Passive eustachian tube opening pressure. Its measurement, normal values, and clinical implications.

To measure passive eustachian tube opening pressure (PETOP) we have developed a pressure recording instrument that is activated by the sudden fall in output voltage of a sensitive acoustic impedance meter that occurs at the moment of transnasal insufflation of the middle ear. The PETOP was measured in 112 normal subjects aged 2 to 40 years. Normal values rose significantly throughout childhood and stabilized in early adolescence. When sequential insufflations were performed in the same subject, the PETOP fell, even though middle ear pressures had completely returned to baseline values before succeeding measurements were taken. Falls were enhanced by sequential swallowing. Our observations may be explained by the activity of surfactants in the eustachian tube. Measurement of PETOP may provide a more direct means of studying eustachian tube function than that provided by tympanometry alone.