Review
PHYSICAL MODALITIES ELECTROSURGERY, ELECTROCAUTERY AND ELECTROLYSIS
MARSHALL L. BLANKENSHIP, M.D.
Any tbrm of physical energy is capable of producing destructive effects when carried beyond the limits of physiologic tolerance. Heat, cold, sound, ionizing radiation and ultraviolet radiation are physical modalities used in dermatologic therapy. Heat can be delivered to the skin by electrosurgery, electrocautery and electrolysis. Electrosurgery: High Frequency Alternating Current Electrosurgery is the use of electrical energy to produce heat to destroy benign and malignant tumors, to excise normal and diseased tissue and to control bleeding. Medical instruments activated by electricity have been used since the early 1900s, The indications, advantages, disadvantages and limitations of electrosurgery are well known to dermatologists. The proper and safe use of electrosurgery depends on Ihe knowledge of the physiologic effects of electrical current on tissue,^-'"' of electrophysics,^-^-'^-^"" of electrosurgital instruments,^•^•^^•''•'^•^'' and of the disease being treated. Expertise depends on experience based on this knowledge. Address for reprints: Marshall L. Blankenship, M.D,, 4647 West 103rd Street, Oak Lawn, IL 60453.
trom the Department of Dermatology, Rush Medical College, Chicago, Illinois
Tissue Response When an alternating current of a sufficiently high frequency to avoid nerve and muscle responses passes through living tissue, there is no other effect except the production of heat. The internal heat produced in the tissue is the direct result of the resistance offered by the living tissue to the passage of the current, and is the basis for treatment by electrosurgery and diathermy. In medical diathermy, a low current density is created in the tissue with an even distribution of energy and heat throughout by the use of large plate electrodes of equal size. With the use of a small active electrode and a larger dispersive electrode, the heat produced by the high frequency alternating current is concentrated in a small area and is highly destructive to tissue. While the active electrode remains cold, the highly concentrated electrical energy creates molecular heat within each cell. By choice of the electrodes and the intensity and type of current, the cellular changes produced by the
001 l-9059/79/O7OO/0443.'$OI.O0 © International Society of Tropical Dermaloiogy, Inc.
443
444
INTERNATIONAL lOURNAL OF DFRMATOLOGY
high frequency electrical energy arc cc)tTtr(jllable, producing different types of tissue destruction. All of the events that occur when a high frequency alternating current produces cellular changes have not been fully explained. Depending on the current density, cells undergo different changes. When high current density is applied between active and dispersive electrodes, molecular heat is generated within each cell to the point that fluids in the cell volatilize and the cell explodes. This explosive vacuolization occurs as the result of Intracellular steam pressure. By applying this electrical energy to individual cells in sequence by moving the electrode through the tissue, the tissue separates ahead of the electrode. The line of destruction of tissue is limited and a cutting effect is produced. Although heat produces the cellular effect, the end result simulates a mechanical disruption of the cells rather than the changes usually produced by heat. If the current density is less concentrated, heat is produced over a relatively larger area and the cells are dehydrated and their protein contents become denatured. Cell outlines are entirely lost and an amorphous mass remains; blood vessels are thrombosed and a coagulating effect is produced. The heat is sufficient to produce donaturation of protein but not the explosive effect. With the use of one electrode, a high frequency alternating current, with a high driving force but less current, dehydrates the tells. Although cells are shriveled, the cell outlines and nuclei are preserved, and desiccating effect is produced. Stronger desiccating currents can produce coagulation and weaker coagulating currents can [produce desiccation. With excessive high trpc|uency alternating current, carbonization atid charring occur. tk'ctruphysic To produce a high voltage, high frequency alternating current lor surgery, the commercial 110 volt current has to be stepped up to several thousand volts by a step up trans-
luiy-August 1979
Vol. 18
forrner in the power circuit of the instrument. The frequency has to be greatly increased from the 60 hertz (cycles per second] commercial current to between 500 kilohertz and 100 megahertz. This is done in the oscillating circuit of the instrument. This circuit contains condensers, a coil of wire and an air gap. The air gap may be a spark gap, a vacuum tube (diode, triode, thermionic, radio or valve tube) or solid state substitutes (transistor). The low voltage, low frequency commercial current is converted to a high voltage, high frequency current of various types that may be c_tirried by the patient circuit to the patient for electrosurgery. The current may be applied to the patient either mono- or bi-terminally, Biterminal electrosurgery employs a large dispersive electrode grounding the patient to the electrosurgical apparatus and a needle active treatment electrode. The patient is incorporated into and is an integral part of the circuit. In monoterminal electrosurgery, the patient is not a part of the circuit and there is no ground to the apparatus. The electrons are shed from the patient to the air, walls, table and floor. One type of electrosurgical current is a damped current: a strong initial burst followed by diminishing waves. The more rapidly the diminishing waves return to zero, the more damped the current (Fig. la). The slower the return to zero, the less damped the current (Fig, lc). The frequencies of the oscillating current are altered by varying the size of the condensers and the coil in this circuit. By increasing the resistance in the oscillating circuit, longer rest periods between the wave trains will occur and produce a greater damping effect. A second type of current used in electrosurgery is an undamped current with constant equal waves of unchanging amplitude. The oscillating circuit contains a vacuum tube with a direct current grid circuit and an alternating platecircuit along with the condensers and the coil. The grid and plate circuits mutually energize each other. Eac h osc illation receives an increase in energy by a feedback mechanism and eciu.il am[jlitucle osc illations
No, 6
PHYSK AL MODAinirs
Figure 1 a Markedly Damped
liL,nk,'n.hii,
Modulated
Figure 1 b Moderatelv Damped
44.S
Figure 1 d Half Wave Rectfftcation
Figure 1 e Modulated • Full Wave Rectification
•Wi/IMAMFigure 1 c Slightly Damped Spark Gap Apparatus
Figs. la-f.
