Quantitative study of the early effects of tracheotomy and endotracheal intubation on the rabbit tracheobronchial tree.

Histopathologic evaluation of the tracheobronchial tree was performed in 12 rabbits to study the effects of 1 hour of tracheotomy or endotracheal intubation. In five animals who underwent oral endotracheal intubation, epithelial erosions and submucosal inflammation in the proximal (bronchial) airway covered 34.9% and 71.3% of the luminal circumference, respectively. This was highly significant (p less than .001) against two control animals, in which 4.8% erosion and 3.9% inflammation were observed. Tracheotomy in three animals caused 22.8% bronchial epithelial erosion and 46.0% inflammation, which were not significantly greater than values of 15.0% and 20.6% observed following "sham" tracheotomy. The severity of the proximal (indirect) consequences of endotracheal intubation may have been attributable to the lack of humidification, but this does not explain the lesser damage caused by tracheotomy. It is postulated that increased inspiratory flow rate and pressures occurring in endotracheally intubated animals may be contributory factors.