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Coricciati L, Gabellone M, Donne PD, Fusco I, Zingoni T. Assessment of the efficacy of 595 nm pulsed dye laser in the management of facial flat angiomas. Results of a case series. Skin Res Technol 2023; 29:e13494. [PMID: 37881052 PMCID: PMC10576172 DOI: 10.1111/srt.13494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 09/26/2023] [Indexed: 10/27/2023]
Abstract
BACKGROUND Studies on pulsed dye laser (PDL) have shown the best efficacy and safety data for treating vascular anomalies among the various lasers used and the 595-nm PDL has been used to treat cutaneous vascular anomalies for about 30 years. The purpose of this study was to assess the efficacy of 595 nm Pulsed Dye Laser in the management of facial flat angiomas present in the form of Port-Wine Stain. MATERIALS AND METHODS Seven cases of PWS in Fitzpatrick skin type ranged from I to III and colour ranging from pink to purple, were treated with 595 nm pulse Dye Laser. Patients underwent to 6-8 laser sessions at 20-30 days intervals. Results obtained were judged by dermatologist, by comparing pre-treatment and post-treatment photographs, 6 months after the last session and a quartile scale of lesion clearance (4-point Investigator Global Assessment scale): 1 = no or low results (0%-25% of the lesion area improved), 2 = slight improvement (25%-50% of the lesion area cleared), 3 = moderate-good improvement (50%-75%), and 4 = excellent improvement (75%-100%) was used. Possible side effects such as blisters, hyper/hypopigmentation, and scarring were monitored. RESULTS All patients observed global improvements. 71% of patients achieved excellent clearance and 29% patients achieved good-moderate clearance of their angioma. Patients were asked for a subjective evaluation of the results: 57% of patients were very satisfied, 29% were satisfied, and 14% patients were not very satisfied with the results. No patients were dissatisfied. No significant side effects were noted. CONCLUSION This research confirms the efficacy of the 595 nm PDL for flat angioma management, without considerable side effects.
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The In Vivo Effect of Ytterbium-Doped Fiber Laser on Rat Buccal Mucosa as a Simulation of Its Effect on the Urinary Tract: A Preclinical Histopathological Evaluation. Int Neurourol J 2017; 21:S17-23. [PMID: 28446013 PMCID: PMC5426434 DOI: 10.5213/inj.1734858.429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 04/02/2017] [Indexed: 11/08/2022] Open
Abstract
Purpose The aim of this study was to perform a histological analysis of the effect of a ytterbium-doped fiber (YDF) laser on oral buccal mucosa tissue in vivo to simulate its effect on the mucosa of the lower urinary tract. Methods A total of 90 8-week-old Sprague-Dawley rats were anesthetized with urethrane (1.2 g/kg intraperitoneally). A prespecified inner buccal mucosal site was irradiated with a YDF master-oscillator power amplifier (MOPA) system for 60 seconds, with output power settings of 0.5, 1, and 2 W, respectively, in 3 treatment groups. Specimens of irradiated tissue were harvested at 2 hours, 24 hours, 2 weeks, and 4 weeks after irradiation. The tissue specimens were stained with hematoxylin and eosin for histological analysis. Results In the group treated with 0.5 W, basal cell elongation and vacuolization were observed at 2 hours and 24 hours after treatment, respectively. No evident injury was observed after 2 or 4 weeks. The group treated with 1 W presented partial basal layer separation, and even complete epidermal ablation, within 2 hours. At 24 hours after laser treatment, new capillaries on an edematous background of fibroblasts and myofibroblasts, as well as profuse infiltration of the neutrophils to the basal layer, were observed. Collagen deposition and reepithelization were observed in specimens taken 2 weeks and 4 weeks after treatment. The group treated with 2 W presented bigger and deeper injuries at 2 hours after irradiation. Meanwhile, subepidermal bullae with full-thickness epidermal necrosis and underlying inflammatory infiltrate were observed 24 hours after treatment. The presence of fibrous connective tissue and collagen deposition were observed 2 weeks and 4 weeks after the treatment. Conclusions To our knowledge, this is the first report regarding the effect of a YDF laser on living tissue. Our study demonstrated that the typical histological findings of the tissue reaction to the YDF MOPA apparatus were very similar to those associated with thermal injuries. The extent and degree of tissue damage increased proportionally to the output power.
