Use of hyperosmotic chemical agent to improve the laser treatment of cutaneous vascular lesions.

A method is presented for decreasing radiant exposures required for photocoagulation of cutaneous blood vessels using a hyperosmotic agent applied to skin prior to laser irradiation. The 50% probability for a given radiant exposure (RE50) to result in photocoagulation of vessels classified by type (arteriole, venule) and diameter was determined following direct (subcutaneous) laser irradiation of 84 vessels in a dorsal skin preparation pretreated with glycerol. Values were compared against results without glycerol pretreatment. A second set of experiments involved irradiation of blood vessels through the skin from the epidermal surface after application of glycerol. Subcutaneous RE50s for vessels treated with glycerol were typically several factors lower than untreated vessels. For example, arterioles in the 80- to 110-microm-diam range in untreated skin had RE50 values approximately 12 J/cm(2), compared to approximately 2 J/cm(2) in glycerol-treated cases. Results from epidermal irradiations also indicate that pretreatment with glycerol decreases radiant exposures required for photocoagulation. Vessels were successfully coagulated from the epidermal side in glycerol-treated samples using radiant exposures ranging from 1.6 J/cm(2) to 5 Jcm(2), compared to the 12 to >16 J/cm(2) range for control cases. We believe that this method could be a powerful technique for reducing the radiant exposures required for vessel photocoagulation.