Evaluation of the Parameter "Mean Impedance" for Representing Eustachian tube Functions During Pressure Increase and Decrease in Pressure Chamber Measurements.

Hypothesis: The hypothesis of the study is that the mean impedance (MI) during compression and decompression provides additional information of the Eustachian tube (ET) function.

Background: The continuous impedance measurement in a pressure chamber can provide valuable information about the opening function of the ET.

Methods: Around 55 ear-healthy volunteers were examined in a pressure chamber. These were subjected to a decompression phase and a compression phase. The pressure change was constantly 20 kPa/min. Using evaluation software, the MI could be determined for both ears in each case for the phases of compression and decompression.

Results: In 49 participants, we could interpret the data successfully. On average, an output value (without pressure changes) of the impedance of 0.58 ±0.11 Pa on the right side and 0.43 ± 0.1 Pa on the left side were measured. During decompression, 0.098 ± 0.05 Pa (right) and 0.087 ± 0.043 Pa (left) could be determined. For compression, values of 0.086 ± 0.044 Pa on the right and 0.079 ± 0.045 Pa on the left were detected. The retest reliability was higher with an intraclass correlation coefficient for the decompression MI of 0.833 than the 0.772 compression MI.

Conclusions: It is possible to measure MI in healthy subjects during compression and decompression. This value represents a good average in terms of the pressure tolerance of the middle ear. In future, studies will be required to determine whether MI will be a useful parameter in differentiating normal and abnormal ET function.