Model-based evaluation of eustachian tube mechanical properties using continuous pressure-flow rate data.

Eustachian tube (ET) dysfunction has been implicated in the development of chronic otitis media, a common childhood disorder. An impaired ability to open the collapsible ET results in fluid accumulation in the middle ear and subsequent infection and inflammation. Abnormal ET function has been casually related to an abnormal mechanical environment. Previous attempts to quantify ET mechanics used summary measures that are not clearly related to the physical properties of the system. In this study, we modified a testing technique to obtain pressure and flow rate measurements in the ET and analyzed these data with a simple model of airflow in a collapsible tube. This model is based on fully developed flow in a noncircular duct and a nonlinear, time-dependent pressure-area relationship. The ability of this model to capture the observed pressure-flow phenomena was demonstrated in 12 cynomolgus monkeys. Correlation between model and experimental data resulted in quantitative estimates of ET compliance and wall viscosity. This technique, which can be implemented in a clinical setting, provides a more accurate description of ET mechanics and may, therefore, prove to be an important diagnostic tool. Future studies will use this technique to quantify the influence of various physiological parameters on ET mechanics.