In-Vivo Histological Analysis of a Fractional CO2 Laser System Intended for Treatment of Soft Tissue
November 2017 | Volume 16 | Issue 11 | Original Article | 1085 | Copyright © 2017
Elisabeth Hurliman MD,a Brian Zelickson MD,b Jeffrey Kenkel MDc
aUniversity of Minnesota, Department of Dermatology, Minneapolis, MN bZel Skin & Laser Specialists, Minneapolis, MN cUniversity of Texas Southwestern Medical Center, Dallas, TX
BACKGROUND: Fractional ablative lasers have been shown to be safe and effective for improving wrinkles, scars, skin texture, and dyspigmentation. However, the exact effects of this technology in vivo on epidermal and dermal skin constituents have not been delineated. This study evaluated the in vivo histological effects over time of treatment with a fractional ablative CO2 system, using different treatment parameters. MATERIALS AND METHODS: Healthy adult volunteers were enrolled in this multicenter clinical study. Study participants, previously scheduled for abdominoplasty, received fractional CO2 laser treatment on the abdomen at a predetermined time prior to surgery. Biopsies were taken at baseline and after CO2 treatment. Morphological and morphometric analyses were performed in the ablated and coagulated tissue areas. RESULTS: Nine healthy adult volunteers were treated. Histologic evaluation showed 800-900 micron diameter zones of ablation and coagulation confined to the upper most layer of the skin in the mode with the greatest fractional skin coverage using Light Mode 30 - 50% (spot diameter of 150 microns, 30-60 millijoules fluence), while ablation to levels of up to 900 microns in depth using the Deep Mode (spot diameter 150 microns, 50-80 millijoules). Healing times of treated tissue varied from 1-day post-treatment with the Light Mode, and up to 10 days post-treatment with the Deep Mode. No remnants of ablation or coagulation were seen after 30 days post CO2 treatment with either mode. There were no adverse events associated with treatments. CONCLUSION: Treatment of the skin using the fractional CO2 device leads to skin resurfacing via ablation and coagulation of the treated area at a depth proportional to the delivered energy. The higher the energy used, the greater the degree of ablation and coagulation in tissue, which can lead to a greater tissue response in terms of fibroblast activity, collagen remodeling, and new collagen formation.
J Drugs Dermatol. 2017;16(11):1085-1090.
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Aging skin can be in part characterized by the appearance of fine lines and wrinkles, as well as an overall decline in skin texture and tone.1 Skin resurfacing refers to techniques used to counteract this process by wounding and removing skin layers with subsequent wound healing and regeneration of a normalized epidermis and dermis. Previous non-fractional approaches did not leave intact skin behind, thus causing a prolonged regenerative phase until healthy skin was recreated. In recent years, the drive to achieve enhanced aesthetic improvements in the signs of skin aging, while keeping procedural risks and downtime to a minimum, has fueled the development of numerous energy-based treatment modalities and techniques, such as fractional skin rejuvenation. Over the past two decades, laser resurfacing has been considered the “gold standard” treatment approach for the cosmetic improvement of rhytids and photodamaged skin.2 Laser-assisted skin resurfacing treatments achieve skin rejuvenation by the complete ablation of the targeted skin with subsequent collagen remodeling, neocollagenesis, and reepithelialization. However, these procedures are often limited by their associated unwanted side effects, including post-in ammatory hypopigmentation (PIH), scarring, prolonged downtimes, as well as discomfort during and after treatment.3-7 These issues paved the way for the development of safer, better tolerated fractional ablative technologies. Ablative fractional resurfacing (AFR, or Ablative Fractional Photothermolysis - AFP) creates small columns of thermally ablative and coagulated zones within the epidermis and dermis (known as MTZ or microthermal zones). The MTZs are evenly spaced in a controlled grid pattern over the skin’s surface. and compromise approximately 15-25% of the skin surface area per treatment session.8-10 Once injured, the skin begins a very rapid process of repair, as MTZs are surrounded by healthy, untreated skin. This intact skin serves as a reservoir of cells guiding safe healing of the targeted area.8,11 The first lasers to employ the concept of fractional skin rejuvenation used wavelengths that were in the near- to mid-infrared