Chemical Peels
Introduction
Since the days of
ancient Egypt, people have been using chemoexfoliation methods, also known
as chemical peeling, to rejuvenate skin. The original chemoexfoliant was
lactic acid, an active ingredient of sour milk that was used topically by
the nobles as part of an ancient skin rejuvenation regimen. In the Middle
Ages, old wine with tartaric acid as its active ingredient was used for
the same purpose. Today, these historical chemoexfoliants are known to
contain alpha hydroxy acids, which are the active ingredients responsible
for the skin exfoliation.
The chemical peel produces a controlled partial thickness injury to the skin. Following the insult to the skin, a wound healing process ensues that can regenerate epidermis from surrounding epithelium and adnexal structures, decrease solar elastosis, and replace and reorient the new dermal connective tissue. The result is an improved clinical appearance of the skin, with fewer rhytides and decreased pigmentary dyschromia.
Modern day chemical peeling originally was promoted by dermatologists, such as P.G. Unna, who first described the properties of salicylic acid, resorcinol, phenol, and trichloroacetic acid (TCA). Slowly, the early practitioners of chemical peels began to develop other peeling agents for varying depths of penetration. In the 1960s, Baker and Gordon developed a deep peeling agent, which was able to smooth deeper furrows, especially around the mouth. From the 1980s to the present, an explosion has occurred in the mass of research on this subject, with the elucidation of many different types of peels, each for a specific range of problems.
STAGES OF WOUND HEALING AFTER
CHEMOEXFOLIATION Clotting factors are activated, as are monophages and lymphocytes.
Inflammatory mediators are activated, such as C5a, leukotriene B4, and
kallikrein.
Reepithelialization
Preventing scab formation is important for faster and more even
healing. Biosynthetic occlusive dressings can be used to hasten the
healing process.
Granulation tissue
Granulation tissue usually appears the second day and consists of
fibroblasts, inflammatory cells, fibronectin, glycosaminoglycans, and
collagen.
Angiogenesis
This process begins with endothelial cell migration to the wound site
and is essential for wound healing. The erythema following a chemical peel
primarily is caused by the new capillary growth in the area.
Collagen remodeling
Collagen remodeling is the main reason that chemical peels are able to
reduce wrinkles. The process of remodeling involves a reorientation of the
collagen in a parallel fashion and begins as collagen is formed following
the peel.
An evaluation of the patient by the clinician is necessary to determine
the appropriate treatment based on the dermal defect. If it is determined
that a chemical peel is warranted, the appropriate agent is selected based
on the patient’s Fitzpatrick skin type and Glogau’s photoaging group, as
well as other variables that may affect peel penetration. The patient must
be educated concerning the chemical peel process and give signed consent
if performing a medium or deep peel.
The skin should be defatted properly with acetone. Delicate areas that
need to be protected should have petroleum jelly applied to the lips,
inside the nose, and optionally in the nasolabial fold, medial canthus,
and lateral canthus. The correct peeling agent then is applied for the
appropriate amount of time. When performing a combination peel, pouring
one agent at a time is advisable because of the ease in which the agents
may be confused when poured into similar cups. Then, the peeled area
should be neutralized, and the patient should be sent home with proper
instructions along with advice to call should any complications arise.
Indications include actinic keratoses, actinic rhytides, pigmentary
dyschromias, superficial scarring, radiation dermatitis, and acne
vulgaris.
Upper epidermal defects, such as melasma, can be treated with
superficial peels, while deeper defects, such as deep wrinkles, may
require a deep peeling agent. Medium depth (superficial dermis) defects,
such as mild dermatoheliosis, require a medium depth peel. Deep perioral
rhytides may require a deep peel, such as the Baker Gordon solution.
Glogau photoaging classification
In type I, the patient, usually aged in the second or third decade,
shows mild, early photoaging that consists of mild pigmentary changes,
absence of keratoses, and minimal wrinkles. The patient requires minimal
or no makeup.
In type II, the patient has "wrinkles in motion" (ie, wrinkles that
appear when making facial gestures or other dynamic facial muscle
activity). Early-to-moderate photoaging is recognized by early senile
lentigines, keratoses that are palpable but not visible, and the emergence
of parallel smile lines. The patient’s age usually is in the third or
fourth decade. Female patients usually wear some foundation.
