Experimental induction of squamous metaplasia in the dog trachea with cuffed endotracheal tubes

Clinical reports cite the development of squamous metaplasia in tracheas following tracheostomy, laryngectomy, and cuffed intubation. The purpose of this study was (1) to develop an experimental model using the dog trachea and study the effects of prolonged cuffed intubation and (2) to determine whether squamous metaplasia is produced by prolonged contact of the endotracheal cuff with the tracheal mucosa. Modifications of widely used high-volume, low-pressure 8-mm endotracheal tubes were made with the distal portion of the tube, its cuff, and the inflating catheter attached. This model formed an implantable cuffed tube approximately 8 cm in length. The dogs remained intubated for 14 days, at which time they were killed; seven animals were available for histologic study. Varying degrees of squamous metaplasia were produced in all animals.