A chemical peel is the topical application of a chemical to the skin surface that induces a controlled injury to a specific depth, resulting in subsequent shedding of damaged tissue and inducing growth of new epithelium.

The earliest use of chemical peels is described in Egyptian medicine in the Ebers papyrus in 1550 BC.

The chemical injury stimulates new skin production with repair mechanisms in the epidermis and dermis. The repair process causes regeneration with collagen remodeling and improved melanin distribution. Chemical peels may be used to improve the cosmetic appearance of the skin (tone, texture, and pigmentation) and they are also useful for therapeutic removal of actinic keratoses.

Chemical peels are classified by depth of destruction:

• Very superficial
• Superficial: exfoliate the epidermal layer
• Medium: to papillary dermis
• Deep: remove papillary dermis and reach reticular dermis

The type and depth of peel is determined by the skin type and indication for the peel.

Indications

• Fine lines/superficial rhytids
• Photodamaged skin
• Dilated pores
• Superficial scars
• Dyschromias
• Melasma
• Lentigines
• Melanoses
• Freckles
• Postinflammatory hyperpigmentation
• Acne
• Epidermal growths
• Milia
• Actinic keratoses
• Seborrheic keratoses

Contraindications

• Relative
• Fitzpatrick skin types V and VI should avoid deeper peels due to risks of post-treatment hyperpigmentation
• Smoking cessation is recommended prior to any deep peel
• Recent facial cosmetic surgery may compromise blood supply to the skin and patients may need to wait 3 months prior to a deep peel
• Patients with history of cardiac arrhythmias and kidney dysfunction should avoid phenol peels due to absorption and potential cardiotoxicity
• Immunocompromised state, active connective tissue disorder or previous radiation treatment
• Pregnancy or breast feeding
• History of previous oral tretinoin treatment requires a recovery interval of 6 months prior to medium or deep chemical peels
• With recent neurotoxin or soft tissue filler treatment, a 1–2‑week interval prior to chemical peel may be advised
• A patient with unrealistic expectations regarding results of the procedure
• Absolute
• Open wounds of the face
• Active bacterial, viral or fungal skin infections
• Active inflammatory skin condition, such as atopic dermatitis or psoriasis.
• Use of medications with photosensitizing potential and risk of hyperpigmentation, e.g. tetracyclines, oral contraceptives, exogenous estrogen supplements
• History of keloid formation or hypertrophic scarring on the face
• A patient who may be noncompliant with post-procedure instructions or cannot avoid post procedure sun exposure

History

• Identify patient's concerns and expectations
• Smoking and other drug use
• History of keloid or hypertrophic scar formation
• Previous post-inflammatory hyperpigmentation (PIH)
• Previous radiation treatment
• Medication history
• Topical retinoids should be held for 3–5 days
• Oral retinoids should be discontinued 6 months prior to treatment and photosensitizing agents can be discontinued as per physician's discretion prior to treatment
• Steroids
• Medical History
• Herpes simplex virus (HSV) infections
• Cardiac arrhythmias
• Psychiatric disorders

Examination

• Assessment of
• Skin type by the Fitzpatrick skin type scale
• Type I: White, always burns, never tans
• Type II: White, usually burns, tans with difficulty
• Type III: White, sometimes burns, average tan
• Type IV: Brown, rarely burns, tans with ease
• Type V: Dark brown, almost never burns, tans very easily
• Type VI: Black, never burns, always darkens
• Severity of actinic damage using the Glogau photoaging classification scale
• Type I: Little or no evidence of photoaging, no wrinkles, mild pigment changes, 20–30 age group
• Type II: Early actinic changes, few wrinkles on animation, early senile lentigines, 30–40 age group
• Type III: More diffuse actinic keratoses with yellowing of skin, wrinkles at rest, dyschromias, wears makeup, 50–60 age group
• Type IV: Diffuse keratoses, history of skin cancers, with sallow skin, diffuse wrinkles and skin laxity, > 60 years of age
• Assessment of skin thickness and oiliness
• Thick, oily skin should be pretreated with topical retinoic acid for several weeks and be adequately defatted with acetone prior to application of peeling agent.
• Photographs of consistent and appropriate resolution and lighting to demonstrate skin textures and quality

