Gas exchange function of the middle ear in patients with otitis media with effusion

Abstract

Gas exchange function through the middle ear mucosa was assessed using nitrous oxide (N2O) in patients with otitis media with effusion (OME), as well as in normal ears during elective surgery for unrelated disorders. In all normal ears except one (n = 43), an increase in pressure was observed after N2O inhalation. In 42 of 84 ears with OME, a pressure increase was observed, but not in the remaining 42 ears (50%), indicating that the gas exchange function in these latter ears was impaired. In 21 of the 42 ears showing no middle ear pressure increase following N2O inhalation, the middle ear pressure was again monitored after myringotomy and aspiration of the effusion A pressure increase was found in 16 ears, indicating that the impairment in gas exchange function in ears with OME may be reversible in most cases. Computed tomography of the mastoid was examined preoperatively in 66 ears, with the presence or absence of a middle ear pressure change well correlated in 57 ears with the presence or absence of mastoid aeration.

Mastoid Condition and Clinical Course of Cholesteatoma

“…The other interpretation is based on our pre- Hasebe/Takahashi/Honjo/Miura/Tanabe vious observations of the transmucosal gas exchange function in the middle ear. We found that the presence or absence of gas exchange function was compatible with the presence or absence of aeration in the middle ear [3][4][5]. The present results, therefore, suggest that impairment of transmucosal gas exchange function in the mastoid may be closely related with progressiveness of cholesteatoma.…”

“…We have developed a method to assess the gas exchange func-tion of the middle ear using nitrous oxide [3], and have shown, through the observation of ears with otitis media with effusion (OME) in children, that the gas exchange function is lost when the airspace (aeration) in the middle ear is completely lost [4]. Furthermore, using the same method, we also showed that complete mastoidectomy results in total loss of the gas exchange function and aeration in the mastoid in ears with chronic otitis media [5] and that the external auditory canal wall skin frequently retracts towards the mastoid after complete mastoidectomy probably due to the loss of gas exchange function and airspace in the mastoid [6].…”

The mastoid as a functional rate-limiter of middle ear pressure change

“…gases characterized by perfusion limited transmucosal exchange). Previously, a significant increase in ME pressure was reported for anesthetized patients breathing gas mixtures that included N 2 O [7,30] and one study reported paired data for pneumatized MACS area and the rate of change in ME pressure during 50% N 2 O breathing in adult subjects [18]. Like N 2 , N 2 O is an inert gas whose rate of exchange across the ME mucosa is primarily perfusion limited [28].…”

The diagnostic and prognostic value of eardrum mobility in otitis media with effusion

“…Since 1994, we have examined gas exchange function through the middle ear mucosa in ears with OME and found that function was impaired in approximately half of the ears with OME, and the presence or absence of function in ears depends upon the presence or absence of aeration (an air space) in the middle ear [7,8]. These results led us to a hypothesis that OME ears with impaired gas exchange function having no aeration in the middle ear might take more prolonged courses than those with intact function having aeration in the middle ear.…”