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The role of dynamic cooling in improving clinical efficacy during pulsed dye laser treatment of port wine stain in Chinese

by Chiu, Chun-hung

Abstract (Summary)
(Uncorrected OCR) Abstract of thesis entitled

The Role of Dynamic Cooling in Improving Clinical Efficacy during Pulsed Dye Laser Treatment of Port Wine Stain in Chinese

submitted by

Chiu Chun Hung

for the degree of Master of Philosophy at the University of Hong Kong

in July 2003

Port-wine stain (PWS) is a form of congenital vascular malformation that affects 0.5 % of newborns and is commonly associated with psychosocial impairment. Pulsed dye laser (PDL) in conjunction with dynamic or cryogen spray cooling (CSC) is effective in improving efficacy and safety in the treatment of PWSs in Caucasians. However, for dark-skinned patients such as Chinese, only retrospective studies have been performed. The purpose of this study is to prospectively compare the clinical efficacy and acute and long-term adverse effects of PDL alone and PDL in conjunction with CSC (pDL-CSC) for the treatment of

PWSs in Chinese patients.

Chinese patients with previously untreated PWSs were recruited. In every patient, a pre-defined test area on the PWS was treated. Half of the tested area was treated with PDL alone and the contralateral half was treated with PDL-CSC. The degree of PWS blanching was objectively assessed by spectrophotometer. Changes in skin elasticity were objectively detected by cutometer. All measurements were taken at baseline and before each subsequent laser session. Patients were interviewed immediately after treatment and again the following week with a visual analog scale questionnaire to measure the degree of pain and swelling. The occurrence of blisters was noted during each follow-up visit. Patients were also evaluated for evidence of long-term effects such as dyspigmentation and scarrmg.

Thirty-five patients (13 male and 22 female) were enrolled, and 131 treatment sessions were performed in this study. Statistically significant higher fluences were used on the PDL-CSC treated halves (6.5 J/cm2 for PDL alone, 10.7 J/cm2 for PDL-CSC). The percentage change in the a* value from spectrophotometry was significantly greater (24.8 % for PDL alone, 40.8 % for PDL-CSC), and hence more PWS blanching after treatment for PDL-CSC. No significant differences were found in important cutometer parameters after three treatments with PDL alone or PDL-CSC. The immediate pain scores were significantly higher for PDL alone (score 3.90) than for PDL-CSC (score 3.12). Blisters were significantly more common on the side that was treated by PDL alone (25 %) than PDL-CSC (15 %). The overall incidence of long-term effects was not significantly different between

PDL alone and PDL-CSC. PDL-CSC was also the preferred treatment modality for most patients (72.5 %).

To summarize, PDL-CSC is more effective than PDL alone in the blanching of PWSs in Chinese patients after three or more treatment sessions. PDL-CSC is also better tolerated, and higher fluences can be used with less blistering. The determination of optimal parameters for laser irradiation and dynamic cooling is still necessary to achieve consistent blanching in the treatment of dark-skinned patients.

Bibliographical Information:

Advisor:

School:The University of Hong Kong

School Location:China - Hong Kong SAR

Source Type:Master's Thesis

Keywords:dye lasers skin diseases cryosurgery

ISBN:

Date of Publication:01/01/2003

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