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França K, Chacon A, Ledon J, Savas J, Izakovic J, Nouri K. Lasers for cutaneous congenital vascular lesions: a comprehensive overview and update. Lasers Med Sci 2012; 28:1197-204. [DOI: 10.1007/s10103-012-1220-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 10/15/2012] [Indexed: 12/20/2022]
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Chen JK, Ghasri P, Aguilar G, van Drooge AM, Wolkerstorfer A, Kelly KM, Heger M. An overview of clinical and experimental treatment modalities for port wine stains. J Am Acad Dermatol 2012; 67:289-304. [PMID: 22305042 DOI: 10.1016/j.jaad.2011.11.938] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/15/2011] [Accepted: 11/10/2011] [Indexed: 01/03/2023]
Abstract
Port wine stains (PWS) are the most common vascular malformation of the skin, occurring in 0.3% to 0.5% of the population. Noninvasive laser irradiation with flashlamp-pumped pulsed dye lasers (selective photothermolysis) currently comprises the gold standard treatment of PWS; however, the majority of PWS fail to clear completely after selective photothermolysis. In this review, the clinically used PWS treatment modalities (pulsed dye lasers, alexandrite lasers, neodymium:yttrium-aluminum-garnet lasers, and intense pulsed light) and techniques (combination approaches, multiple passes, and epidermal cooling) are discussed. Retrospective analysis of clinical studies published between 1990 and 2011 was performed to determine therapeutic efficacies for each clinically used modality/technique. In addition, factors that have resulted in the high degree of therapeutic recalcitrance are identified, and emerging experimental treatment strategies are addressed, including the use of photodynamic therapy, immunomodulators, angiogenesis inhibitors, hypobaric pressure, and site-specific pharmaco-laser therapy.
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Affiliation(s)
- Jennifer K Chen
- Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, USA
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An overview of three promising mechanical, optical, and biochemical engineering approaches to improve selective photothermolysis of refractory port wine stains. Ann Biomed Eng 2011; 40:486-506. [PMID: 22016324 PMCID: PMC3281205 DOI: 10.1007/s10439-011-0436-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 10/06/2011] [Indexed: 11/25/2022]
Abstract
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).
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Leão JC, Issa JPM, Pitol DL, Rizzi EC, Dias FJ, Siéssere S, Regalo SCH, Iyomasa MM. Histomorphological and angiogenic analyzes of skin epithelium after low laser irradiation in hairless mice. Anat Rec (Hoboken) 2011; 294:1592-600. [PMID: 21809465 DOI: 10.1002/ar.21451] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 06/14/2011] [Indexed: 11/07/2022]
Abstract
It is not well-understood how low-laser therapy affects the skin of the applied area. This study analyzes skin of the masseteric region of mice from the HRS/J strain after three different application regimens (three, six or ten applications per regimen) of low intensity laser at 20 J/cm(2) and 40 mW for 20 sec on alternate days. Three experimental groups according to the number of laser applications (three, six or ten) and three control groups (N = 5 animals for each group) were used. On the third day after the last irradiation, all animals were sacrificed and the skin was removed and processed to analyze the relative occupation of the test area by each epithelial layer and the aspects of neovascularization. Data were submitted to statistical analyzes. The irradiated groups compared to their respective controls at each period of time, showed no significant difference in relative occupation of the test area by the layers and epithelium areas for three and six applications, but for ten applications, a significant decrease (P < 0.05) in the basal and granulosum layers, and epithelium areas were found. From the comparisons of the three irradiated groups together, the group with six laser applications showed statistical difference (P < 0.05) in total epithelium and on the layers. Vascular endothelial growth factor (VEGF) and VEGFR-2 immunoreactivities were similar for the control and irradiated groups. Results suggested a biostimulatory effect with low risks associated with superficial tissues, when the treatment aims the deeper layers after six applications.
