Electrosurgery

Electrosurgery is a term used to describe multiple modalities that use electricity to cause thermal destruction of tissue through dehydration, coagulation, or vaporization. ^{[1, 2]} The two types of electrosurgery most commonly used are high-frequency electrosurgery and electrocautery.

High-frequency electrosurgery refers to four different methods: electrocoagulation, electrodesiccation, electrofulguration, and electrosection. These methods involve high-frequency alternating current, which is converted to heat by resistance as it passes through the tissue. ^[1] The result of heat buildup within the tissue is thermal tissue damage. These modalities are commonly used for hemostasis, debulking procedures such as rhinophyma excision, and treatment of benign and malignant skin conditions ranging from acrochordons (skin tags) to basal cell carcinoma (BCC). ^[1]

Electrocautery is a form of direct transference of heat to tissue. Instead of passing electrical current through the tissue, the current is used to heat a handheld element, which is then applied to the tissue. This form of electrosurgery is most commonly used for hemostasis and tumor destruction when high-frequency electrosurgery is contraindicated.

Additional modalities of electrosurgery include electrolysis, which uses a chemical reaction created by direct current to damage tissue, and coblation, used for facial rejuvenation, which uses an electrical current to ionize a conduction medium such as isotonic saline. The ionized medium is then used to transmit heat to tissue.

There are multiple indications for electrosurgery (see Table 1); in many cases, electrosurgery is combined with another modality such as a scalpel, scissors, or curette. Preserving a specimen for histopathological examination and better control of the depth of destruction are the primary benefits of combination therapy. ^[1]

Electrodesiccation and curettage (ED&C) of BCC is likely the most common indication for electrosurgery. ^[1] ED&C is indicated for nodular and superficial forms of BCC. Other forms of BCC, such as micronodular, recurrent, or morpheaform BCC, should be excised with adequate margins because of the likelihood of deeper infiltration in the dermis.

Table 1. Indications for Electrosurgery* ^[1] (Open Table in a new window)

Anatomical location and the presence of an implantable electronic device (IED) are the two main considerations when evaluating for possible contraindications to electrosurgery.

Anatomical locations of concern include sites near the eye and any site/mass with a narrow stalk or base such as the scrotum, finger, or large papilloma. ^[1]

Application of current at sites with a narrow stalk or base can cause a phenomenon called “channeling,” in which the current is concentrated as it passes through the narrowed region, creating the potential for tissue damage at the base. ^[1] Channeling may also result in distant damage if the current contacts and then travels along tissue that is more conductive than the surrounding tissue (eg, nerves or vessels). This form of channeling may result in distant coagulation with severe consequences if it occurs on a finger or the penis. ^[1]

Ocular injury is not a result of the channeling phenomenon; rather, it is caused by sparks or direct thermal injury and can be prevented by avoiding use of the treatment electrode near the eye or by using corneal shields.

While not an absolute contraindication to the use of electrosurgery, IEDs such as cardiac and gastric pacemakers, implantable cardioverter defibrillators (ICDs), cochlear implants, and deep brain, nerve, spinal cord or bone stimulators create unique risks. Patients with these devices require thorough preprocedure evaluation and may require intraoperative monitoring and postprocedure device assessment. ^[3] (See Complications.)

For a detailed discussion of the electrical principles involved in electrosurgery, including waveforms and tissue effect, circuit types, transformers, direct and alternating current, and ohmic heating, please refer to Surgery of the Skin; Procedural Dermatology, 2nd edition, Chapter 9. ^[1]

For technical aspects of electrocautery, electrodesiccation, electrofulguration, electrocoagulation, and electrosection, please refer to Technique.