Figure 1 f Undamped Vacuum Tube Apparatus
High frequency wave forms.
are produced. A triode vacuum tube in the circuit produces a fully undamped current (Fig, I 0. By varying the tubes and other components of the oscillating circuit, the undamped current,^ The type of current (damped or un((am[)ed), the application of the current a moderately cl.imped current or a full-wave rectification (Fig. Ie) resembling a slightly damtx'd c urrent.*^ The ty|x- ol current (damped or undamped), the ii|)p(i( ation of the c urrent (monoterminal or biterminal) and the current intensity, voltage and amperage, determine the types of tissue effects produced—cutting, coagulation or desiccation. Completely undamped c urrents arc bitermin.il, rt'f|uiring.in active and dispersive electrode; produced by a vacuum tube or solid state substitute oscillating circuil; and very high fnxiLicncy, high atn[>er,ige, low voltage curretils. This current explodes the cells, pro-
ducing maximal cutting effect which [hermits healing by first intention under ideal conditions. Minimal heat effects such as coagulation and hemostasis are produced. Damped currents may be applied either mono- or biterminally. Monoterminal application is used with a spark gap oscillating circuit with only the active electrode. Because the patient is not a ()art of the circuit, a higher v(;ll,ige driving force is required to produce effective tissue destruc tion at the electrode. There is correspondingly less amperage and thus less heat. This high frequency, very high voltage, low amperage current produces a dehydration of the cells with tissue destruction and effective superficial hemostasis. With biterminal application of a spark gap damped current, the patient is incorporalecl into the circ uit whic h allows the production f)f ci high arnptT.igc < urrcnt at a lower voltage.
446
INTFRNATIONAI. lOURNAL OF DERMATOLOCY
Vol. 18
luly-August 1479
c — aj _0 u T!
01
c
ji^
^
t/l
. _
_E2
^3 - ~
t: •- 6
0 t?
—
.^ E
C 00
>.
QJ
c Q; 5 E a; - > «
ive
S" ra
>
ery o Itei'nalin
QC
m
s istor
0 TJ
iformi
c
c
tj
o
tr
01
"5
c _ o c O
Tl
ra
Ol
0/
c
c
O
o
"ra
c ,9
;ulat
ery
c ,o in
c •—
Blankenship
447
This high frequency- low voltage, high amperage current produces heat with coagulation tissue effect with maximal tissue destruction and hemostasis. When two electrodes closely spaced in the same handle are inserted into the tissue, localized coagulation between the electrodes is produced. This is referred to as bipolar coagulation and is not commonly used in dermatology. Completely undamped currents produce excellent cutting but little hemostasis and fully damped currents produce maximal tissue destruction and hemostasis but no cutting effect. However, by modifying the currents between these two extremes, a current can be produced which cuts easily and, although coagulation is decreased, will still provide adequate hemostasis and allow bloodless cutting. A slightly damped current from the biterminal application of a spark gap apparatus and a modulated full-wave rectified current from a vacuum apparatus will provide cutting with hemostasis, A spark gap moderately damped current and a vacuum tube modulated half-wave rectified current provides more coagulation and hemostasis, Monoterminal application of a spark gap apparatus will provide only a damped current and cannot provide currents for cutting. Thus, the spark gap apparatus can provide currents for cutting, coagulation and desiccation, and the tube type apparatus can provide currents for cutting and coagulation. Maximal tissue destruction from the spark gap apparatus and maximal cutting ability from the tube type apparatus are preferred by some electrosurgeons for certain procedures. However, either type of apparatus has the capability of producing current types for most routine procedures, i.e., cutting and coagulation. Types of Electrosurgery Using these available current types, four types of electrosurgery can be performed: electrodesiccation, electrofulguration, electrocoagulation and electrosection (Table 1), With all forms of electrosurgery, the amount of tissue destruction depends upon; (1) the amount of power, (2) the lengh of application, (31 the size of the electrode and (4) the density and
448
INTERNATIONAL lOLJRNAl OF DFR'MATOLOGY
moisture of the tissue being treated. The electrode is cold and does not produce heat or other physical effects and only conducts the concentrated electrical energy to the tissue. This energy produces heat for tissue destruction. The electrodes should be securely seated. In general, a straight wire electrode is used for cutting and fine tissue removal; the loop for removing heavier tissue, planing, and contouring; and the ball for coagulation. The electrode should be clean and shiny allowing better current concentration and a more precise application. Tissue shreds on the electrode impede the passage of the electrode through tissue. Very sharp needle electrodes may catch on the tissue and make cuts, A moderately sharp needle of medium thickness seems best. Increased power is needed for an electrode in motion and less power for a stationary electrode. It is perferable to work in healthy tissue, Withdiseased tissue, the extent of tissue destruction is impossible to predict, so restoration of the tissue to a healthy state or removal of the diseased tissue by other methods is advisable before electrosurgery, Electrodesiccation occurs when a monoterminal damped current is applied to the tissue with the electrode in contact with or in the tissue. When the electrode is held away from the tissue, a spark will iumpto the tissue, resulting in what is termed electrofulguration. If the power is increased, coagulation will occur, Electrodesiccation produces a sharper limitation of tissue destruction than coagulation and saves the time of placing the dispersive electrode. The current is "cool," so small lesions can be removed without anesthesia. At times, with fulguration, areas that cannot be reached with an electrode can be treated by jumping the spark to the lesion. By increasing resistance in the monoterminal circuit, the destructive effect can be regulated to destroy a hair follicle—a mild epilating current. Pinhead-sized lesions up to several centimeter exophytic tumors can be destroyed by electrodesiccation. Active bleeding disperses the desiccating current and very
luly-August 1974
Vol. 18
little hemostasis results. Higher power is required to control the bleeding and excessive tissue destruction results. Small, relatively avascular lesions are best suited for electrodesiccation. Biterminal currents from a spark gap, vacuum tube or solid state electrosurgical units require the patient to be a part of the circuit. Active and dispersive electrodes are required. The dispersive electrode can become active if improperly placed and secured, resulting in injury. The dispersive electrode should be insulated at the clip connection of the metal plate. This plate, usually 1 3 x 1 7 cm, should be smooth and free of points, angles, or bends, must be in good contact with the bare skin of the patient and insulated from and not in contact with metal parts of the operating table. Bony prominences and uneven skin contact should be avoided. With electrocoagulation, either from a damped spark gap or a modulated rectified undamped current, the electrode should contact the tissue before the current is applied, A white area appears on the tissue spreading from the point of contact with the electrode. The depth of destruction approximately equals the visible lateral spread of tissue destruction. As coagulated tissue has a greater resistance to the current than normal tissue, coagulation Is self-limiting. The surface coagulation first created protects the underlying tissue against excessive depth of destruction. The coagulating current is useful in a wet field with many small bleeding vessels. Witb the use of a slightly damped spark gap current or an undamped current for electrosection, the active electrode should be activated before contacting the tissue and the current stopped after leaving the tissue. The power used should be the minimum needed to accomplish tbe procedure. Too much power will discolor the tissue and result in sparking when the electrode contacts the surface. Too little powerwill cause the electrode to drag, producing tearing and cooking of the tissue. Most electrosurgeons agree that too much power is better then too little power.
