistance to the current so that a burn may more easily occur. Also, caution should be used when treating areas that for one rea-son or another have reduced sensation.
Once this electrode has been prepared, it then becomes the active electrode, and the lead wire to the generator is attached such that the polarity of the wire is the same as the polarity of the ion in solu-tion. A second electrode, the dispersive electrode, is prepared with water, gel, or some other conductive material as recommended by the manufacturer.
Both electrodes must be securely attached to the skin such that uniform skin contact and pressure is maintained under both electrodes to minimize the risk of burns. Electrodes via the lead wires should not be connected to the generator unless both the generator and the amplitude or intensity control are turned off. At the end of the treatment, the intensity control should be returned to zero and the generator turned off before the electrodes are detached from the patient.
Figure 6–5 Electrodes used for iontophoresis.
Figure 6–4 The commercially produced, self-adhering electrodes used with most iontophoresis systems have a small chamber that is covered by some type of semipermeable membrane that contains the ionized solution.
Lead wire
Electrode cavity that holds ion
Semipermeable membrane Skin adhesive
CHAPTER 6 Iontophoresis 173
The size and shape of the electrodes can cause a variation in current density and affect the size of the area treated. 28 Smaller electrodes have a higher cur-rent density and should be used to treat a specific lesion. Larger electrodes should be used when the target treatment area is not well defined.
Recommendations for spacing between the active and dispersive electrodes seem to be variable.
They should be separated by at least the diameter of the active electrode. One source has recommended spacing them at least 18 inches apart. 16 As spacing between the electrodes increases, the current den-sity in the superficial tissues will decrease, perhaps minimizing the potential for burns.
The newest type of electrode utilizes an extended time-released electronic transdermal drug delivery system ( Figure 6–6 ). A self-adhesive patch has a self-contained, built-in battery that produces a low-level electric current to transport ions to underlying tissue. Drug delivery is shut off automatically when the prescribed dosage has been administered. The patch is single use and disposable.
Selecting the Appropriate Ion
It is critical that the athletic trainer be knowledge-able in the selection of the most appropriate ions for treating specific conditions ( Table 6–1 ). For a compound to penetrate a membrane such as the skin, it must be soluble in both fat and water. It must be water soluble if it is to remain in an ionized state in solution. However, human skin is relatively impervious to water ions, which are soluble only in water and do not diffuse in the tissues. 10 They must be fat soluble to permeate the tissues of the body. 40 Penetration is relatively superficial and is generally less than 1 mm. 39 The majority of the ions depos-ited in the tissues are found primarily at the site of the active electrode, where they are stored as either a soluble or insoluble compound. They may be used locally as a concentrated source or trans-ported by the circulating blood, producing more systemic effects. 58
The tendency of some ions to form insoluble precipitates as they pass into the tissues inhibits their ability to penetrate. This is particularly true with heavy metal ions, including iron, copper, silver, and zinc. 23
An accumulation of negative ions produces an acidic reaction through the formation of hydrochlo-ric acid. This is sclerotic and produces hardening of the tissues by increasing protein density. In addi-tion, some negative ions can also produce an anal-gesic effect (salicylates). It should be added that this response occurs under the positive pole.
The majority of the ions used for iontophoresis are positively charged. An accumulation of positive ions produces an alkaline reaction with the
• The negative electrode should be larger than the positive.
Figure 6–6 The Iontopatch has a self-contained battery that uses a low-level current to drive ions into the skin.
Clinical Decision-Making Exercise 6–2 A field hockey player is getting her first iontophoresis treatment for patellar tendonitis.
Dexamethasone has been prescribed in a dose of 40 mA-min. What can the athletic trainer do to minimize the chances of an adverse sensitivity to this medication during this first-time treatment?
Battery
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TABLE 6–1 Recommended Ions for Use by Athletic Trainers47
POSITIVE
Antibiotics, gentamycin sulfate (+), 8 mg/mL, for suppurative ear chondritis.