In type III, the patient has "wrinkles at rest." Advanced photoaging is
recognized by obvious dyschromia, telangiectasias, visible keratoses, and
wrinkles at rest. The patient is usually 50 years or older, and female
patients almost always wear heavy foundation.
In type IV, the patient has "only wrinkles." Severe photoaging is
characterized by yellow-gray coloration of the skin, prior history of skin
malignancies, and skin that is thoroughly wrinkled. The patient’s age is
usually in the sixth or seventh decade. In addition, the patient cannot
wear makeup because it "cakes and cracks."
The Glogau photoaging classification is a visual grading system used to
quantify photodamage. Patients with photoaging type I are not good
candidates for deep peeling because the peel may be more damaging than
beneficial, while a superficial peel would be more efficacious. Patients
with type IV may benefit from deep peeling, while a superficial peel may
hardly make a difference on this type of skin. Patients with skin types II
and III ordinarily benefit from superficial or medium depth peels
depending on the exact circumstances concerning the patient. Other
variables described in this article also should be considered, including
the Fitzpatrick skin type, when determining which peeling agent to use.
Fitzpatrick skin typing is graded from 1-6, with the first 3 skin types
being of white skin and with progressively more active response to
tanning. Type 4 is light brown skin, and type 5 is dark brown skin. Type 6
skin never tans and is essentially black skin with an equivalent SPF of 8.
Fitzpatrick skin types 5 and 6 are usually not ideal candidates for medium
and deep peels. The best candidates are the light skin types 1, 2, and 3,
which have less chance for such complications as pigment dyschromia and
scarring. Although skin types 5 and 6 are not ideal for peels, they can be
peeled using such superficial agents as salicylic acid or glycolic acid.
Degree of photoaging damage
Patients with severely damaged skin may not be good candidates nor are
those at the opposite end of the spectrum with excellent skin.
Smoking
Patients must understand the necessity for smoking cessation. The
dynamic action of puffing can worsen perioral rhytides, and the chemicals
in the smoke can cause enzymatic reactions that weaken the skin and cause
further wrinkling around the mouth and eyes.
Prior cosmetic surgery
Waiting several months following surgery that involves the face is
recommended. Give the skin time to heal prior to subjecting it to
chemoexfoliation.
General health
With phenol peels, the patient should be in good general health since
phenols can cause arrhythmias. Good kidney and liver function are
necessary for adequate excretion and detoxification. A screening blood
chemistry that includes blood urea nitrogen (BUN), creatinine, and liver
function is wise. ECG monitoring is necessary during the peeling process.
Mental health
Patients who are mentally unstable may be overly self-conscious and may
not be prepared for their aesthetic appearance immediately following the
peel.
Medications
Oral contraceptive pills can cause melasma, further worsening the skin
discoloration that the chemical peel was intended to eradicate. Patients
taking blood thinners, such as warfarin, should avoid deep peels because
of the possibility of blood oozing from the peel site. Patients taking
aspirin usually do not have complications, but, if the medication is not
necessary, advising them to stop taking it 1 week prior to a deep peel is
advised.
Herpes
Treating patients who have a history of herpes simplex with acyclovir
is prudent. Acyclovir (400 mg) should be started 2 days prior to the peel
and continued for 5 days after the peel to reduce the risk of recurrent
herpes infection.
History of scarring
Patients need to be asked if they have a history of hypertrophic
scarring. Many people who have hypertrophic scarring can develop keloids.
This usually is found in patients with Fitzpatrick skin types 5 and 6 but
can develop in patients with skin types 1, 2, 3, and 4. Medium and deep
peels penetrate into the superficial and deep dermis, which may stimulate
keloidal development in patients who are inclined to develop keloids. Weak
superficial peels can be considered in skin types 4 and 5 since
penetration is only into the epidermis. Patients with a history of
scarring are not candidates for major skin resurfacing, such as laser or
medium/deep peels.
Expectations
A discussion between the physician and patient is necessary prior to a
chemical peel, especially a deep peel. Examples of “before and after”
results should be shown, and the possibility of complications must be
explained to the patient.
