Lasers in Plastic Surgery Flashcards
What does laser stand for and how is it different from other forms of light?
Light
Amplication by
Stimulated
Emission of
Radiation
Lasers are more organized, monochromatic, (CCHI)
- Collimated (travels in a collimated beam - parallel)
- coherent (travels synchronously)
- homogeneous (form the same source/monochromatic) - Intense
What is the wavelength of UV, visible and IR light
- UV 100-400nm
- Visible 380-700
- IR 780-3000
What is the difference between ablative and non-ablative lasers
* vaporization of epidermis and superficial dermal coagulation:
- Ablative (neodynium-YAG, CO2) produces
- vaporization of the epidermis
- coagulation of the dermis with surrounding thermal damage
- => resulting in collagen remodelling, tightening skin, reversing actinic changes
- Non-ablative laser
- no vaporization of epidermis - protect epidermis by cooling during treatment
- eg. thermage - monopolar radiofrequency with simutaenous cryogenic cooling
- does coagulate deeper dermis with collagen remodelling
- no vaporization of epidermis - protect epidermis by cooling during treatment
What is a chromophore
- substance in tissue capable of absorbing light
- chormophores absorb light and convert to thermal energy
- Eg of chromophore (substances that can absorb light)=
- Hb, OxyHb
- betacarotene
- collagen in dermis
- melanin
- water
- tattoo ink
What are clinical applications of lasers
- skin resurfacing
- scarring
- tattoo
- acne
- hair removal
- benign skin lesions: pigmented/nonpigmented/vascular
What contraindications to laser use
Absolute
- active bacterial/viral infection
- Isotretinoin (Accutane) use in last 1-2yrs
- ectropion
Relative
- CVD
- hx of keloid/HTS
- hx of radiation at site for laser
- ongoing UV exposure
Caution
- smokers
- dark skinned individual
- neck resurfacing
- hs of chemical peel, dermabrasion, laser
What lasers are used for Vascular lesions (targeting OxyHb, Hb)
Lasers
o Potassium titanyl phosphate (KTP) 532 nm
o Yellow pulsed dye 585 or 600 nm
o Alexandrite 755 nm
o Diode 800, 810, 940, 980 nm
o Neodymium:yttrium-aluminum-garnet (Nd:YAG) 1064 nm
Lesions
o Hemangioma – Nd-YAG (contraindicated in proliferative stage)
o Capillary malformation (post-wine stain) – pulsed yellow dye
o Venous & venolymphatic malformations – Nd-YAG (done with surgical debulking or sclerotherapy)
o Facial telangiectasia & rosacea – KTP > pulsed yellow dye > diode > Nd:YAG
o Spider veins – Nd:YAG >KTP, pulsed dye (address venous insufficiency as well)
o Kaposi’s sarcoma – pulsed dye (585nm) – less scarring but required repeated treatment q4 weeks
What pigmented lesions are treated with lasers (targets melanin)
o Lentigines
o Seborrheic keratoses
o Ephelides (freckles)
o Café-au-lait macules (High recurrence rate)
o Becker’s nevus (Brown irregular patch with dark, coarse hair)
- Q-switched ruby slightly more effective for pigment, but long pulsed lasers better for hair removal
o Melasma (caution with treatment, may worsen and recurrence common)
o Congenital nevi (Controversial, creates difficulty in surveillance for malignant transformation)
o Nevus of Ota: Blue-black, brown, or grey patch in trigeminal nerve distribution. Nevus of Ito: Blue-black, brown, or grey patch on shoulder
Lasers are Q-swtiched (pulsed to shorter duration)b/c longer wavelength than what is needed for absoption of visible light (melanin)
How do lasers treat tattoo
?
Laser fragments the pigment and macrophages phagocytyse the pigment
What lasers are used for which color pigment of a tattoo?
- Dark ink (black, blue) – Nd:YAG 1064nm (although many will work)
- Green ink: Q-switched alexandrite
- Red inks (purple, red, brown): frequency doubled Q-switched Nd:YAG (KTP) 532 nm
- Yellow and orange ink highly resistant to treatment
What lasers are used for scarring (target OxyHgb)
- HTS/keloid/burn:
- Pulsed Dye 585/595
- freqeuncy doubled NdYAG 532 (KTP)
What lasers are used for skin resurfacing (target H20) and how do they effect the skin
- CO2
- Er:YAG
- IPL
Effects
- can reach upper reticular dermis ->stimulate angiogenesis, neocollagenf ormation, elastic fiber formation
- less hypopigmentation as melanocytes retain function
Which laser are used for hair removal and what is the optimal peri-operative treatemnt/preparation
- seletive photolysis of the bulb
- Q-switched ruvy or alexandrite
- Peri-operative prep
- hydroxyquinone pretreatment
- Hair in anagen phase (to increase melanin relative to skin)
- no hair removal for 1mth before
- no sun exposure 4wks before
What are commonly used lasers, their uses and wavelengths
- Pulsed Dye = 585
- Qswitched Ruby = 694
- Alexandrite = 755
- Q-switched Nd-YAG = 1064/532
- Erbium = 2940
- Carbon dioxide = 10600
What is the pulse width, wavelength and spot size
- All factors determing the depth of penetration
- Pulse width: DURATION of exposure
- the larger the Pw, the greater the penetration
- Wavelength: distance between peaks
- the longer the wavelength, the deeper
- Spot size: area over which the laser is distribtued
- the larger the spot size, the deeper b/c less scatter
