Therapeutic effects of eustachian tube surfactant in barotitis media in guinea pigs

Background: Previous research has shown that the eustachian tube (ET) in animals and humans is lined with a substance that lowers surface tension and thus facilitates the opening of the eustachian tube and aeration of the middle ear. The aims of the present study were to observe the role of eustachian tube surfactant (ETS) on the opening of the ET and to explore the therapeutic effect of natural and artificial ETS on barotitis media (BOM). Methods: BOM was successfully established in 50 guinea pigs by simulated ascent in an altitude chamber. Subsets of the affected ears were treated by flushing with natural ETS, artificial ETS, artificial phospholipid, or saline. The effects were evaluated by measuring eustachian tube pressure opening level (POL). Other animals with BOM were treated with artificial ETS on one side and saline in the other, after which the clinical signs were observed. Results: The POL of the saline group remained unchanged. Natural ETS decreased the POL from 11.98 to 6.11 kPa (p < 0.01); artificial ETS reduced the POL from 11.91 to 6.67 kPa (p < 0.01); there was no significant difference between the two treatments. Artificial phospholipid was less effective, decreasing POL from 11.86 to 8.61 kPa (p < 0.05). Clinical observations showed that after 1 wk of treatment with artificial ETS, the congestion in the tympanic membrane was alleviated, the hearing threshold improved, and the effusion in tympanic cavity diminished. Conclusion: Artificial ETS was as effective as natural ETS in facilitating the opening of eustachian tube and had definite therapeutic effects on BOM in this model.