30 - 206 - CRYOSURGERY AND ELECTROSURGERY Flashcards
cryogen of choice for treating benign and malignant neoplasm
liquid nitrogen
- boiling point of −195.8 Celsius
- has the lowest temperature of all the common cryogens, causing rapid freeze of treated tissue
MOST sensitive to the destructive effects of cryosurgery
Melanocytes
LEAST sensitive to the destructive effects of cryosurgery
fibroblasts
refers to the use of extreme cold to destroy cells of abnormal or diseased tissue
Cryosurgery
refers to the study of the effects of subzero temperature on living systems
Cryobiology
causes intracellular ice crystal formation with the disruption of electrolytes and pH changes
Rapid freezing
- Therefore, tissue effects and cell death are most readily achieved when tissue is frozen rapidly.
- During thawing, recrystallization occurs when ice crystals fuse to form large crystals that disrupt cell membranes.
- As the ice melts further, the extracellular environment becomes hypotonic, causing water to infuse into cells and cause cell lysis.
- The longer the thawing time, the greater the damage to cells because of increased solute effect and greater recrystallization
causes extracellular ice formation and less cell damage
slow freezing
major mechanism of injury from cryosurgery
- After freezing, stasis within the vasculature occurs.
- This **loss of circulation and resultant anoxia **is a major mechanism of injury from cryosurgery.
cell destruction of melanocytes occur at what temperature?
−4°C to −7°C (24.8°F to 19.4°F)
cell destruction of keratinocytes occur at what temperature?
**−20°C to −30°C **(−4°F to −22°F)
cell destruction of fibroblasts occur at what temperature?
−30°C to −35°C (−22°F to −31°F)
cell destruction of malignant lesions occur at what temperature?
−50°C to −60°C (−58°F to −76°F)
Absolute contraindications to cryosurgery
- lesions that require histopathology for diagnosis
- recurrent nonmelanoma skin cancers.
Relative contraindications to cryosurgery
- cold urticaria,
- abnormal cold intolerance,
- cryoglobulinemia, or cryofibrinogenemia, or
- tumors with indistinct borders or darkly pigmented features
Risks and potential complications of cryosurgery
- pain
- bleeding
- pigmentation change
- nerve damage
- scarring
- alopecia
- insufflation of soft tissue
most disconcerting complication following cryosurgery
Hypopigmentation or hyperpigmentation
Freeze times longer than how many seconds may result in alopecia?
20 seconds
reactions expected from treated areas within 24 hours posttreatment of cryosurgery
Edema, vesicles, bullae, and weeping
n general, superficial lesions should have a clinical freeze margin of how many mm?
2 - 3 mm
malignant or deeper lesions should have a clinical freeze margin of how many mm?
5 mm
technique that uses the transmission of electricity to cut tissue, destroy tissue, and cauterize vessels
Electrosurgery
- uses a damped sine wave, high-voltage, low-amperage alternating current to generate a spark from a monoterminal electrode to the tissue via the air
- There is no contact between the electrode and the tissue
Electrofulguration
- This modality is the least tissue damaging of all of the high-frequency electrosurgery techniques, and results in rapid tissue healing.
- Most of the tissue damage is superficial, primarily involving the epidermis.
Electrofulguration
- damped sine wave, high-voltage, low-amperage alternating current to generate a current from direct contact of a monoterminal electrode to the tissue
- Superficial tissue damage occurs as** heat is transferred to tissue**, causing cell death.
Electrodessication
- The extent of tissue damage is directly related to electrode contact time with the skin.
- Although skin injury is greater with electrodessication compared to electrofulguration, most of the tissue damage remains superficial
- uses a moderately damped sine wave, low-voltage, high-amperage alternating current to generate a current from direct contact of a biterminal electrode to the tissue.
- Tissue damage is deeper than with electrofulguration and electrodessication, providing tissue coagulation through the generation of heat in the tissue.
Electrocoagulation
- Another distinguishing feature of electrocoagulation is the involvement of the patient within the circuit.
- This allows the use of a lower voltage and higher amperage to generate more coagulation.
- uses a heating filament tip connected to a low-voltage, high-amperage direct current, usually a battery.
- Heat is transferred from the filament to the target tissue, causing protein denaturation and tissue coagulation.
Electrocautery
- undamped or slightly damped sine wave, low-voltage, high-amperage alternating current to cut tissue with minimal peripheral heat damage
Electrosection
- The “Bovie” knife incorporates a blended undamped and damped sine wave that provides both cutting and coagulation at the same time
There is no electric current transfer to the target tissue, and the patient is not part of the circuit loop.
Electrocautery
- most used for patients with pacemakers or implantable cardiac defibrillators (ICDs) who are high-risk candidates for receiving electrosurgery.
- because patients are not part of the circuit loop, it is useful for nonconductive tissue areas of the body, such as the** cartilage, bone, and nails.**
Electrocautery
- uses low-voltage, low-amperage direct current from a negative electrode to the positive electrode
- The negative electrode is applied to the target tissue where electrons are released.
- The electrons interact with the tissue to produce** sodium hydroxide **and hydrogen gas resulting in tissue liquefaction.
- Acids are produced at the **positive electrode **resulting in tissue coagulation.
Electrolysis
The main use of electrolysis is for hair removal.
With the exception of what electrosurgical techniques, electrosurgical units used in dermatologic procedures have high-frequency alternating current
electrocautery or electrolysis
refers to the use of a treatment electrode without an indifferent or dispersing electrode
Monoterminal
The dispersing electrode (grounding pad) should be placed in a location that directs the current pathway away from the cardiac device (usually the right lower leg). If a pedal is used, it should be placed near the surgeon’s feet.
refers to the use of both treatment and indifferent electrodes.
Biterminal
The dispersing electrode (grounding pad) should be placed in a location that directs the current pathway away from the cardiac device (usually the right lower leg). If a pedal is used, it should be placed near the surgeon’s feet.
denotes 1 tip in electrosurgical unit
Monopolar
denotes 2 tips in electrosurgical units
bipolar
most common application of electrosurgery
maintaining hemostasis in the operative field
Coagulation can be achieved using what electrosurgical techniques?
electrofulguration, electrodessication, or electrocoagulation
- direct application of the electrode to the bleeding vessel.
- This provides conduction of heat to the vessel, resulting in tissue coagulation
electrosurgical technique that is an effective treatment modality for papular or plaque-like tumors of the epidermis, such as seborrheic keratoses, verrucae, dermatosis papulosis nigra, molluscum, or flat warts
Electrodessication
indications for Curettage and electrodessication (C+D) for BCC and SCC
- Tumors should be primary;
- have distinct clinical borders;
- be located on sites of low recurrence, such as the trunk, extremities, or non-”H”-zone regions of the face;
- have a superficial or nodular histologic subtype; and
- have a diameter of less than 1 cm on the face and less than 2 cm on the trunk and extremities.
Tumors not acceptable for C+D
- indistinct borders,
- tumors on the “H”-zone of the face,
- tumors with an aggressive histologic pattern,
- tumors with high metastatic potential,
- tumors that require histologic diagnosis.
