The Deflation (Passive) Opening Pressure of the Eustachian Tube

OBJECTIVE: To compare the air deflation pressure of the eustachian tubes in patients with tympanic membrane perforations due to various forms of otitis media and those with myringotomy or blast injury perforations. METHODS: The study group consisted of 321 patients (407 ears) aged 4 months to 91 years with tympanic membrane perforations due to otitis media (318 ears), blast injury (27), and myringotomy (62). Air at 230 cm H2O or less was deflated from the external canal to the nasopharynx in all patients. The deflation opening pressure was measured and compared among groups. RESULTS: In 1087 measurements (169 ears underwent multiple measurements), the deflation opening pressure was found to be higher in patients with otitis media than in those with normal tympanic membranes (P=.004). Patients with blast-injured tympanic membranes had lower deflation opening pressure than patients with normal ones (P=.002). The deflation opening pressure did not differ between age groups, showed fluctuation in almost all ears, and was not influenced by inflammation or its severity. Deflation opening pressure was higher in patients with otitis media with effusion than with other forms of otitis media (P<.0005). In 17% of the measurements, air did not pass through the eustachian tube: 3% in blastinjured tympanic membranes, 8% in normal tympanic membranes (P=NS), and 20% in inflamed ears (P<.0005 between the last two groups). CONCLUSIONS: Deflation opening pressure measures the passage of air through the passive eustachian tube. This pressure frequently fluctuates. There is a correlation between various forms of otitis media (especially otitis media with effusion) and higher deflation opening pressure. The high pressure needed for air passage suggests that the eustachian tube transfers air only when actively opened. Department of Otolaryngology and Head and Neck Surgery (Cohen, Perez, Peleg); Infectious Diseases Unit Shaare Zedek Medical Centes affiliated with the Faculty Health Sciences (Raveh); Ben-Gurion University of the Negev, Jerusalem, Israel (Raveh)