Advances In Chemical Peeling
Gary D. Monheit, M.D.
Associate Professor
Department of Dermatology
University of Alabama at Birmingham
Birmingham, Alabama

The explosion of interest in chemical peeling by cosmetic surgeons and dermatologists has paralleled the general public interest in youthful appearance, photo aging skin and it's rehabilitation. A number of home treatment programs, cosmetic agents and over the counter chemicals have entered the general market to rejuvenate skin and erase the marks of sun damage and age. Though 90% of these products do little more than abrasive exfoliation and moisturization, the quest for youthful skin continues and the cosmetic surgeon remains at it's forefront.

Concurrent to the public's desire for rehabilitation of aging skin has been a new renaissance in chem-exfoliation. Just fifteen years ago, the name chemical peel was associated only with the deep phenol peel and heavy concentrations of trichloracetic acid. There was little understanding of the injury pattern created and its correlation with skin regrowth, potential side effects and complications. Objective analysis by Gordon-Baker, Litton and Kligman documented the histologic depth and injury pattern of the deep peel.1 With the pioneer work of Drs. Reznick and Ayres, a clinical and scientific background for the use of trichloracetic acid was begun.2 Histologic correlation of peel depth with varying concentrations of phenol and trichloracetic acid performed by Dr. Sam Stegman, serves as the scientific basis for our objective understanding of wounding depth and the efficacy of chemical peeling.3 A classification of peeling agents emphasizes depth penetration as a reflection of activity rather than chemical formulas. Thus, labeling a peel as superficial, medium, and deep depth is more meaningful than the chemical names phenol or trichloracetic acid. A new understanding of peel injury and repair has emerged, along with an appreciation of variations in patient skin type, pigmentation, and degree of photo aging. Utilizing the Fitzpatrick,(Table I) and the Glogau system (Table II) of pigmentation and sun damage, one can individualize the strength of chemical agents to match skin types.4 Wounding depth of each agent has been correlated with histology. Trichloracetic acid light and medium depth peeling has been quantitated with depth of injury, morbidity and degree of results. The risks of deep peeling with greater than 50% trichloracetic acid can be weighed against the patient's need and degree of photo damage.

A new emphasis has been placed on the medium depth peel, the combination peels and repeated lighter peeling regimens. Brody has pioneered the use of 35% trichloracetic acid with carbon dioxide freeze in selective areas.5 The physical and chemical agent used together produces a deeper peel than that found with 35% trichloracetic acid alone. Similarly, a combination of chemical agents, the Jessner - Trichloracetic acid peel has combined wounding agents to create an enhanced level of efficacy.6

This brings us to our present usage of peeling agents and the future of chem-exfoliation. The successful usage of the newer agents available depend upon the cosmetic surgeon's full understanding of photoaging skin and skin types. The photo types are taken into careful consideration in the choice of agents used to prepare the skin, to peel the skin, and for skin after care. The cosmetic surgeon can assess the degree of skin damage and choose the appropriate wounding agent to achieve realistic and desirable results for the patient. Mild photoaging damage may respond better to repeated light TCA peels or the alpha-hydroxy acid (AHA) peels. These should be performed in combination with retinoids, abrasives and sunscreen protection. For this type of patient, an ongoing program of daily skin care, multiple peels and protection against further photo aging is the full package necessary for skin rejuvenation. Physicians and patients must understand that repetitive superficial peels do not produce the same effects of deeper chemical peels as promised by many lay concerns.

Patients with moderate photoaging skin will achieve a more desirable result with a combination medium depth peel. The combination includes either the Jessner 35% trichloracetic acid peel or the CO2 freeze - 35% trichloracetic acid peel. Both of these combinations achieve more desirable results than 35% TCA alone. The combination enhances the depth of the peel to a moderate depth chemical peel (i.e. mid dermis).7 It's use for pigmentary dyschromia, fine rhytides, weathering of the skin and sallow texture, gives greater results than 35% trichloracetic acid alone. Other choices would include the use of plain phenol, or one of the new combination peels such as additive trichloracetic acid as per Drs. Fulton or Obagi.8

Severely damaged photo aged skin including perioral rhagades, deeper rhytides and textural changes require a deeper peel, and the Gordon-Baker phenol peel is my choice. The depth of this peel though, will produce hypopigmentation and a change in texture of the underlying skin in many patients. This is especially important in Fitzpatrick skin types III-VI, and those patients with sebaceous skin.

