An Overview of Three Promising Mechanical, Optical, and Biochemical Engineering Approaches to Improve Selective Photothermolysis of Refractory Port Wine Stains

During the last three decades, several laser systems, ancillary technologies, and treatment modalities have been developed for the treatment of port wine stains (PWSs). However, approximately half of the PWS patient population responds suboptimally to laser treatment. Consequently, novel treatment modalities and therapeutic techniques/strategies are required to improve PWS treatment efficacy. This overview therefore focuses on three distinct experimental approaches for the optimization of PWS laser treatment. The approaches are addressed from the perspective of mechanical engineering (the use of local hypobaric pressure to induce vasodilation in the laser-irradiated dermal microcirculation), optical engineering (laser-speckle imaging of post-treatment flow in laser-treated PWS skin), and biochemical engineering (light- and heat-activatable liposomal drug delivery systems to enhance the extent of post-irradiation vascular occlusion)

Laser treatment of port-wine stains

Lori A Brightman,1 Roy G Geronemus,1 Kavitha K Reddy2 1Laser and Skin Surgery Center of New York, New York, NY, USA; 2Department of Dermatology, Boston University School of Medicine, Boston, MA, USA Abstract: Port-wine stains are a type of capillary malformation affecting 0.3% to 0.5% of the population. Port-wine stains present at birth as pink to erythematous patches on the skin and/or mucosa. Without treatment, the patches typically darken with age and may eventually develop nodular thickening or associated pyogenic granuloma. Laser and light treatments provide improvement through selective destruction of vasculature. A variety of vascular-selective lasers may be employed, with the pulsed dye laser being the most common and well studied. Early treatment produces more optimal results. Advances in imaging and laser treatment technologies demonstrate potential to further improve clinical outcomes. Keywords: laser, port-wine stain, capillary vascular malformation, vascular birthmark, selective photothermolysis, photodynamic therapy, intense pulsed ligh

Cryogen spray cooling in combination with nonablative laser treatment of facial rhytides.

BackgroundCryogen spray cooling can be used to provide epidermal protection while still achieving spatially selective photocoagulation in the upper dermis. The objective of this study is to determine the efficacy and safety of cryogen spray cooling in combination with a nonablative Nd:YAG (lambda = 1320 nm) laser treatment of facial rhytides in human volunteers.ObservationsThirty-five adults with bilateral periorbital rhytides were treated with cryogen spray cooling in combination with 3 nonablative laser treatments performed sequentially at intervals of 2 weeks. Small but statistically significant improvements were noted in the mild, moderate, and severe rhytid groups 12 weeks after the final laser treatment. A final assessment performed 24 weeks after the last treatment showed statistically significant improvement only in the severe rhytid group. The procedure was found to be safe; 4 sites (5.6%) developed transient hyperpigmentation. Two sites (2.8%) subsequently developed barely perceptible pinpoint pitted scars.ConclusionsCryogen spray cooling is a safe and effective method for protecting the epidermis during nonablative laser treatment of facial rhytides thereby avoiding much of the morbidity associated with other resurfacing procedures. Minor improvements in rhytides can be achieved with the current technology. Optimization of treatment parameters may further improve these results

Effect of dynamic cooling on 585-nm pulsed dye laser treatment of port-wine stain birthmarks.

Background and objectiveThe objective of this study was to determine the effectiveness of a dynamic cooling device (DCD), spraying the skin with a brief spurt of cryogen prior to the laser pulse, in reducing transient pain associated with 585-nm pulsed dye laser (PDL) treatment of port-wine stains (PWS), and reducing epidermal damage (hypo/hyperpigmentation) caused by this laser during PWS treatment.Materials and methodsMatched treatment sites were compared with and without the use of the cryogen spray in 47 patients at two investigational sites. Pain ratings, clearance of the PWS, and pigmentation changes were assessed. The results were analyzed by skin type and patient age.ResultsA statistically significant reduction in pain ratings was found in all patient groups using the DCD without changing the efficacy of PWS clearance. Pain reduction was most remarkable in patients with darker skin types. Dynamic cooling prevented the occurrence of epidermal damage or pigmentation change in most cases.ConclusionsThis study suggests that dynamic cooling can dramatically diminish pain during PWS treatment with the 585-nm PDL without reducing treatment efficacy. The absence of epidermal damage in most patients suggests that precooling with the DCD may allow the use of higher laser fluences to expedite clearance without inducing epidermal change. Dynamic cooling has potential use with other lasers and different lesions where discomfort and epidermal effects limit therapy