Advanced Techniques in Dermatologic Surgery - part 7

232 Goldman Figure 12 Histologic examination immediately after (A) eight passes with the Er:YAG laser alone at 1.7J with a 4mm diameter spot and 10 to 20% overlap. (B) Immediately after three passes with the Derma-KTM at identical Er:YAG settings but with the addition of the CO2 laser at 10W and 50msec pulse duration. (C) Immediately after four passes with the Derma-KTM at identical Er:YAG settings but with the addition of the CO2 laser at 5W and 50msec pulse duration (hematoxylin–eosin 200). Note minimal amount of non-specific thermal damage at these laser fluences. Abbreviation: Er:YAG, erbium:YAG. Source: From Ref. 3. to be used by combining short- and long-pulse passes to ablate and provide thermal effects relatively independently. Adrian and Colleagues reported a side-by-side comparison with the UPCO2 laser on periorbital and perioral areas. They compared the UPCO2 laser set at a density of 53 passes with 10, 10-msec pulses of the Er:YAG at 5J/cm2 with a 5-mm diameter spot size on the other side. Postoperative discomfort, erythema, and time for re-epithelialization were similar. Patients treated with the UPCO2 laser had a better response on deeper wrinkles (13). Sciton ContourTM LR This Er:YAG laser combines two separate laser heads to combine inde-pendent thermal and ablative effects by having one laser head operate LR with the UPCO2 + Er:YAG Lasers 233 in a short pulse (0.5msec) with the other head operating in a long pulse mode (1–10msec). In this manner, the Sciton ContourTM laser ablates tissue with a sequential thermal seal. This laser provides 45W of power with a 50-Hz repetition rate. At 50% overlap of 3-mm diameter spots, fluences of up to 100J/cm2 can be generated. The ablative mode has a short 200msec suprathreshold pulse. A coagulative pulse immediately follows the ablative pulse. The Sciton ContourTM pattern generator gives a 4-mm spot dia-meter with a scanning field variable to 3.5cm3.5cm. Spots can be over-lapped from 10% to 50%. The pattern has an autorepeat mode of 0.5 to 2.5 seconds delivering 1 to 50 pulses/sec in the single pulse mode. All of the standard patterns are available. Typical settings that we have found useful are two passes with a 30% overlap at 16J/cm2 plus coagulative settings of 100mm coagulation (machinepresetsthatlengthenthepulsewidthandadjustfluencetoachieve measured coagulation depth). The third pass is given as an ablative pass only at 6J/cm2. In a side-by-side comparative study of 18 patients with one side treated with these settings and the other side treated as described above with the CO2 laser with 2 passes at 10msec and 2 passes at 0.5msec we found no apparent clinical difference between the two sides of the face (Fig. 13). Patients had a slightly quicker healing rate, decreased degree Figure 13 Side-by-side comparison of ling pulsed Er:YAG laser treatment: Sciton versus CO3. (A) Before treatment and (B) immediately after treatment. The right side was treated with two passes of the Sciton laser given with a 50mm coagulation depth, at 15J/cm2 followed by two passes with zero coagulation at 15J/cm2. The left side was treated with two passes of the CO3 at 10msec pulse with 15J/cm2 followedbytwopassesat0.5msecat5J/cm2.Bothlaserswereused with a 4mm diameter spot size. Note equal clinical appearance between the two sides (C) seven weeks after treatment. Note slight erythema with equal clinical appearance in the two sides. (D) Six months after treatment. Note equivalent results between the two sides. 234 Goldman Figure 14 Long-term follow-up of laser resurfacing. (Left) Immediately before full face laser resurfacing. (Middle) Three months after laser resurfacing with three passes of the UPCO2 laser at 300mJ, density pattern of 6 followed by 5, fol-lowed by 4. (Right) Five years after resurfacing. Note continued improvement without recurrence of rhytids. of erythema, and other postoperative adverse sequelae at one and two weeks postoperatively with the Sciton laser (46). This was associated with slightly less nonspecific thermal effects. However, the same degree of new collagen formation as well as clinical improvement was seen with the Sciton followed by Er:YAG laser (23). Thus, we believe that the Sciton ContourTM laser functions as two separate lasers. These observations are similar to those reported by Chris Zachary and Roy Grekin, who per-form resurfacing with the ContourTM at varying parameters ranging from 25 to 100mm of coagulation and 10 to 16J/cm2 with 20% to 50% overlap (LaserNews.net, 1999). Thus, the ideal parameters are not yet apparent. What is apparent is the safety and efficacy of this laser. Recommendations The goal of LR is to replace the photodamaged epidermis with nonpho-todamaged cells and the elastotic dermis with healthy collagen and elastin fibers. This combined technique has also been demonstrated to result in both a contraction of existing collagen fibers as well as formation of new dermal collagen. Unfortunately, many patients develop prolonged erythema, pigmentary changes, and delayed healing with aggressive CO2 LR. We have shown that the beneficial effects of LR can be main-tained with a reduction of adverse sequelae through minimizing the extent of nonspecific thermal damage by using a combination of UPCO2 laser followed by Er:YAG laser. Using the Sciton ContourTM or Cyno- sure CO3 lasers, first with thermal necrosis settings approximating that LR with the UPCO2 + Er:YAG Lasers 235 of pulsed CO2 LR and then following passes with pure ablative Er:YAG settings, approximates the clinical results seen with sequential CO2/Er: YAG resurfacing. There appears to be a slightly superior efficacy in combining the UPCO2 laser with the Derma-KTM laser. However, patients must be pre-pared to live with a few