Medium Depth Chemical Peels
Gary D. Monheit, M.D.
Associate Professor
Department of Dermatology
University of Alabama at Birmingham
Birmingham, Alabama

Synopsis
Medium Depth Chemical Peeling
Gary D. Monheit, M.D.

The combination medium depth chemical peel – Jessner’s solution + 35% TCA, has been accepted as a safe, reliable and effective method for the treatment of moderate photoaging skin.

Chemical peeling involves the application of a chemical exfoliant to wound the epidermis and dermis for the removal of superficial lesions and improve the texture of skin. Various acidic and- basic chemical agents are used to produce the varying effects of light to medium to deep chemical peels through differences in their ability to destroy skin. The level of penetration, the nature of destruction and the inflammatory response determines the level of the peel. The stimulation of epidermal growth through the removal of the stratum corneum without necrosis consists of light superficial peel. Through exfoliation, it thickens the epidermis with qualitative regenerative changes. Destruction of the epidermis defines a full superficial chemical peel inducing the regeneration of the epidermis. Further destruction of the epidermis and induction of inflammation within the papillary dermis constitutes a medium-depth peel. Then, further inflammatory response in the deeper reticular dermis induces new collagen production and ground substances which constitutes a deep chemical peel.1 These have now been well classified and usage has been categorized for various degenerative conditions associated with photoaging skin based on levels of penetration. The physician, thus, has tools capable of solving photoaging skin problems that may be mild, moderate or severe with agents that are very superficial, superficial, medium-depth, and deep peeling chemicals. The physician must choose the right agent for each patient and condition.

Medium depth peeling is thus defined as the use of a chemical agent to wound skin through papillary dermis. It is most useful for the removal of epidermal or superficial lesions and to improve skin texture in moderate photodamaged skin (grade II Glogau photoaging skin)2. Medium depth peeling agents create changes through necrosis of the epidermis and part or all of the papillary dermis with an inflammatory reaction in the upper reticular dermis. The procedure is performed to remove actinic keratoses, mild photoaging of the skin including rhytides, treat pigmentary dyschromias, and improve depressed scars.3 (Table I)
Trichloracetic acid has been the gold standard in quantitating chemical peel strength and depth. Ten to 30% has been quantitated as superficial wounding while above 50% is deep chemical peeling. The level, 35-50% trichloracetic acid is the spectrum of medium depth peeling. It is standard to think of 45 or 50% trichloracetic acid corresponding to a wounding level of mid to deep reticular dermis. This concentration of trichloracetic acid, though, has been found unreliable and associated with a higher incidence of pigmentary dyschromia, textural change, and even scarring.4 In an attempt to reduce the morbidity of higher concentration trichloracetic acid, a combination of products have been devised that improve the absorption of the lower concentration of trichloracetic acid without the associated complications.5 The combination peels include:
1. Solid carbon dioxide freezing with trichloracetic
acid 35%.
2. Jessner's solution + 35% trichloracetic acid.
3. Glycolic acid 70% plus 35% trichloracetic acid.
The combinations produce a more even peel with deeper penetration of the wounding agent without the associated complications of higher concentration trichloracetic acid. This chapter will review the scope of medium depth peeling, the patients and conditions most commonly treated, the techniques of application, wound healing, and complications.

Trichloracetic Acid
Trichloracetic acid has become the gold standard of chemical peeling agents for its long history of usage, its versatility in peeling, and its chemical stability. It has been useful in many concentrations because it has no systemic toxicity and can be used to create superficial, medium or even deep wounds in the skin. Trichloracetic acid is naturally found in crystalline form and is mixed weight-by-volume with distilled water. It is not light sensitive, does not need refrigeration and is stable on the shelf for over six months. The standard concentrations of trichloracetic acid should be mixed weight-by-volume to accurately assess the concentration. That is, 30 gm. trichloracetic acid crystals mixed with 100 cc. distilled water will give an accurate 30% concentration, weight by volume. Any other dilutional system - volume dilutions and weight by weight, are inaccurate in that they do not reflect the accepted weight by volume measurements.

