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Cryogen Spray Cooling (cryogen + spray_cooling)

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Medical Sciences100%

Selected Abstracts

Treatment of Port-Wine Stain Birthmarks Using the 1.5-msec Pulsed Dye Laser at High Fluences in Conjunction with Cryogen Spray Cooling

DERMATOLOGIC SURGERY, Issue 4 2002
Kristen M. Kelly MD
Background. The majority of port-wine stain (PWS) patients treated with the pulsed dye laser (PDL) do not achieve complete blanching. Safe administration of higher fluences has been proposed as a means of improving treatment efficacy. Objective. To determine the safety and efficacy of PWS treatment with the 1.5-msec PDL at high fluences in conjunction with cryogen spray cooling. Methods. Twenty PWS patients were treated with the PDL in combination with cryogen spray cooling utilizing a 7 or 10 mm spot size and fluences ranging from 6 to 15 J/cm2. Before and after treatment photographs were compared on a blinded basis. Results. No scarring or skin textural changes occurred. Blanching scores were as follows: 20% of patients achieved 75% or greater blanching after an average of 3.3 treatments, 30% achieved 50,74% blanching, 20% achieved 25,49% blanching, and 30% achieved less than 25% blanching. Conclusion. In conjunction with cryogen spray cooling, the PDL can be safely used at high fluences. At this time it is not clear that the use of higher fluences improves treatment efficacy; however, as other aspects of PWS laser treatment are optimized, safe administration of higher fluences is likely to be advantageous. [source]

Cryogen spray cooling: Effects of droplet size and spray density on heat removal

LASERS IN SURGERY AND MEDICINE, Issue 2 2001
Brian M. Pikkula BS
Abstract Background and Objective Cryogen spray cooling (CSC) is an effective method to reduce or eliminate non-specific injury to the epidermis during laser treatment of various dermatological disorders. In previous CSC investigations, fuel injectors have been used to deliver the cryogen onto the skin surface. The objective of this study was to examine cryogen atomization and heat removal characteristics of various cryogen delivery devices. Study Design/Materials and Methods Various cryogen delivery device types including fuel injectors, atomizers, and a device currently used in clinical settings were investigated. Cryogen mass was measured at the delivery device output orifice. Cryogen droplet size profiling for various cryogen delivery devices was estimated by optically imaging the droplets in flight. Heat removal for various cryogen delivery devices was estimated over a range of spraying distances by temperature measurements in an skin phantom used in conjunction with an inverse heat conduction model. Results A substantial range of mass outputs were measured for the cryogen delivery devices while heat removal varied by less than a factor of two. Droplet profiling demonstrated differences in droplet size and spray density. Conclusions Results of this study show that variation in heat removal by different cryogen delivery devices is modest despite the relatively large difference in cryogen mass output and droplet size. A non-linear relationship between heat removal by various devices and droplet size and spray density was observed. Lasers Surg. Med. 28:103,112, 2001. © 2001 Wiley-Liss, Inc. [source]

Treatment of Port-Wine Stain Birthmarks Using the 1.5-msec Pulsed Dye Laser at High Fluences in Conjunction with Cryogen Spray Cooling

DERMATOLOGIC SURGERY, Issue 4 2002
Kristen M. Kelly MD
Background. The majority of port-wine stain (PWS) patients treated with the pulsed dye laser (PDL) do not achieve complete blanching. Safe administration of higher fluences has been proposed as a means of improving treatment efficacy. Objective. To determine the safety and efficacy of PWS treatment with the 1.5-msec PDL at high fluences in conjunction with cryogen spray cooling. Methods. Twenty PWS patients were treated with the PDL in combination with cryogen spray cooling utilizing a 7 or 10 mm spot size and fluences ranging from 6 to 15 J/cm2. Before and after treatment photographs were compared on a blinded basis. Results. No scarring or skin textural changes occurred. Blanching scores were as follows: 20% of patients achieved 75% or greater blanching after an average of 3.3 treatments, 30% achieved 50,74% blanching, 20% achieved 25,49% blanching, and 30% achieved less than 25% blanching. Conclusion. In conjunction with cryogen spray cooling, the PDL can be safely used at high fluences. At this time it is not clear that the use of higher fluences improves treatment efficacy; however, as other aspects of PWS laser treatment are optimized, safe administration of higher fluences is likely to be advantageous. [source]

Pilot study examining the combined use of pulsed dye laser and topical Imiquimod versus laser alone for treatment of port wine stain birthmarks