more weeks of erythema. We therefore reserve the combination CO2/Derma-KTM laser for severely photodamaged and wrinkled patients and/or those with severe acne scars and/or for neck resurfacing. All other patients were treated with the combination UPCO2/Er:YAG laser, except those with minimal photodamage who can be treated with the Er:YAG laser alone, single pass UPCO2 laser alone, or single to double pass Derma-KTM laser alone. Other techniques using the Er:YAG laser alone or an ultrashort CO2 laser (Tru-Pulse) (24), or the Derma-KTM laser (25–27), which pro-duce a decrease in nonspecific thermal damage, have been found to result in a decreased extent and duration of erythema and pigmentary changes with quicker re-epithelialization. Unfortunately, these lasers are more time-consuming and tedious to perform than standard CO2 LR with the UPCO2 or other short-pulsed CO2 laser systems. Therefore, the com-bination technique for resurfacing appears superior. This technique takes advantage of the predictable thermal effects of the UPCO2 laser resulting in heating dermal collagen to 60 to 65C causing its contraction, and adds to it the highly specific effect of the Er:YAG laser to reduce the resulting nonspecific thermal damage yielding the best and most predictable results in our practice. Combination long-pulsed Er:YAG systems may also work as well as the UPCO2 laser followed by the Er:YAG laser without the need to purchase or rent two laser systems. Long-Term Efficacy (Fig. 14) The duration of improvement that can be expected following LR: We have followed a significant number of our patients since first performing this procedure in 1993. Our impression is that although patients continue to age, the wrinkles that have been softened or eliminated at the three month follow-up look the same at 5 to 10 years. We have performed a detailed study of 104 patients, followed for 12 to 44 months (average 24month) that confirm our impression (4). We found a 31% improve-ment in perioral wrinkles at three months that persisted at a rate of 85% and an average of two years. An average 38% improvement in perioral wrinkles at three months showed 96% persistence at an average of two years. More importantly, histologic evaluation of our patients showed an increase in both the epidermal thickness of 20mm at both 3 and 24 months and the Grenz zone from 25 to 75mm at 3 months and 170mm at 5 years associated with a decrease in solar elastosis from 850mm before treatment to 300mm at three months, 750mm at one year and 650mm at two years. This argues for not only persistent improve-ment clinically but also continuing improvement histologically. Natu-rally, after undergoing full face LR, patients are motivated to avoid 236 Goldman excessive sun exposure and to continue with a topical rejuvenation program consisting of retinoids, alpha and beta hydroxyacids, and others. The histologic improvement is probably secondary to a com-bination of continued topical treatments with sun-avoidance and perhaps stimulation from LR. LR in Patients with Dark Skin In fair-skinned patients, the most common indication for skin resurfacing is to treat chronic sun-damage, wrinkles, traumatic scars, surgical scars, and acne scars. In nonwhite-skinned patients, acne scarring is the most common indication for this procedure. Unfortunately, the risk of prolonged or permanent dyspigmentation, especially postinflammatory hyperpigmentation parallels the degree of the patient’s constitutive skin color or pigment; the darker the skin color, the greater the potential for pigmentary dysfunction (28,29). Postinflammatory hyperpigmenta-tion, the most common complication seen following cutaneous CO2 LR in nonwhite patients, usually develops around the first month after treat-ment in 25% of Hispanic patients (skin phototypes II–V) (30). This was compared to a 3% to 7% incidence of hyperpigmentation after CO2 LR in skin phototypes I to IV where hyperpigmentation occurred only in patients with skin phototypes III and IV (28,29). Studies on CO2 (30–35) and Er:YAG (34,36–39)LR in nonwhite skin (skin phototypes III–V) have shown that these procedures can be performed effectively and safely. Pre- and postoperative treatment regi-mens have been recommended to reduce the incidence of postinflamma-tory hyperpigmentation (28,30,31,40,41). In addition to topical retinoic acid applied each night, patients with skin phototypes III to VI are given topical preparations of hydroquinone, kojic acid, azelaic acid, or vitamin C to be used for one to two months preoperatively. Although an arbi-trary minimum preoperative treatment time of two weeks is often recom-mended, achieving maximum benefit may require months of use. Although we believe in its efficacy, the advantage of the preopera-tive treatment remains debatable. A study by West and Alster noted no significant difference in the incidence of post-CO2 LR hyperpigmentation between subjects who received pretreatment with either topical glycolic acid cream or combination tretinoin/hydroquinone cream and those who received no pretreatment regimen (42). In our experience, postin-flammatory hyperpigmentation may occur in spite of careful preoperative treatment. From a retrospective review of 22 of our Fitzpatrick Type IV patients, who underwent full face LR, a 68% incidence of PIH beginning one month postoperative and lasting 3.8 months was found (43). Pre-operative treatments did not prevent or minimize PIH. PIH did respond to appropriate treatments once it has developed. The application of broad-spectrum sunscreen and sun-avoidance pre- and postoperatively would seem necessary to minimize hyperpig-mentation. The advantage of sun-avoidance has been demonstrated in a study showing that pre- and postoperative ultraviolet exposure on ... - tailieumienphi.vn