Laryngeal Thermal Injury Model

A lack of reliable laryngeal thermal injury models precludes laryngeal burn wound healing studies and investigation of novel therapeutics. We hypothesize that a swine laryngeal burn model can allow for laryngeal burn evaluation over time. Twelve Yorkshire crossbreed swine underwent tracheostomy and endoscopically directed laryngeal burns using heated air (150-160°C). Swine larynges were evaluated and sectioned/stained at 12 hours, 1, 3, 7, 14, and 21 days. A board-certified veterinary pathologist assessed anatomic regions (left and right: epiglottis, true/false vocal folds, and subglottis) using a nine criteria histological injury scoring scale. Six swine were euthanized at scheduled endpoints, three prematurely (airway concerns), and three succumbed to airway complications after 16 to 36 hours. Endoscopic and gross examination from scheduled endpoints revealed massive supraglottic edema and tissue damage, particularly around the arytenoids, extending transglottically. Swine from premature endpoints had comparatively increased edema throughout. Microscopic evaluation documented an inverse relationship between injury severity score and time from injury. Inflammation severity decreased over time, nearly resolving by 14 days. Neutrophils predominated early with histiocytes appearing at 3 days. Granulation tissue appeared at 3 days, and early epiglottic and/or subglottic fibrosis appeared by 7 days and matured by 14 days. Edema, abundant initially, decreased by day 3 and resolved by day 7. This approach is the first to provide longitudinal analysis of laryngeal thermal injuries, reflecting some of the first temporal wound healing characteristic data in laryngeal thermal injuries and providing a platform for future therapeutic studies.