Squamous metaplasia in the trachea: the tracheotomized rabbit as an experimental model and implications in recurrent papillomatosis.

Squamous metaplasia following tracheotomy has been well documented. Most studies have dealt primarily with changes at--or adjacent to--the cuff site and have failed to evaluate its effect in the distal trachea. We have used rabbits as experimental models for the induction of tracheal squamous metaplasia, using uncuffed tracheotomy tubes. Rabbits were routinely killed 24, 36, 48, 72, 120, and 168 hours posttracheotomy, and the entire larynx, trachea, and main-stem bronchi were step-sectioned for histologic examination. Patchy areas of squamous metaplasia were found in all rabbits with tracheotomy equal to or longer than 48 hours. The metaplasia appeared to increase with time of intubation. Induction of squamous metaplasia (following tracheotomy as a contributing factor to the spread of laryngeal papillomatosis) is discussed.