Since TCA itself is an agent more likely to be fraught with complications, especially scarring, in strengths of 50% or higher, the higher concentration has fallen out of favor.6 It is for this reason that the combination products along with a 35% TCA formula have been found equally effective in producing this level of control damage without the risk of side effects.

Brody first developed the use of solid CO2 applied with acetone to the skin as a freezing technique prior to the application of 35% trichloroacetic acid. The preliminary freezing appears to break the epidermal barrier for a more even and complete penetration of the 35% trichloroacetic acid.7

Monheit then demonstrated the use of Jessner’s solution prior to the application of 35% trichloroacetic acid. The Jessner’s solution was found effective in destroying the epidermal barrier by breaking up individual epidermal cells. This also allows a deeper penetration of the 35% TCA and a more even application of the peeling solution.8 Similarly, Coleman has demonstrated the use of 70% glycolic acid prior to the application of 35 % trichloroacetic acid. Its effect has been very similar to that of Jessner’s solution.9 (Table II)

All three combinations have proven to be as effective as the use of 50% trichloroacetic acid with a greater safety margin. The application of acid and resultant frosting are better controlled with the combination so that the “hot spots” with higher concentrations of TCA can be controlled, creating an even peel with less incidence of dyschromias and scarring. The combination peel produces an even, uniform peel. The Monheit version of the Jessner’s solution – 35% TCA peel is a relatively simple and safe combination. The technique is used for mild-to-moderate photoaging including pigmentary changes, lentigines, epidermal growths, dyschromias, and rhytids. It is a single procedure with a healing time of seven to ten days. It is useful also to remove diffuse actinic keratoses as an alternative to chemical exfoliation with topical 5-fluorouracil chemotherapy. Topical chemotherapy is applied for three weeks creating erythema, scabs and crusts for up to six weeks.10 The combination peel will produce similar therapeutic benefits within ten days of healing. It thus reduces the morbidity significantly and gives the cosmetic benefits of improved photoaging skin.

Skin preparation is of vital importance to encourage correct healing and avoid complications. Agents used prior to the peel to prepare the skin correctly include:11 (Table III)
1. Sunscreen
2. Exfoliations - abrasive cleansers, 5-10% glycolic
acid lotion
3. Tretinoin .05% used six weeks to three months prior
to the peel
4. Bleaching products - hydroquinone 4-8% used in patients
with pigmentary dyschromias and those with type III-VI
Fitzpatrick skin pigmentation.
5. Anti-viral agents in selected patients with history of
facial HSV I infections.

The procedure is usually performed with mild preoperative sedation and nonsteroidal antiiflammatory agents. The patient is told that the peeling agent will sting and burn temporarily
and aspirin is given before the peel and continued through the first twenty-four hours if the patient can tolerate the medication. Its inflammatory effect is especially helpful in reducing swelling and relieving pain. If given before surgery, it may be all the patient requires during the postoperative phase. For full-face peels, though, it is useful to give preoperative sedation (diazepam 5 to 10 mg orally) and mild analgesia, meperidine 25 to 50 mg (Demerol – Winthrop, New York), and hydroxyzine hydrochloride 25 mg intramuscularly (Vistaril – Lorec, New York). The discomfort from this peel is not long lasting, so short acting sedatives and analgesics are all that are necessary.12

Vigorous cleaning and degreasing is necessary for even penetration of the solution. The face is scrubbed gently with Ingasam (Septisol - Vestal Laboratories, St. Louis, Missouri) four-inch by four-inch gauze pads and water, then rinsed and dried. Next, an acetone preparation is applied to remove residual oils and debris. The skin is essentially debrided of stratum corneum and excessive scale. A thorough degreasing is necessary for an even penetrant peel. The physician should feel the dry, clean skin to check the thoroughness of degreasing. If oil is felt, degreasing should be repeated. A splotchy peel is usually the result of uneven penetration of peel solution due to residual oil or stratum corneum, and a result of inadequate degreasing.

