Higher rates of pressure decrease in inflamed compared with noninflamed middle ears

Abstract

Recent clinical trials have renewed interest in middle ear inflation as a treatment for otitis media with effusion. However, air inflation in human beings with significant negative middle ear pressures was shown to be followed by a rapid pressure decrease to approach the preinflation values. In this experiment, the middle ears of anesthetized rhesus monkeys with unilateral inflammation were inflated at different times with air or N₂, and pressures were recorded by tympanometry until they had stabilized or the animal had recovered from anesthesia. The results for air inflations reproduced those reported for human beings with negative pressures. Similarly, after N₂ inflation a significantly greater rate of pressure decrease and significantly lesser terminal pressures were observed for inflamed ears when compared with the contralateral control ears. However, the rate of pressure decrease and the magnitude of the pressure drop were dampened by sequential N₂ inflations. These observations have clinical implications with respect to the efficacy of inflation as a treatment for otitis media with effusion. (Otolaryngol Head Neck Surg 1999;121:98-102.)