PATENCY OF THE EUSTACHIAN-TUBE IN DIFFERENT BODY POSITIONS

The Eustachian tube function was studied during simulated descents and ascents in 5 experienced divers, all known to have a good capacity for equilibrating static pressure differences across the ear-drum. Their ability to equilibrate by deglutitions during descents was greatly reduced in the recumbent as compared with the sitting position, and when tilted with the head downwards no one could equilibrate completely. The pressure level required to passively force the Eustachian tubes open during ascent was recorded higher in recumbency and still higher when the subject was tilted as compared with the sitting position. The pressure level in the rhinopharynx required to force the Eustachian tubes open during Valsalva's manoeuvre was also higher in the recumbent and tilted position. It was also observed that a higher speed of pressure increase in the rhinopharynx resulted in a higher pressure level for passive opening of the tubes.