Skin Resurfacing - Laser Surgery

Ablative facial resurfacing involves wounding the skin to the dermal level, thereby removing photodamaged areas of the epidermis. Dermal wound healing stimulates collagen production. Ultimately, ultrastructural remodeling results in rejuvenated skin. Resurfacing occurs at the following 3 levels:

• Superficial (wounds from the stratum corneum through the papillary dermis)

• Medium (wounds of the upper reticular dermis)

• Deep (wounds of the midreticular dermis)

Options for ablative facial resurfacing include chemical peeling, dermabrasion, and laser surgery.

The popularity of dermabrasion has diminished because of an increased prevalence and awareness of blood-borne pathogens. Additionally, maintaining the proper depth during dermabrasion is technically difficult. Dermabrasion can be used for the treatment of facial rhytides; however, it is better suited for the treatment of facial scars.

While superficial peeling agents (eg, glycolic acid) remain popular, they do not penetrate the dermis. A medium-to-deep chemical peel must be used to perform ablative resurfacing. However, the use of medium and deep peeling agents has diminished. This trend probably reflects the greater operator control that lasers provide.

Laser skin resurfacing (LSR) has become an important component of rejuvenation surgery. The results in treating severely photodamaged skin, photoinduced facial rhytides, dyschromias, and atrophic scars have been favorable. In addition, LSR has been used for benign epidermal and dermal lesions and certain premalignant and malignant skin lesions. Finally, LSR can be performed as an isolated procedure or as an adjunct to procedures such as transconjunctival blepharoplasty (TCB), facelift, and endoscopic browlift.

Although this technology is relatively new, its benefits are clear. The laser allows for precise control of ablation depth, and it permits the surgeon to vary these depths as needed. In addition to such precision, LSR causes favorable heating of the dermis, which tightens collagen fibers and stimulates neocollagen secretion by fibroblasts. (A study by El-Domyati et al found that fractional Er:YAG laser therapy for upper facial rejuvenation stimulated new collagen formation [types I, III, and VII] up to 6 months posttreatment.[1] )

Currently, 2 laser wavelengths are in common use for facial skin resurfacing: pulsed carbon dioxide (CO2) and erbium:yttrium-aluminum-garnet (Er:YAG). The practice of combining these wavelengths in sequence is also gaining popularity. The latest generation of resurfacing lasers combines Er:YAG with subablative carbon dioxide energy in the same unit. The operative principles of these lasers and their use are described in this article. Although specific models with which the author has experience are discussed, the same principles apply to those from other manufacturers.

Comparison of tissue effects of carbon dioxide and Er:YAG lasers

Each Er:YAG pulse removes only 25-30 µm of tissue compared to the pulsed carbon dioxide, which removes 50-100 µm.

The laser output of Er:YAG is directly absorbed by collagen and dermal proteins, whereas the carbon dioxide laser vaporizes extracellular water in the dermis. Each Er:YAG pass generates the same amount of ablation, whereas the pulsed carbon dioxide generates a decreased vaporization depth with each pass. Also, a very small additive effect of increasing thermal damage occurs with the number of passes; proportionately, pulsed carbon dioxide has more energy contributing to thermal damage per pass.

Carbon dioxide laser

The CO2 laser (wavelength of 10,600 nm) is absorbed by tissue water, causing the temperature of the water to rise to more than 100°C. The laser penetrates approximately 30 µm within the skin. Thermal injury is prevented when the laser pulsewidth is less than the thermal relaxation time of the tissue (the time required for 50% of the heat to diffuse). The critical pulsewidth is less than 1 millisecond.[2]

The first pass of the CO2 laser causes approximately 50-70 µm of ablation. Since the resulting layer of thermal necrosis has less tissue water than the uninjured skin, successive passes result in less tissue vaporization. With each pass, however, the total depth of thermal necrosis increases slightly. Keep in mind that the thermal necrosis does not exceed a depth of 100 µm if the pulsewidth is kept at less than 1 millisecond.

