Repeated inflation does not prevent otitis media with effusion in a monkeymodel

Objective: Investigate the efficacy of repeated middle ear inflation with a n inert gas (argon) for preventing the development of middle ear effusion i n monkeys with functional eustachian tube obstruction. Study Design: Prospe ctive controlled trial of daily middle ear inflation with five monkeys assi gned to the inflation group and four to the control group. Methods: The lig ht tensor veli palatini muscle of nine monkeys was paralyzed with botulinum toxin, Tympanometry was done before the procedure and then daily for 21 da ys. Presence and distribution of effusion were assessed before paralysis an d on day 15 using magnetic resonance imaging (MRI), In five right ears infl ation was done beginning at the first observation of negative middle ear pr essure of less than or equal to-200 nun H2O and repeated on all days with p ressures less than or equal to-100 mm H2O. Four right ears served as uninfl ated controls, Results: Right middle ear pressure de creased in all animals over the course of the study. Pressure returned to near-ambient levels imm ediately following the argon inflation but was decreased to control levels at the subsequent observation on the following day. MRI at day 15 documente d effusion in all right ears with no quantifiable differences in amount or distribution between ears that were and were not inflated with argon, Concl usions: Repeated inflation with an inert gas does not prevent middle ear ef fusion in monkeys with functional eustachian tube obstruction.