Preliminary studies of gas resorption from the middle ear.

Abstract

133Xenon, dissolved in physiological NaCl, was introduced into the middle ear systems of 9 subjects with normal otoscopic findings. The activity over the middle ear system was measured with a scintillation detector and the activity in the expired air was simultaneously recorded with a separate, shielded detector. In 3 tracheotomized cases the expired air was collected directly from the tracheal cannula. The recordings on living subjects as well as model experiment and measurements on dead subjects show a primary phase of faster decrease mainly due to the mixing of xenon and air in the closed middle ear system. A secondary and slower phase represents the resorption and removal of xenon from the cavity. This means that the decrease of activity of a radioactive gas introduced into the ear does not reflect a real absorption by the vessels in the mucosa before the end of a 8–10-minute period. The half-life has been calculated. There was no correlation between the volume of the middle ear system and the disappe...