gms | German Medical Science

Impaired middle ear ventilation can cause a sensation of pressure and otalgia. Persistent impairment can lead to tympanic membrane retraction and chronic otitis media. The usual clinical tests of tube function rarely yield valid results. Diagnostic tests in a hyperbaric chamber enable the dynamic measurement of middle ear pressure under physiological conditions. In our prospective study, patients with tube dysfunction were compared with a control group. Measurements were taken in a hyperbaric chamber with ambient pressure changes generating relative underpressures and overpressures in the tympanic cavity.

The eardrum distension caused by pressure changes led to a change in eardrum impedance, which was measured and analyzed. The tube closing pressure and antagonistic tissue pressure in the nasopharynx could thus be determined.

Subjects with normal tube function could be differentiated from patients with failure of tube closing or opening. The groups differed in the number of pressure equalizations needed. It was impossible for patients with tube opening disorders to equalize pressure differences beyond a certain limit. Ambient pressure changes caused only small impedance changes in patients with tube closing failure.

Determining tube function by measuring the impedance under variable ambient pressure is a valid method for identification of tube dysfunction. The findings provide an important basis for the establishment of therapeutic strategies for tube dysfunction and those associated with middle ear diseases.