Jiang, Tao, Liping Zhao, Yanbo Yin, Huiqian Yu, and Qingzhong Li. Evaluation of middle ear function by tympanometry and the influence of lower barometric pressure at high altitude. High Alt Med Biol. 22:70-76, 2021. Objective: To evaluate middle ear function in residents of high-altitude areas in comparison to sea-level participants. Design: Prospective observational study. Setting: All experiments were performed by experienced audiologists with a calibrated tympanometry machine. Participants: Young adults between the age of 17 and 23 were recruited. Seventy-five participants from Shanghai (altitude 4 m) and 133 participants from the Shigatse area (altitude 4,040 m) were recruited. Any participant with any otological disorder was excluded. Main Outcome Measure: Four indexes of the tympanogram were evaluated in the two groups from different altitudes. Results: Our results showed that the peak of static compliance for the participants in Shigatse was smaller, but the absolute compliance of tympanic membrane remained the same. Similarly, the ear canal volume (ECV) from tympanometry was also affected by the elevated altitude in Tibet. In addition, the tympanometric peak pressure was decreased in high-altitude residents, which suggests a slightly declined function of the Eustachian tube at lower barometric pressure. However, no difference was found in the tympanometric width (TW). Conclusion: Our results indicate that tympanograms were affected by decreased atmospheric pressure at high altitude. Therefore, other than pressure-related indexes, TW is better for evaluating the function of the middle ear in high-altitude regions.
Keywords: high altitude; middle ear; tympanometry.