Biomedical Engineering Reference
In-Depth Information
full-face laser resurfacing and
supplemented topical anesthesia
Traditionally, full-face laser resurfacing, which removes the
epidermis and upper portions of the dermis, has required gen-
eral anesthesia or regional nerve blocks (with or without IV
sedation and regional infiltration). The complications associ-
ated with general anesthesia were previously discussed.
Regional nerve blocks often leave areas that are still sensitive to
pain and require needle injections that increase patient dis-
comfort. Research indicates that EMLA in a supplemented
topical anesthesia protocol for full-face CO
2
laser resurfacing
is safe, tolerable, and effective (100). This protocol is as fol-
lows: After washing the face, hot compresses are placed for 10
minutes. Then, 30 g of EMLA cream is applied to the face
under occlusion. An hour-and-a-half later, the patient is given
one to two tablets of 5 mg hydrocodone/500 mg acetamino-
phen PO, 5-10 mg of diazepam PO, and/or 30-60 mg ketolac
IM. Then, an additional 30 g of EMLA is applied under occlu-
sion (anatomic areas are covered with individual pieces of
plastic wrap). Approximately 1 hour later, laser resurfacing is
performed by removing the plastic wrap from one area and
wiping the area clean with a dry gauze. If possible, repeat
passes are performed on the same area before moving to the
next quadrant. This protocol was applied to 200 patients
requiring full-face CO
2
laser resurfacing procedures. The pro-
cedure was tolerated with minimal pain, and only 5% required
adjuvant anesthesia (nerve blocks or local infiltration). No
adverse effects were seen in the study with topical EMLA.
Patients generally reepithelialized by day 7. One year later, only
one patient had hypopigmentation and scarring. In addition,
EMLA-treated skin and skin without EMLA treatment revealed
similar depths of thermal damage as indicated through histo-
logic examination. It has been hypothesized that because CO
2
lasers target water, the hydrating effects of EMLA may contrib-
ute to the low rate of hypopigmentation and scarring seen in
this study. In addition, research indicates that there is potential
to use EMLA as a single agent since it has been shown to pen-
etrate up to 5 mm 2.5 hours after application (the minimum
required depth of anesthesia is general 100 mm) (100).
Fractionated ablative lasers also require signifi cant anesthe-
sia. We have used a similar technique where patients are medi-
cated with either IM Demerol and Phenergan or IV midazolam
and fentanyl along with topical anesthetic. Newer topical anes-
thetics that do not require hours of occlusion may be used
such as 7% lidocaine and 7% tetracaine. Pretreatment of the
treatment area with microdermabrasion may facilitate pene-
tration of the topical anesthetic. However, patients should be
monitored to prevent lidocaine toxicity.
pass of the Er:YAG (wavelength 2940 nm) laser enhanced the
absorption and penetration of lidocaine, by disrupting the
stratum corneum (101). With this method, anesthesia can be
induced in just 5 minutes compared with the 60 minutes
required if lidocaine was applied under occlusion. Data from
clinical trials evaluating pain associated with hypodermic nee-
dle insertion indicate that there is a 62% pain reduction with
laser pretreatment plus lidocaine compared with laser pre-
treatment plus placebo and a 61% pain reduction with laser
pretreatment plus lidocaine compared with lidocaine alone.
Although this technique may not be adequate for invasive pro-
cedures, it may minimize pain and discomfort for more
superficial cutaneous procedures, such as hypodermic needle
insertion.
Despite these advances in safety in the office-based setting,
patients with severe medical problems, such as poorly con-
trolled hypertension, congestive heart failure, severe/easily
triggered asthma, orthopnea, morbid obesity, and other
significant conditions, are better treated in a hospital or outpa-
tient surgery center setting. Nonetheless, with proper pre-
operative screening, appropriate patient selection, and careful
monitoring, the anesthetic techniques described can readily be
adapted to meet the specific needs of practitioners and patients
in a variety of clinical settings.
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lasers and penetration
of topical anesthetics
The skin forms a barrier to the penetration of topically applied
anesthetics. Therefore, traditionally lidocaine has been admin-
istered via subcutaneous injection (which is often painful),
iontophoresis-aided delivery (which may cause irritation and
burning), topical application after repeated tape stripping of
the skin (which is inconvenient and uncomfortable), or topical
application with occlusion (which is time consuming). The
Er:YAG laser is used in superficial skin resurfacing and is read-
ily absorbed by the epidermis. Research indicates that a single
