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Electro-SurgeryElectro-surgery is the application of a high-frequency electric current to biological tissue as ameans to cut, coagulate (form blood clots), desiccate (remove water), or fulgurate (destroy andremove) tissue. Its benefits include the ability to make precise cuts with limited blood loss.Electrosurgical devices are frequently used during surgical operations in hospital operatingrooms or in outpatient procedures.Electro-surgery is performed using an electrosurgical generator (also referred to as a powersupply or waveform generator), in a circuit made up of an active electrode, the patient and anactive return electrode. The tissue is heated by an AC current; the AC current is used to directlyheat the tissue itself, whereas in electro-cautery the tip of the instrument is heated.Fig 1 – Mono-polar Electro-surgery (Covidien, 2014) Fig 2 – Bi-polar Electro-surgery (Covidien, 2014)Standard electrical current alternates at a frequency of 50Hz, at this frequency the currenttransmitted to the body tissue would cause excessive neuromuscular stimulation and possiblyelectrocution. Nerve and muscle stimulation cease at 100 kHz so at frequencies above this,typically 200 kHz – 3.3 MHz, electro-surgery can be performed with the energy passing throughthe patient with minimal neuromuscular stimulation and no risk of electrocution meaningelectro-surgery can be performed safely.

Mono-polarMono-polar is the most commonly used electro-surgical mode. In mono-polar electro-surgery,the active electrode is in the surgical site, with the patient return electrode somewhere else onthe patient’s body. The current passes through the patient as it completes the circuit from theactive electrode to the return electrode. The return electrode placement should be onconductive tissue over a large surface area to prevent a build-up of heat which could potentiallycause a burn. Other factors that may cause the return electrode to be compromised areexcessive hair, adipose tissue (fat), bony prominences, fluid invasion, metal implants and scartissue. Fig 3 – Patient return electrode placement (Covidien, 2014)Return Electrode Contact Quality Monitoring (RECQM)RECQM was developed to protect patients from burns due to inadequate contact of the returnelectrode pad site by using a split plate system. RECQM equipped generators actively monitorthe amount of impedance between the two split plates. If the impedance is high, due to poorcontact on either side of the split plate, the electrosurgical unit will alarm to warn the clinicaluser of the problem. If the impedance between the two plates is very high or not symmetricalthe unit will alarm and the system will deactivate the generator before an injury can occur Fig4 – Return Electrode Contact Quality Monitoring (RECQM) (Covidien, 2014)

Bi-polarIn bipolar electro-surgery, both the active electrode and return electrode functions areperformed at the site of the surgery. The tines of the forceps perform the active & returnelectrode with only the tissue being grasped included in the circuit. As one of the tines of theforceps performs the return function no patient return electrode is needed. Bipolar diathermyis perceived to be safer as the current pathway is much shorter than that utilised in mono-polardiathermy. Bipolar diathermy is generally utilised in the following situations:  When coagulation only is required.  When coagulation is required in peripheral areas of the body such as hands or feet or other areas where channelling (tissue damage caused by heat) may occur.  In procedures where pinpoint or micro coagulation is required.  When a patient has a pacemaker in situ.Electrosurgical ModesElectrosurgical generators are able to produce a variety of electrical waveforms. As waveformschange, so will the corresponding tissue effects. Using a constant waveform, like cut, thesurgeon is able to vaporize or cut tissue. This waveform produces heat very rapidly.Using an intermittent waveform, like coagulation, causes the generator to modify the waveformso that the duty cycle (on time) is reduced. This interrupted waveform will produce less heat.Instead of tissue vaporization, a coagulum is produced.A blended current is not a mixture of both cutting and coagulation current but rather amodification of the duty cycle. In the example below, as you go from Blend 1 to Blend 3 theduty cycle is progressively reduced. A lower duty cycle produces less heat. Consequently, Blend1 is able to vaporize tissue with minimal haemostasis whereas Blend 3 is less effective at cuttingbut has maximum haemostasis. Fig 5 – Electrosurgical Modes (Covidien, 2014)The only variable that determines whether one waveform vaporizes tissue and anotherproduces a coagulum is the rate at which heat is produced. High heat produced rapidly causesvaporization. Low heat produced more slowly creates a coagulum.Any one of the five waveforms can accomplish both tasks by modifying the variables that impacttissue effect.

The electrosurgical generator or unit can produce three distinct surgical effects, known asfulguration, desiccation and cutting. The electrosurgical generator creates different wave formswhich are determined by the setting on the machine, universally known as COAG, CUT andBLEND. The settings and desired effects are linked as follows:CuttingThe CUT waveform is a continuous waveform at a lower voltage but higher current than COAG.This creates a high density of current in a specific tissue area within a short period of timecausing cellular fluid to burst into steam and disrupt the structure which results in vaporisationof tissue. This results in cell explosion due to the localised but intense heat Fig 6 – Electrosurgical Cut (Covidien, 2014)CoagulationCoagulation is performed using waveforms with a lower average power, generating insufficientheat for explosive vaporisation, but performing a thermal coagulum instead.FulgurationWhen the COAG waveform is used at a high power setting it will create the effect known asfulguration. The high power generates sparks which create intermittent heating of tissuecausing cells to dry out quickly rather than explode into steam. In fulguration mode theelectrode is held away from the tissue so that when the air gap between the electrode and thetissue is ionised an electric arc discharge develops. Fulguration coagulates and chars the tissueover a wide area. In this application the burning of the tissue is more superficial; therefor thistechnique is used for very superficial or protrusive lesions such as skin tags. Fig 7 – Electrosurgical Coagulate (Covidien, 2014)DesiccationElectrosurgical desiccation occurs when the electrode is in direct contact with the tissue.Desiccation is achieved most efficiently with the cutting current. By touching the tissue with theelectrode, the current concentration is reduced. Less heat is generated and no cutting actionoccurs. The cells dry out and form a coagulum rather than vaporize and explode.