LASERS IN SURGERY AND MEDICINE, Issue 9 2008
Cheng-Jen Chang MD
Abstract Background and Objective The objective of this study was to improve port wine stain (PWS) therapeutic outcome in response to laser therapy. Our specific aim was to determine whether the combined use of pulsed dye laser (PDL) therapy and topical Imiquimod versus PDL alone can improve PWS therapeutic outcome. Study Design/Materials and Methods This pilot study involved a retrospective review of 20 subjects, all Asian, with PWS. Subject ages ranged between 3 and 56 years. Upon enrollment, three test sites were prospectively identified on each subject for treatment assignments to the following regimens: (A) PDL+Imiquimod; (B) PDL alone; and (C) Imiquimod alone. PDL test sites received a single treatment with a 585 nm wavelength; 1.5 milliseconds pulse duration; spot size 7 mm using a light dosage of 10 J/cm2 with cryogen spray cooling. For the PDL+Imiquimod and Imiquimod alone test sites, subjects were instructed to apply Imiquimod topically to the sites once daily for 1 month after PDL exposure. Subjects were followed-up at 1, 3, 6, and 12 months after PDL exposure to evaluate each of the three test sites. The primary efficacy measurement was the quantitative assessment of blanching responses as measured by a DermoSpectrometer to calculate the hemoglobin-index of each site at 1, 3, 6, and 12 months after PDL exposure. Subjects were also closely monitored for any adverse effects. Results Based on paired sample test analysis, there were clinically, and statistically significant, differences in blanching responses over time favoring PWS receiving PDL+Imiquimod as compared to either PDL or Imiquimod alone (P<0.05). At 12 months, it should be noted that there was some evidence of redarkening of PWS test sites treated by PDL+Imiquimod and PDL alone, presumably due to revascularization of blood vessels. However, based on comparison of the hemoglobin-indices determined at 1 and 12 months after PDL exposure, there was less revascularization of PWS test sites treated with PDL+Imiquimod as compared to PDL alone (P<0.05). Transient hyperpigmentation was noted in 10% (n,=,2) and 40% (n,=,8) of subjects on the PDL+Imiquimod and PDL alone test sites, respectively. On all sites, hyperpigmentation resolved spontaneously without medical intervention within 6 months. Permanent hypopigmentation or scarring was not observed on any test site. Conclusion Based on the results of this pilot study, PDL+Imiquimod resulted in superior blanching responses over time as compared to PDL alone for treatment of test sites on PWS lesions. Although the PDL+Imiquimod approach is intriguing, clinical validation in large PWS patient samples is required. Lesers Surg. Med. 40:605,610, 2008. © 2008 Wiley-Liss, Inc. [source]

Improvement of port wine stain laser therapy by skin preheating prior to cryogen spray cooling: A numerical simulation

LASERS IN SURGERY AND MEDICINE, Issue 2 2006
Wangcun Jia PhD
Abstract Background and Objectives Although cryogen spray cooling (CSC) in conjunction with laser therapy has become the clinical standard for treatment of port wine stain (PWS) birthmarks, the current approach does not produce complete lesion blanching in the vast majority of patients. The objectives of this study are to: (1) experimentally determine the dynamic CSC heat flux when a skin phantom is preheated, and (2) numerically study the feasibility of using skin preheating prior to CSC to improve PWS laser therapeutic outcome. Study Design/Materials and Methods A fast-response thin-foil thermocouple was used to measure the surface temperature and thus heat flux of an epoxy skin phantom during CSC. Using the heat flux as a boundary condition, PWS laser therapy was simulated with finite element heat diffusion and Monte Carlo light distribution models. Epidermal and PWS blood vessel thermal damage were calculated with an Arrhenius-type kinetic model. Results Experimental results show that the skin phantom surface can be cooled to a similar minimum temperature regardless of the initial temperature. Numerical simulation indicates that upon laser irradiation, the epidermal temperature increase is virtually unaffected by preheating, while higher PWS blood vessel temperatures can be achieved. Based on the damage criterion we assumed, the depth and maximum diameter of PWS vessels that can be destroyed irreversibly with skin preheating are greater than those without. Conclusions Skin preheating prior to CSC can maintain epidermal cooling while increasing PWS blood vessel temperature before laser irradiation. Numerical models have been developed to show that patients may benefit from the skin preheating approach, depending on PWS vessel diameter and depth. Lasers Surg. Med. 38:155,162, 2006. © 2006 Wiley-Liss, Inc. [source]

Port wine stain treatment with a dual-wavelength Nd:Yag laser and cryogen spray cooling: A pilot study,

LASERS IN SURGERY AND MEDICINE, Issue 2 2004
an MD
Abstract Background and Objectives We report on a pilot study of port wine stain (PWS) treatment with a prototype Nd:YAG/KTP laser system, emitting simultaneously at 1,064 and 532 nm, and equipped with a cryogen spray cooling (CSC) device. Study Design/Patients and Methods On 10 patients (4,36 years old, mean: 16.2 years) with skin types II-III, therapeutic efficacy of the dual-wavelength laser (KTP+) was compared with a standard KTP laser (532 nm only) at the same pulse duration (25 millisecond), spot diameter (3 mm), and CSC parameters. The fluences were selected in order to obtain the same immediate response with both laser systems. Blanching of each test segment was assessed 8 weeks post treatment by an independent evaluator and by the subjects, and graded on a 1,4 scale. Results Significant blanching of PWS was noted 8 weeks after a single therapeutic session with the KTP+ laser (mean: 532 nm radiant exposure: 8.2 J/cm2), very similar to that observed with KTP at 12.4 J/cm2. The evaluator noticed a slight brownish coloration in areas treated with the KTP+ laser. Isolated beam-sized atrophic scars were present in two patients where KTP+ (9 and 10 J/cm2) and KTP (14 J/cm2) lasers were used. Conclusions The addition of 1,064 nm radiation allowed a significant reduction of 532 nm radiant exposure with no loss of efficacy in PWS treatment. Lasers Surg. Med. 34:164,167, 2004. © 2004 Wiley-Liss, Inc. [source]