Re: “The Effects of Hypoxia on Middle Ear Pressure Regulation” by Alshukry et al.

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High Altitude Medicine & BiologyVol. 21, No. 2 Letters to the EditorFree AccessRe: “The Effects of Hypoxia on Middle Ear Pressure Regulation” by Alshukry et al.Avi ShupakAvi ShupakAddress correspondence to: Avi Shupak, MD, Unit of Otoneurology, Lin Medical Center, 35 Rothschild Avenue, Haifa 3515209, Israel E-mail Address: shupak@012.net.ilUnit of Otoneurology Lin and Carmel Medical Centers, and The Bruce Rappaport Faculty of Medicine, The Technion, Haifa, Israel.Search for more papers by this authorPublished Online:17 Jun 2020https://doi.org/10.1089/ham.2020.0018AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Dear Editor,I have read with great interest the article by Alshukry et al. (2020) entitled “The Effects of Hypoxia on Middle Ear Pressure Regulation.” The authors reported that mild systemic hypoxia of 95% SO2 would hamper Eustachian tube function as reflected by increased latency between pressure application in the nasopharynx and the measurement of a pressure change in the ear canal. The main role of the Eustachian tube is middle ear ventilation enabling pressure equalization with the ambient atmosphere. This function is modulated by physiological stimuli having sensory and effector components of feedback circuits between the middle ear and Eustachian tube (Eden et al., 1990). In that regard, the most likely sensory component includes those associated with chemoreception involving detection of altered oxygen and carbon dioxide tensions. One would wonder why mild hypoxia, which increases the ventilatory drive mediated by chemoreceptors, would have the opposite effect on the Eustachian tube ventilatory function?I would like to draw the attention of interested readers to our previous publications related to the effects of middle ear cleft hypoxia and systemic hyperoxia on the Eustachian tube function, which unfortunately were not cited or discussed in Alshukry et al. article. In these studies on the cynomolgus monkey model, the Eustachian tube function was evaluated by the forced response and inflation–deflation tests. When flushing the middle ear with hypoxic gas mixture of 12% oxygen 88% nitrogen we found lower opening, steady-state, and closing pressures, lower passive and active resistance, and greater dilatory efficiency of the Eustachian tube for the forced response test. In addition, for applied middle ear 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 condition (Shupak et al., 1996). Under systemic condition of breathing 100% oxygen, higher opening, closing, and steady-state pressures were observed. Also, the percentage of the applied pressure equalized, and the maximal pressure change on a single swallow in the deflation test were both lower under hyperoxic conditions (Shupak et al., 1997). These results demonstrate that in contrast to Alshukry et al. (2020) findings, hypoxia would improve Eustachian tube function, whereas hyperoxia might impair it.ReferencesAlshukry A, Lagier C, Della Vedova C, Salburgo F, Lavieille JP, and Montava M. (2020). The effects of hypoxia on middle ear pressure regulation. High Alt Med Biol 21:99–104. Link, Google ScholarEden AR, Gannon PJ, and Laitman JT. (1990). Mechanisms of middle ear aeration: anatomic and physiologic evidence in primates. Laryngoscope 100:67–75. Crossref, Medline, Google ScholarShupak A, Tabari R, Swarts JD, Bluestone CD, and Doyle WJ. (1996). Effects of tympanic-cavity oxygen and carbon-dioxide tensions on the eustachian tube ventilatory function. Laryngoscope 106:221–224. Crossref, Medline, Google ScholarShupak A, Tabari R, Swarts JD, Bluestone CD, and Doyle WJ. (1997). Effects of systemic hyperoxia on eustachian tube ventilatory function. Laryngoscope 107:1409–1413. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetails Volume 21Issue 2Jun 2020 InformationCopyright 2020, Mary Ann Liebert, Inc., publishersTo cite this article:Avi Shupak.High Altitude Medicine & Biology.Jun 2020.210-210.http://doi.org/10.1089/ham.2020.0018Published in Volume: 21 Issue 2: June 17, 2020Online Ahead of Print:April 6, 2020PDF download