The cosmetic surgeon, thus, should be familiar with at least two or three chemical peeling agents so that he can use the appropriate tool for the patient's skin type and degree of photoaging.(Table III) It is impossible to be familiar with all the agents on the market, and I think it is best for the clinician to be proficient in a light, a medium depth and a deep peeling agent. My choices are:

1. Light chemical peel 15% to 30% trichloracetic acid, glycolic acid or Jessner's solution.
2. Medium depth chemical peel, Jessner's - 35% trichloracetic acid.
3. Deep chemical peel, Gordon - Baker phenol peel.

The chemical peel procedure itself is not an all or none phenomena, in that the steps taken in the procedure each add a variability to the depth of the peel. This allows the clinician to modify peel depth in patients, and even in regions of the face or neck. For example, a deeper injury may be necessary in the perioral area to improve skin texture and rhagades, while that may not be necessary on the cheeks and temples. The surgeon can choose a Baker-Gordon peel for the lip and Jessner's TCA 35% for the remainder of the face.

Several stages can be modified to enhance the efficacy of the peel: skin preparation, cleansing and degreasing the skin, application of an adjunct agent and application of active peeling agent.

1. Skin preparation. Prior to the peel, patients are begun on retinoic acid, sunscreen protection and moisturization. Retinoic acid increases peel penetration by it's ability to limit the thickness of the stratum corneum by changing the epidermal kinetics. This prepares the skin to respond to the peel injury with a brisk epidermal regeneration and more lasting changes in collagen synthesis. Patients with pigmentary problems and dyschromias begin using a hydroquinone bleach along with hydrocortisone and Retin A up to six weeks prior to the chemical peel.9 Hydroquinone blocks the tyrosinase enzyme in the creation of new melanin; consequently it will limit the production of new pigmentation and prevent repigmentation from occurring after the chemical peel. It's usefulness is enhanced by the retinoic acid and hydrocortisone (Table IV). Repeated epidermabrasion, the use of sunscreens, and other light chemical exfoliants all are helpful in preparing the skin for the chemical peel. It's effect will be to speed up epidermal regenerative kinetics and slow down pigment production.

2. Cleansing and degreasing. The degree of degreasing is a variable controlling the depth of peel. Vigorous removal of oils and debris in the dead skin layer increases the effectiveness of the peel by allowing greater penetration. The use of Ingasan (septisol) scrubbed with 4 x 4's followed by Acetone is repeated until the skin is totally degreased over the entire face. It is especially important for this degreasing to be uniform, as streaks of oil and stratum corneum left behind will produce a blotchy, irregular chemical peel.

3. Adjunct agent. In medium depth peels, the use of Jessner's solution or other chemical or physical adjuncts increase the depth of the trichloracetic acid to be applied later. The Jessner solution is applied evenly with 2 x 2's producing a light white frosting with erythema. Layering will increase the acid absorption by effectively removing the epidermis as a barrier. The amount of Jessner solution used, the evenness of application, and the degree of frosting and erythema are all quantitative variables in the depth of this peel. The use of CO2, methyl salicylate and tween-40 has also been used to enhance peel strength.

4. Application of trichloracetic acid. Both the percentage of trichloracetic acid and the amount applied are variable factors in the depth of the peel. The TCA concentration I prefer is 35%. Instead of using higher concentrations to increase the depth of penetration, I will apply additional layers of 35% TCA since the depth of injury is increased with each application. One can layer a greater quantity of acid in facial areas with more severe photo aging and less over those areas with a greater risk to scarring, such as the lateral cheeks and jawline. An even white frosting is the end point for the chemical peel. I can more precisely control my peel depth by re-applying the medium concentration, rather than using higher concentrations of this acid.

