Temperature distribution in the upper airway after inhalation injury.

OBJECTIVE: The aim of the study was to establish an animal model of laryngeal burn and to investigate the temperature distribution of heated air in the upper airway. METHODS: The animal model was established by inhalation of dry heated air at 80, 160 and 320°C in 18 healthy, male, adult hybrid dogs. Time for inducing injury was set at 20min. The distribution of temperatures after heated-air inhalation was examined at different locations including the epiglottis, laryngeal vestibule, vocal folds and trachea. RESULTS: The temperatures of the heated air decreased to 47.1, 118.4 and 193.8°C at the laryngeal vestibule and to 39.3, 56.6 and 137.9°C at the lower margin of vocal folds in the 80, 160 and 320°C groups, respectively. CONCLUSION: Due to its special anatomy and functions, the larynx has different responses to dry heated air at different temperatures. The air temperature decreases markedly when the air arrives at the larynx. By contrast, the larynx has a low capacity for blocking high-temperature air and retaining heat. As a result, high-temperature air often causes more severe injury to the larynx and the lower airway. [ABSTRACT FROM AUTHOR]