In an attempt to obtain more consistent results while giving the physician more control over the peel, variations of the TCA peel (Monheit’s Jessner-TCA peel, Coleman’s glycolic acid-TCA peel, Obagi’s blue peel) have been developed (Table 11.1). Anatomically, they are designed to peel through the papillary dermis and into the most superficial aspect of the reticular dermis (Obagi’s blue peel). Their main indications are for epidermal and upper dermal pathology: photodamage, actinic keratoses, lentigines, ephelides, fine rhytides, and very superficial, non-fibrotic scars. Deeper cutaneous abnormalities such as expression lines, deep furrows, or deep scars are not amenable to correction with these peels.

Table 11.1 Summary of modified TCA peel solutions

Modified TCA peels	Peel components	Speed of TCA peel
Jessner’s solution + TCA	Jessner’s solution^a Followed by the application of a light coat of 35% TCA	Stratum corneum is disrupted. Faster TCA penetration
Glycolic acid + TCA	70% glycolic acid Followed by the application of a light coat of 35% TCA	Stratum Corneum is disrupted. Faster TCA penetration
Obagi’s blue peel	Obagi’s blue peel base^b 2 mL Mixed with a specific volume of 30% TCA to achieve 15%, 20% or 25% TCA-blue peel	Stratum corneum is left intact and a lower concentration of TCA is used. TCA peel speed is slowed down

^a Jessner’s solution: 14% resorcinol, 14% salicylic acid and 14% lactic acid mixed in ethanol

^b Obagi’s blue peel base: non-ionic blue dye, glycerin, saponin

In an attempt to speed the penetration and depth of TCA peels, two modified peels were created which incorporate the use of a keratolytic agent. Monheit described a Jessner’s-TCA peel utilizing a keratolytic acid preparation, Jessner’s solution, applied prior to the application of TCA. Jessner’s solution is comprised of 14% each of resorcinol, salicylic acid, and lactic acid mixed in ethanol. Application of the Jessner’s solution allows for faster and deeper penetration of the subsequently applied 35% TCA. A similar mechanism is employed with Coleman’s glycolic acid-TCA peel, which uses 70% glycolic acid, also acting as a keratolytic, prior to application of 35% TCA.

The Obagi’s TCA blue peel is unique in that instead of increasing the speed and depth of the peel, the process is slowed down. This allows the physician better control of depth during the peel. The Obagi’s TCA-blue peel incorporates a non-ionic blue dye, glycerin, and a saponin with a specific volume of 30% TCA to yield a 15%, 20%, or higher percentage of TCA-blue peel solution. Traditionally, straight TCA is a colorless solution that requires close attention to avoid reapplication over previously treated areas. Part of the reason for incorporating a blue dye into the blue peel solution is to stain the stratum corneum thus helping the physician to visualize even application of the peel. The saponin is an emulsifying agent that creates a homogenous TCA-oil-water emulsion that penetrates the skin in a slower and more even fashion.

• Modified phenol peels

For the most part, phenol peels fall into the category of deep peels. In a fashion similar to TCA, phenol exerts its actions by protein denaturation and coagulation; however it quickly penetrates the skin to the level of the reticular dermis. Thus, phenol peels are typically ‘quick’ peels with little time for adjusting the peel depth. There are a number of phenol peel solutions used historically with the Baker-Gordon formulation being the most recognized. Most solutions have phenol, water, croton oil, and either Septisol (Steris Corp., Mentor, OH), or other oils such as sesame seed or olive oil.

The Baker-Gordon formula resulted in impressive clinical outcomes but was fraught with about one year of postoperative erythema followed by permanent hypopigmentation. There was also a substantial risk of scarring or textural change. This limited the use of this solution to older, very fair-skinned patients.

Both Stone and Hetter evaluated the role of the different components in the various phenol solutions and they both came to the conclusion that the croton oil concentration was the most important factor in predicting the depth of skin injury (Table 11.2). Croton oil is a very strong desiccant with cytotoxic properties even in minute concentrations. Croton oil is not water-soluble but is soluble in alcohol, benzene, ethyl acetate, and chloroform. Thus it is believed that phenol, which has a benzene ring in its structure, acts as a carrier for the croton oil.

