Attempt to obtain greater dermal depth of vascular injury using dye-enhanced laser technique: a new approach

Although pulsed dye laser has been successfully used in the treatment of portwine stains, a number of patients had incomplete clearance because the depth of penetration by the pulsed dye laser was inadequate. This study was performed to establish the greater penetration depth of vascular injury using a dye-enhanced laser technique.

The ruby laser at 694.3 nm was used, and the corresponding specific dye was Prussian blue solution (maximum absorbance 694 nm). We compared the penetration depth of vascular injury by the ruby laser irradiation after the Prussian blue injection with that by the dye laser irradiation. A flashlamp dye laser with a pulse duration of 300 microseconds and a 5 mm diameter spot size was used to 6.2 J/cm2 at 590 nm. The Prussian blue solution was injected into the superficial epigastric artery of white male Japanese rabbits, immediately followed by the ruby laser exposure to 6.2 J/cm2 at a pulse duration of 283 microseconds in a 15 x 15 mm spotsize. Depth of penetration was measured from the dermoepidermal junction to the deepest site of vascular injury at 24 hours after laser exposure.

Mean penetration of 590 nm of the dye laser light was 1.45 mm; mean penetration of the 694.3 nm ruby laser irradiation after the Prussian blue injection was 2.33 mm. Ruby laser penetration was greater than that of the dye laser.

This study emphasizes that the ruby laser irradiation after the Prussian blue injection can induce deeper vascular injury than the dye laser inducing similar pathological changes.