After thorough cleaning, the Jessner’s solution is applied with either cotton-tip applicators or 2” x 2” gauze. (Table V) The Jessner’s solution is applied evenly with usually one or two coats to achieve a light but even frosting. The frosting achieved with Jessner’s solution is much lighter than that produced by TCA and the patient is usually comfortable, feeling only heat. A mild erythema appears with a faint tinge of splotchy frosting over the face. Even strokes are used to apply the solution to the unit area covering the forehead to the cheeks to the nose and chin. The eyelids are treated last creating the same erythema with blotchy frosting. (Fig 1). The application of Jessner’s solution alone is equal to a superficial or light chemical peel.13

After the Jessner’s solution has dried, the TCA is applied. The TCA is painted evenly with one to four cotton-tipped applicators that can be applied over different areas with light or heavier doses of the acid. Four cotton-tipped applicators are applied in broad strokes over the forehead and also on the medial cheeks. Two mildly soaked cotton-tipped applicators can be used across the lips and chin, and one damp cotton-tipped applicator on the eyelids. Thus, the dosage of application is technique dependent on the amount used and the number of cotton-tipped applicators applied. The cotton-tipped applicator is useful in quantitating the amount of peel solution to be applied. Care must be taken to ensure the acid is not dripped inadvertently over unwanted areas such as neck or eyes.

The white frost from the TCA application appears complete on the treated area within 30 seconds to 2 minutes. Even application should eliminate the need to go over areas a second or a third time, but if frosting is incomplete or uneven, the solution should be reapplied. Thirty-five percent TCA takes longer to frost than Baker’s formula or straight phenol, but a shorter period of time than the superficial peeling agents do. The surgeon should wait at least 3 to 4 minutes after the application of TCA to ensure the frosting has reached its peak. He then can document the completeness of a frosted cosmetic unit and touch up the area as needed. Areas of poor frosting should be retreated carefully with a thin application of TCA. The physician should achieve a level II to level III frosting. Level I frosting is erythema with a stringy or blotchy frosting, seen with light chemical peels. Level II frosting is defined as white-coated frosting with erythema showing through. A level III frosting, which is associated with penetration through the papillary dermis, is a solid white enamel frosting with little or no background of erythema.14 A deeper level III frosting should be restricted only to areas of heavy actinic damage and thicker skin. Most medium-depth chemical peels use a level II frosting and this is especially true over eyelids and areas of sensitive skin. Those areas with a greater tendency to scar formation, such as the zygomatic arch, the bony prominences of the jawline, and chin, should only receive up to a level II frosting. Overcoating trichloroacetic acid will increase its penetration so that a second or third application will drive the acid further into the dermis, creating a deeper peel. One must be careful in overcoating only areas in which the take up was not adequate or the skin is much thicker. (Fig 2)

Anatomic areas of the face are peeled sequentially from forehead to temple to cheeks and finally to the lips and eyelids. The white frosting indicates keratocoagulation or protein denaturation of keratin and at that point the reaction is complete. Careful feathering of the solution into the hairline and around the rim of the jaw and brow conceals the line demarcation between peeled and non-peeled skin. The perioral area has rhytids that require a complete and even application of solution over the lip skin to the vermilion. This is accomplished best with the help of an assistant who stretches and fixates the upper and lower lips while the peel solution is applied.

Certain areas and skin lesions require special attention. Thicker keratoses do not frost evenly and thus do not pick up peel solution. Additional applications rubbed vigorously into the lesion may be needed for peel solution penetration. Wrinkled skin should be stretched to allow an even coating of solution into the folds and troughs. Oral rhytides require peel solution to be applied with the wood portion of a cotton-tipped applicator and extended into the vermilion of the lip. Deeper furrows such as expression lines will not be eradicated by peel solution and thus should be treated like the remaining skin.