No. 6
449
PHYSICAL MODALITIES
The electrodes should float through the tissue without drag or resistance. There should be slight if any color change of the tissue and tissue sbreds should not adhere to the electrode. The surgeon should plan the cutting stroke, activate the electrode, pass the electrode at a deliberate but slow speed, keep the electrode moving, remove the electrode from the tissue and deactivate the electrode. Only with experience can a proper power setting for the various electrosurgical procedures be determined. The physician can practice on a piece of excised skin or moist lean beef at room temperature. Practicing techniques are outlined in the operating manuals which accompany the electrosurgical Electrosurgical Units Modern electrosurgical machines are fabricated with various types of circuits allowing such versatility that multiple types of currents areproduced by means of spark gaps, vacuum tubes and transistors. These currents may be used for whatever type of destructive effect desired. Generally less expensive electrosurgical equipment is satisfactory for most dermatological procedures. The current and the machine needed to produce this current depend on the individual surgeon's objectives in using electrosurgery. The lower priced units have a spark gap circuit and produce monoterminal currents for electrodesiccation and fulguration and biterminal currents for coagulation. There is no cutting capacity. Such units are Hyfrecator (Birtcher),'^ Coagulator (Ritter), Electrocoagulator (Stratham), and Electricator (Burton).^ Some units have built in foot pedals and others have handle finger switches. Also available are units with a solid state electronic circuit producing biterminal undamped cutting currents or modulated rectified currents tor coagulating. The spark gap current is not produced by this type of unit, so there are no electrofulguration capabilities. By regulating the current intensity, electrodesiccation can be done, Cameron-Miller
Model 26-2:i() is such a unit. Cameron-Miller Model 26-240 produces the same currents, but has separate controls for each current type, eliminating the need to reset controls and to change cords and handles from one terminal to another when changing modes oi current. The more expensive units have both a spark gap circuit and a solid state electronic or vacuum tube circuit in the same unit. These units will produce the full range ofavailable current types and permit the selection of correct current for any procedure. The spark gap circuit has monoterminal outlets for desiccation and fulguration and biterminal outlets for coagulation. Transistorized or vacuum tube circuits allow biterminal undamped cutting and modulated current for coagulation. Units with these capabilities are Cameron-Milter Model 26-0269, Hyfrecuter (Birtcher), and the Bovie Bantam (Ritter), Good electrosurgical equipment requires very little maintenance. The unit must be properly grounded and the external wires and connections must be in good repair, Electrocautery
Electrocautery involves the heating of a metal tip due to the resistance of the tip of the passage of the electric current. Electrocautery is not a form of electrosurgery. The commercial 110 volt, 60 hertz current is reduced by a step-down transformer and the low voltage, high amperage, low frequency current heats a platinum or silver needle. A rheostat allows variable current which alters the temperature of the metal tip. The patient is not a part of the circuit and electricity does not pass through him. Destruction oftissue is due purely to heat conducted from the hot tip to the colder tissue with resultant coagulated, amorphous material, charred tissue, and at times formation of steam spaces. With cauterization, microorganisms are destroyed and bleeding stopped. The cautery tip should be dull to bright cherry red with experience indicating the amount of heat desired for the procedure being done. Hemostasis is usually adequate,
450
INTERNATIONAL JOURNAL OF DFRMATOLOGV
especially in a wet field. Too little heat allows coagulated tissue to adhere to the needle and too much heat produces excessive tissue destruction. Primary closure is impossible with electrocautery. Healing usually occurs in 10 to 14 days but large wounds may require more than one month. The electrocautery apparatus is itiexpensive, simple, relatively foolproof and virtually maintenance free, although excessive current can burn out the tip. Clinical Applicalion of Electrosurgery and Electrocautery Best results from electrosurgery or electrocautery require three major factors: a clinical and histologic knowledge of the lesion, a workingknowledgeof the equipment and experience. Dermatologists understand the gross and microscopic characteristics of benign and malignant cutaneous lesions. Electrodesiccation, electrocoagulation and electrocautery often in conjunctic^n with some form of cutting such as a curette, scalpel or scissors are frequently used for the dermatologic therapy of such lesions. Necrotic tissue under the postoperative crust appears as pus and infection to the inexperienced electrosurgeon. Large, loose, soggy crusts are best removed, but dry adherent crusts should be left undisturbed, Dryness of the postoperative site is desirable for healing and is covered only for protection or cosmetic reasons. Coagulation can cause extreme damage to larger nerves and blood vessels and at times delayed hemorrhage from unsuspected injury to blood vessel walls. Delayed postoperative bleeding with the sloughing of the crust can occur and the patient should be instructed beforehand in applying direct pressure to control any bleeding. Scars are usually acceptable cosmetically with even large round surgical defects often healing in a linear fashion. The occurrence of posttreatment hypertrophic scars, which may result especially on the back and chest, can be reduced by minimizing tissue destruction.