Fluence (energy density) rather than peak power is more clinically relevant to tissue ablation because it is a measure of the energy (in J) delivered to the treatment region (in cm2) based on spot size. Increasing the fluence increases the depth of ablation. The threshold for skin vaporization is approximately 5 J/cm2. A fluence of 5-7 J/cm2 provides clean and efficient tissue ablation and dissipates much of the heat in the plume of vaporized tissue.

Er:YAG laser

The Er:YAG laser (wavelength of 2940 nm) offers precise tissue ablation with minimal thermal damage. This wavelength corresponds to the main peak of water absorption. When compared with the CO2 laser, the Er:YAG laser is more efficiently absorbed by water-containing tissues. Since the epidermis is mostly water, the Er:YAG laser is more superficially absorbed. This translates into less collateral thermal damage.[3]

Pulsewidths of 200-350 microseconds result in thermal necrosis of less than 10 µm in depth. Unlike the CO2 laser, with successive passes of the Er:YAG laser, the thermal injury depth remains stable. Additionally, stacking Er:YAG pulses slightly reduces the ablative efficiency. With the CO2 laser, the ablative efficiency decreases with successive passes.

The vaporization threshold of the Er:YAG laser is between 0.5 and 1.7 J/cm2. The fluence and depth of tissue ablation are directly related. For every J/cm2, 2-4 µm of tissue depth is ablated. This allows for precise control of tissue ablation.

Combined carbon dioxide and Er:YAG laser

The benefit of a combined system is derived from the precise tissue ablation and minimal necrosis of Er:YAG systems coupled with the favorable heating of deeper tissue layers typical of carbon dioxide systems. A distinct advantage of this laser is that the nuisance of oozing with Er:YAG alone is avoided with the addition of coagulative carbon dioxide effects. In addition, fewer passes are required to reach depths equivalent to those of Er:YAG alone.

Carbon dioxide and Er:YAG lasers in sequence

Carbon dioxide laser treatment followed by Er:YAG results in thermal necrosis and collagen injury similar to those of Er:YAG alone. This phenomenon may be secondary to Er:YAG removal of carbon dioxide thermal injury. In other words, following carbon dioxide passes with Er:YAG removes the zone of thermal necrosis and promotes prompt healing.

The images below depict laser skin resurfacing.

In considering laser skin resurfacing (LSR), the clinician should consider the patient's skin type. This sun-reactive skin type (Fitzpatrick) is recorded preoperatively.

Fitzpatrick sun-reactive skin types and skin color tanning response

See the list below:

• Type I - White, always burns, never tans

• Type II - White, usually burns, tans with difficulty

• Type III - White, sometimes burns mildly, achieves average tan

• Type IV - Brown, rarely burns, tans with ease

• Type V - Dark brown, very rarely burns, tans very easily

• Type VI - Black, never burns, tans very easily

Patients with Fitzpatrick type I or II skin are generally better candidates for LSR. Nonablative techniques usually offer better results to individuals with type III skin and greater. These patients are often at risk for postprocedure pigmentary changes.

The carbon dioxide laser is well suited to the treatment of perioral vertical furrows, periorbital dynamic lines (crow's feet) and mild dermatochalasis, glabellar dynamic lines, actinic damage,[4] generalized facial elastosis, shallow scars, and epidermal-dermal lesions. When treating crow's feet dynamic lines, ensure that the patient understands that the benefit is apparent only when in repose (ie, the furrows reappear upon squinting [unless botulinum toxin type A is also used]).

The Er:YAG laser causes more superficial tissue ablation compared with the CO2 laser. Therefore, patients with actinic damage, dyschromias, mild photodamaged skin, or superficial rhytides are excellent candidates for Er:YAG skin resurfacing. An equally important factor is patient request for early recovery (ie, patients may want laser treatment but request that they not appear red for months). Unlike the carbon dioxide laser, Er:YAG appears safe for use on the skin of the neck, chest, and hands, which expands its role. Additionally, a decreased incidence of hyperpigmentation with skin types IV and V may be associated with use of the Er:YAG.