Eyelid skin must be treated delicately and carefully. A semidry applicator should be used to carry the solution within 2 to 3 mm of the lid margin. The patient should be positioned with the head elevated at 30 degrees and the eyelids closed. Excess peel solution on the cotton tip should be drained gently on the bottom before application. The applicator is then rolled gently on the lids and periorbital skin. Never leave excess peel solution on the lids because the solution can roll into the eyes. Dry the tears with a cotton-tipped applicator during peeling because they may pull peel solution to the puncta and eye by capillary attraction. (Fig 3) The solution should be diluted immediately with cool saline compresses at the conclusion of the peel. The Jessner’s-TCA peel procedure is as follows:
1. The skin should be cleaned thoroughly with Septisol to remove oils.
2. Acetone or acetone alcohol is used to further debride oil and scale from the surface of the skin.
3. Jessner’s solution is applied.
4. Thirty-five percent TCA is applied until a light frost appears.
5. Cool saline compresses are applied to dilute the solution.
6. The peel will heal with 0.25% acetic acid soaks and a mild emollient cream.
There is an immediate burning sensation as the peel solution is applied, but this subsides as frosting is completed. Cool saline compresses offer symptomatic relief for a peeled area as the solution is applied to other areas. The peel reaction is not neutralized by saline solution as the reaction is completed when frosting occurs.15 The compresses are placed over the face for 5 to 6 minutes after the peel until the patient is comfortable. The burning subsides fully by the time the patient is ready to be discharged. At that time, most of the frosting has faded and a brawny desquamation is beginning.

Postoperatively, edema, erythema, and desquamation are expected. With periorbital peels and even forehead peels, eyelid edema can occur and may be enough to close the lids. For the first 24 hours, the patient is instructed to soak four times a day with a 0.25% acetic acid compress made of 1 tablespoon white vinegar in 1 pint of warm water. A bland emollient is applied to the desquamating areas after soaks. After 24 hours, the patient can shower and clean gently with a mild nondetergent cleanser. The erythema intensifies as desquamation becomes complete within 4 to 5 days. Thus, healing is completed within 1 week to 10 days. At the end of 1 week, the bright red color has faded to pink and has the appearance of a sunburn. This can be covered by cosmetics and will fade fully within 2 to 3 weeks.

The medium-depth peel is dependent on three components for therapeutic effect: (1) degreasing, (2) Jessner’s solution, and (3) 35% TCA. The amount of each agent applied creates the intensity and thus the effectiveness of this peel. The variables can be adjusted according to the patient’s skin type and the areas of the face being treated. It is thus the workhorse of peeling and resurfacing in my practice as it can be individuated for most patients we see.

The medium-depth chemical peel thus has five major indications: (1) destruction of epidermal lesions – actinic keratoses, (2) resurfacing the level II or III moderate photoaging skin, (3) pigmentary dyschromias, (4) mild acne scars, (5) blending photoaging skin with laser resurfacing and deep chemical peeling.

