Oxygen ears FAQ

Oxygen ears 

DAN medics and researchers answer your questions about dive medicine.

What is “oxygen ear”?
Also known as middle-ear oxygen absorption syndrome, oxygen ear describes a gas volume imbalance in the middle ear after diving with breathing gas that has a higher oxygen fraction than air. The phenomenon is commonly associated with open-circuit diving using nitrox and closed-circuit rebreather diving. The high-oxygen-content gas fills the middle-ear space over the course of the dive. Postdive, the tissues metabolise the oxygen, reducing the total gas volume below what it would be if the spacewere filled with air. If this loss in gas volume is not equalised, relative negative pressure will develop. This is in effect a squeeze, which can present as ear fullness, mild discomfort and/or impaired hearing.
This problem can be avoided easily with occasionalequalisation for several hours after diving. A person who is active, talking and/or laughing during this period may not needto equalise actively. On the other hand, a person who goes to bed immediately after diving might wake up several hours later with mild discomfort. Full resolution is best achieved using gentle equalisation techniques.
— Neal W. Pollock, PhD.

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