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Effects of Middle Ear Oxygen and Carbon Dioxide Tensions on Eustachian Tube Ventilatory Function
Author(s) -
Shupak Avi,
Tabari Reza,
Swarts J. Douglas,
Bluestone Charles D.,
Doyle William J.
Publication year - 1996
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1097/00005537-199602000-00022
Subject(s) - carbon dioxide , oxygen , eustachian tube , respiration , anesthesia , chemistry , middle ear , medicine , surgery , anatomy , organic chemistry
The objective of this study was to determine the effect of middle ear (ME) gas composition on eustachian tube ventilatory function (ETVF). ETVF was evaluated by using forced‐response and inflation‐deflation tests in four alert cynomolgus monkeys during test sessions with different gas compositions. The ME was flushed with one of the four gas mixtures: 1. air; 2. 12% oxygen, 88% nitrogen; 3. 100% oxygen; and 4. 5% carbon dioxide, 21% oxygen, and 74% nitrogen before and during testing. The results documented lower opening, steady‐state, and closing pressures, lower passive and active resistance, and greater dilatory efficiency following ME flushes with the hypercarbic and hypoxic gas mixtures when compared to the others. Also, for applied ME overpressure, the maximum pressure change during a swallow, the average pressure drop for all swallows, and the percentage of the applied pressure equalized were greater under hypoxic and hypercarbic conditions. These results show that ME gas composition affects ETVF and support feedback modulation of ME pressure regulation.