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*The three main chromophores of the skin are water,
hemoglobin, and melanin, and laser therapy is directed
toward these targets (Fig. 9-1).
Figure 9-1 Wavelength depth of
commonly used lasers. (Adapted from
DiBernardo BE, Cacciarelli A. Cutaneous
lasers. Clin Plast Surg. 2005;32:141-150,
with permission from Elsevier.)
SKIN RESURFACING
Can improve fine to medium wrinkles in patients with
Fitzpatrick I or II skin (eg, perioral rhytids) due to skin
contraction from synthesis and reorganization of new collagen
and elastin.
Results in thermal injury to the skin with wound healing.
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Reepithelialization occurs through proliferation of progenitor
cells within hair follicles and sweat glands.
Increased dermal collagen synthesis for 3-6 months.
Reorganization of elastic fibers into a parallel and tight
configuration.
Ablative vs nonablative lasers
Ablative: removes dermis/epidermis, thermal injury induces
wound healing response (eg, CO2, Er:YAG)
Nonablative: heat underlying tissue to induce wound-
healing response without trauma (eg, pulsed-dye, ND:YAG,
alexandrite)
Contraindications
Relative: smoking, previous resurfacing, diabetes, prior
skin irradiation, active acne, hypertrophic scarring, skin
hypersensitivity, vitiligo, and pigmentation disorders
Absolute: keloids, scleroderma, systemic lupus
erythematosus, and isotretinoin use within the previous
year
CO2 laser: ablative
Pulsed or continuous wave modes. Fractional setting
decreases amount of thermal injury but still stimulates
tissue regeneration.
Water absorbs energy, converting light to heat which
vaporizes or ablates tissue. Effects are similar to a
controlled partial-thickness burn.
Ablation threshold—the necessary amount of energy that
achieves tissue vaporization. Ablation threshold for CO
2
laser is 5 J/cm2.
Side effects: prolonged healing or erythema, scarring
(infrequent), transient hyperpigmentation, risk of permanent
hypopigmentation (infrequent), possible yeast, bacterial,
viral infections, HSV outbreak (*can give valcyclovir PO
for prophylaxis), contact dermatitis.
Indications: photoaged skin, rhytids, acne scars, skin laxity,
hypertrophic burn scars, some linear epidermal nevi,
sebaceous hyperplasia, and seborrheic keratoses.
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Relative contraindications: vitiligo, scleroderma, darker skin,
unrealistic expectations.
Best candidate: Fitzpatrick type I or II skin.
Avoid using supplemental oxygen to prevent fires from CO
2
laser.
Erbium:yttrium-aluminum-garnet (Er:YAG): ablative
Compared with the CO2 laser, more passes are required for
the same depth of penetration but with less thermal
damage.
Ablation threshold for Er:YAG laser is 1.6 J/cm2.
Side effects similar to CO2.
Indications: rhytids, photodamage, acne scars, skin laxity.
Best candidate: Fitzpatrick type I or II skin.
VASCULAR LESIONS
Indications: capillary malformations and hemangiomas are most
common.
Selective photothermolysis targets hemoglobin and
oxyhemoglobin molecules in order to shrink or eliminate blood
vessels.
*Treatment of choice: IPL, 1064 nm Nd:YAG, 810 nm diode,
532 nm KTP, and 595 nm PDL.
Flashlamp pulsed dye laser
Indications: capillary vascular malformations,
hemangiomas, telangiectasias, port-wine stains, recalcitrant
verrucae.
Side effects: erythema/purpura for 7-14 days,
dyspigmentation.
Usually requires several treatments for lightening of
vascular lesions.
Best results for port-wine stains depends on location and
size.
Lesions on the face and neck respond better than
those on the leg and hand.
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Lesions on forehead and lateral face respond better
than central face.
Chest, upper arm, and shoulder respond well.
Initial port-wine stain <20 cm2 clear more than those
larger than 20 cm2.
