CO2 lasers

• Used for laser skin resurfacing
• Chromophore is water
• Hyperpigmentation is most common adverse effect of laser resurfacing for Fitzpatrick Type III or IV
• Treat with hydroquinone and tretinoin, usually resolves within a few months. Must stop isotreinoin or acutane for 12-18 months prior. Tretinoin is used as pretreatment
• Rates of hyperpigmentation reduced by pretreatment with retinoic acid and bleaching agents
• Erythema is normal and can last 1-4 months depending on type of laser used
• Ascorbic acid decreases duration and severity of erythema following laser resurfacing
• Hypopigmentation is the main long term complication
• Er: YAG: treatment of choice for ablative resurfacing of skin: 2940nm- greatest affinity for water, (compared to CO2) decreased thermal heating, minimal contraction of dermis, creates transudative wound (photomechanical), less coagulative necrosis, decreased permanent hypopigmentation

Vascular lesions

• Pulsed dye  good for capillary lesions, port wine stains 585nm
• Chromophore is oxyhemoglobin
• KTP 532 good for superficial vascular telangectasias; especially in face, red facial capillaries
• Ed:YAG, diode, and erbium (infrared lasers at wavelengths 1064 to 1540)- best for acne scars

Tattoo removal

• Q-switched good for tattoos (includes ruby -violet, ND:yag, alexandrite). Uses principles of photothermolysis
• ND yag 532 good for red/orange/yellow
• ND yag targets blood vessels, red blood cells, collagen, melanin
• Q-switched alexandrite (755 nm) for green tattoo ink
• ND YAG 1064 (pulse duration short, high affinity for water, minimal tissue necrosis, low coag necrosis, photomechanical, collagen contraction less than CO2)- black
• Good for foreign body removal 
• Good for vessel reduction in the leg
• Long pulsed 1320 used for non-ablative skin remodeling (varicose veins)

Laser hair removal

• Targets melanin in hair follicle so it is not useful in fair haired patients
• Electrolysis used for hair removal in fair skin patients
• Otherwise, often use long-pulse Nd:YAG
• Safety 

• Can have acne post-laser treatment of herpes simplex outbreak in those with and without a history
• Reactivation of HSV is most common infectious complication after resurfacing
• Antiviral prophylaxis now used in all patients undergoing laser resurfacing
• Herpes outbreak despite oral management: IV antiviral and antibiotic; give prophylactic HSV prior to laser treatment
• High-efficiency smoke evacuator placed within 1 to 2 cm of the smoke plume, high-filtration or laser masks should be used instead of standard surgical masks
• To prevent fire for laser: use conscious sedation, nerve blocks, and no supplemental oxygen