Many surgeons routinely cut with the coagulation current. Likewise, you can coagulate with thecutting current by holding the electrode in direct contact with tissue. It may be necessary toadjust power settings and electrode size to achieve the desired surgical effect. The benefit ofcoagulating with the cutting current is that you will be using far less voltage. Likewise, cuttingwith the cut current will also accomplish the task with less voltage. This is an importantconsideration during minimally invasive procedures.Variables Impacting Tissue EffectIn addition to waveform and power setting, other variables impact tissue effect. They include:Size of the electrode: The smaller the electrode, the higher the current concentration.Consequently, the same tissue effect can be achieved with a smaller electrode, even though thepower setting is reduced.Time: At any given setting, the longer the generator is activated, the more heat is produced. Andthe greater the heat, the farther it will travel to adjacent tissue (thermal spread).Manipulation of the electrode: This can determine whether vaporization or coagulationoccurs. This is a function of current density and the resultant heat produced while sparking totissue versus holding the electrode in direct contact with tissue.Type of Tissue: Tissues vary widely in resistance.Eschar: Eschar (dead tissue produced by a thermal burn) is relatively high in resistance tocurrent. Keeping electrodes clean and free of eschar will enhance performance by maintaininglower resistance within the surgical circuit. Fig 8 – Electrosurgical Mode Effects (NATN, 2013)

Argon-Enhanced Electro-surgeryArgon-enhanced electro-surgery incorporates a stream of argon gas to improve the surgicaleffectiveness of the electrosurgical current.Argon gas is inert and non-combustible, making it a safe medium through which to passelectrosurgical current. Electrosurgical current easily ionizes argon gas, making it moreconductive than air. This highly conductive stream of ionized gas provides the electrical currentan efficient pathway.There are many advantages to argon-enhanced electrosurgical cutting and coagulation.  Non-combustible  Decreased smoke & odour  Non-contact in coagulation mode  Decreased blood loss.  Decreased tissue damageFig 9 – Argon enhanced electro-surgery (Covidien, 2014) Fig 10 – Argon enhanced electro-surgerySurgical Smoke (NATN, 2013)Surgical smoke is created when tissue is heated and cellular fluid is vaporized by the thermalaction of an energy source. Viral DNA, bacteria, carcinogens and irritants are known to bepresent in electrosurgical smoke. Universal precautions indicate a smoke evacuation systemshould be used. The National Institute of Occupational Safety and Health (NIOSH) and theCentre for Disease Control (CDC) have also studied electrosurgical smoke at length. Theorganisations concluded: “Research studies have confirmed that this smoke plume can containtoxic gases and vapours such as benzene, hydrogen cyanide, formaldehyde, bio-aerosols, deadand live cellular material (including blood fragments) and viruses.”When electro-surgery is used in the context of minimally invasive surgery, it raises a new set ofsafety concerns. Two of these are insulation failure and direct coupling of current.Direct CouplingDirect coupling occurs when the user accidentally activates the generator while the activeelectrode is near another metal Instrument (scopes, graspers, etc.). Electrical current will flowfrom the first conductor into the secondary one and energize it. This energy will seek a pathwayto complete the circuit to the patient return electrode. There is potential for significant patientinjury.

Insulation FailureMany surgeons routinely use the coagulation waveform. This waveform is comparatively highin voltage. This voltage can spark through compromised insulation. Also, high voltage can causebreaks in weak insulation. Breaks in insulation can create an alternate route for the current toflow. If this current is concentrated, it can cause significant injury. Also radio frequency is notalways confined by insulation and current leakage does occur. It is recommended that Cordsnot be wrapped around metal instruments and Cords not be bundled together. Fig 11 – Possible injury through compromised insulation (Gov.uk, 2014)Further precautions to take for safe use are; the electrosurgical device should not be used in thepresence of flammable agents such as alcohol and /or tincture based (alcoholic extract of plantor animal) agents.Use of electrosurgical devices should be avoided in oxygen enriched environmentsActive electrodes should be placed in clean, dry, well insulated safety holsters when not in useto avoid any accidental injury if the generator is accidently activated.Maintenance and service proceduresMaintenance procedures should include a thorough visual inspection of all elements of theelectrosurgical device.Error logs should be checked and any regular or serious errors should be rectified.The system that checks pad resistance should be checked to ensure the correct errors occur atthe correct resistances.The power output should be checked across all setting at various levels and effects.Argon plasma units should be checked alongside the correct electrosurgical device.Flow rates of the argon gas output should be measured. All functions should be checked.A full electrical safety test should be carried out, it is important to consult the service manual/protocol to ensure the unit is in the correct mode to ensure the output relays are all closed forthe duration of the safety test.

BibliographyCovidien, 2014. Principles in Electro-surgery. [Online]Available at: http://www.asit.org/assets/documents/Prinicpals_in_electrosurgery.pdf[Accessed July 2015].Gov.uk, 2014. Electro-surgery Equipment Safety. [Online]Available at:https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/403384/Electro-surgery_equipment_safety_poster.pdf[Accessed July 2015].MHRA, n.d. Electrosurgical Module. [Online]Available at: info.mhra.gov.uk/learning/ESUGenericModule/player.html[Accessed July 2015].NATN, 2013. Electro-surgery managing the risk – National Association of Theatre Nurses. [Online]Available at: www.afpp.org.uk/filegrab/electrosurgeryguidance.pdf?ref=5[Accessed July 2015].