1. Actinic keratoses – This procedure is well suited for the patient with epidermal lesions such as actinic keratoses which has required repeated removal with either cryosurgery or chemoexfoliation (5-fluoruracil). The entire face can be treated as a unit or subfacial cosmetic unit such as forehead, temples, and cheeks, and can be treated independently. Active lesions can be removed, as well as incipient growths as yet undetected, will be removed as the epidermis is sloughed. Advantages for the patient with photodamaged skin include a limited recovery period – 7 to 10 days, with little post operative erythema after healing.16 There is little risk of pigmentary changes either hypopigmentation or hyperpigmentation, thus, the patient can return to work after the skin has healed.(Fig 4)
2. Moderate photoaging skin – Glogau level II or III damage responds well to this peeling combination with removal of the epidermal lesions and dermal changes that will freshen photoaging characterized as sallow, atrophic skin with fine rhytides. This peel is favored over deeper resurfacing procedures such as CO2 laser and deep peel in that it will heal in ten days with minimal risk of textural or color complications. It, though, is only designed for medium-depth damage. (Fig 5)
3. Pigmentary dyschromias - Though color change can be treated with repetitive chemical peeling, the medium-depth peel will be a single treatment preceded and followed by the use of bleaching agents and retinoic acid.17 In most cases, the pigmentary problems are resolved with this single peel as an adjunct to the skin care program.
4. Blending other resurfacing procedures – In a patient in which there is advanced photoaging changes such as crow’s feet and rhytides in the periorbital and/or perioral area with medium-depth changes on the remaining face, a medium-depth peel can be used to integrate these procedures together. That is, laser resurfacing or deep chemical peeling can be performed over the periorbital and perioral areas that has more advanced photoaging changes, while the medium-depth chemical peel is used for the rest of the face. This will blend the facial skin as a unit so that the textural and color changes will not be restricted to one area. The patients requiring laser resurfacing in a localized cosmetic unit will have the remaining areas of their face blended with this medium-depth chemical peel. Patients having laser resurfacing or deep peeling to the perioral or periorbital areas alone develop a pseudo hypopigmentation that is a noticeable deformity. The patient requiring laser resurfacing at a localized cosmetic unit will have the remaining areas of their face blended with this medium-depth peel. The alternative – a full-face deep peel or laser resurfacing has an increased morbidity, longer healing and risk of scarring over areas such as the lateral jaw line, malar eminences, and forehead. If deep resurfacing is needed only over localized areas such as perioral or periorbital face, a blending medium-depth peel does reduce morbidity and healing time.18 (Fig 6)

Results
This medium depth peel will produce superior results for the conditions listed.(Table III) Removal of actinic keratoses, both present and incipient, affords the patient a single procedure with healing time within one week to ten days, as a preventive therapeutic modality for the removal of precancerous growths over the face.(Fig 4) A comparison study of the efficacy of Jessner's solution plus 35% trichloracetic acid with 5-Fluorouracil documented superior effectiveness of this single procedure with a significant reduction in morbidity.19 It is, thus, an effective, safe and simple single procedure that can be used to remove actinic keratoses and epidermal growths as both a therapeutic and cosmetic procedure.

Glogau grade II photoaging skin can be effectively treated for improvement in both texture, color change, and epidermal growths with a medium depth Jessner's - TCA peel. Of equal importance to the procedure is choosing the correct patient for the procedure. Patients with superficial textural changes and those with epidermal growths seem to respond best to this peel. Fine wrinkles, cross-hatched lines, sallow color changes of photoaging along with the crinkly appearance are the textural changes that will respond to this peel. Additionally, epidermal growths such as freckles, lentigenes, actinic keratoses, and seborrheic keratoses will also respond well.(Fig 5) The more advanced changes seen with deeper grooves and wrinkles, pebbly appearance of the skin and more pronounced gravitational changes of Glogau III and IV photoaging skin require either deep chemical peeling or laser resurfacing. Using trichloracetic acid or any of its combinations as a deep chemical peel for these more advanced indications will only risk potential side effects and complications.

Pigmentary dyschromias such as melasma, blotchy hyperpigmentation, and pigmentary growths do respond well to medium depth chemical peeling. This is especially suited for those problems which have not resolved well with medical treatment or repeated light chemical peeling. Epidermal pigment seems to respond the best and this can be identified with Wood's light examination. Dermal pigment will show some response but not as effective as epidermal pigment. This combination peel is effective in that it will fully remove the epidermis as well as have an effect on melanocytes in the pilar apparatus during reepithelialization. It is important that these patients be prepared correctly with 4-8% hydroquinone, tretinoin and sunscreen begun at least six weeks prior to the peeling procedure. The bleaching agent is reinstituted after reepithelialization and tretinoin six weeks later. It should be continued for up to three months after the chemical peel and sunscreen used for longer period of time to insure the dyschromia does not return. There are many bleaching agents on the market today which have some lightening effect, but hydroquinone is the most effective.

