Surface alterations due to endotracheal intubation.

The varied complication of prolonged endotracheal intubation, including tracheal stenosis, stricture and tracheomalacia, are thought to be directly related to lateral tracheal wall pressure. To investigate the initiation, relevance and duration of these changes, studies were undertaken to assess the effects of intubation on the surface anatomy of the trachea by scanning electron microscopy. Tracheal mucosal morphology was studies in (1) anesthetized "normal" dogs; (2) d-ogs sacrificed 2 hours after intubation with cuff deflated or inflated to the "just seal" point using a cuff system producing the lowest tracheal wall pressure; and (3) dogs intubated for 2 hours and then examined at 2 and 7 days after extubation. Intubation without cuff inflation resulted in distinct linear areas of nearly complete ciliary denudation along the tract of tubal insertion within 2 hours. Inflated cuffs produced similar but more widespread changes especially over tracheal rings, indicating that pressure in areas of least resiliency significantly contributes to these alterations. Regeneration of cilia could be seen 2 days after extubation, but many anatomic features remained distorted; at 7 days, regeneration was nearly complete, but isolated areas of denudation could still be identified. Scanning electron micrographs of human tracheas taken at autopsy from patients who had had prolonged intubation with the same cuff system correlated well with those obtained from dogs.