The Jessner - trichloracetic peel will produce excellent results for moderate photo aged skin. However, deeper rhagades and rhytides in the perioral area, in the periorbital area and glabella, show limited response to this level of chemical peeling. For those patients with moderate photo aging on the cheeks and forehead and more severe aging skin in the periorbital area, a combination chemical peel may be the answer. The author has used the Baker's phenol peel in the periorbital, the perioral and glabellar area while using the Jessner 35% trichloracetic acid peel over the rest of the face. This combination has a distinct advantage in that the clinician has specifically chosen the peel solution to be used for each of these facial areas, and thus will not be over-treating the entire face with a deep chemical peel. He can thus limit the morbidity and complications of the deep chemical peel and simplify the procedure. Because the deep agent is only used on limited portions of the face, the patient would not need IV fluid loading and the necessary monitoring required for a full face phenol peel.10 The medium depth peel used over the rest of the face will blend since deep peels result in hypopigmentation and/or textural changes. The patient will have a softer, more even result when a medium depth peel is on the rest of the face to achieve "blending". Combining individual agents in distinctive areas in our patients provides the surgeon with more precise tools to treat the many faces of aging skin.

This brings us to the horizon of chem exfoliation, and I feel the future will offer us a greater understanding in the nature of photo damage and it's early correction. Programs of skin care will be more common and patients will be treated with ongoing protocols to continuely reverse the factors and environmental wear and tear of aging. These will include repeated peelings, as well as using topical pharmacologic agents, home exfoliants, and sunscreen protection. The physician will remain in the forefront in the field of cosmetic pharmacology and surgery. He must function as a guide to his patients who are barraged daily with promises from proprietary companies, cosmetic counters and salons. He must dispel the promised miracles and discuss the benefits of skin care realistically and objectively. This is an exciting time for the cosmetic surgeon to explore the new tools and techniques of chemical peeling.

FITZPATRICK'S CLASSIFICATION OF SKIN TYPES

Skin Type Color Reaction to Sun

I. Very white or freckled Always burns
II. White Usually burns
III. White to olive Sometimes burns
IV. Brown Rarely burns
V. Dark brown Very rarely burns
VI. Black Never burns

TABLE II

PHOTO AGING GROUP - GLOGAU'S CLASSIFICATION

I. Group I Mild (typically age 28-35)
A. Little wrinkling or scarring
B. No keratoses
C. Requires little or no make-up

II. Moderate (age 35-50)
A. Early wrinkling; mild scarring
B. Sallow color with early actinic keratoses
C. Little make-up

III. Advanced (age 50-65)
A. Persistent wrinkling or moderate acne scarring
B. Discoloration with telangiectasias and actinic keratoses
C. Wears make-up always

IV. Severe (age 60-75)
A. Wrinkling: photo aging, gravitational and dynamic
B. Actinic keratoses with or without skin cancer or
severe acne scars
C. Wears make-up with poor coverage

TABLE III

I. Superficial Chemical Peel

Agent Ingredients Indications

CO2 slash or liquid Physical agent Comedonal or nodular
nitrogen spray acne

Alpha-hydroxy acids Glycolic or lactic acid Comedonal and
5 to 30% inflammatory acid,
mild photo aging

Trichloracetic acid Aqueous dilutions of Mild photo aging and
10 to 30% trichloracetic acid comedonal acne

Jessner's solution Resorcinol, salicylic Acne peel
acid, lactic acid

Tretinoin .01% to .1% cream or Comedonal acne,
gel, tretinoin photo aging

II. Medium Depth Peel

Agent Ingredients Indications

Trichloracetic acid 45% Aqueous trichloracetic acid Moderate photo aging
skin

CO2 + 35% trichloracetic Aqueous trichloracetic acid Moderate photo aging
acid skin

Jessner's solution + Aqueous trichloracetic acid Moderate photo aging
35% trichloracetic acid skin

89% Phenol solution, Moderate to severe
aqueous photo aging skin

Alpha-hydroxy acids Pyruvic acid - 50% in ethanol Moderate photo aging
skin


"Hot rod" peel (Fulton) 35% trichloracetic acid, Moderate photo aging
5 to 10% methyl salicylate, skin
1% polysorbate 20

Obagi peel Trichloracetic acid with Moderate photo aging
"unknown additives" skin

III. Deep Chemical Peel

Agent Ingredients Indications

Baker's formula peel Phenol 88% with water, Severe photo aging
septisol and crotin oil skin

Trichloracetic acid Aqueous trichloracetic acid Severe photo aging
greater than 50% skin