The patient's wrinkle severity is classified preoperatively. Regions are graded on a scale of 1-6 (1 means essentially unwrinkled; 6 is profoundly wrinkled). Repeat treatments may yield the most optimal results. Treatment for patients with severe rhytides should be planned in this manner. Retreatments are generally spaced 4 months apart.

Absolute contraindications include active acne, deep acne pits or picks, and isotretinoin (Accutane) use in the past 2 years. Accutane is effective for cystic acne because it targets the sebaceous glands. However, a compromise in gland function impairs skin reepithelialization and increases the risk of scarring. Similarly, patients with reduced adnexal structures (eg, scleroderma, irradiation or burns) are poor candidates. History of herpetic infection is a relative contraindication only because most patients do not know their true status. Smokers are not excluded, which is a clear advantage over standard rhytidectomy.

Unlike Er:YAG, full-face treatment is strongly preferred with carbon dioxide (alone or in combination) to avoid demarcation lines. This not only improves camouflage while healing, it avoids obvious differences in skin quality and small step-offs between adjacent regions.

Always keep 2 treatment factors in mind. First, always maintain a balance between results and morbidity (ie, err on the conservative side). Take care on the eyelids to avoid a full-thickness injury or cicatricial ectropion. If significant dermatochalasis exists, then consider a blepharoplasty. Similarly, if severe facial elastosis is present, then consider a rhytidectomy. Second, never use a watts (carbon dioxide) or joules (Er:YAG) per pulse setting below that recommended for the handpiece being used. Remember that sufficient energy is required to reach the fluence necessary for char-free ablation. Turning the power too low forces heat into the tissue instead of the laser vapor.

No consensus exists regarding the most appropriate preoperative regiment for patients undergoing laser skin resurfacing (LSR). Controversy exists on the preoperative use of topical retinoic acid compounds, hydroquinone bleaching agents, or alpha-hydroxy acids in decreasing postprocedure hyperpigmentation. West and Alster demonstrated no effect on hyperpigmentation with the preoperative use of topical tretinoin, hydroquinone, or glycolic acid.[5]

Given the deepithelialized state of laser-resurfaced skin, the use of prophylactic antibiotics has been suggested to decrease secondary bacterial contamination. This practice is also controversial. In contrast, protection against herpetic outbreaks is necessary. For herpes prophylaxis in all patients undergoing laser resurfacing, administer valacyclovir 500 mg twice a day (starting 24 h prior to LSR) continued to postoperative day 10.

Administer nerve blocks and 1 mg of lorazepam (Ativan) by mouth to patients on arrival. No intravenous or intramuscular medications are necessary. Perform regional blocks using 1 mL of 0.25% bupivacaine HCl (Marcaine) with 1:200,000 epinephrine with a 1.5-inch 27-gauge needle at the level of the foramen periosteum. Achieve mental nerve blocks using an intraoral approach, injecting 2-3 cm laterally to the symphysis. Also approach infraorbital nerve blocks intraorally, injecting above the canine fossa. Perform supraorbital nerve blocks externally with location by foramen or notch palpation over the medial brow region. Remember that the supraorbital, infraorbital, and mental nerve foramina all lie in a straight vertical line.

Patients undergoing carbon dioxide LSR also require subdermal local anesthetic using 1% Lidocaine with 1:200,000 epinephrine delivered with a 30-gauge needle. Use small amounts (< 2 mL) in each treatment region because overinjecting distorts furrows. The author no longer marks individual furrows because the ink seems to seep deeper than a safe level of treatment allows. For patient comfort and dissipation of the injected anesthetic, delay the laser treatment for half an hour. Er:YAG LSR treatment is not painless, but it is significantly less painful than that of carbon dioxide. A eutectic mixture of local anesthetics (EMLA) cream (topical lidocaine) applied 2 hours prior to the procedure provides sufficient topical anesthesia.

