Influence of surface condition of mucosa of eustachian tube on tubal compliance.

To clarify the influence of the mucosal condition of the eustachian tube (ET) upon its collapsibility, three experimental studies were performed by using the forced response test. First, by washout of the mucous blanket of ET, the tubal compliance index (TCI), the ratio of passive tubal resistances at two different airflow rates, significantly increased in all the 6 ETs of 5 cats, and all returned to the baseline within 50 min. Second, the TCIs significantly decreased in all the 7 ETs of 5 cats after application of Triton X (surfactant) into the ET washed out by saline. Third, the increased TCIs of a tubal model by application of saline significantly decreased after application of Triton X. These results seem to support our hypothesis that compliance of the ET, which means its collapsibility, may depend upon the mucosal condition as well as on the property of the cartilaginous framework of ET.