July-August 1979
Vol, 18
Hypertrophic scars that form can be treated effectively with intralesional steroids. Ectropion can follow eyelid electrosurgery or cautery and the destruction of deep lesions may lead to contracture of the upper lip and nasal ala, to depression of the nose tip and to notching of the rim of the ear. Inflammable substances such as alcohol on the skin or in gauze can be dangerous. The high frequency electric current can affect cardiac pacemakers^^; the recommendations of Krull '** or another treatment modality should be used. High frequency currents can also interfere with monitoring devices such as electrocardiogram machines, if the patient is not properly grounded, the high frequency current will seek the path of least resistance from the patient and the current may become concentrated at the exit point resulting in thermal burns,*-" Pedunculated fibromas, papillomas, telangiectasia, spider and senile angiomas, verrucae, seborrheic keratoses, cysts and nevi are benign lesions that are readily removed by the various types of electrosurgery or electrocautery. Expert shave excision and subsequent electrosurgery or cautery of biopsyproven benign pigmented nevi give the best cosmetic results. This is a technique considered safe by many dermatologists. To my knowledge, no one has proven that electrosurgery or electrocautery of any type has ever been responsible for a malignant melanoma.^'^•^•''•^^•^^ Flat nevi cannot be removed by shave excision and should be excised surgically for histopathologic examination. Actinic keratoses, precancerous lesions, carcinoma in situ and basal and squamous cell epitheliomas can be eradicated by electrosurgery or electrocautery; 95% and higher cure rates for both basal cell and squamous cell epitheliomas have been reported,•^•"•'^•2""^° The details of the dermatologic procedures and actual techniques used for specific lesions are available in the
No. 6
PHYSICAL MODALITIES
Electrolysis: Direct Current Direct current flows unidirectionally through the body and produces strong polarity at each electrode. The low voltage, low amperage direct current from a storage battery or a rectified alternating commercial current produces little subjective sensation. Any abrupt change in current flow produces a painful harmless shock. The strong polarity around the electrodes produces chemical ionization with the formation of acids and the release of metallic ions at the positive pole and hydroxides and the attraction of metallic ions at tbe negative pole. Acids cause pain and coagulate and tattoo the tissue. Hydroxides cause minimal pain and liquefy the tissue. Any pain with electrolysis is due to the caustic products and not the current. The dissolution of tissues by the hydroxides is the basis for the use of direct current for electrolysis. Thus, the negative pole is the small treatment electrode used to concentrate the chemicals and the positive pole is the larger inactive electrode used to disperse, harmlessly, the chemical changes.^ The circuit is composed of a battery or other source of direct current, a milliammeter, a variable resistor, an indifferent electrode, an active electrode and the patient. To be effective therapeutically, an electrode must be connected to the proper pole. Reversal will produce pain, tattooing with metallic ions at the treatment electrode and the sticking of the needle to the tissue. Electrolysis implies the direct current destruction of the hair root and this is the most important use of the direct current. Epilation Epi lation by an electric current is a safe, cosmetically acceptable method for removing hair permanently. High frequency current, as discussed earlier, produced by decreasing the current density of a spark gap or vacuum tube apparatus, or direct current electrolysis, can be used for epilation. Direct current removal is safer, less likely to scar, less painful, but
BIdnkenship
451
slower than high frequency current epilation. The latter is simpler but, as the bair is destroyed quickly, mistakes are more difficult to prevent and correct. More skill is required than with electrolysis. With the biterminal application of a spark gap unit, the control is manual and the minimal spark is used. Vacuum tube units have been designed with automatic power and time controls. When the switch is closed a definite amount of current is applied for a preset time. Some units give both direct and alternating currents and hair can be removed by a combination of currents. Clean skin, comfortable positions and good light are required for epilation, A fine needle is attached to the negative pole for electrolysis and to the active electrode for high frequency epilation. The needle is slipped into the pore and passed parallel to the hair to the bottom of the hair follicle. The current is switched on after insertingtheneedleand turned off before removing the needle. Shocks will result otherwise. A 0,5 to 1.0 milliamp current is applied for 15 to 60 seconds for electrolysis. High frequency epilation requires 3 to 6 bursts of less than one second, either manually or automatically. When the hair is destroyed, the hair is easily removed. Hairs being epilated should be 3 to 4 mm apart and 75 to 100 hairs may be epilated at one sitting depending on the operator's skill and type and location of the hair. Hair density is decreased more rapidly by high frequency epilation, but there is no difference in the time required for complete destruction. Patients with excessive hair should be advised that epilation is a lengthy process requiring, at times, up to several years. Today most epilation is done by the high frequency altemating current. References 1. Battig, C. C : Electrosurgital burn injuries and their prevention. )AMA 204:91, 1968. 2. Bodian, E, L.: Elet trosurgery by bipolar modalities. ). Dermdiol. Surg, Oncol. 4:235, 1978. 3. Burdirk, K, H.: Electrosurgital Apparatus and Their Application in Dermatology. Springfield, Charles C Thomas, 1966.
452
INTFRNATIONAI JOURNAL OF DFRMATOLOGY
4. Burdic k, K. H.: Eleclrocautery nt minor skin lesions. ln:Skin Surgery. Edited by Epstein, F, Springlield, Charles C Thomas, 1970, p. 273. 5. Burton Flee tritalor. Operating Instructions. Cavitron. Burton Division. Van Nuys, CA, 1978. 6. Case History: A third degree burn secondary to faulty eleclro( autery ground. Aneslh. Analg. 49:402. 1970. 7. Crissey, |. T.: ( ureltage and eieitrodesi
PHYSICAL MODALITIES ELECTROSURGERY, ELECTROCAUTERY AND ELECTROLYSIS
MARSHALL L. BLANKENSHIP, M.D.