Table 11.2 Summary of various phenol-croton oil peel solutions

Modified phenol peels	Phenol (%)	Croton oil (%)
Baker-Gordon	50	2.1
Fintsi	64	0.6–0.7
Stone-2	60	0.2
Stone V-K	62	0.16
Hetter	50	0.7
Hetter ‘all around’	35	0.4
Hetter neck/eyelid	30	0.1

Modified from: Rullan et al. 2004 The 2-Day Light Phenol Chemabrasion for Deep Wrinkles and Acne Scars: A Presentation of Face and Neck Peels. American Journal of Cosmetic Surgery 21:15–26

A few conclusions can be drawn about phenol peel solutions. Phenol solutions increase in depth penetration depending on the concentration of phenol (50–88%). Any amount of croton oil added to a phenol peel solution will increase the depth of penetration of the solution. The peel depth will increase as the amount of croton oil is increased. Multiple coats of phenol-croton oil solution will increase the depth of penetration. Taping the skin or occluding the skin with petrolatum-based ointments will increase the depth of penetration of the peel solution. Lastly, the depth of the peel can be judged clinically somewhat by the clinical signs popularized by Obagi.

Treatment Techniques

• Modified TCA peels and modified phenol peels

TCA and phenol peels are used to achieve a greater depth of penetration than glycolic or salicylic acid peels. Upon application, a burning sensation develops which peaks after several minutes before subsiding. To alleviate this discomfort, some physicians use electric fans or dynamic cooling units which blow cold air on the treated site. Sublingual diazepam may also be used, although patients who receive IM or IV sedation tolerate the procedure better and allow the peel to proceed at a faster speed. The authors currently use oral sedation with a combination of ibuprofen (400 mg), diazepam liquid (5–10 mg), hydroxyzine (50 mg), and meperidine (50–100 mg).

It is important to note that topical anesthetics, while useful in laser resurfacing procedures, should not be used prior to skin peels. Topical anesthetics can allow the peel solution to penetrate more greatly due to their ability to hydrate the skin. Local anesthesia, including nerve blocks, should be avoided, as it masks the ability to accurately ‘read’ the skin.

TCA and phenol create sequential changes in the skin that can be monitored intraoperatively to judge depth. These signs appear in all TCA peels, however they will appear more rapidly in skin that has been preconditioned or treated with a keratolytic agent, such as glycolic acid or Jessner’s solution. Additionally, these signs will appear more rapidly in phenol peels.

Since certain TCA peel modifications speed up TCA penetration, physicians less experienced with TCA peels are encouraged to start with relatively slower peeling techniques. Anatomic variations in skin thickness must also be considered when performing chemical peels to achieve uniform depth and to avoid complications from peeling too deeply in areas of thinner skin.

Frosting is the first sign to develop and represents coagulation of epidermal and dermal proteins. The frost is initially light and non-organized as epidermal proteins are coagulated. As TCA or phenol penetration proceeds into the papillary dermis, the frost becomes a thin but even layer with a pink background referred to as the ‘pink sign’. This sign indicates the blood vessels of the papillary dermis are still patent. The endpoint for the standard, papillary dermis level peel is the level in which the ‘pink sign’ is achieved along with a thin transparent, organized frost.

Continued application of acid will result in vasospasm of the capillary loops in the papillary dermis. Blood flow to the area will cease, and the pink sign will disappear. The frost will appear as a solid white sheet (absence of the ‘pink sign’; Fig. 11.1). This is the endpoint for a superficial reticular dermis peel. The loss of the ‘pink sign’ implies that the entire papillary dermis is involved and the upper reticular dermis has been reached but not penetrated. In darker-skinned individuals, the ‘pink sign’ may be difficult to visualized, thereby ‘epidermal sliding’ must be used instead to gauge depth.

Figure 11.1 Different levels of frost during a TCA peel. The cheeks show frost with the ‘pink sign’ while the periorbital skin shows a solid frost with absence of the ‘pink sign’

‘Epidermal sliding’ refers to the exaggerated wrinkling of the skin when it is pushed or pinched, occurring when papillary dermal edema formation disrupts the anchoring fibrils and allows the epidermis to move freely (Fig. 11.2). The ‘epidermal sliding’ sign indicates the peel has progressed through the epidermis and has entered the papillary dermis. As the papillary dermal proteins become coagulated and adhere to the epidermal coagulated proteins, the ‘epidermal sliding’ will disappear. Therefore, one must pay attention as this sign can be easily missed. As epidermal sliding disappears, so does the ‘pink sign’. In thick skin, ‘epidermal sliding’ may not be very obvious and the ‘pink sign’ must be used alone to determine depth. This sign is usually missed during phenol peels due to the quick nature by which they penetrate through the epidermis and into the dermis.