When working in the periorbital area, use metallic laser eye shields for protection of the globes. Use tetracaine 0.5% ophthalmic drops for topical anesthesia; lubricate the shields well to avoid corneal abrasions. Physicians and assistants should wear goggles with protection specific for the wavelength(s) being used. Finally, allow no oxygen on the field because it will ignite a fire.

Carbon dioxide

Remove skin lesions and actinic regions by sequential ablative passes. The endpoint is reached when the lesion base has been removed or when a depth to the mid reticular dermis has been achieved (ie, whichever comes first). This depth is denoted by a chamois-brown color and may yield pinpoint bleeding spots.

Treat wrinkles by direct lasering into the furrows. Perform a light pass so as not to deepen the furrow. Do this to remodel the furrow base and to take advantage of favorable dermal collagen heating. Next, flatten the wrinkle shoulders using the laser as a planing tool. As a rule, laser only as deep as necessary, with the absolute endpoint being the mid reticular dermis. The region immediately adjacent to the wrinkle(s) is treated with ablative passes as indicated. These passes also include the wrinkles, so they accumulate more cumulative laser passes.

Finally, in a regional procedure, blend the aesthetic unit within its boundaries for optimal camouflage. If a full-face procedure is performed, take care to feather the inferior boundary approximately 2 fingerbreadths below the jaw line to avoid a sharp demarcation line. Likewise, take care to extend treatment into the facial hairlines. Moisten the hairline and the eyebrows to avoid singeing because the popping and plume can disturb the patient.

Less severely wrinkled adjacent regions may require only a dermal ablative depth to the upper reticular dermis (denoted by a gray color), while the peripheral aesthetic unit may require only a superficial peel to the upper papillary dermis (denoted by a pink color). Using this multilayer technique, only the areas that require aggressive treatment receive it. This minimizes morbidity and possible complications.

In general, perform subsequent passes at reduced wattage. First, wipe regions to be re-treated with gauze (sterile) soaked in isotonic sodium chloride solution. Always perform single-pulse vaporization (ie, no overlap) to reduce surrounding thermal damage. The author rarely performs more than 2 regional passes on the eyelids with pulsed carbon dioxide. Remember that eyelid skin has an extremely thin dermis, hence the value of blepharoplasty.

Er:YAG

The technique is similar to that of carbon dioxide, except pulses are overlapped by 10%. From a tissue interaction perspective, avoiding overlap with the Er:YAG is not as critical as with the pulsed carbon dioxide laser because virtually no tissue debris is produced. However, repeatedly firing at the same spot produces a hole in the skin. Also, wiping between passes or mechanically abrading with the sponge is unnecessary.

Because of the lack of coagulation necrosis produced by Er:YAG, the characteristic skin depth-color changes of the pulsed carbon dioxide laser are not observed. A useful depth indicator is pinpoint bleeding that occurs when in the papillary dermis. If this continues to ooze, hold a lidocaine-epinephrine soaked sponge over the region for 15-30 seconds. A smoke evacuator is mandatory because this high-powered laser turns the superficial skin layer into airborne particulate matter. In addition to eye protection for 2940 nm, physicians and assistants should wear laser masks that filter 0.1-µm particles. The author rarely performs more than 3 passes on the eyelids with the Er:YAG.

Combined carbon dioxide and Er:YAG laser

The procedure is performed identically to that of the Er:YAG. Fewer passes are required because of the presence of subablative carbon dioxide energy. Oozing rarely occurs because of these heating properties.

Carbon dioxide and Er:YAG in sequence

This is a simple technique of using the carbon dioxide as the primary resurfacing laser, followed by Er:YAG to remove the zone of thermal necrosis. This zone consists of thermally damaged tissue that ultimately peels; however, its presence leads to the persistent erythema observed with carbon dioxide. The favorably heated deeper dermis remains, and the fibroblasts have been stimulated to secrete neocollagen.

