Tubomanometry Measurement Success Rate in Clinical Practice

Tubomanometry (TMM) is an objective method for investigating Eustachian tube (ET) function, but difficulties in technique and interpretation may reduce its usability. The objective of our study was to investigate common difficulties with TMM in different ET dysfunction (ETD) patient groups and at different pressures (30, 40, and 50 mbars) when first introducing TMM to otologic practice. Furthermore, we wanted to investigate whether it would be possible to perform TMM at only one pressure and obtain a representative result.

A retrospective chart review of a 2-year cohort of 114 patients with a history of ETD treated at a tertiary referral center. Primary outcome was the success rate of TMM, secondary the reasons for unsuccessful measurements. Tertiary outcome was the correlation of TMM results at adjacent pressures.

TMM success rate was 91%, varying 81 to 94% in different ETD patient groups and 87 to 94% at different pressures. Unsuccessful measurements resulted from air-leaks from the external ear canal, abnormal ear canal pressure curves (R < 0) and at 50 mbar, difficulties in reaching sufficient nasopharyngeal pressure. TMM results were similar in 88% of cases at 30 and 40 mbars and in 86% of cases at 40 and 50 mbars.

TMM success rate seems sufficiently high for clinical diagnostics, and most difficulties may be overcome with proper interpretation during the TMM measurement session, and thus repeating the measurements when necessary. Considering the diagnostic information that would be lost if using only a single, predefined pressure, we suggest using all three pressures.