LXV Histologic Changes Produced by Endotracheal Intubation

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Abstract
Ulceration of the tracheal mucosa overlying the cricoid cartilage was produced consistently in anesthetized cynamolgus monkeys by insertion of an oversized endotracheal tube. The tubes remained in place for 2 hours. The tracheas were excised at periods ranging from 24 to 144 hours after termination of intubation, stained, sectioned and studied histologically. All but 2 of the larynges showed a rather marked polymorphonuclear infiltration. The ulcers appeared only over the cricoid cartilage. Epithelial regeneration had begun by 48 hours after intubation and was complete in some larynges by 144 hours. Edema was present over the cricoid cartilage in all larynges. During the first 48 hours, acid mucopolysaccharides increased in the submucosa of the larynges intubated with oversized tubes. This increase was greatest in the area around the conus elasticus, and had disappeared by 144 hours. The fine elastic fibrils that run through the submucosa and under the epithelium remained relatively intact in all specimens in all stages even in the area of polymorphonuclear infiltration and ulcera-tion. No significant vascular changes were noted. Dexamethasone given as a single 4 mg intramuscular injection to some of the animals just after the period of intubation apparently decreased the number of inflammatory cells infiltrating the traumatized area. It appeared to have no effect on edema, the speed with which epithelial regeneration occurred, or acid mucopolysaccharides.