Fractional photothermolysis

Fractional photothermolysis (FP) delivers pulses intradermally to create an array of microscopic treatment zones. This leaves islands of viable epidermis and untreated dermis. By doing so, the skin's barrier function remains intact, allowing for quicker reepithelialization.

A prospective study by Kohl et al reported good results from fractional CO2-laser resurfacing on patients with rhytides and photoaged skin. The study, which included 24 female patients, found through a 14-item questionnaire that pretreatment patient expectations regarding the effectiveness of the procedure, though high, were slightly exceeded in terms of posttreatment satisfaction.[6]

Following LSR, patients experience 1 week of erythema and edema while reepithelialization occurs. Head elevation and ice application may help to alleviate these symptoms. Postoperatively, an open or closed wound care system may be used.

An open technique entails application of a thick healing ointment to the de-epithelialized skin surface. This system allows for easy visualization of the procedural sites. A closed wound care system entails a semi-occlusive dressing to promote moist healing while preventing an exudative phase. This practice decreases crust formation, which impedes reepithelialization and can lead to infection, scarring, or both. Additionally, complete facial coverage decreases postprocedure pain and provides camouflage. Remove the closed wound dressing after 2 postoperative days. For superficial Er:YAG peels, apply mupirocin 2% (Bactroban) ointment to keep the face moist for these first 2 days. For periorbital peels, apply tobramycin sulfate 0.3% (Tobramycin) ophthalmic ointment to keep the region moist for 2 postoperative days. This provides satisfactory protection against pseudomonads and some occlusive coverage.

After postoperative day 2, the patient must wash the face 2-3 times a day with Cetaphil soap. Instruct the patient not to rub the skin but to pat skin dry in a gentle manner. Also, patients must soak treated region(s) with dilute acetic acid soaks (1 tbsp of white vinegar per pt of tap water) for at least 15 minutes 3-4 times a day. After soaks, instruct patients to apply a light coating of Vaseline or Aquaphor until the skin reepithelializes.

Routine postoperative medications include ciprofloxacin 500 mg twice a day for 5 postoperative days for pseudomonal coverage. For herpes prophylaxis on all laser-treated patients, administer valacyclovir 500 mg twice a day (starting 2 d prior) continued to postoperative day 10. While the routine use of perioperative antibiotics is debatable, most authorities believe that herpes prophylaxis is the standard of care. After reepithelialization, instruct patients to apply a UV-A/UV-B sunscreen with a sun protection factor (SPF) of more than 25 to treated areas for 1 year.

Erythema

Expect some erythema following carbon dioxide laser skin resurfacing (LSR). This may persist for 12 weeks or more. Hydrocortisone 2.5% cream twice a day for 3-4 weeks can be used for persistent focal areas of erythema. Diffuse erythema may be secondary to contact dermatitis. This may occur with excessive intraoperative use of wet gauze or early postoperative use of topical tretinoin. A green-based makeup appears to offer the best camouflage. Note that, for some patients, persistent erythema is more disconcerting than a few residual wrinkles.

Hyperpigmentation

Patients with higher Fitzpatrick skin types are generally more prone to hyperpigmentation following LSR. Treat persistent hyperpigmentation with a cream mixture of hydrocortisone 1%, hydroquinone 5%, and Retin-A 0.05% twice a day for 1 month on and 1 month off, until resolved. The hydroquinone component can be increased to 8% in severe cases, and Retin-A can be increased to 0.1% for thick sebaceous skin. Do not concurrently increase both because this can cause significant skin irritation. Note that the problem usually resolves in 6-8 weeks, so the author delays commencing such a regimen. At the author's clinic, a need to perform sequential micropeels (30-50% glycolic acid) for refractory hyperpigmentation has not occurred.