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Affiliation(s)
- Juliane Caroline Leão
- Department of Morphology, Stomatology and Physiology, School of Dentistry at Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Bodendorf MO, Grunewald S, Simon JC, Paasch U. Efficacy and cosmetic results of contact gel cooling of the skin during non-ablative laser procedures. J Dtsch Dermatol Ges 2008; 6:647-52. [DOI: 10.1111/j.1610-0387.2008.06610.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Dai T, Yaseen MA, Diagaradjane P, Chang DW, Anvari B. Comparative study of cryogen spray cooling with R-134a and R-404a: implications for laser treatment of dark human skin. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:041116. [PMID: 16965144 DOI: 10.1117/1.2338001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cutaneous laser treatment in dark skin patients is challenging due to significant light absorption by the melanin at the basal layer of epidermis, which can result in irreversible nonspecific thermal injury to the epidermis. Cryogen spray cooling (CSC) with R-134a (boiling point approximately -26.2 degrees C at 1 atm), which is currently used during cutaneous laser treatment, has shown poor efficacy in protecting dark human skin. We investigated the potential of CSC with R-404a (boiling point approximately -46.5 degrees C at 1 atm), which has a lower boiling point than R-134a, for improved therapeutic outcome in dark human skin at three levels: in vitro (epoxy resin skin phantom), ex vivo (normal dark human skin sample), and in vivo (skin of the rabbit external ear). The skin phantom was used to acquire the surface and internal temperature profiles in response to CSC with R-134a or R-404a at various spurt durations, based upon which CSC-induced heat removal from the skin phantom was estimated using an algorithm that solved a one-dimensional inverse heat conduction problem. CSC with R-404a increased the temperature reductions within the phantom and subsequently the amount of heat removal from the phantom in comparison to that with R-134a. Normal ex vivo Fitzpatrick types V-VI human skin samples were used to investigate the thermal response of dark human skin epidermis to CSC (R-134a or R-404a) at various spurt durations in conjunction with 595-nm pulsed dye laser irradiation at various radiant exposures. Cryogen R-404a increased the threshold radiant exposures for irreversible thermal injury to the epidermis in dark pigmentation skin. No obvious CSC-induced morphological changes to human skin was observed when sprayed with R404-a spurts using durations up to 300 ms. In vivo rabbit ear vasculature was used as a model of cutaneous anomalies to assess the influences of CSC (with R-134a or R-404a) on the photothermolysis of dermal blood vessels. CSC (R-134a or R-404a) with the spurt durations of 100 to 300 ms increased the most superficial depth of thermally damaged dermal blood vessel compared with the sites without CSC, implying possible nonspecific cooling of superficial dermal blood vessels by the cryogen spurts with the settings applied.
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Affiliation(s)
- Tianhong Dai
- Rice University, Department of Bioengineering, MS 142, P.O. Box 1892, Houston, Texas 77251, USA
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Loffeld A, Zaki I, Abdullah A, Lanigan S. Study of patient-reported morbidity following V-beam pulsed-dye laser treatment of port wine stains. Lasers Med Sci 2005; 20:114-6. [PMID: 16047083 DOI: 10.1007/s10103-005-0351-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 06/20/2005] [Accepted: 07/01/2005] [Indexed: 11/30/2022]
Abstract
The V-beam pulsed-dye laser (PDL) (595 nm) has gained popularity in the treatment of port wine stains (PWS). It uses longer pulse durations than the standard flashlamp-pumped pulsed-dye laser (FPDL) (585 nm) and has an in-built cooling system to protect the epidermis. This should, theoretically, reduce the treatment-associated side effects, including discomfort. The aim of this questionnaire-based study was to confirm the clinical impression that V-beam PDL is well tolerated. The results were compared with a historical group of 62 PWS patients treated with FPDL. Fifty-one patients took part in the current study. Only 35.7% (vs. 81% in the historical comparison group) required topical anaesthetic prior to laser treatment. A shortening in the duration of bruising (8 vs. 10 days) and of symptoms such as burning and tightness (3 vs. 10 days) was recorded. Lifestyle change after treatment was recorded by fewer patients (39 vs. 57%). We conclude that V-beam PDL is better tolerated than FPDL when used at therapeutic levels in patients with PWS.