Appropriate depth

• Determination of appropriate depth of treatment based on above evaluation
• Patients with lighter skin (Fitzpatrick types I–III) and advanced photoaging would benefit from deeper peels with minimal risk of abnormal pigmentation, whereas darker skin types (types IV–VI) are at higher risk of post-procedure hyper- or hypopigmentation.
• More superficial peels are best for patients with minimal photoaging and can be used on almost all skin types.
• Patients with Glogau III or IV aging will require medium or deep chemical peels to effect noticeable change. Medium to deep wrinkles do not respond significantly to superficial chemical peels.

• Laser skin resurfacing
• Fractionated
• Nonfractionated
• Intense pulsed light (IPL)
• Radiofrequency energy
• Neurotoxin injections
• Soft tissue fillers
• Autologous fat injections

Chemical peeling should be performed under the supervision of a physician as per regional guidelines and standards.

Classification of peels based on depth

• Very superficial: Remove the stratum corneum.
• Superficial peels: Extend from the epidermis to papillary dermis (0–0.45 mm).
• Trichloroacetic acid (TCA) 10–30%
• The depth of acid penetration is directly proportional to the concentration of acid.
• End point is frosting of the skin.
• No need to neutralize
• Jessner solution (resorcinol, salicylic acid, and lactic acid in ethanol)
• End point is a light frosting of the skin.
• Usually applied with soft applicator, but can be rubbed in with gauze in patients with thick, oily skin.
• Salicyclic acid 20–35%
• Beta-hydroxy acid peels
• Light pseudofrosting of skin as peel crystallizes
• Fat soluble, therefore useful in patients with acne
• Alpha hydroxy acid (AHA) 20–35%
• Glycolic acid peels
• Lactic acid peels
• Likely have both a metabolic and caustic effect
• Weak acids do not coagulate proteins, so little or no frosting is seen.
• Must be neutralized at specific time or based on patient comfort
• Medium-depth peels: papillary dermis to upper reticular dermis (0.45–0.6 mm)
• TCA 30–50%
• TCA 40%–50% is seldom used due to higher risk of scarring.
• Combination peels decrease risk of scarring
• Jessner's solution and TCA 35% can be used for medium depth peels and was popularized by Monheit.
• Glycolic acid 70% and TCA 35%
• Deep peels: mid-reticular dermis (0.6–0.8 mm)
• Baker-Gordon phenol peel (phenol 88%, distilled water, septisol soap, croton oil)
• Must be used only by experienced physicians
• Increased risks, but results most dramatic
• Phenol is cardiotoxic and can induce arrhythmias.
• Phenol can be painful and sedation is helpful.
• Cardiac monitoring during procedure
• Should be applied slowly with a full-face treated over a 60–90‑minute period
• Alternatively, different regions of the face can be treated over several sessions.
• Hypopigmentation is common.
• Phenol is not neutralized by water.

Equipment

• Chemical peeling agent
• Acetone
• Lubricating eye ointment
• Neutralizing agent if necessary
• 1% sodium bicarbonate solution
• Cold sterile water
• Cotton tipped applicators
• Cotton balls
• 4 x 4 gauze
• A handheld fan

Anesthesia

• Superficial- and medium-depth peels generally do not require anesthesia because the chemical solution acts as an anesthetic.
• A fan can be used to cool any mild stinging.
• Deep phenol peels can be uncomfortable and are often done under IV sedation or with topical anesthetics.