Figure 11.2 The ‘epidermal sliding’ sign. When slight tension is placed on the skin an exaggerated amount of wrinkling occurs. This indicates that the peel has entered the papillary dermis level but has not coagulated enough proteins for the epidermis to become adherent to the papillary dermis

Further application of TCA or phenol will penetrate the reticular dermis. We recommend caution with performing peels to this level. At this point the solid frost begins to take on a gray color. This is the maximum recommended depth for TCA peels. As with all resurfacing modalities that reach this depth, there is an increased incidence of scarring and hypopigmentation.

Intraoperative edema and protein coagulation give a firmer texture to the skin. This textural change can be appreciated upon pinching the skin, becoming more pronounced as the peel extends deeper. Since firmness is a sign of peel depth, usually into the dermis. Therefore it is not present in superficial peels. Detecting textural changes intraoperatively is an acquired skill. All physicians are urged to develop this skill by assessing skin firmness in each peel performed.

• Modified TCA Peels

• Modified phenol peels

Since cardiotoxicity is a dreaded complication of systemic phenol absorption, phenol-based peels are performed according to strict guidelines. Patients should be screened for hepatic, cardiac, or renal insufficiency. Perioperative monitoring of vital signs is recommended. An intravenous line is also used to deliver a steady and moderate flow of normal saline during the procedure so as to encourage excretion of the phenol.

It appears that percutaneous absorption of phenol is more related to the body surface area treated rather than the concentration used. For this reason, the face is usually divided into cosmetic units and the peel is performed on one unit at a time. A 15-minute break is taken prior to the treatment of the next cosmetic unit. Syringes filled with saline should be kept accessible to flush the eyes should the peel solution inadvertently enter the eye.

The face is degreased two or three times with alcohol or acetone. The solution is applied to the skin using cotton-tipped applicators. An immediate frost begins to develop and to become more solid as more solution is applied. This will be followed by reactive erythema and edema as the frost begins to dissipate. Unlike with TCA peels, phenol based solutions results in a rapid frosting and a fairly quick defrosting. For this reason, it is critical that the surgeon performing the peel monitors the progression of the peel depth signs closely.

It is important to keep ‘swirling’ the phenol solution prior to applying it since the croton oil will separate out from solution (Fig. 11.3). Once the entire cosmetic unit has been treated, deeper rhytids or scars can be retreated if needed to achieve a slightly deeper peel in this area. This can be done using the pointed end of a cotton tipped applicator stick that has been ‘snapped’ in half (Fig. 11.4).

Figure 11.3 Phenol croton oil solution and the cotton-tipped applicators (CTA) used to apply it to the skin. To keep the solution homogenized, one must ‘swirl’ the solution in the bowl prior to dipping the CTA in it

Figure 11.4 Use of the sharp end of a CTA that is snapped in half. This method is used to address focal deeper rhytids or acne scars

The patient will sense an immediate and strong burning sensation that quickly dissipates. However, within about 30 minutes the burning recurs and remains steady for about 4 to 6 hours. The patient may require prescription strength analgesics during the first 24 hours of the peel.

Complications of Skin Resufacing

Skin resurfacing risks and complications are identical whether they are from peels, lasers, or dermabrasion. Most of these complications such as hypertrophic scarring, prolonged erythema (over 3 months), and pigmentary changes are related to wound depth and not specifically to the modality used. Other complications, such as infections and contact dermatitis occur due to the impaired skin barrier function.

A good home hygiene regimen will help greatly reduce the risk of infection. This should minimize the need to use prophylactic antibiotics, which can alter the flora and favor the development of infection with less commonly seen bacteria Pseudomonas aeruginosa and other gram negative organisms. Usually infections are most commonly bacterial (Staphylococcus aureus) followed by yeast (Candida) or virus (Herpes simplex virus). Cultures and potassium hydroxide preps should be performed as indicated to identify the organism. The authors also advise patients not to ‘blow’ their noses for the 7 to 10 days it takes to heal from the peel. This alone has greatly reduced the number of staphylococcal infections seen.