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Affiliation(s)
- A Loffeld
- Lasercare Clinics, City Hospital, Dudley Road, Birmingham, B18 7QH, UK
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Kono T, Erçöçen AR, Nakazawa H, Nozaki M. Treatment of Hypertrophic Scars Using a Long-Pulsed Dye Laser With Cryogen-Spray Cooling. Ann Plast Surg 2005; 54:487-93. [PMID: 15838209 DOI: 10.1097/01.sap.0000155276.93061.93] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Hypertrophic scars are common and cause functional and psychologic morbidity. The conventional pulsed dye laser (585 nm) has been shown previously to be effective in the treatment of a variety of traumatic and surgical scars, with improvement in scar texture, color, and pliability, with minimal side effects. This prospective study was performed to determine the effectiveness of the long-pulsed dye laser (595 nm) with cryogen-spray cooling device in the treatment of hypertrophic scars. Fifteen Asian patients with 22 hypertrophic scars were treated by the long-pulsed dye laser (595 nm) with cryogen-spray cooling device. In 5 patients, the scar area was divided into halves, one half of which was treated with the laser, whereas the other half was not treated and was used as a negative control. All patients received 2 treatments at 4-week intervals, and evaluations were done by photographic and clinical assessment and histologic evaluation before the treatment and 1 month after the last laser treatment. Treatment outcome was graded by a blind observer using the Vancouver General Hospital (VGH) Burn Scar Assessment Scale. Symptoms such as pain, pruritus, and burning of the scar improved significantly. VGH scores improved in all treated sites, and there was a significant difference between the baseline and posttreatment scores, corresponding to an improvement of 51.4 +/- 14.7% (P < 0.01). Compared with the baseline, the mean percentage of scar flattening and erythema elimination was 40.7 +/- 20.7 and 65.3 +/- 25.5%, respectively (P < 0.01). The long-pulsed dye laser (595-nm) equipped with cryogen spray cooling device is an effective treatment of hypertrophic scars and can improve scar pliability and texture and decrease scar erythema and associated symptoms.
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Affiliation(s)
- Taro Kono
- Department of Plastic and Reconstructive Surgery, Tokyo Women's Medical University, Tokyo 162-8666, Japan.
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Shen W, Zhang J, Yang F. Three-dimensional model on thermal response of skin subject to laser heating. Comput Methods Biomech Biomed Engin 2005; 8:115-25. [PMID: 16154875 DOI: 10.1080/10255840500180849] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank-Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.
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Affiliation(s)
- Wensheng Shen
- Laboratory for High Performance Scientific Computing and Computer Simulation, Department of Computer Science, University of Kentucky, Lexington, KY 40506-0046, USA.
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Sivarajan V, Mackay IR. Noninvasive In Vivo Assessment of Vessel Characteristics in Capillary Vascular Malformations Exposed to Five Pulsed Dye Laser Treatments. Plast Reconstr Surg 2005; 115:1245-52. [PMID: 15809581 DOI: 10.1097/01.prs.0000156776.03772.fb] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The treatment of capillary vascular malformations by pulsed dye laser results in fading of these disfiguring lesions in the majority of patients. In only a minority, however, is full clearance of the lesion achieved. It is believed that the capillary composition of a capillary vascular malformation is an important determinant of whether it will respond to further laser treatment. Moreover, by determining the type, size, and depth of the ectatic capillaries within a capillary vascular malformation, it may be possible to target these vessels with specific laser parameters. METHODS The noninvasive technique of depth measurement videomicroscopy was used to delineate the capillary structure of 22 previously untreated capillary vascular malformations and examine how this structure changes after five treatments with a 0.45-msec pulse duration using a 585-nm pulsed dye laser. RESULTS After one and five treatments, there was a statistically significant lightening (p < 0.02 and p < 0.001, respectively) of the lesions, as seen on Munsell Color Chart testing. Before any laser treatment, the majority (59 percent) of capillary vascular malformations displayed a superficial type 1 or mixed capillary pattern, whereas after five laser treatments, the majority displayed a deep type 2 pattern (81 percent). After five laser treatments, there was a statistically significant increase in the depth of the remaining capillaries within the lesion compared with normal skin (p < 0.02) and a statistically significant reduction in the vessel diameters (p < 0.001). CONCLUSIONS The authors found that vessels with a diameter greater than 50 mum were adequately treated, whereas those smaller than 50 microm appeared resistant to laser treatment. These data would suggest that pulse durations longer than 0.45 msec are not required to treat large ectatic capillary vascular malformation vessels. The authors suggest that the failure to treat very-small-diameter vessels is attributable to thermal dissipation from the target vessels, whose thermal relaxation time is much shorter than the pulse duration of the laser used.
