Dependence of middle ear gas composition on pulmonary ventilation

Haya Mover-Lev, Moshe Harell, Dalia Levy, Amos Ar, Mlchal Luntz, Jacob Sadé

Research output: Contribution to journalArticlepeer-review

Abstract

The middle ear (ME) steady state gas composition resembles that of mixed venous blood. We changed arterial and venous blood gases by artificially ventilating anesthetized guinea pigs and measured simultaneous ME gas changes during spontaneous breathing, hyperventilation, and hypoventilation. During hyperventilation, PaCO2 and PvCO2 (a = arterial, v = venous) decreased from 46.0 and 53.0 mm Hg to 17.9 and 37.5 mm Hg, respectively, while PaO2 and PvO2 (85.6 and 38.2 mm Hg) did not change. This was accompanied by an ME PCO2 decrease from 70.4 to 58.8 mm Hg and a PO2 decrease from 36.8 to 25.4 mm Hg. During hypoventilation, PaCO2 and PvCO2 increased to 56.8 and 66.4 mm Hg, while PvO2 decreased to 21.8 mm Hg. The ME PCO2 increased simultaneously to 88.8 mm Hg and the ME PO2 decreased to 25.4 mm Hg. The ME PO2 decrease during hyperventilation may be explained by a 33% decrease in ME mucosa perfusion, calculated from the ME ventilation-perfusion ratio. This study shows that ME gas composition follows fluctuations of blood gas levels and thus may affect total ME pressure.

Original languageEnglish
Pages (from-to)314-319
Number of pages6
JournalAnnals of Otology, Rhinology and Laryngology
Volume106
Issue number4
DOIs
StatePublished - 1997

Keywords

  • blood gases
  • guinea pig
  • hyperventilation
  • hypoventilation
  • middle ear gases
  • middle ear pressure
  • ventilation-perfusion ratio

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