GAS-COMPOSITION OF THE HUMAN NOSE AND NASOPHARYNGEAL SPACE

Since it was established that middle ear (ME) gas composition is close r to venous gas composition than to air, the question arose regarding the composition of gas which enters the ME from the nasopharynx. Using a mass spectrometer, gaseous partial pressure was measured at three l ocations in the nose and nasopharynx of 6 volunteers. All three locati ons showed similar gas composition (O-2 = 15.7%, CO2 = 4.5%, N-2 + Ar = 79.8%) which is similar to expired air. The gas that enters the ME v ia the Eustachian tube is a mixture closer to the final ME gas equilib rium than is air. This minimizes the changes in steady state ME gas co mposition incurred by gas influx into the ME.