While bacterial infections are the most commonly seen, viral infections can be the most devastating. Although the use of herpes prophylaxis has greatly decreased the incidence of viral infection, some patients can experience an outbreak even while on suppressive treatment. If a viral infection is suspected, patients should be treated with antiviral therapy dosed as if treating a herpes zoster infection (i.e., Valtrex 1 gram three times a day for 7 days).

Allergic contact dermatitis to the postoperative skin care agents is oftentimes a challenging diagnosis. Patients will usually complain of itching or burning of their skin along with increased redness. These patients usually show normal wound healing until the allergic reaction occurs but then begin to show a set back in wound healing. If an allergic contact dermatitis is still the most likely diagnosis, the patient should stop all offending agents, cleanse the skin with water and apply only white petrolatum to the skin. A topical mid-potency steroid ointment can be used as long as it does not contain propylene glycol.

Any procedure that reaches the reticular dermis can result in permanent hypopigmentation. While the color discrepancy may not be as apparent in lighter-skinned individuals, darker skinned patients are more likely to notice any color discrepancy.

Postinflammatory hyperpigmentation, although transient, can overshadow the results of resurfacing. Thus it is better to anticipate this and treat it before it manifests by having patients resume their skin reconditioning regimens once the wound has healed.

It is not unusual to see a flare of acne or rosacea postoperatively. Systemic antiinflammatory antibiotics can help resolve the flare before scarring occurs. Systemic antibiotics and topical anti-acne agents should be used in combination to quell the flare-up.

The most important harbinger of incipient scarring is erythema lasting more than 3 weeks. Prolonged erythema in general is seen commonly for several months following laser resurfacing, dermabrasion, and modified phenol peels. However, an area of persistent and ‘angry’ erythema is an ominous sign of impending scar formation. This is more likely to occur in areas treated to the level of the reticular dermis or in areas that were traumatized during the wound healing process. The treatment of this erythema consists of applying an ultrapotent topical steroid (betamethasone valerate, clobetasol, halobetasol, diflorasone) to the area two days out of each week for several weeks. Too much steroid use can have adverse effects therefore close patient monitoring is needed. Low-level flashlamp pulsed dye laser can be used for erythema that fails to respond to topical steroids. The goal with the pulsed dye lasers is to treat at subpurpuric doses but to treat frequently (every 2–4 weeks) until the erythema subsides.

Should scarring occur, one must intervene early and on a regular basis. Scars can take a variety of morphologies such as atrophic, hypertrophic, or keloid-like. Oftentimes they are preceded by an area that is pruritic, erythematous, has delayed healing, or skin thickening. Early detection and intervention is crucial. The area of impending scar formation should be treated with an ultrapotent topical steroid twice a day for 3 to 4 weeks. Care should be taken not to apply the steroid to normal skin as it may result in atrophy and telangiectasias. Intralesional steroid injections and manual massage should begin if the topical steroids fail to improve the scar. The thicker areas of the scar are injected at 2–4 week intervals with triamcinolone acetonide 1–10 mg/mL. The concentration used is based on scar thickness. Alternatively, a combination of triamcinolone acetonide and 5-fluorouracil can be used. Some scars respond to flashlamp pulsed dye laser treatment performed biweekly at a low to moderate setting.

Case Studies

• Case study 1

This case illustrates a healthy female patient in her late forties. She has light Caucasian skin with mild dyschromia, fine rhytides with heavier rhytides in the periorbital, glabellar, and perioral region (Fig. 11.5A). She underwent a full face 25% Obagi’s blue peel and a Hetter VL peel of the periorbital region, glabella, and focal perioral rhytides (Fig. 11.5B). At postoperative day 4 the patient shows edema and erythema. The areas treated with the phenol solution show crusting and more pronounced erythema. At one week (Fig. 11.5C) she is fully reepithelialized from the blue peel and is still healing from the Hetter VL peel. She is shown 3 months postoperatively (Fig. 11.5D) with nice firming of the skin, rhytid reduction, and a nice blending of the areas treated with the two different solutions.