Performance of the 808-nm diode laser on equine upper airway tissue is enhanced by intravenous administration of indocyanine green.
OBJECTIVE
The objective was to develop a protocol whereby 808-nm diode laser irradiation combined with intravenous (IV) indocyanine green (ICG) could be used in non-contact mode with equal surgical efficacy to the Nd:YAG on equine tissues.


BACKGROUND
The 808-nm diode laser, delivering 20-40 W of power, has been produced for veterinary medical applications. This laser's power output is less than that of most neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers. ICG is absorbed at a wavelength of 810 nm, which when concentrated in tissue should be an excellent absorber for the energy produced by the 808-nm diode laser.


METHODS
This study compares the depths and widths of thermal penetration achieved with the 808-nm diode laser in equine respiratory tissue after intravenous injection of ICG. ICG was administered at two doses: 1.5 mg/kg and 3 mg/kg. The 808-nm diode laser and Nd:YAG laser were set to deliver 200 J of energy. The depths and widths of thermal penetration obtained were compared.


RESULTS
Lesion depth and width tended to be greater in the ICG + 3 mg/kg group than in the ICG + 1.5 mg/kg group. Even so, the 1.5-mg/kg dose substantially increased the efficacy of the diode laser. Plasma ICG concentrations peaked at 5 min post-administration and then dropped markedly; lesion depth decreased after peaking at 7 min post-administration.


CONCLUSIONS
This study demonstrated that the 808-nm diode laser, when augmented with intravenous ICG, will be as effective a surgical tool as the Nd:YAG laser on equine upper airway tissues when applied using a non-contact fiber.
Tate
Lloyd P
LP
Department of Clinical Sciences (LPT, ATB), North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina 27606, USA. jock_tate@ncsu.edu
Blikslager
Anthony T
AT
Papich
Mark G
MG
D000818:Animals; D004396:Coloring Agents / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006736:Horses; D007208:Indocyanine Green / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D054023:Lasers, Semiconductor; D009297:Nasal Mucosa / Q000187:drug effects* / Q000528:radiation effects*
D004396:Coloring Agents; D007208:Indocyanine Green