Follicle unit density
Previous use of isotretinoin must be noted. Patients should wait until
6 months after the last dose of isotretinoin to reduce the risk of
scarring. Patients who have had recent radiation treatment need to have a
skin biopsy performed to ascertain the existence of hair follicle units,
since these follicle units are where the reepithelialization
occurs. History is taken to determine the amount of sun-induced damage, history
of hypertrophic scarring or keloid formation, and a general medical
history. Items of interest include a history of prior surgeries,
dermabrasion, or recent laser therapy. In addition, medicines, such as
isotretinoin, need to have been stopped for at least 6 months prior to
chemical peeling.
Peeling agent concentration
Peeling agent concentration can vary, even though the label indicates
the same concentration. The different methods used to determine
concentration of acid can produce some variation. From strongest to
weakest, these methods are dilutions of a saturated solution,
weight-to-weight method, weight-to-volume method, and grams of acid
crystal mixed to 100 cc of water.
Free acid availability
The pH of the agent, or free acid available pKa, is another
measurement. The pKa of the solution is the pH at which half is in acid
form; therefore, a lower pKa means that more free acid is available. Many
products advertise the acid percentage; however, pKa is a more accurate
determinant of strength.
Application of peeling agent
The clinician can vary the number of coats depending on the depth of
peel desired. The peel frost, or facial whitening indicating depth of
epidermal damage, can aid in the determination of this number.
Frequency that patient receives a peel
Most patients can tolerate a monthly superficial peel, while medium
depth peels can be performed at 6-month intervals if necessary.
Method of application
The acid should be applied with a brush, cotton, or sponge applicator.
The acid should not form pools in the facial folds nor drip from the face.
The more acid that the clinician applies, the deeper the peel.
Contact time
How long the peeling agent is applied also determines the depth of the
peel. After the appropriate time has past, neutralization is performed.
Some chemical peels, such as salicylic acid and trichloroacetic acid, do
not require a neutralization step since the skin neutralizes the acid.
Glycolic acid peels must be neutralized. Always wash the patient's face
with water following the peel.
Density of adnexal structures
Recent radiation treatment can affect the density of adnexal
structures. The reepithelialization process partially occurs from the
adnexal structures; therefore, some clinicians advise that a punch biopsy
be performed to verify their existence.
Occlusion
Products available, such as biosynthetic occlusive dressings, may
decrease pain and speed healing. Examples include hydrogel membrane
products, such as Vigilon (Hermal Labs, Delmar, New York); polyurethane
membranes, such as Meshed Omiderm (Doak Dermatologics, Fairfield, New
Jersey); and silicone membrane Silon II (BomMed Inc, Bethlehem,
Pennsylvania).
Rejuvenation regimen
Patients may treat the skin before and after a peel with such agents as
tretinoin, hydroquinone, or an alpha hydroxy acid. These may help the skin
heal faster and also allow the chemical peel agent to achieve better
penetration.
Ointments
Petroleum jelly and other occlusive ointments may act as an occlusive
barrier to a minor degree.
Defatting
The skin should be cleaned and excess fat removed with such agents as
acetone, rubbing alcohol, or Septisol, or a combination of these agents.
Three parts alcohol with 1 part acetone works well. A thorough defatting
of the skin is necessary for proper penetration of the peeling agent since
most agents are not lipid soluble.
Application
The peeling agent can be applied with 4X4 gauze, cotton swabs, or the
foam applicator that comes with the peel kit. Popsicle sticks are good
applicators for the paste form. Apply the peeling agent in cosmetic units,
beginning with the forehead and finishing with the chin. Feather the
peeling agent into the hairline and the shadow of the mandible.
Reapplication of the peeling agent may be necessary if the frost is uneven
or is not white enough.
Frost
The change in coloration of the skin to a whitish tint is called frost.
This represents the end stage of the chemical peel and shows that keratin
agglutination has occurred. Depending on the agent used, the white tint
may vary from a brighter white in a superficial peel to a grayish white in
a deep peel.
Neutralization
Neutralization of the chemical peeling agent is an important step once
the clinician has achieved the proper depth of the peel, which is
determined either by the frost or how much time has elapsed.
Neutralization can be achieved by cold water or wet, cool towels applied
to the face following the frost. This soothes the sharp tingling
discomfort caused by the peeling agent. Other neutralizing agents that can
be used include bicarbonate spray or soapless cleanser. Peels for which
this neutralization step is less important include salicylic acid,
Jessner's, and phenol.