Calcium (+), from calcium chloride, 2% aqueous solution, believed to stabilize the irritability threshold in either direction, as dictated by the physiologic needs of the tissues. Effective with spasmodic conditions, tics, and “snapping fingers” (joints).
Copper (+), from a 2% aqueous solution of copper sulfate crystals; fungicide, astringent, useful with intranasal conditions, e.g., allergic rhinitis or “hay fever,” sinusitis, and also dermatophytosis or “athlete’s foot.”
Hyaluronidase (+), from Wydase crystals in aqueous solution as directed; for localized edema.
Lidocaine (+), from Xylocaine 5% ointment; anesthetic/analgesic, especially with acute inflammatory conditions (e.g., bursitis, tendinitis, tic doloreux, and TMJ pain).
Lithium (+), from lithium chloride or carbonate, 2% aqueous solution; effective as an exchange ion with gouty tophi and hyperuricemia.
Magnesium (+), from magnesium sulfate (“Epsom Salts”), 2% aqueous solution; an excellent muscle relaxant, good vasodilator, and mild analgesic.
Mecholyl (+), familiar derivative of acetylcholine, 0.25% ointment; a powerful vasodilator, good muscle relaxant, and analgesic. Used with discogenic low back radiculopathies and sympathetic reflex dystrophy.
Priscoline (+), from benzazoline hydrochloride, 2% aqueous solution; reported effective with indolent ulcers.
Zinc (+), from zinc oxide ointment, 20%; a trace element necessary for healing, especially effective with open lesions and ulcerations.
NEGATIVE
Acetate (−), from acetic acid, 2% aqueous solution; dramatically effective as a sclerolytic exchange ion with calcific deposits.
Chlorine (−), from sodium chloride, 2% aqueous solution; good sclerolytic agent. Useful with scar tissue, keloids, and burns.
Citrate (−), from potassium citrate, 2% aqueous solution; reported effective in rheumatoid arthritis.
Dexamethasone (−), from Decadron; used for treating musculoskeletal inflammatory conditions.
Iodine (−), from Iodex ointment, 4.7%; an excellent sclerolytic agent, as well as bacteriocidal, and a fair vasodilator.
Used successfully with adhesive capsulitis (“frozen shoulder”), scars, etc.
Salicylate (−), from Iodex with methyl salicylate, 4.8% ointment; a general decongestant, sclerolytic, and anti-inflammatory agent. If desired without the iodine, may be obtained from Myoflex ointment (trolamine salicylate 10%) or a 2% aqueous solution of sodium salicylate powder. Used successfully with frozen shoulder, scar tissue, warts, and other adhesive or edematous conditions.
EITHER
Ringer’s solution (+/−), with alternating polarity for open decubitus lesions.
Tap water (+/−), usually administered with alternating polarity and sometimes with glycopyrronium bromide in hyperhidrosis.
Clinical Decision-Making Exercise 6–3 The athletic trainer gets a prescription from the team physician for using dexamethasone, an anti-inflammatory, to treat Achilles tendinitis.
What considerations and treatment parameters are important for preparing the patient for this iontophoresis treatment?
formation of sodium hydroxide. Positive ions are sclerolytic; thus they produce softening of the tis-sues by decreasing protein density. This is useful in treating scars or adhesions. This response occurs under the negative pole. Table 6–1, modified from a list compiled by Kahn, lists the ions most commonly used with iontophoresis. 54
CHAPTER 6 Iontophoresis 175 Clinical Applications for Iontophoresis
A relatively long list of conditions for which ionto-phoresis is an appropriate treatment technique has been cited in the literature. 5 Clinically, ionto-phoresis is most often used in the treatment of in-flammatory musculoskeletal conditions. 22 It may also be used for analgesic effects, scar modifica-tion, wound healing, and in treating edema, cal-cium deposits, and hyperhidrosis. Many of these published studies are case reports that attempt to establish the clinical efficacy of iontophoresis in treating various conditions. 31 , 90 Table 6–2 pro-vides a list of studies that have treated various conditions using iontophoresis.
