The function of the eustachian tube is to maintain pressure equality across the tympanic membrane. A number of tests have been utilized to study the condition of the eustachian tube. Of these, some tests measure only patency.
Several methods have been devised to test tubal function by determining the tubal transport of sound, air, radiopaque media, fluorescene, or a solution of sulfisoxazole diolamine (Gantrisin).
The results of tubal malfunction can also be determined. The pneumatophone and the otomanometer indirectly measure the pressure change in the tympanum resulting from poor tubal function. The Buckingham test confirms the presence or absence of a negative pressure in the tympanum. The results of tubal function tests have proven useful in predicting success at myringoplasty surgery.
James A. Donaldson. Physiology of the Eustachian Tube. Arch Otolaryngol. 1973;97(1):9–12. doi:10.1001/archotol.1973.00780010013003