Any tbrm of physical energy is capable of producing destructive effects when carried beyond the limits of physiologic tolerance. Heat, cold, sound, ionizing radiation and ultraviolet radiation are physical modalities used in dermatologic therapy. Heat can be delivered to the skin by electrosurgery, electrocautery and electrolysis. Electrosurgery: High Frequency Alternating Current Electrosurgery is the use of electrical energy to produce heat to destroy benign and malignant tumors, to excise normal and diseased tissue and to control bleeding. Medical instruments activated by electricity have been used since the early 1900s, The indications, advantages, disadvantages and limitations of electrosurgery are well known to dermatologists. The proper and safe use of electrosurgery depends on Ihe knowledge of the physiologic effects of electrical current on tissue,^-'"' of electrophysics,^-^-'^-^"" of electrosurgital instruments,^•^•^^•''•'^•^'' and of the disease being treated. Expertise depends on experience based on this knowledge. Address for reprints: Marshall L. Blankenship, M.D,, 4647 West 103rd Street, Oak Lawn, IL 60453.
trom the Department of Dermatology, Rush Medical College, Chicago, Illinois
Tissue Response When an alternating current of a sufficiently high frequency to avoid nerve and muscle responses passes through living tissue, there is no other effect except the production of heat. The internal heat produced in the tissue is the direct result of the resistance offered by the living tissue to the passage of the current, and is the basis for treatment by electrosurgery and diathermy. In medical diathermy, a low current density is created in the tissue with an even distribution of energy and heat throughout by the use of large plate electrodes of equal size. With the use of a small active electrode and a larger dispersive electrode, the heat produced by the high frequency alternating current is concentrated in a small area and is highly destructive to tissue. While the active electrode remains cold, the highly concentrated electrical energy creates molecular heat within each cell. By choice of the electrodes and the intensity and type of current, the cellular changes produced by the
001 l-9059/79/O7OO/0443.'$OI.O0 © International Society of Tropical Dermaloiogy, Inc.
443
444
INTERNATIONAL lOURNAL OF DFRMATOLOGY
high frequency electrical energy arc cc)tTtr(jllable, producing different types of tissue destruction. All of the events that occur when a high frequency alternating current produces cellular changes have not been fully explained. Depending on the current density, cells undergo different changes. When high current density is applied between active and dispersive electrodes, molecular heat is generated within each cell to the point that fluids in the cell volatilize and the cell explodes. This explosive vacuolization occurs as the result of Intracellular steam pressure. By applying this electrical energy to individual cells in sequence by moving the electrode through the tissue, the tissue separates ahead of the electrode. The line of destruction of tissue is limited and a cutting effect is produced. Although heat produces the cellular effect, the end result simulates a mechanical disruption of the cells rather than the changes usually produced by heat. If the current density is less concentrated, heat is produced over a relatively larger area and the cells are dehydrated and their protein contents become denatured. Cell outlines are entirely lost and an amorphous mass remains; blood vessels are thrombosed and a coagulating effect is produced. The heat is sufficient to produce donaturation of protein but not the explosive effect. With the use of one electrode, a high frequency alternating current, with a high driving force but less current, dehydrates the tells. Although cells are shriveled, the cell outlines and nuclei are preserved, and desiccating effect is produced. Stronger desiccating currents can produce coagulation and weaker coagulating currents can [produce desiccation. With excessive high trpc|uency alternating current, carbonization atid charring occur. tk'ctruphysic To produce a high voltage, high frequency alternating current lor surgery, the commercial 110 volt current has to be stepped up to several thousand volts by a step up trans-
luiy-August 1979
Vol. 18
forrner in the power circuit of the instrument. The frequency has to be greatly increased from the 60 hertz (cycles per second] commercial current to between 500 kilohertz and 100 megahertz. This is done in the oscillating circuit of the instrument. This circuit contains condensers, a coil of wire and an air gap. The air gap may be a spark gap, a vacuum tube (diode, triode, thermionic, radio or valve tube) or solid state substitutes (transistor). The low voltage, low frequency commercial current is converted to a high voltage, high frequency current of various types that may be c_tirried by the patient circuit to the patient for electrosurgery. The current may be applied to the patient either mono- or bi-terminally, Biterminal electrosurgery employs a large dispersive electrode grounding the patient to the electrosurgical apparatus and a needle active treatment electrode. The patient is incorporated into and is an integral part of the circuit. In monoterminal electrosurgery, the patient is not a part of the circuit and there is no ground to the apparatus. The electrons are shed from the patient to the air, walls, table and floor. One type of electrosurgical current is a damped current: a strong initial burst followed by diminishing waves. The more rapidly the diminishing waves return to zero, the more damped the current (Fig. la). The slower the return to zero, the less damped the current (Fig, lc). The frequencies of the oscillating current are altered by varying the size of the condensers and the coil in this circuit. By increasing the resistance in the oscillating circuit, longer rest periods between the wave trains will occur and produce a greater damping effect. A second type of current used in electrosurgery is an undamped current with constant equal waves of unchanging amplitude. The oscillating circuit contains a vacuum tube with a direct current grid circuit and an alternating platecircuit along with the condensers and the coil. The grid and plate circuits mutually energize each other. Eac h osc illation receives an increase in energy by a feedback mechanism and eciu.il am[jlitucle osc illations
No, 6
PHYSK AL MODAinirs
Figure 1 a Markedly Damped
liL,nk,'n.hii,
Modulated
Figure 1 b Moderatelv Damped
44.S
Figure 1 d Half Wave Rectfftcation
Figure 1 e Modulated • Full Wave Rectification
•Wi/IMAMFigure 1 c Slightly Damped Spark Gap Apparatus
Figs. la-f.
