Nasal gas composition in humans and its implication on middle ear pressure.

The amount and composition of gas that enters the middle ear by the Eustachian tube is of interest in the study of middle ear pressure regulation. We have studied the gas composition in the nasal cavity through the respiratory cycle in humans by mass spectrometry. The findings were correlated to earlier findings regarding synchronization of swallowing and breathing. The composition of the gas that may pass the Eustachian tube at openings during swallowing seems to be very close to expiratory values: nitrogen 79.19%, oxygen 14.69%, argon 1.00% and carbon dioxide 5.10%.