ND:YAG laser
Indications: early stage hemangiomas, capillary vascular
malformation, venous malformations, facial telangiectasias,
spider veins
Side effects: pain, redness, swelling, bruising, pigmentary
changes
KTP (potassium-titanyl-phosphate) laser
Indications: epidermal pigmented lesions and vascular
lesions. Similar response rates as PDL for some lesions,
red tattoo-ink.
Side effects: less purpura than PDL; scarring has been
reported.
Consider for resistant port-wine stains and large venous
malformations.
PIGMENTED SKIN LESIONS
Common lesions amenable to laser treatment: lentigines,
ephelides, café au lait macules, thin seborrheic keratoses,
nevus of Ota, nevus of Ito, blue nevi.
May require multiple treatments, especially for café au lait
macules, nevus of Ota/Ito.
Diagnose melanocytic nevi before treating. Controversial as
inadvertent treatment may slow the diagnosis of dysplasia or
melanoma.
Chromophore: melanin.
*Q-switched lasers are now the treatment of choice for
pigmented lesions.
Q-switched ruby laser: 694 nm
Q-switched alexandrite: 755 nm
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Q-switched Nd:YAG: 1064 nm; use for patients with darker
skin because of decreased risk of dyspigmentation
Complications: pigmentary changes (hypopigmentation or
hyperpigmentation), partial removal, infection, bleeding, textural
changes, scarring (<5%).
TATTOO REMOVAL
Lasers in Q-switched mode are used for tattoo removal.
Chromophore: tattoo pigment.
*Three types of lasers are currently used for tattoo removal.
Q-switched ruby (694 nm) and Q-switched alexandrite (755
nm)
Q-switched Nd:YAG (532 nm)
Q-switched Nd:YAG (1064 nm)
Absorption peak of pigment must match wavelength of laser,
which heats the tattoo particles within lysosomes, leading to
cavitation and epidermal whitening.
Multiple treatments are necessary with treatments separated by
5-10 weeks. Complete clearance may not be achieved.
Tattoos exhibit “complementary matching” of laser with pigment
(Table 9-2).
TABLE 9-2 Tattoo Pigment Wavelength
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Caution with cosmetic tattoos (eg, tattooed lip liner) due to
oxidation of certain tattoo pigments (ie, ferric oxide and titanium
oxide) leading to paradoxical darkening.
Complications: pigmentary changes (hypopigmentation or
hyperpigmentation), partial removal, infection, bleeding, textural
changes, tattoo ink darkening, scarring (<5%).
HAIR REMOVAL
Numerous lasers targeting unwanted hair include diode laser,
normal mode ruby, alexandrite, and normal Nd:YAG.
Using lasers with longer pulse duration achieves two goals.
Epidermal melanosomes are not affected.
The light-absorbing melanized bulb and shaft diffuses heat
to surrounding follicle.
Higher fluences lead to better results but also more discomfort
and complications.
Requires multiple treatments. All lasers lead to hair reduction,
not permanent removal.
Cooling essential for safe reduction in darkly pigmented skin.
Ideal patients have dark hair and fair skin. The treatment of light
or white hairs remains a challenge due to lack of melanin target.
FRACTIONAL PHOTOTHERMOLYSIS
Only a portion of the epidermis and dermis is treated with
columns of energy to create targeted areas of thermal damage
(microthermal treatment zones [MTZs]).
The untreated areas are a reservoir of collagen and promote
tissue regrowth.
Allows for greater penetration with decreased risk of scarring.
Pattern density: number of MTZs within the treatment area.
Greater number of MTZs yields a greater surface of the skin
treated at each pass.
Energy: depth of MTZ penetration into the dermis.