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Affiliation(s)
- Vivek Sivarajan
- Canniesburn Plastic Surgery Unit, Glasgow Royal Infirmary, Glasgow, Scotland, United Kingdom
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Pikkula BM, Chang DW, Dai T, Anvari B. Epidermal and vascular damage analysis of in vivo human skin in response to 595 nm pulsed laser irradiation. Lasers Surg Med 2005; 37:19-28. [PMID: 15971245 DOI: 10.1002/lsm.20191] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVES Laser irradiation is the current modality for treatment of cutaneous hypervascular malformations such as port wine stains and telangiectasia. Although cryogen spray cooling (CSC) is used to protect the epidermis from non-specific laser-induced thermal damage in moderately-pigmented skin types, individuals with high melanin content are still at risk for epidermal damage using the current laser irradiation and CSC parameters. The objective of this study was to investigate the influence of the spray Weber number (1,100 or 5,100) on epidermal protection and examine vascular coagulation in response to pulsed dye laser irradiation. STUDY DESIGN/MATERIALS AND METHODS Normal, in vivo human skin from eight subjects of Fitzpatrick skin types I-V were precooled with either low or high Weber number cryogen sprays and subsequently irradiated with a pulsed dye laser at 595 nm. Analysis of gross purpura, morphological vascular damage, and apoptosis of the vascular walls were performed. RESULTS Results demonstrated a high Weber number spray of 5,100 decreased the level of epidermal damage in darker and moderate pigmented individuals compared to a Weber number spray of 1,100. This study also established a positive correlation between gross purpura and the level of vessel wall apoptosis. CONCLUSIONS This study has demonstrated that CSC with a high Weber number spray can decrease nonspecific thermal damage to the epidermis in response to laser irradiation in vivo. We have also established a positive correlation between gross purpura and the level of vessel wall apoptosis. Lasers Surg. Med. (c) 2005 Wiley-Liss, Inc.
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Affiliation(s)
- Brian M Pikkula
- Department of Bioengineering, Rice University, PO Box 1892, Houston, TX 77251, USA
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Abstract
PURPOSE OF REVIEW Since the theory of selective photothermolysis was described, the field of facial plastic surgery has advanced the science behind laser: tissue interactions. Particular advances in skin cooling, hair removal, intense pulsed light, and uses for aesthetic and nonaesthetic skin problems are described in this review. RECENT FINDINGS Continued basic science research in lasers has led to improvements in current technology available to the facial plastic surgeon. Advances in skin cooling have allowed for wider use in all Fitzpatrick skin types without concomitant adverse reaction. SUMMARY Our understanding of laser science continues to expand our knowledge in basic laser: tissue interaction. An improvement in various laser mediums and adjunctive devices provides the facial plastic surgeon with instruments to treat a wider patient population. The benefit is a successful clinical and aesthetic result with improved safety.
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Affiliation(s)
- Liesl K Nottingham
- Vanderbilt Bill Wilkerson Center for Otolaryngology and Communication Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Aguilar G, Vu H, Nelson JS. Influence of angle between the nozzle and skin surface on the heat flux and overall heat extraction during cryogen spray cooling. Phys Med Biol 2004; 49:N147-53. [PMID: 15214549 DOI: 10.1088/0031-9155/49/10/n03] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
High speed video imaging and an inverse heat conduction problem algorithm were used to observe and measure the effect of the angle between the nozzle and surface of a skin phantom on: (a) surface temperature; (b) heat flux q; and (c) overall heat extraction Q during cryogen spray cooling (CSC). A skin phantom containing a fast-response temperature sensor was sprayed with 50 ms cryogen spurts from a commercial nozzle placed 30 mm from the surface. The nozzle was systematically positioned at angles ranging from 5 to 90 degrees (perpendicular) with respect to the phantom surface. It is shown that angles as low as 15 have an insignificant impact on the surface temperature, q and Q. Only exaggerated angles of 5 show up to 10% lower q and 30% lower Q with respect to the maximal values measured when nozzles are aimed perpendicularly. This study proves that the slight angle that many commercial nozzles have does not affect significantly the CSC efficiency.
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Affiliation(s)
- Guillermo Aguilar
- Department of Mechanical Engineering, University of California, Riverside, CA 92521, USA.
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