LSR of sun-reactive skin types IV and V is likely to precipitate manageable hyperpigmentation. The author does not consider this a complication in these patients and does not hesitate to treat them as long as they are pretreated and understand the long-term course. Physicians must stress to these patients that sunlight (including through glass) causes their hyperpigmentation.

Infection

Significant pain that occurs after postoperative day 2 may indicate a bacterial, fungal, or viral infection. A high degree of vigilance and suspicion is necessary because signs may be subclinical, and the patient may be dismissed as having a low pain threshold. A significant number of infections have been cultured as Pseudomonas or Candida infections. Fungal infections may reveal satellite lesions, erythema, and slow reepithelialization. For candidal treatment, use 100-200 mg of fluconazole per day. Although more expensive than ketoconazole, fluconazole causes fewer adverse interactions. Topically, use clotrimazole 1% cream.

For herpes eruption, increase valacyclovir to 1000 mg 3 times a day for 10 days.

Scarring

Postprocedure scarring may occur with excessive thermal damage or infection. Areas most often affected include the upper lip, lateral cheeks, and mandibular areas. Predisposing factors include recent history of isotretinoin use, radiation therapy, or other conditions that may have decreased adnexal structures.

Treat hypertrophic scarring as soon as signs appear. Use clobetasol propionate 0.05% (Temovate) cream twice a day for 2 weeks for early induration. Exercise caution not to exceed 50 g/wk, and the treatment course should not exceed 2 weeks.

BOT is a useful adjunct to LSR for hyperdynamic facial lines such as crow's feet. These lines are furrows caused by the repeated pull on the skin of underlying facial mimetic muscles and are differentiated from rhytides, which are caused by age-related dermal laxity and gravity. BOT temporarily paralyzes such muscles. The authors have had excellent results with combined treatment of interbrow furrows (corrugator muscles) and crow's feet (orbicularis oculi muscles). As explained to patients, the laser works on the skin part of the problem, and the BOT works on the muscle component.

Transconjunctival blepharoplasty (TCB) and periorbital LSR surfacing are an excellent combination because they address the 2 most common problems of the aging lower eyelid: TCB for pseudoherniated fat and LSR for mild skin laxity. Because the skin-muscle complex is undisturbed during a retroseptal TCB, immediately resurfacing the lower eyelid skin is safe. Similarly, performing forehead LSR concurrent with subgaleal or subperiosteum browlift procedures (eg, endoscopic browlift) is safe. The author does not perform concurrent LSR on skin that has been incised, such as after a traditional upper eyelid blepharoplasty.

The combination of rhytidectomy and LSR is another excellent option.[7, 8] Appropriate patients are those with severe facial elastosis, poor dermal recoil, and actinic damage. The author prefers to accomplish the facelift first followed by the laser resurfacing at 3-4 months. This practice allows the physician to laser resurface the rhytidectomy scars. Resurfacing of newly undermined skin (eg, as with non–deep plane approaches) is risky because full-thickness skin loss may result.

The clinical effects of LSR, thought primarily to result from heat-induced immediate collagen tightening and initiation of a wound-healing response to injury, may result, in part, from cytokine secretion at the cellular level. In 2000, Nowak et al evaluated the effect of pulsed carbon dioxide laser energy on keloid and normal dermal fibroblast secretion of growth factors in an in vitro model.

At a fluence of 4.7 J/cm2 (commonly used in LSR), secretion of basic fibroblast growth factor (bFGF) was stimulated and that of transforming growth factor beta-1 (TGFB1) was inhibited in both keloid-producing and normal dermal fibroblasts. The known ability of bFGF to promote organized collagen bundles may account for the observed clinical and histologic effects with LSR.

In addition, the inhibition of TGFB1, which causes tissue fibrosis, may have a protective role in minimizing scar production during the healing process. The laser can be considered a biostimulator that initiates a wound healing response. Research into precisely controlling the wound healing response with different sources of biostimulation will change the way skin surgery is performed.