Treatment Protocols: Iontophoresis 1. Prepare electrodes according to
manufacturer’s instructions; secure electrodes to patient. Electrode location will vary depending on the drug being phoresed;
anionic drugs are repelled from the cathode;
cations are repelled from the anode.
2. Remind the patient to inform you when he or she feels something. Do not tell the patient what he or she will feel; for example, do not say,
“Tell me when you feel a burning or stinging.”
3. Turn on the stimulator, and increase the amplitude slowly. Monitor the patient’s response, not the stimulator.
4. After the patient reports the onset of the stimulus, adjust the amplitude to the appropriate intensity.
5. Continue to monitor the patient during the duration of the treatment.
T A B L E 6 – 2 Conditions Treated with Iontophoresis
CONDITION IONS USED IN CONDITION IONS USED IN
TREATMENT TREATMENT
INFLAMMATION Gangarosa 199326
Bertolucci 19828 Hydrocortisone, salicylate Abell et al. 19741
Kahn 198254 Dexamethasone Shrivastava, Sing 197787
Chantraine et al. 198613 Grice et al. 197232
Harris 198239 Hill 197643
Hasson 199142 Stolman 198792
Hasson et al. 199241
Delacerda 198218 FUNGI
Glass et al. 198030 Kahn 199157 Copper
Zawislak et al. 1996100 Haggard 193937
McEntaffer et al. 199664
Gurney et al. 200536 OPEN SKIN LESIONS
Hamann, 200638 Cornwall 198115 Zinc
Banta 19956 Jenkinson et al. 197447
Petelenz et al. 199274 Balogun et al. 19904
Panus et al. 199970 Ketoprofen
HERPES
ANALGESIA Gangarosa et al. 198942
Evans et al. 200121
Schaeffer et al. 197184 Lidocaine, magnesium ALLERGIC RHINITIS
Russo et al. 198081 Kahn 199157 Copper
(Continued)
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T A B L E 6 – 2 (Continued)
CONDITION IONS USED IN CONDITION IONS USED IN
TREATMENT TREATMENT
Garzione 197828 GOUT
Pellecchia et al. 199472 Kahn 198249 Lithium
Reid et al. 199378
Schultz 200285 BURNS
Yarrobinno et al. 200699 Rapperport et al. 196577 Antibiotics
Pasero et al. 200671
SPASM Rigano et al. 199279
Kahn 197552 Calcium, magnesium Driscoll et al. 199920 Kahn 198553
REFLEX SYMPATHETIC
DYSTROPHY
ISCHEMIA Bonezzi et al. 19949 Guanethidine
Kahn 199157 Magnesium, mecholyl, iodine
LATERAL EPICONDYLITIS
EDEMA Demirtas et al. 199819 Sodium salicylate
Kahn 199157 Magnesium, mecholyl Sodium diclofenac
Boone 196911 Hyaluronidase, salicylate Baskurt 20037 Naproxen
Magistro 196462
Schwartz 195586 PLANTAR FASCIITIS
Gudeman et al. 199733 Dexamethasone
CALCIUM DEPOSITS Gulick 200035 Acetic acid
Ciccone 200314 Osborne, 200669
Weider 199298 Acetic acid
Kahn 197749 PATELLAR TENDINITIS
Psaki 195576 Huggard et al. 199945 Dexamethasone
Kahn 199650 Perron et al. 199773
Tygiel 200395 ROTATOR CUFF
Gard, 200427 Preckshot 199975 Dexamethasone
Bringman et al. 200312 Lidocaine
Leduc et al. 200359
SCAR TISSUE PLANTAR WARTS
Tannenbaum 198094 Chlorine, iodine, salicylate Soroko et al. 200291 Sodium salicylate Kahn 198553
EPICONDYLITIS
HYPERHIDROSIS Nirschl 200367 Dexamethazone
Kahn 197358 Tap water
Levit 196861 Gillick et al. 200429
CHAPTER 6 Iontophoresis 177