Stephen T. Flock

Flash pump dye laser treatment of laryngeal papillomas.

To evaluate the feasibility and safety of the flash pump dye (FPD) laser for the treatment of laryngeal papillomas, we performed a prospective nonrandomized trial comparing FPD and carbon dioxide (CO2) laser treatment of laryngeal papillomas in a tertiary care childrens hospital. Nine patients from 2 to 20 years of age with severe recurrent laryngeal papillomas were enrolled in the study. All patients underwent CO2 laser debulking of papillomas on the left hemilarynx, with 8 W continuous or pulsed energy. The right hemilarynx was treated with the FPD laser with 12 to 77 pulses at 8 to 12 J, through a custom-designed 90° firing fiber. An end point of blanching and purpura of the papillomas was used. The main outcome measures were the safety and ease of operation with the FPD laser, and decreased papilloma size based on visual inspection at 2 weeks postoperative and at the next laser procedure. Seven patients were irradiated 1 time with an FPD laser, and 2 patients 2 times. No intraoperative complications were noted. One patient developed early postoperative stridor. No patients described more discomfort, and 5 patients described their voice as being the same as or better than it was after prior CO2 laser procedures. Five patients had a 90% or more decrease in size of papillomas on the FPD-irradiated side 2 weeks postoperatively. Three patients had approximately a 50% reduction. A treatment effect was noted in all patients, and was similar to the results noted on the CO2 laser-treated side. Early results with FPD laser treatment of laryngeal papillomas suggest the protocol is relatively safe and feasible. Long-term results are pending. Because the FPD laser coagulates rather than vaporizing tissue, potential advantages may include decreased scarring relative to CO2 laser treatment, and improved patient and operator safety.

Photodynamic Therapy with Chloroaluminum Sulfonated Phthalocyanine in the Rat Window Chamber

The efficacy of photodynamic therapy tumor destruction is dependent upon both the interruption of the tumor vasculature and the resultant production of unstable oxygen species causing cellular oxidation and death. Chloroaluminum sulfonated phthalocyanine (CASP) is a recently developed photosensitizer. In order to study the direct vascular effects of CASP on a non-tumor system, a rat window chamber was utilized. Twelve rats were implanted with the window chamber, and were divided into two groups of six. Three rats served as controls for each group (receiving light alone, CASP alone, or no treatment). The remaining 6 rats received 10 mg/kg CASP intravenously 4 days after chamber placement. Photoactivation with light was performed 24 hours after injection (power density 200 mW/cm2, irradiance 100 J/cm2, lambda = 675 nm). Utilizing integrating sphere measurements and image analysis, marked vascular changes in the form of initial vasospasm followed by vaso-constriction and loss of chamber neovascularization were noted in the CASP-PDT group. The control groups exhibited no significant changes. Manipulation of the chamber vasculature at strategic time-points may translate into improved response rates for photodynamic therapy in a tumor model.

Chloroaluminum sulfonated phthalocyanine versus dihematoporphyrin ether: Early vascular events in the rat window chamber

The development of a simple and well‐tolerated rat window chamber has allowed direct comparison of the vascular effects of two photosensitizers, chloroaluminum sulfonated phthalocyanine (CASP) and dihematoporphyrin ether (DHE).

An implantable tumor-window chamber model for the study of photodynamic therapy.

In order to study both the anti-tumor effects and early vascular events in photodynamic therapy, a useful animal model has been developed. A window chamber is surgically placed on the dorsum of the Fischer-344 rat, and 500-μm fragments of the rat mammary adenocarcinoma 13672 are placed under direct vision into the subcutaneous tissue. Implantation of the chamber has been successfully completed in more than 50 rats. The operative procedure Is straightforward and is accomplished in less than 1 hour. Using tumor fragments, tumor viability has been 60%. We have demonstrated obvious and reproducible neovascularization occurring as soon as 1 day after implantation. The application of this system to an experimental protocol comparing the photosensitizes dihematoporphyrin ether (DHE) and chloroaluminum sulfonated phthalocyanine (CASP) has yielded important information on early vascular events resulting from photodynamic therapy.

08:00 AM: Port-Wine Stains: An Assessment of Five Years of Treatment

Objective: Treatment of port-wine stains (PWS) with the flashlamp pumped dye laser (FPDL) is well established; however, reports of clinical efficacy and complication rates have been extremely variable. The purpose of this study was to objectively assess the results of FPDL treatment of 102 patients with PWS at our institutions from 1989 to 1994. Methods: Evaluation was performed by comparing preand post-treatment photographs to the patients presenting appearance at follow-up examination. Clinical response was determined by assigning a percentage of lesional lightening score by two physicians and the patient and by reflectance spectrophotometric measurements. Results: Of 102 patients with 118 PWS seen in follow-up evaluation, 18 (15.3%) had greater than 90% lesional lightening (complete/near complete response), 77 (65.3%) had 1996