Reliability of a measure of eustachian tube function in normal subjects.

Short-term reliability of a tympanometric pressure-swallow technique for assessing eustachian tube (ET) ventilating efficiency was measured in 20 normals with intact tympanic membranes on otoadmittance and impedance instruments. Tympanograms were examined for middle ear pressure and amplitude after a swallow maneuver and manipulation of ear canal pressure in a repeated measures design. Test-retest correlations were examined for both pressure shift and amplitude. Poor reliability was obtained for pressure measures with otoadmittance, while high reliability was observed for pressure values on impedance trials and amplitude for both instruments. Findings suggested significant probability of misclassification of normals for repeated measures of ET efficiency, using the currently accepted criterion for minimum pressure shift.