When localized areas of the face have advanced or severe photoaging such as deeper wrinkles around the eyelids and rhagades on the lips, the combination Jessner's trichloracetic acid peel can be used to blend the remaining areas of the face if they have only moderate photoaging of the skin. Thus, eyelids and lips can be resurfaced with a pulsed carbon dioxide laser and the remainder of the face treated with the Jessner's - trichloracetic acid peel. In this instance, the peel should be performed first in the manner described above and then appropriate anesthesia, eye protection and preparation be used to laser the designated areas. Healing will occur in the usual manner for either laser or peel with soaks and occlusive ointments. This is an effective method of reducing morbidity with deeper agents to areas that don't need them. It will also blend the photoaging skin, texture, color and appearance to that of the laser treated skin.(Fig 6)

Post-Operative Care and Complications
The four stages of wound healing are apparent after a medium depth chemical peel.20 They include:
1. Inflammation
2. Coagulation
3. Reepithelialization
4. Fibroplasia

At the conclusion of the chemical peel, the inflammatory phase has already begun with a brawny, dusky erythema that will progress over the first twelve hours. With the medium depth peels, the epidermis will begin to separate, creating a leathery, dry, cracking appearance to the epidermis. This is an accentuation of pigmented lesions on the skin as the coagulation phase separates the epidermis, producing serum exudation, crusting and pyoderma. It is during this phase that it is important to use debrident soaks and compresses as well as occlusive salves. These will remove the sloughed necrotic epidermis and prevent the serum exudate from hardening as crust and scab. I prefer the use of 1/4% acetic acid soaks found in the vinegar water preparation (one teaspoon white vinegar, one pint warm water), as it is antibacterial, especially against pseudomonas and gram negatives. In addition, the mildly acidic nature of the solution is physiologic for the healing granulation tissue, mildly debrident, as it will dissolve and cleanse the necrotic material and serum. Occlusive dressings including bland emollients and salves and biosynthetic membranes. For medium depth peeling, I prefer the occlusive salves as these can be monitored carefully day by day for potential complications.

Reepithelialization begins on day three and continues until day seven to ten. Occlusive salves promote faster reepithelialization and less tendency of delayed healing.21 The final stage of fibroplasia continues well beyond the initial closure of the peeled wound and continues with neoangiogenesis and new collagen formation for three or four months. Prolonged erythema may last two to four months in unusual cases of sensitive skin or with contact dermatitis. New collagen formation can continue to improve texture and rhytides for a period up to four months during this last phase of fibroplasia.

Many of the complications seen in peeling can be recognized early on during healing stages. The cosmetic surgeon should be well acquainted with the normal appearance of a healing wound in its time frame for medium depth peeling. Prolongation of the granulation tissue phase beyond one week may indicate delayed wound healing. This could be the result of viral, bacterial or fungal infection, contact irritants interfering with wound healing, or other systemic factors. A red flag should alert the physician that careful investigation and prompt treatment should be instituted to forestall potential irreparable damage that may result in scarring. Thus, it is vitally important to understand the stages of wound healing in reference to medium depth peeling. The physician then can avoid, recognize and treat any and all complications early on. Specific complications will be discussed in the appropriate chapter.

Longterm care of peeled skin would include sunscreen protection for up to six months along with reinstitution of medical treatment such as low strength hydroxy acid lotions and tretinoin. Re-peeling areas should not be performed for six months from the previous peel. If any erythema or edema persists, the peel should not be performed as the re-injury may create complications. This peel should not be performed on undermined skin such as facelift or flap surgery performed up to six months prior to the peel.22

The evolution of medium depth chemical peeling has changed the face of cosmetic surgery. It has introduced new techniques into the armamateria of the cosmetic surgeon to treat problems that previous have been approached with tools inadequate to obtain the results for moderate photoaging skin or with overly-aggressive treatment using deep peeling agents. The combination peels have provided some of the more popular tools needed to approach a burgeoning population with photoaging skin.