Fundamentals of Cutaneous Surgery

1

How does one define dermatologic surgery?

Dermatologic surgery describes procedures involving the skin and/or its appendages. Although many specialties may perform dermatologic surgery, dermatologists receive specific training in treating the skin both medically and surgically. Some dermatologists undergo additional fellowship training in micrographic surgery and dermatologic oncology (MSDO). In this fellowship, a dermatologist focuses on skin tumor extirpation using the Mohs micrographic surgery technique (see Mohs Surgery chapter). Additionally, during the MSDO fellowship, the dermatologist is taught the principals of surgical defect reconstruction (with an emphasis on facial reconstruction) including simple side-to-side closure, flaps, and grafts. Dermatologic surgery also includes cryosurgery, laser treatment of vascular lesions, pigmented skin lesions, and laser skin resurfacing for photodamaged skin. Dermabrasion, chemical peels, sclerotherapy, hair transplantation, liposuction, and soft tissue augmentation are described as types of dermatologic surgery as well.

2

Local anesthetics are divided into two groups. Name these two groups and list their defining characteristics

The ester group of local anesthetics is metabolized by plasma pseudocholinesterase and then the kidneys. Some patients have an increased risk of toxicity to ester anesthetics because of inherently atypical forms of plasma pseudocholinesterase. Some examples of ester anesthetics are procaine, chloroprocaine, and tetracaine. The amide group of local anesthetics is metabolized by the hepatic P450 system. Caution must be used when administering an amide anesthetic in a patient with liver failure. Some examples of amide anesthetics include lidocaine, mepivacaine, bupivacaine, and prilocaine.

3

How do local anesthetics work?

Local anesthetics decrease the sodium permeability of the nerve fiber membrane, thereby lowering the action potential of the nerve fiber and preventing depolarization of the fiber.

4

What should you do if a patient reports a lidocaine allergy?

Reactions to lidocaine are usually due to an allergy to the methylparaben preservatives found in lidocaine solution. Cutaneous patch testing may be employed to elucidate a true lidocaine allergy versus an allergy to methylparabens. One can also use an ester anesthetic. One percent diphenhydramine or 0.9% normal saline injected in the skin in a very superficial fashion can be used to achieve cutaneous anesthesia.

5

Why is it beneficial to mix lidocaine with epinephrine?

Epinephrine is a vasoconstrictor and therefore helps to slow systemic absorption of lidocaine. The duration of lidocaine activity is prolonged. Also, epinephrine decreases bleeding at the surgical site, thus aiding in hemostasis and decreasing surgical morbidity.

6

What are the maximum doses of lidocaine?

5 mg/kg if without epinephrine, 7 mg/kg if mixed with epinephrine.

7

What are the symptoms and signs of lidocaine toxicity and how is it treated?

See Table 50.1 .

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