Transendoscopic soft-tissue laser ablation in the equine upper respiratory tract

Abstract

Transendoscopic application of Nd:YAG laser energy for treatment of partial upper respiratory obstruction in the horse has been practiced for the last 12 years in both contact and non-contact modes. Endoscopic laser ablation has been limited to wavelengths transmitted through flexible optical fibers. Devices used for this purpose have been primarily the Nd:YAG (1064 nm), KTP (532 nm), holmium (2100 nm), and diode (805 nm) lasers. Few investigations have focused on use of the holmium or diode lasers. Objectives of this study were to evaluate use of fiber-deliverable laser wavelengths provided by newer, more portable, user-friendly, solid-state diode and holmium lasers for ablation of laryngeal tissues of the equine upper respiratory tract. In addition, information on efficacy and dosimetry for both the contact and non-contact modes was obtained using an in vitro cadaveric model. Preliminary conclusions based on histologic evaluation and scanning electron microscopy revealed that diode laser energy has the ability to penetrate laryngeal tissue easily and deeply with minimal collateral coagulation, but is sensitive to tissue color. Holmium laser energy can be used to incise laryngeal tissue easily in contact mode with moderate collateral damage, and absorption does not seem dependent on tissue color.