The success rate of ED&C for BCC depends on the clinician’s skill using the curette. When using the curette for BCC, the tumor’s physical consistency is different from surrounding normal skin. A skilled clinician can detect subclinical extension of the tumor based on this physical consistency and obtain adequate margins beyond this subclinical border (usually 2-4 mm). Reported recurrence rates are as low as 1.6% in a prospective cohort study of 93 patients treated with ED&C at a VA hospital ^[4] to a range of 5.7-18.8% reported in a structured review. ^[5]

Electric shocks are a risk, especially when a grounding pad is not used and the current is dispersed randomly throughout the body, creating the buildup of static electricity. Shocks may be felt by the patient if there is contact with grounded objects such as nearby metal or metal on the treatment table. Shocks may also be delivered to grounded people nearby, including the practitioner. Not making or breaking contact with the patient during current application may minimize the risk. ^[1]

Burns may occur in the presence of flowing oxygen or when flammable cleansers such as alcohol are used. The use of nonflammable cleansers such as povidone-iodine or chlorhexidine may eliminate the risk. ^[6] It may also occur after the use of aluminum chloride solutions that contain alcohol.

Electrical burns may occur if a patient is in contact with a grounded object, creating a low-resistance path that concentrates the current in a small surface area. Intravenous poles, rectal temperature probes, and electrocardiography needles or plates are hazards. ^[1] In addition, electrical burns may result from current channeling (see Contraindications) and faulty placement of the grounding pad. Avoiding placement of the grounding pad over metal implants, scar tissue, and bony prominences, as well as ensuring good contact between the grounding pad and the skin, will minimize the risk of burns. ^[1]

Eye injury may result from sparks or direct thermal injury when electrosurgery is used near the orbit. Injury can be prevented by avoiding use of the treatment electrode near the eye or using corneal shields. ^[1]

Transmission of infection is a theoretical and real risk of treatment with electrosurgery. Bacterial and viral particles may be transferred directly or via aerosolization during treatment. ^[7] Precautions include the use of surgical masks and eyewear, as well as the use of a smoke evacuator with the nozzle placed within 2 cm of the operative site. ^{[1, 7, 8, 9]}

Electromagnetic interference with IEDs is a much-discussed risk of electrosurgery. Heat electrocautery is generally considered the safest form of electrosurgery in these patients, as no current passes through the body. The main risk of electrocautery is direct thermal injury to an underlying implantable device when using the instrument directly over the device. ^{[1, 3]}

The next safest form of electrosurgery is biterminal (bipolar) electrosurgery, such as electrocoagulation or electrosection. The electrical current in biterminal electrosurgery passes from one electrode through the patient to the other terminal, thus minimizing random dispersion of electrons within the body and interaction with an IED. When used properly, data suggest that biterminal electrosurgery poses no risk of device malfunction with cardiac devices. ^{[1, 3]}

Monoterminal (monopolar) electrosurgery (ie, electrofulguration and electrodesiccation) has the highest risk for electromagnetic interference (EMI) with an IED ^[1] because of the dispersion of the electrical current throughout the body. High-powered units found in hospital operating rooms seek to minimize this risk by using a grounding pad attached to the patient. The electrical current initiated in the unit is delivered through the single unheated electrode to the body, where it travels through the tissue to the grounding pad and then back to the unit to complete the circuit. ^[3]

Proper placement of the grounding pad to avoid a direct line of travel for the current from the electrode through the IED to the grounding pad may reduce but not completely eliminate the risk for electromagnetic interference. Low-power units used in outpatient settings generally do not require a grounding pad, and the current is left to disperse randomly throughout the body, increasing the risk of interference. ^[3]

Modern cardiac pacemakers may have more protection from EMI, at least in part, owing to efforts by manufacturers to protect the devices. ^{[1, 3]} Examples include metallic shielding, which helps protect against high-frequency interference; “bandpass filters,” which ignore signals falling outside the narrow range of cardiac depolarization frequencies; bipolar leads; and noise-sampling periods that convert the pacemaker to a fixed rate if ongoing EMI is sensed. ^{[1, 3]}

Of all patients with implantable cardiac devices, those who have no underlying rhythm (pacemaker-dependent) should be identified. ^[3] This special subset comprises 5%-10% of patients with implantable cardiac pacemakers. ^[3] Prolonged EMI could lead to symptomatic disruption of the pacemaker. Unfortunately, this status is not always known by the patient. The cardiologist or the device representative should know whether the patient is pacemaker-dependent and may place the device into an asynchronous pacing status thought to minimize the potential for disruption, although complications have still been reported. ^[3]