The patient should be instructed to remain vigilant for signs of
infection. If the patient has a history of cold sores, treating the
patient with acyclovir (400 mg PO bid) or an equivalent drug is advisable,
beginning 2 days prior to the peel and continuing for 7 days after the
peel.
TCA (10-35%) has been used for many years and is safe to use at lower
concentrations. At higher concentrations, such as 50% and above, TCA has a
tendency to scar and is less manageable than other agents used for
superficial peels. TCA is found in several proprietary peels at varying
concentrations, and some kits have instructions and buffering agents so
the peel can be diluted as deemed necessary.
Jessner’s peel is a combination of salicylic acid 14%, lactic acid 14%,
and resorcinol 14% in alcohol. This agent is easy to use, with no timing
necessary. Apply the agent, wait for a light frost, and then neutralize
with water. Salicylic acid is lipid soluble; therefore, it is a good peeling agent
for comedonal acne. The salicylic acid is able to penetrate the comedones
better than other acids. The anti-inflammatory and anesthetic effects of
the salicylate result in a decrease in the amount of erythema and
discomfort that generally is associated with chemical peels. The most
common concentration used today is 20-30% and can be purchased in
easy-to-use kits.
Carbon dioxide (CO2) uses a solid block of CO2
ice dipped in an acetone-alcohol mixture and then applied to the skin for
5-15 seconds, depending upon the desired depth. CO2 is easier
to use, and the depth of the peel can be controlled more easily than with
liquid nitrogen; CO2 is at - 78°C, while liquid nitrogen is at
- 196°C.
Alpha hydroxy acid peels include lactic acid, glycolic acid, tartaric
acid, and malic acid that are synthesized chemically for use in peels.
Various concentrations can be purchased, with 10-70% concentration used
for facial peels, most commonly 50% or 70%.
Medium depth peels
Three combination peels currently being used are CO2 and TCA
35%, Jessner’s and TCA 35%, and glycolic and TCA 35%. These peels are as
effective as the other medium depth peels with less chance of scarring and
pigment dyschromia. An endless number of combinations are possible, more
than can be covered in this overview.
TCA 50% is seldom used because of a higher risk of scarring and the
availability of the combination peels.
Full strength phenol (88%) is a very caustic agent that causes
immediate keratin agglutination, preventing further penetration of the
agent deeper into the dermis. Again, the increased risk of scarring and
pigment dyschromia makes this agent less attractive to the practitioner.
If diluted and mixed with other complimentary chemicals, this agent can be
used effectively as a deep peeling agent.
Pyruvic acid rarely is used today because of its fast action that
causes difficulty in controlling the depth of this peeling agent. A
product currently is being developed that uses ethyl pyruvate and has a
higher pH and greater buffering ability than other related products.
Deep peels
Baker Gordon peel produces the most dramatic results and is the most
effective peeling agent currently used. The phenol produces a new zone of
collagen that is thicker than that produced by laser. This solution is
very effective in smoothing wrinkles related to aging and sun damage.
This advantage is countered by several disadvantages. A long healing
time is required, with erythema occasionally lasting as long as 6 months.
In addition, the potential for pigmentary changes, scarring, and infection
are high with this peel. Despite the problems that may be encountered, a
properly administered phenol peel is unmatched by the other peeling
agents, and, for perioral wrinkles, the phenol peel even surpasses laser
resurfacing. Although dramatic results can be achieved with the phenol
peel, the risks and benefits should be weighed carefully before
proceeding. Only experienced clinicians should attempt a phenol
agent–based peel.
The Baker Gordon solution is made of phenol 88%, 2 mL distilled water,
8 drops Septisol, and 3 drops croton oil. This formula penetrates into the
middle reticular dermis and requires special monitoring devices, such as
an ECG monitor and pulse oximeter, because of the potential of the phenol
to cause arrhythmias. The Baker Gordon formula is not often used today
because of resurfacing laser technology; however, a deep peel works well
on deep perioral rhytides. Deep peels can be occluded or nonoccluded.
Occluded method uses zinc oxide tape or other artificial barrier product
to prevent evaporation of the phenol from the skin, thus enabling the
solution to penetrate deeper.
Two variants of the Baker Gordon peel are Litton’s formula, which
replaces Septisol with glycerin, and the Beeson McCollough formula, which
uses aggressive defatting and heavier application of Baker Gordon
solution.