Figure 1 f Undamped Vacuum Tube Apparatus
High frequency wave forms.
are produced. A triode vacuum tube in the circuit produces a fully undamped current (Fig, I 0. By varying the tubes and other components of the oscillating circuit, the undamped current,^ The type of current (damped or un((am[)ed), the application of the current a moderately cl.imped current or a full-wave rectification (Fig. Ie) resembling a slightly damtx'd c urrent.*^ The ty|x- ol current (damped or undamped), the ii|)p(i( ation of the c urrent (monoterminal or biterminal) and the current intensity, voltage and amperage, determine the types of tissue effects produced—cutting, coagulation or desiccation. Completely undamped c urrents arc bitermin.il, rt'f|uiring.in active and dispersive electrode; produced by a vacuum tube or solid state substitute oscillating circuil; and very high fnxiLicncy, high atn[>er,ige, low voltage curretils. This current explodes the cells, pro-
ducing maximal cutting effect which [hermits healing by first intention under ideal conditions. Minimal heat effects such as coagulation and hemostasis are produced. Damped currents may be applied either mono- or biterminally. Monoterminal application is used with a spark gap oscillating circuit with only the active electrode. Because the patient is not a ()art of the circuit, a higher v(;ll,ige driving force is required to produce effective tissue destruc tion at the electrode. There is correspondingly less amperage and thus less heat. This high frequency, very high voltage, low amperage current produces a dehydration of the cells with tissue destruction and effective superficial hemostasis. With biterminal application of a spark gap damped current, the patient is incorporalecl into the circ uit whic h allows the production f)f ci high arnptT.igc < urrcnt at a lower voltage.
446
INTFRNATIONAI. lOURNAL OF DERMATOLOCY
Vol. 18
luly-August 1479
c — aj _0 u T!
01
c
ji^
^
t/l
. _
_E2
^3 - ~
t: •- 6
0 t?
—
.^ E
C 00
>.
QJ
c Q; 5 E a; - > «
ive
S" ra
>
ery o Itei'nalin
QC
m
s istor
0 TJ
iformi
c
c
tj
o
tr
01
"5
c _ o c O
Tl
ra
Ol
0/
c
c
O
o
"ra
c ,9
;ulat
ery
c ,o in
c •—
Blankenship
447
This high frequency- low voltage, high amperage current produces heat with coagulation tissue effect with maximal tissue destruction and hemostasis. When two electrodes closely spaced in the same handle are inserted into the tissue, localized coagulation between the electrodes is produced. This is referred to as bipolar coagulation and is not commonly used in dermatology. Completely undamped currents produce excellent cutting but little hemostasis and fully damped currents produce maximal tissue destruction and hemostasis but no cutting effect. However, by modifying the currents between these two extremes, a current can be produced which cuts easily and, although coagulation is decreased, will still provide adequate hemostasis and allow bloodless cutting. A slightly damped current from the biterminal application of a spark gap apparatus and a modulated full-wave rectified current from a vacuum apparatus will provide cutting with hemostasis, A spark gap moderately damped current and a vacuum tube modulated half-wave rectified current provides more coagulation and hemostasis, Monoterminal application of a spark gap apparatus will provide only a damped current and cannot provide currents for cutting. Thus, the spark gap apparatus can provide currents for cutting, coagulation and desiccation, and the tube type apparatus can provide currents for cutting and coagulation. Maximal tissue destruction from the spark gap apparatus and maximal cutting ability from the tube type apparatus are preferred by some electrosurgeons for certain procedures. However, either type of apparatus has the capability of producing current types for most routine procedures, i.e., cutting and coagulation. Types of Electrosurgery Using these available current types, four types of electrosurgery can be performed: electrodesiccation, electrofulguration, electrocoagulation and electrosection (Table 1), With all forms of electrosurgery, the amount of tissue destruction depends upon; (1) the amount of power, (2) the lengh of application, (31 the size of the electrode and (4) the density and
448
INTERNATIONAL lOLJRNAl OF DFR'MATOLOGY
moisture of the tissue being treated. The electrode is cold and does not produce heat or other physical effects and only conducts the concentrated electrical energy to the tissue. This energy produces heat for tissue destruction. The electrodes should be securely seated. In general, a straight wire electrode is used for cutting and fine tissue removal; the loop for removing heavier tissue, planing, and contouring; and the ball for coagulation. The electrode should be clean and shiny allowing better current concentration and a more precise application. Tissue shreds on the electrode impede the passage of the electrode through tissue. Very sharp needle electrodes may catch on the tissue and make cuts, A moderately sharp needle of medium thickness seems best. Increased power is needed for an electrode in motion and less power for a stationary electrode. It is perferable to work in healthy tissue, Withdiseased tissue, the extent of tissue destruction is impossible to predict, so restoration of the tissue to a healthy state or removal of the diseased tissue by other methods is advisable before electrosurgery, Electrodesiccation occurs when a monoterminal damped current is applied to the tissue with the electrode in contact with or in the tissue. When the electrode is held away from the tissue, a spark will iumpto the tissue, resulting in what is termed electrofulguration. If the power is increased, coagulation will occur, Electrodesiccation produces a sharper limitation of tissue destruction than coagulation and saves the time of placing the dispersive electrode. The current is "cool," so small lesions can be removed without anesthesia. At times, with fulguration, areas that cannot be reached with an electrode can be treated by jumping the spark to the lesion. By increasing resistance in the monoterminal circuit, the destructive effect can be regulated to destroy a hair follicle—a mild epilating current. Pinhead-sized lesions up to several centimeter exophytic tumors can be destroyed by electrodesiccation. Active bleeding disperses the desiccating current and very
luly-August 1974
Vol. 18
little hemostasis results. Higher power is required to control the bleeding and excessive tissue destruction results. Small, relatively avascular lesions are best suited for electrodesiccation. Biterminal currents from a spark gap, vacuum tube or solid state electrosurgical units require the patient to be a part of the circuit. Active and dispersive electrodes are required. The dispersive electrode can become active if improperly placed and secured, resulting in injury. The dispersive electrode should be insulated at the clip connection of the metal plate. This plate, usually 1 3 x 1 7 cm, should be smooth and free of points, angles, or bends, must be in good contact with the bare skin of the patient and insulated from and not in contact with metal parts of the operating table. Bony prominences and uneven skin contact should be avoided. With electrocoagulation, either from a damped spark gap or a modulated rectified undamped current, the electrode should contact the tissue before the current is applied, A white area appears on the tissue spreading from the point of contact with the electrode. The depth of destruction approximately equals the visible lateral spread of tissue destruction. As coagulated tissue has a greater resistance to the current than normal tissue, coagulation Is self-limiting. The surface coagulation first created protects the underlying tissue against excessive depth of destruction. The coagulating current is useful in a wet field with many small bleeding vessels. Witb the use of a slightly damped spark gap current or an undamped current for electrosection, the active electrode should be activated before contacting the tissue and the current stopped after leaving the tissue. The power used should be the minimum needed to accomplish tbe procedure. Too much power will discolor the tissue and result in sparking when the electrode contacts the surface. Too little powerwill cause the electrode to drag, producing tearing and cooking of the tissue. Most electrosurgeons agree that too much power is better then too little power.
