Northwest Dive Club

After every dive, for roughly the next 24 hours I need to keep equalizing. I'll equalize, and then a minute or two later I need to equalize again. What causes that?

I heard a theory that your ears are still off-gassing, but I don't buy it. That would be a lot of gas coming out of solution and diffusing into your middle ear.

My pet theory is that the eustachian tube is slightly inflamed or has some fluid in it, and that's making it act like a one-way valve. Every time you move your head it forces air out of the middle ear, causing a lower pressure inside.

On the drive home from a dive site, I often find myself popping my ears quite a bit. I just suspected it was because of habit to equalize and being more aware of the pressure differences.

Irritation of the throat from diving might be worth considering. The gas we breathe is extremely dry, and there's so much more passing into our lungs. Because of this, the back of the throat can be irritated, resulting in the sensation to equalize more.

Also, consider barotrauma from diving. I had bruising of my eardrum a few years ago and felt the need to frequently equalize until it healed. It's known that diving down just 6 feet from the surface without equalizing can cause some injury. A lot of us may be having sub-clinical barotrauma each time we dive.

You're right that the Eustachian tube does act like a one-way valve. It's easier for air to vent out of the middle ear, than to accumulate pressure.

I doubt turning your head forces air in or out. There would need to be both a pressure difference between the throat and middle ear, and the Eustachian tube open for a equalization to occur.

I constantly have to re equalize my ears after diving.. I think it just depends on the person but usually for me I have to pound some water down and then my ears are blocked kind of stuffed up inside... I have messed up ears from 18 years of diving massive calcium deposits on my eardrums and a condition called otitus.. yep I'm wrecked

Your Eustachian tubes and ears get a workout on a dive. The number and intensity of equalization you go through are way beyond 'design parameters'.
You could be reacting to some micro-trauma from adequate but not exceptional equalization. Everyone's ears are different. I need to go slowly, pay a lot of attention to equalizing, and sometimes ascend a bit and start over. If equalizing is AT ALL even....slightly....difficult you are putting some strain on pretty delicate tissues. It's actually kind of amazing we get away with it at all.

It's way worse with a rebreather. I have "crunchy ears" anywhere from a day to two days after a dive depending on deep, time and how often I've been diving.

http://www.dansa.org/blog/2018/04/06/oxygen-ears-faq

https://www.scubadivingchicago.us/carbo ... -dive.html

I dunno. With all due respect to Dr. Pollock, I'm still not buying the 'oxygen ear' theory.

Points:

- Virtually all of the online literature that discusses 'oxygen ear' or 'middle ear oxygen absorption' quotes other websites, notably the US Navy Diver Manual, which talks about it but doesn't reference a source.

- None of the discussions about Oxygen Ear actually reference a scientific study on the topic. I couldn't find any source study at all. (This is a big red flag for people in medical research, where common folklore supplants rigorous studies-- until it's proven wrong.)

- There is actually evidence against the idea.
https://www.ncbi.nlm.nih.gov/pubmed/3920459
https://www.tandfonline.com/doi/abs/10. ... 9509139341

- For nitrox divers, the PPO2 percentage is typically ~50% higher than ambient air (for EAN32). Let's assume the middle ear (ME) is flushed with nitrox during the dive, so that on surfacing the ME contains pure nitrox. If all of the extra oxygen were to be absorbed, this corresponds to a ~10% reduction in ambient pressure within the ME (Before O2 absorption: .68 PPN2 + .32 PPO2; After O2 absorption: .68 PPN2 + .21 PPO2 @ 1ATA). That 10% change in pressure is the equivalent of about the first 3 fsw at the beginning of a dive, a difference easily cleared with a single Valsalva maneuver -- or a yawn if you happen to be riding up in a fast elevator. And yet... the ear clearing continues on for 12, 24 hours...

Note: in the course of researching this I found out that the ME does not normally contain the same mix of gasses as air; more closely the mix of gasses in venous blood: a super high concentration of CO2, low O2, and high N2. How that fits in this discussion I'm not sure. Source: https://www.tandfonline.com/doi/abs/10. ... 9009122520

So I think there's more to it, perhaps due to high PO2 levels affecting the ME chemoreceptors, which regulate ME aeration, as A. Shupak (1994) suggests. That would explain why the problem is worse after high-O2 dives and long rebreather dives.