Technique

• Patient is supine with the head elevated.
• Hair is kept off the face with a head band and surgical head cover.
• Cotton is placed into each ear canal.
• Ointment is placed onto both eyes and over lips.
• Area around the region to be peeled is draped off with towels.
• The skin must be thoroughly cleansed to remove fats and oils with gauze soaked in acetone.
• The skin needs to be properly defatted for adequate penetration of the peeling agent because most agents are fat insoluble.
• Do not allow acetone to drip into the eyes.
• For AHA peels, care should be taken not to abrade the skin as this can reduce the effect of the peel, therefore acetone is carefully applied with cotton balls.
• The peeling agent is applied with 4 x 4 gauze, cotton tipped applicators, cotton balls, or foam applicators.
• Peeling agent is applied in a consistent manner to each cosmetic unit, usually starting with the forehead and working down.
• The chemical agent can be reapplied until an adequate and even frost is obtained or, in the case of AHA peels, the patient complains of discomfort.
• Additional "spot" treatments can be applied to problem areas of the skin.
• Once the proper depth of the peel appears to be achieved, the agent is neutralized by applying cold sterile water and wet, cool towels, or applying 1% sodium bicarbonate.

The depth of the peel corresponds to degree of complications. Patient selection and thorough preoperative assessment help to identify potential risks. Postoperative compliance improves clinical outcomes.

• Superficial irritation, edema and burning
• Allergic reaction
• Uneven peeling, desquamation, vesicles, erosions, ulcers
• Pigmentation: hyperpigmentation or hypopigmentation
• Hypopigmentation most commonly seen with medium-depth and deep peels
• Hyperpigmentation more common and can appear even after superficial peels
• Risk can be reduced by priming the skin with mild retinoic acid and hydroquinone creams 2–4 weeks prior to the procedure, especially in patients with Fitzpatrick type IV or higher skin.
• Once the skin has finished peeling, the patient can be restarted on the tretinoin/hydroquinone cream.
• Scarring
• Risk of scarring increases with the depth of the peel; e.g., phenol peel, > 50% TCA peel.
• Delay peel for 6–12 months after facial cosmetic surgery or after discontinuing isotretinoin (Accutane).
• Avoid medium and deep peels in patients with a history of keloids.
• Patients should be instructed not to pick or try to peel off healing skin.
• Infections should be treated aggressively.
• Infection
• Infections are rare, especially after more superficial peels.
• Peeling agents are generally bactericidal.
• Infections usually occur as a result of poor wound hygiene.
• If infection is suspected, cultures should be taken and the patient should be started on broad-spectrum antibiotics.
• Patients with a history of HSV outbreaks and all patients undergoing medium to deep peels should be given antiviral prophylaxis.
• Cutaneous candidiasis seen as pustules around the mouth can be treated with fluconazole after cultures are taken.
• Prolonged erythema
• Erythema after superficial peels generally resolves within 2 weeks.
• In medium-depth and deeper peels, skin erythema can last up to 3 months.
• If erythema is present longer than 2 weeks, suspect infection or contact hypersensitivity reaction.
• Prolonged erythema in the absence of infection can be treated with topical steroids or IPL treatments.
• Milia
• Small inclusion cysts
• Result from occlusion of pilosebaceous units in the skin by petrolatum ointments applied after the peel
• Usually appear 2–4 weeks after re-epithelialization
• Can be extracted using an 18‑g needle
• Cardiac arrhythmias with deep phenol peels
• Phenol at high enough blood levels can produce cardiac as well as liver and kidney toxicity.
• When phenol is applied to large areas of skin too quickly, it can produce cardiac arrhythmias.
• Cardiac monitoring and IV fluid administration is important during phenol-based peels.

• Follow-up is typically recommended at 3 days, 1 week, and 6 weeks following the procedure.
• Use a light petrolatum ointment over the treated area several times a day to keep the skin from becoming dry
• Cold white vinegar (acetic acid 0.25%) soaks can be used over the treated area 4 times a day as an antiseptic and to encourage peeling
• Petrolatum ointment should be reapplied after cool soaks until re-epithelialization is complete, usually within 5–7 days of the treatment
• Advise not to pick or manipulate peeling skin
• Avoid being around chemical or household cleaner fumes
• Avoid being in the sun throughout the healing process
• Start using sunscreen once re-epithelialization is complete
• Patients may resume makeup application 7–10 days following the procedure
• Can restart topical tretinoin 4–6 weeks after the peel

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