No. 6
449
PHYSICAL MODALITIES
The electrodes should float through the tissue without drag or resistance. There should be slight if any color change of the tissue and tissue sbreds should not adhere to the electrode. The surgeon should plan the cutting stroke, activate the electrode, pass the electrode at a deliberate but slow speed, keep the electrode moving, remove the electrode from the tissue and deactivate the electrode. Only with experience can a proper power setting for the various electrosurgical procedures be determined. The physician can practice on a piece of excised skin or moist lean beef at room temperature. Practicing techniques are outlined in the operating manuals which accompany the electrosurgical Electrosurgical Units Modern electrosurgical machines are fabricated with various types of circuits allowing such versatility that multiple types of currents areproduced by means of spark gaps, vacuum tubes and transistors. These currents may be used for whatever type of destructive effect desired. Generally less expensive electrosurgical equipment is satisfactory for most dermatological procedures. The current and the machine needed to produce this current depend on the individual surgeon's objectives in using electrosurgery. The lower priced units have a spark gap circuit and produce monoterminal currents for electrodesiccation and fulguration and biterminal currents for coagulation. There is no cutting capacity. Such units are Hyfrecator (Birtcher),'^ Coagulator (Ritter), Electrocoagulator (Stratham), and Electricator (Burton).^ Some units have built in foot pedals and others have handle finger switches. Also available are units with a solid state electronic circuit producing biterminal undamped cutting currents or modulated rectified currents tor coagulating. The spark gap current is not produced by this type of unit, so there are no electrofulguration capabilities. By regulating the current intensity, electrodesiccation can be done, Cameron-Miller
Model 26-2:i() is such a unit. Cameron-Miller Model 26-240 produces the same currents, but has separate controls for each current type, eliminating the need to reset controls and to change cords and handles from one terminal to another when changing modes oi current. The more expensive units have both a spark gap circuit and a solid state electronic or vacuum tube circuit in the same unit. These units will produce the full range ofavailable current types and permit the selection of correct current for any procedure. The spark gap circuit has monoterminal outlets for desiccation and fulguration and biterminal outlets for coagulation. Transistorized or vacuum tube circuits allow biterminal undamped cutting and modulated current for coagulation. Units with these capabilities are Cameron-Milter Model 26-0269, Hyfrecuter (Birtcher), and the Bovie Bantam (Ritter), Good electrosurgical equipment requires very little maintenance. The unit must be properly grounded and the external wires and connections must be in good repair, Electrocautery
Electrocautery involves the heating of a metal tip due to the resistance of the tip of the passage of the electric current. Electrocautery is not a form of electrosurgery. The commercial 110 volt, 60 hertz current is reduced by a step-down transformer and the low voltage, high amperage, low frequency current heats a platinum or silver needle. A rheostat allows variable current which alters the temperature of the metal tip. The patient is not a part of the circuit and electricity does not pass through him. Destruction oftissue is due purely to heat conducted from the hot tip to the colder tissue with resultant coagulated, amorphous material, charred tissue, and at times formation of steam spaces. With cauterization, microorganisms are destroyed and bleeding stopped. The cautery tip should be dull to bright cherry red with experience indicating the amount of heat desired for the procedure being done. Hemostasis is usually adequate,
450
INTERNATIONAL JOURNAL OF DFRMATOLOGV
especially in a wet field. Too little heat allows coagulated tissue to adhere to the needle and too much heat produces excessive tissue destruction. Primary closure is impossible with electrocautery. Healing usually occurs in 10 to 14 days but large wounds may require more than one month. The electrocautery apparatus is itiexpensive, simple, relatively foolproof and virtually maintenance free, although excessive current can burn out the tip. Clinical Applicalion of Electrosurgery and Electrocautery Best results from electrosurgery or electrocautery require three major factors: a clinical and histologic knowledge of the lesion, a workingknowledgeof the equipment and experience. Dermatologists understand the gross and microscopic characteristics of benign and malignant cutaneous lesions. Electrodesiccation, electrocoagulation and electrocautery often in conjunctic^n with some form of cutting such as a curette, scalpel or scissors are frequently used for the dermatologic therapy of such lesions. Necrotic tissue under the postoperative crust appears as pus and infection to the inexperienced electrosurgeon. Large, loose, soggy crusts are best removed, but dry adherent crusts should be left undisturbed, Dryness of the postoperative site is desirable for healing and is covered only for protection or cosmetic reasons. Coagulation can cause extreme damage to larger nerves and blood vessels and at times delayed hemorrhage from unsuspected injury to blood vessel walls. Delayed postoperative bleeding with the sloughing of the crust can occur and the patient should be instructed beforehand in applying direct pressure to control any bleeding. Scars are usually acceptable cosmetically with even large round surgical defects often healing in a linear fashion. The occurrence of posttreatment hypertrophic scars, which may result especially on the back and chest, can be reduced by minimizing tissue destruction.
