Lasers in Plastic Surgery

Question 1

What does laser stand for and how is it different from other forms of light?

Answer 1

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

Question 2

What is the wavelength of UV, visible and IR light

Answer 2

• UV 100-400nm
• Visible 380-700
• IR 780-3000

Question 3

What is the difference between ablative and non-ablative lasers

Answer 3

* 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

Question 4

What is a chromophore

Answer 4

• 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

Question 5

What are clinical applications of lasers

Answer 5

• skin resurfacing
• scarring
• tattoo
• acne
• hair removal
• benign skin lesions: pigmented/nonpigmented/vascular

Question 6

What contraindications to laser use

Answer 6

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

Question 7

What lasers are used for Vascular lesions (targeting OxyHb, Hb)

Answer 7

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

Question 8

What pigmented lesions are treated with lasers (targets melanin)

Answer 8

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)

Question 9

How do lasers treat tattoo

?

Answer 9

Laser fragments the pigment and macrophages phagocytyse the pigment

Question 10

What lasers are used for which color pigment of a tattoo?

Answer 10

• 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

Question 11

What lasers are used for scarring (target OxyHgb)

Answer 11

• HTS/keloid/burn:
  
  • Pulsed Dye 585/595
  • freqeuncy doubled NdYAG 532 (KTP)

Question 12

What lasers are used for skin resurfacing (target H20) and how do they effect the skin

Answer 12

• CO2
• Er:YAG
• IPL

Effects

• can reach upper reticular dermis ->stimulate angiogenesis, neocollagenf ormation, elastic fiber formation
• less hypopigmentation as melanocytes retain function

Question 13

Which laser are used for hair removal and what is the optimal peri-operative treatemnt/preparation

Answer 13

• 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

Question 14

What are commonly used lasers, their uses and wavelengths

Answer 14

• Pulsed Dye = 585
• Qswitched Ruby = 694
• Alexandrite = 755
• Q-switched Nd-YAG = 1064/532
• Erbium = 2940
• Carbon dioxide = 10600

Question 15

What is the pulse width, wavelength and spot size

Answer 15

• 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

Question 16

What is thermal relaxation time and selective photothermolysis

Answer 16

• Thermal relaxation - time it takes for cell to cool off by 50% after laser pulse exposure.
  
  • if Tr is shorter than duraiton of laser pulse, will get spill over of laser E to other cells and collateral damage. Want long Tr or short laser pulse time
• Selective photothermolysis
  
  • targeted absorption of laser E by particular chormophores in select tissues to limit thermal E delivery to particular tissue

Question 17

What is the mechanism of action of Q-switched Nd-YAG = 1064/532

Answer 17

fragmentation of intracellular targeted pigment whcih is then cleared by phagocytosis

The Q-switched (quality) means the skin is exposed to lase rpulse for 20 and 50ns = very short exposure time relative to Thermal relaxation of the cell = resulting in less collateral damage

Question 18

Why is consideration fo fitzpatrick classification so important for the application of lasers

Answer 18

Pigmentary changes post laser is most common complications = Fitzpatrcik 4-6 - darker skin types - complication is more common

Question 19

What is the mechanism of action of CO2 laser in skin resurfacing

Answer 19

• targets water
• causes vaporization of target cell and denaturaion of extracellular protein
• get removal of epidermis and part of dermis - depending on energy delivered
  
  • get smoothening of rhytids but secondary erythema, edema, pigmentary changes
• Erbium:YAG laser also targets H20 but with higher affinity than CO2
  
  • = less thermal collateral damage but also less effect on rhytids

Question 20

Describe your perioperative care of patient undergoing Laser treatment

Answer 20

• Sunscreen/protection 1yr pre and post laser
• Topical Retinoic acid (0.025-0.01%) daily 8wks
• Topical vit C for 2-8wks
• topical hydroquinone (2-4% BID) for 8wks
• HSV prophylaxis
  
  • Hx: Valtrex 500mg BID x3days pre, 10d post
  • no Hx: Valtrex post only 10d

INTRA-op

• OCular protection : teatracaine and metal shields
• Anesthesia - EMLA/local/GA/sedation
• closed systems for O2 delivery
• Skin: moist towels in site, teeth protection
• skin prep non flammable

POST-op

• Abx (clox,cipro x14days)
• • fluconazole 400mg x1 if hx yeast infx
• • steroid
• Dressing: no poly
  
  • Closed - opsite - moist, less pain but can trap bacteria
  • Open - soaks intermittent w 0.025% acetic acid, lots of vaseline and ice pack

Question 21

What are complications of laser treatment

Answer 21

• PIGMENT
  
  • ​Hyper: 1/3 of people 6wk-6m post T in Fitz 3/4 if no hydroquinone preTx. Due to upward melnoacyte migration
    
    • Rx: topical hydroquinone/cortison, tretinoin, vitc&E
  • Hypo: 6-24mths later in Fitx 1-3
    
    • Rx: tretinoin
• WOUND HEALING
  
  • ​Swelling and Erythema - 100% - last 6wks to 6m
    
    • Rx: hydrocortisone topical after re-epi
  • Pruritus: common wk 2
    
    • Rx antihistamines
  • Scarring
  • Ectropion
• PHOTOSENSITIVITY
• INFECTION
  
  • ​HSV - Tzank smear - Valtrax 1000mg tid
  • Candida - KOH slide - fluconzaone 200 daily
  • pseudomonas - cipro 500 bid
• ACNE AND MILIA
  
  • ​parallels thermal injury +/- occlusve dressing/vaseline
    
    • Rx: tretinoin+ tetracyline
• CONTACT DERMATITIS
  
  • ​occurs because direct contact w langerhans cells - makeup/topical antimicrobial
    
    • ​rx: d/c topical

Question 22

What is intense Pulsed light and how does it differ from laser light

Indications and contraindications

Answer 22

• non-coherent
• polychromatic
• 510-1200nm
  
  • targets water Hb 550-580
  • superficial pigment 550-570 - melanin, Oxyhb
  • darker pigment 590-775
• filters are used to incl/excl particular Wavel

Used for treatment of

• hyperpigmentation (solar lentigines, melasma, freckling)
• hypervascularity (telangiectasia, rosacea, flushing)
• hair reduction
• improvement in skin texture and decrease pore size

Pre-treatment not necessary, expect only 24hrs of redness

Contraindications

• wound healing
• photosensitizing agets
• active accutane treatment
• skin cancer
• fitz 6