Pigmentary change is not an uncommon complication, especially with the
deeper peeling agents. In some cases, the peeled area remains stark white.
Taking proper precautions (as described earlier) can prevent undesirable
pigmentary changes.
Scarring
By matching the patient and peeling agent properly, the risk of
scarring can be decreased. Also, to further decrease the risk of scarring,
the patient should be advised to refrain from picking at the healing skin.
Patients with a history of keloids should not undertake medium or deep
peels because of the risk of scarring. Medium and deep peels penetrate to
the superficial and reticular dermis and, thus, may stimulate keloids.
Weaker superficial peels that only exfoliate the stratum corneum or
superficial epidermis can be used.
Infection
By using bacitracin for the medium and deep peels and cleaning the face
with a povidone wash, the risk of infection is decreased. Cold sores can
be prevented with acyclovir (400 mg PO bid), beginning 2 days prior to the
peel and continuing 7 days after the peel. Candidiasis infection also can
develop, for which a short course of ketoconazole can be used. Cultures
need to be taken, and appropriate antibiotics should be administered.
Prolonged erythema
Patients usually do not complain of erythema because it generally
subsides in 30-90 days, but sometimes erythema continues. Prolonged
erythema is usually not permanent, and topical hydrocortisone can be used
to speed the healing process.
Acne
Some patients develop acne after a chemical peel. This usually occurs
between days 3-9. Cultures should be taken, and an antibiotic that covers
gram-positive bacteria should be prescribed. If it is a true acne
occurrence, then the appropriate topical treatment also should be started.
If severe enough, isotretinoin may be initiated.
Milia
Small inclusion cysts, sometimes called milia, can appear in the
healing process after a chemical peel. These usually appear about 2-3
weeks after reepithelialization and may be aggravated by ointments due to
occlusion of the sebaceous glands.
Summary Chemical peels are not a cure-all, and patient expectations should be
realistic. Dynamic wrinkles caused by muscle action or sagging due to old
age usually requires an alternative treatment, such as face-lift, Botox,
or collagen injections. The clinician should assess each patient, explain
the alternatives, and then decide on a course of action. The correct
peeling agent needs to be chosen if chemoexfoliation is decided. Proper
defatting of the skin is critical for an even peel. Application of the
peeling agents needs to be performed correctly. Postpeel instructions need
to be explained carefully. If performed correctly, the chemical peel can
give excellent results with many satisfied patients.
IMAGES
Caption: Picture 1.
The defatting process is important for the even penetration of the
peeling agent. This patient is a Fitzpatrick type II, Glogau type I,
using alcohol and acetone mixture to defat the skin. Caption: Picture 3.
Men also request chemical peeling. This 56-year-old male patient is
in the process of a salicylic acid peel. REFERENCES MEDCEU
Continuing Education Courses CEU for Nurses and Healthcare Professional
Coagulation
and inflammation
The process of performing a chemical peel
Indications for chemical peel
Relative contraindications
FACTORS AFFECTING PEEL DEPTH
Patient history
INSTRUCTION AND CONSENT
Following the peel, it is
important that the patient follow instructions given by the physician to
prevent complications. If possible, the patient should stay out of the
sun; when unavoidable, the patient should apply a strong sunscreen and
wear a hat. An ointment, such as petroleum jelly or bacitracin, should be
applied to the involved skin.
The patient should be made
aware that the skin will exfoliate and may look cosmetically unattractive
for a period of time depending on the depth of the peel. For superficial
peels, a follow-up appointment can be scheduled at the time of the next
peel. For deeper peels, patients should be seen 2-3 times the week
following the peel to provide for early intervention if problems develop.
Superficial peeling
agents
Salicylic acid has been used for several decades and
is found in medications, such as Whitfield’s ointment at 4% and Trans-Ver-Sal at 17% concentrations. Adverse effects, usually only found
with high-dose oral ingestion, include headache, nausea, and ringing of
the ears, each of which may be resolved with a few glasses of water and
rest. These have never been reported with a peel procedure.
Pigmentary change
Novices at chemical peeling should educate
themselves through dermatology conferences, journals, and, possibly, a
preceptorship with a local dermatologist. After sufficient knowledge is
obtained, starting with superficial problems, like acne, general skin
rejuvenation, or melasma, using a superficial peel such as 20% salicylic
acid, is recommended.