July-August 1979
Vol, 18
Hypertrophic scars that form can be treated effectively with intralesional steroids. Ectropion can follow eyelid electrosurgery or cautery and the destruction of deep lesions may lead to contracture of the upper lip and nasal ala, to depression of the nose tip and to notching of the rim of the ear. Inflammable substances such as alcohol on the skin or in gauze can be dangerous. The high frequency electric current can affect cardiac pacemakers^^; the recommendations of Krull '** or another treatment modality should be used. High frequency currents can also interfere with monitoring devices such as electrocardiogram machines, if the patient is not properly grounded, the high frequency current will seek the path of least resistance from the patient and the current may become concentrated at the exit point resulting in thermal burns,*-" Pedunculated fibromas, papillomas, telangiectasia, spider and senile angiomas, verrucae, seborrheic keratoses, cysts and nevi are benign lesions that are readily removed by the various types of electrosurgery or electrocautery. Expert shave excision and subsequent electrosurgery or cautery of biopsyproven benign pigmented nevi give the best cosmetic results. This is a technique considered safe by many dermatologists. To my knowledge, no one has proven that electrosurgery or electrocautery of any type has ever been responsible for a malignant melanoma.^'^•^•''•^^•^^ Flat nevi cannot be removed by shave excision and should be excised surgically for histopathologic examination. Actinic keratoses, precancerous lesions, carcinoma in situ and basal and squamous cell epitheliomas can be eradicated by electrosurgery or electrocautery; 95% and higher cure rates for both basal cell and squamous cell epitheliomas have been reported,•^•"•'^•2""^° The details of the dermatologic procedures and actual techniques used for specific lesions are available in the
No. 6
PHYSICAL MODALITIES
Electrolysis: Direct Current Direct current flows unidirectionally through the body and produces strong polarity at each electrode. The low voltage, low amperage direct current from a storage battery or a rectified alternating commercial current produces little subjective sensation. Any abrupt change in current flow produces a painful harmless shock. The strong polarity around the electrodes produces chemical ionization with the formation of acids and the release of metallic ions at the positive pole and hydroxides and the attraction of metallic ions at tbe negative pole. Acids cause pain and coagulate and tattoo the tissue. Hydroxides cause minimal pain and liquefy the tissue. Any pain with electrolysis is due to the caustic products and not the current. The dissolution of tissues by the hydroxides is the basis for the use of direct current for electrolysis. Thus, the negative pole is the small treatment electrode used to concentrate the chemicals and the positive pole is the larger inactive electrode used to disperse, harmlessly, the chemical changes.^ The circuit is composed of a battery or other source of direct current, a milliammeter, a variable resistor, an indifferent electrode, an active electrode and the patient. To be effective therapeutically, an electrode must be connected to the proper pole. Reversal will produce pain, tattooing with metallic ions at the treatment electrode and the sticking of the needle to the tissue. Electrolysis implies the direct current destruction of the hair root and this is the most important use of the direct current. Epilation Epi lation by an electric current is a safe, cosmetically acceptable method for removing hair permanently. High frequency current, as discussed earlier, produced by decreasing the current density of a spark gap or vacuum tube apparatus, or direct current electrolysis, can be used for epilation. Direct current removal is safer, less likely to scar, less painful, but
BIdnkenship
451
slower than high frequency current epilation. The latter is simpler but, as the bair is destroyed quickly, mistakes are more difficult to prevent and correct. More skill is required than with electrolysis. With the biterminal application of a spark gap unit, the control is manual and the minimal spark is used. Vacuum tube units have been designed with automatic power and time controls. When the switch is closed a definite amount of current is applied for a preset time. Some units give both direct and alternating currents and hair can be removed by a combination of currents. Clean skin, comfortable positions and good light are required for epilation, A fine needle is attached to the negative pole for electrolysis and to the active electrode for high frequency epilation. The needle is slipped into the pore and passed parallel to the hair to the bottom of the hair follicle. The current is switched on after insertingtheneedleand turned off before removing the needle. Shocks will result otherwise. A 0,5 to 1.0 milliamp current is applied for 15 to 60 seconds for electrolysis. High frequency epilation requires 3 to 6 bursts of less than one second, either manually or automatically. When the hair is destroyed, the hair is easily removed. Hairs being epilated should be 3 to 4 mm apart and 75 to 100 hairs may be epilated at one sitting depending on the operator's skill and type and location of the hair. Hair density is decreased more rapidly by high frequency epilation, but there is no difference in the time required for complete destruction. Patients with excessive hair should be advised that epilation is a lengthy process requiring, at times, up to several years. Today most epilation is done by the high frequency altemating current. References 1. Battig, C. C : Electrosurgital burn injuries and their prevention. )AMA 204:91, 1968. 2. Bodian, E, L.: Elet trosurgery by bipolar modalities. ). Dermdiol. Surg, Oncol. 4:235, 1978. 3. Burdirk, K, H.: Electrosurgital Apparatus and Their Application in Dermatology. Springfield, Charles C Thomas, 1966.
452
INTFRNATIONAI JOURNAL OF DFRMATOLOGY
4. Burdic k, K. H.: Eleclrocautery nt minor skin lesions. ln:Skin Surgery. Edited by Epstein, F, Springlield, Charles C Thomas, 1970, p. 273. 5. Burton Flee tritalor. Operating Instructions. Cavitron. Burton Division. Van Nuys, CA, 1978. 6. Case History: A third degree burn secondary to faulty eleclro( autery ground. Aneslh. Analg. 49:402. 1970. 7. Crissey, |. T.: ( ureltage and eieitrodesi
