Electrosurgery is used in dermatological procedures to stop bleeding (haemostasis) or to destroy abnormal skin growths.
In electrosurgery, high-frequency, alternating electric current at various voltages (200 to 10,000V) is passed through the skin to generate heat. It requires a power supply and a handpiece with one or more electrodes. The device is controlled using a switch on the handpiece or a foot switch.
Electrosurgery includes:
- Electrofulguration (results in sparks)
- Electrodesiccation (dehydration of superficial tissue)
- Electrocoagulation (cause bleeding blood vessels to clot)
- Electrosection (cut through tissue)
Monopolar electrosurgery
Uses single pointed probe to carry electrical current from power generator to surgical site.
Requires indifferent electrode, typically large metal plate or flexible metalised plastic pad placed on skin distant from surgical site.
Current passes from tip of probe through patient to indifferent electrode and completes circuit by returning to electrosurgical generator.
Electrofulguration and electrodesiccation
Electrofulguration and electrodesiccation are used to destroy superficial lesions that are unlikely to bleed profusely when disturbed, such as viral warts and seborrhoeic keratoses.
Electrofulguration and electrodesiccation use a single electrode to produce high voltage and low amperage current. The current accumulates in the patient but there is minimal tissue damage.
Electrofulguration
- Electrofulguration is used to treat skin tags and protruding warty lesions such as seborrhoeic keratoses, viral warts, xanthelasma and dermatosis papulosa nigra.
- Electrode is held 1–2 mm from skin surface, and produces spark or electric arc.
- This causes superficial tissue dehydration and carbonisation over wide area.
- High voltage allows current to overcome resistance of air gap between tissue and electrode tip.
- Carbonised epidermis insulates and minimises further damage to the underlying dermis.
Electrodesiccation
- Electrodesiccation is used to remove flat seborrhoeic keratoses and lesions under the skin such as syringoma, milia, comedones, sebaceous hyperplasia and molluscum contagiosum.
- It can be also used for hair removal and to treat fine facial blood vessels.
- Electrode contacts skin directly and heats it up
- Results in dehydration of surface and slightly deeper skin
- Dry coagulum forms on skin surface.
- Treated areas usually heal rapidly with minimal scarring or loss of pigment
Electrocoagulation
Electrocoagulation is used to cause deeper tissue destruction and to stop bleeding with minimal carbonisation. The haemostatic and destructive capacity of electrocoagulation makes it ideal for the treatment of skin cancers and vascular skin conditions such as pyogenic granuloma. It can also be used to stop small blood vessels from bleeding during skin surgery.
Electrocoagulation uses monopolar or bipolar electrodes to produce low voltage and high-amperage current at relatively low power. An indifferent electrode prevents accumulation of current in the patient, hence low voltage is sufficient to establish current flow. High amperage causes deep tissue destruction and haemostasis by fusion of blood vessel collagen and elastic fibers.
The electrode is applied across the lesion until slightly pink to pale coagulation occurs. Coagulated tissue has greater resistance to electrical current than normal skin, and limits the amount of damage.
Electrocoagulation may result in permanent scarring and white marks (hypopigmentation).
Electrosection
Electrosection is used to simultaneously cut skin and seal bleeding vessels by blending damped and undamped wavetrains. It is suited for excision of large, relatively vascular lesions, such as benign dermal naevi (moles), skin tags, or for shaving off seborrhoeic keratoses, folliculitis keloidalis nuchae and rhinophyma (see rosacea). Electrosection requires almost no manual pressure from the operator as the electrode glides through tissue with minimal resistance.
Electrosection uses an monopolar electrode to produce low-voltage and high-amperage current at higher power than is used for electrocoagulation. The current is highly focused to vaporise tissue with minimal peripheral heat damage. The electrode is usually a fine tungsten wire or loop.
The destruction of chemical bonds or decomposition of tissue arises through thermolysis (heat-induced) and electrolysis (via DC electric-current). The main component of tissue is water, which is broken down into its components, hydrogen and oxygen.
Risks of electrosurgery
The risks of electrosurgery include electric shock, thermal burns, transmission of infection and production of toxic gases.
Electric shock
Electric shock can be minimised by:
Use of earthing/indifferent electrode
Surgeon wearing plastic surgical gloves
Electric/thermal burns
Electric/thermal burns can be minimised by:
- Use of non-flammable cleanser such as chlorhexidine or povidone-iodine
- Ensuring indifferent electrode has broad contact with skin and is not placed over a bony prominence, scar tissue, or implanted metal
- Ensuring patient is not in contact with grounded metal objects
- Removal of eschar: this is a fire hazard as it can ignite.
Transmission of infection and production of toxic gases
Electrosurgery may be used to treat viral warts. Thermolysis will generate smoke/fumes which may contain human papillomavirus (HPV) particles that may be transmitted to the operator who breaths in or comes into contact with the fume. When working with HPV-related lesions, minimise the risk of transmission.
- Use smoke evacuator with intake nozzle 2 cm from operative site
- Wear surgical mask (N95 is most effective) and eye protection.
Other viral DNA, bacteria, carcinogens, and irritants are also known to be present in electrosurgical smoke. NIOSH (the National Institute of Occupational Safety and Health) a division of CDC (Center for Disease Control, USA) have also studied electrosurgical smoke at length. They state: “Research studies have confirmed that this smoke plume can contain toxic gases and vapors such as benzene, hydrogen cyanide, and formaldehyde, bioaerosols, dead and live cellular material (including blood fragments), and viruses.”
Smoke can be removed using hand held suction. Newer smoke evacuation devices can be attached directly to a standard electrosurgical pencil reducing the work of an assistant during surgery.