Nonablative fractional devices
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Lasers: erbium-glass laser (1540 nm); Nd:YAG (1320 nm);
diode (1450 nm)
Indications: skin resurfacing, acne, striae, scarring,
melisma, burn scars
Can be performed under topical anesthetic
Mild erythema and swelling, dry skin, flaking, superficial
scratches, pruritus, pigmentary changes, and acneiform
eruptions
Risk of herpes simplex virus and varicella zoster virus
reactivation (use valacyclovir for prophylaxis as indicated)
Ablative fractional devices
Ablative CO2 or erbium lasers.
Fine rhytids, dyspigmentation, skin laxity.
Can be performed under topical anesthetic with nerve
block.
May result in prolonged erythema, hypopigmentation, and
scarring, although the risks are less compared with fully
ablative therapy.
LASER SAFETY
Signs
Signs on room door should have information about laser, its
wavelength, and energy.
A pair of appropriate eyewear placed on the door outside
the room.
Eye Protection
CO2 and Er:YAG lasers can injure cornea.
PDL and ruby lasers can injure retina.
Special glasses that match the emission spectrum of a
laser must be worn by laser operator and all other
personnel in the room.
Manufacturer of protective eyewear has the wavelengths of
light for which protection is provided printed on goggles.
Patient can wear
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Metal corneal eye shields if laser will be used around
orbits.
Burnished stainless steel eye cups.
Fire Risk
Prep solution should be nonflammable (avoid chlorhexidine
or alcohol).
Surround the area to be treated with wet towels.
*Laser Plume
Ablative lasers create a plume, which may contain bacteria
(coagulase negative Staphylococcus, Corynebacterium,
Neisseria, and HPV).
Laser operator and personnel should wear surgical masks.
Use a smoke evacuator ~1-2 cm from laser smoke plume
source.
PEARLS
1. Vascular lesions are most effectively treated using PDLs (585595 nm).
2. Tattoos can be effectively treated with Q-switched lasers, and
the appropriate wavelength depends on the color and depth of
the pigment.
3. Fractional technologies are increasingly popular for skin
rejuvenation and resurfacing, and only treat a portion of the skin
surface. These techniques can potentially minimize patient side
effects and complications.
QUESTIONS YOU WILL BE ASKED
1. Know the chromophores of each laser. Know for each clinical
application, what are the lasers of choice?
2. What medication(s) should patients with history of HSV
undergoing cutaneous laser resurfacing receive as prophylaxis?
Valacyclovir.
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1.
2.
3.
4.
5.
3. Which skin types are at greatest risk for side effects or
complications following laser therapy?
Fitzpatrick IV and above.
Recommended Readings
Alam M, Warycha M. Complications of lasers and light treatments. Dermatol
Ther. 2011;24:571‐580.
Azadgoli B, Baker RY. Laser applications in surgery. Ann Transl Med.
2016;4:452.
Chuang J, Barnes C, Wong BJ. Overview of facial plastic surgery and current
developments. Surg J. 2016;2:e17‐e28.
Khalkhal E, Rezaei-Tavirani M, Zali MR, et al. The evaluation of laser
application in surgery: a review article. J Lasers Med Sci. 2019;10:S104.
Nelson AA, Lask GP. Principles and practice of cutaneous laser and light
therapy. Clin Plast Surg. 2011;38:427‐436.
*
Denotes common in-service examination topics.
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10
Burns
Emily Barrett
OVERVIEW OF THERMAL BURN
INJURY
PATHOPHYSIOLOGY OF BURN
INJURY
Coagulation of protein due to intense heat
Release of local inflammatory mediators
Change in blood flow due to vasoconstriction and thrombosis
Tissue edema
SYSTEMIC EFFECTS
Loss of skin’s barrier function leads to fluid loss and massive
fluid shifts.
Injured tissues release vasoactive mediators with secondary
interstitial edema, hypoproteinemia, fluid shifts, and organ
dysfunction.
Bacterial translocation.
Immune Function: hypermetabolic state
*Initial response: decreased cardiac output, decreased
metabolic rate.
24-48 hour after injury: increased cardiac output (2 times
normal), increased metabolic rate (2 times normal).
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