Our modern beautification techniques are reminiscent of these ancient techniques in that they rely on resurfacing techniques and peels to decrease scars, wrinkles, and other forms of photo- and chemical skin damage. Several natural and environmental causes of skin damage have prompted the innovation of beautification techniques. Ageing, photodamage, and chemicals result in wrinkles and scars; photodamage alters the structure and function of the skin via ultraviolet radiation. The overall thinning of the dermis is a result of both intrinsic factors—such as aging, which alters the skin’s collagen—and extrinsic factors such as cigarette smoke and ultraviolet rays. These extrinsic factors cause an increase in collagenase and gelatinization that hastens collagen degradation. Further, they cause an acute decrease incapillary and arteriolar blood flow in the skin, decreasing skin integrity, causing thinning and wrinkling. Skin is composed of three primary layers as shown in Fig 1: the epidermis, which serves as a barrier to infection; the dermis, which is a location for the appendages of the skin; and the hypodermis, which is the layer of subcutaneous adipose tissue.
The epidermis contains no blood vessels and is made up of keratinocytes with melanocytes and Langerhans’s cells. The epidermis is divided into the corneum, granulosum, spinosum, and basale. Cells are formed through mitosis at the basale layer, which regenerates and forms new skin every 12-14 days. The dermis consists of connective tissue and is connected to the epidermis via the basement membrane. It is divided into a papillary region (superficial) and a reticular region (deep). The papillary region has papillae that strengthen the connection between the epidermis and the dermis. The reticular region is much thicker and is composed of dense irregular connective tissue. The reticular region houses the roots of the hair, sebaceous gland, sweat glands, nerve receptors, nails, and blood vessels.
A chemical skin peel applies a variety or combination of acids to denature the protein framework of the skin, wounding the papillary/upper reticular dermis in a medium peel and the mid-reticular dermis in a deep peel. All peeling acids provide a means to exfoliate the outer layer of the skin, the most common acids being alpha-hydroxy acid and trichloroacetic acid (TCA). Alpha-hydroxy acid penetrates into the outermost layer of the skin and reduces cell adhesion to promote exfoliation. TCA is used in concentrations of 30-50% and is often combined with other wounding agents to increase penetration. For deeper peels, a phenol is often utilized—in the Baker-Gordon solution a phenol is combined with croton oil and Septisol.
Many of the products currently on the market are combination products designed to increase the concentration and penetration of the TCA while decreasing the scarring associated with concentrations greater than 50%.8 one common example is Gessner’s solution, a combination of 70% glycolic acid and solid carbon dioxide with 35% TCA.6 Moreover, it can be used prior to the 35% TCA to break the epidermal cells and allow for greater penetration of the TCA.6 Application of 70% glycolic acid prior has similar efficacy as Gessner’s solution.
The choice of acids and peeling treatment should consider the skin type; some types have a greater ability to withstand chemical damage, whereas others will exaggerate the damage based on poor barrier function or exaggerated inflammatory reactions. Fitzpatrick skin typing is a manner to characterize the skin type to decide candidates for skin peels. Skin typing is graded 1-6, where grades 1-3 are white skin and 4-6 progress to dark black skin. The best candidates for skin peels are 1-3 because they are less prone to scar and have pigment changes.
For all types of peels, postoperative edema, erythema, and desquamation are to be expected. The healing stages are inflammation, coagulation, re-epithelialization (day 3-14), and fibroplasia. For all procedures, the general healing time is 7-10 days and can be used for mild to moderate photoaging including pigmentary changes.
Light- and medium-depth chemical peels are used for patients with Glogau categories I, II, or III. The technique includes the three following main steps: cleansing the skin, applying TCA, and augmenting the healing process.
Cleansing the Skin. The skin is first cleansed with Septisol, a surfactant that decreases skin tension to allow for greater penetration and to remove oils. The second cleansing agent is an acetone, applied to debride oil and scale the surface of the skin. Finally, the physician applies Gessner’s solution to further increase the penetration of TCA.
Applying TCA. The peel itself is a 35% solution of TCA. The depth of the peel is based on the amount and percentage of the TCA solution. A white frost from the TCA application appears in the treated area within 30 seconds to 2 minutes. All TCA chemical peels are characterized by the colour of the skin (levels I-III) during the acid application, which corresponds to dermal penetration. During a light chemical peel, erythema with a blotchy frosting appears (level I). A medium-depth peel develops a white-coated frosting with surrounding erythema (level II). A deep peel discussed further below, penetrates the papillary dermis and is M characterized by solid white enamel frosting with little to no erythema (level III).
Augmenting the Healing Process. After applying TCA, cool saline compresses are applied to cool the skin and thereby decrease the inflammatory response. After treatment, the patient applies a mild emollient cream and 0.25% acetic acid soaks to further expedite healing.6 The patient should maintain regular follow-ups with the physician to
assess the healing and identify signs of infection.
Deep chemical peels entail either the use of TCA 50% or the Baker-Gordon phenol peel. Historically, physicians utilized the TCA 50% solution but now favour the Baker-Gordon phenol peel or combination treatments because the application of over 45% TCA is associated with scarring and infection.
The Baker-Gordon peel was first described in 1961 and since then has been widely successful. The peel includes the following components: phenol USP 88%: 5 mL 47%; distilled water: 4 mL 49%; croton oil: 3 gutta 1.2%; Septisol: 8 guttas, 2.6%. This peel requires sedation, an IV line for hydration, and an electrocardiogram for monitoring—its goal is to increase phenol absorption through the skin while decreasing the phenol concentration in the serum.6 The phenol is diluted to 50%, triggering keratolysis and keratocoagulation and increasing penetration. The treatment spans 60-90 minutes of constant IV hydration to dilute the serum phenol concentration. This peel has recently suffered a decline in usage, partly due to associated risks. First, the phenol component of the peel can be absorbed
systemically, resulting in cardiac abnormalities in up to 23% of patients. Phenol is directly toxic to the myocardium and can lead to ectopic beats such as premature atrial conduction (PACs), premature ventricular conduction (PVCs), or potentially life-threatening ventricular tachycardia. In a study by Landau in 2007, she looked at 181 patients treated with a full-face deep chemical peel. In 6.6% of the patients, cardiac arrhythmias including bigeminy and polytopic extrasystole were recorded during the procedure. Cardiac arrhythmias were more common in patients with diabetes, hypertension, and depression. Slow application of the peel with a pause of 10 to 15 minutes between each cosmetic unit and proper ventilation has decreased the incidence of cardiac abnormalities. Any patient with a history of cardio arrhythmia, a history of hepatic or renal compromise, or on medications for arrhythmia should not undergo the Baker-Gordon phenol peel. The setbacks of this technique prompted the advent of newer combination peels.