bizarre breathing problem

PCDiver

Rick,

perhaps you could try to dive with a high volume mask, and see whether the problem reoccurs?

Peter

decoweenie

Do you notice if you have trailing bubbles from your mask when you dive ? Sounds like you might nose-breath a lot if you can't control the water coming thru the nose...

May be the bigger mask just provide enough tidal volume for you to breath more from it, thus the snorting. And the smaller mask is "too restrictive" to start the snorting ?

Just some wild-ass guesses here...

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DaveT2

I get it occasionally - but I've found a solution that works for me.

I always try and dive with absolute minimum CL volume, so sometimes completely flatten the CL on inhale. My ADV take quite a good suck to get it to fire, so I end up in that no mans land of empty CL, but not quite enough neg pressure to activate the ADV. Then all of a sudden the nose (that's been determinedly not breathing) lets go & gives a bit of a snort. After a couple of these it seems to produce some particularly strange consistency snot that just sits somewhere at the top of the throat trying it's damnedest to block all normal breathing.

A quick push on the dil button stops the snorts, but unfortunately the snot stays put until you take off your mask in front a crowd (usually girlies) then lets go all over your lower face.

Dave

Dave & Sandy

Hi,

PM Gasman on this site. He has had a similar episode on a 130m dive.

He is also a Doctor so his insight might answer your questions.

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PCDiver

No trailing bubbles. I probably breath in via nose/mouth and breath out via mouth only.
I think you are right about the tidal volume. The Mares mask is a very good fit and low volume. The big eye mask is a lot bigger and doesn't seal off as well.

Unvoluntary nose breathing. I had never heard the term and was surprised about the number of people affected by it.

Gasman

Wow! And I thought I was the only one…too!

As Dave and Sandy mentioned, a similar experience happened to myself and another diver during 130m dive. There was very strong current and I was having to pull myself down the shot line hand over hand, relying on the ADV to maintain loop volume. By the time I got to 85m I was breathing hard and stopped to wait for my buddy to join me (he was even slower as he had camera gear to carry…. We took 8 minutes to get to 80m!). Within a very short space of time I developed the snoring that people have described as well as “palatal incompetence” i.e. couldn’t stop gas going in and out of my nose. So with each breath I was loosing diluent. This was all very distressing and I had a rising feeling that I couldn’t breathe which as assumed to be CO2 build up….note, not from a failure to scrub but from an inability to breathe. Flushing the loop did not help. Because of the current I couldn’t close the mouthpiece and bail to O/C so bailed the dive and ascended. By the time I got to about 60m my breathing had returned to normal.

The other fellow who had it on the same dive was on a KISS. He switched to O/C via his BOV, took a few breaths and it settled down and he continued the dive.

I have had my Inspiration @ 100m in the past without problems and have done strenuous dives @ 70m without experiencing this problem.

So what happened?

The high breathing rate and WOB causes a few problems. The point of the back of the tongue and soft palate are a relative narrow point. At high flow rates there will potentially be a localised reduction in pressure (as per Bernoulli). This could potentially suck the soft palate down and prevent it from sealing. When one is attempting to breathe hard the muscles in the throat actively work to keep the throat open. With age and maleness or nasal congestion these muscles can become weakened and lead to snoring and obstructive sleep apnoea.

In the setting of:

• Generating high negative pressures either related to posture or WOB
• High flow rates with localised pressure reduction
• Both

It is conceivable that these muscles could be overcome (i.e. partial pharyngeal collapse) and the combination of palatal incompetence and a feeling of obstruction results. This, if allowed to continue may result in CO2 retention etc.

PS this is all supposition.

How to stop it? I’m not sure….but minimising WOB, minimising negative pressure breathing and lowering flow rates (i.e. don’t get SOB, optimise CL volume) would all be expected to help. Head neutral position and tongue forward (don’t close the mouth piece off by gripping it too tightly) would also be expected to help (Martin Parker has written on this). Decongestants may also help but should be used with caution for deep diving. If in doubt bail to O/C or ascend. I’ve now fitted a BOV to allow a few O/C sanity breaths in such situations.

For calculating the optimal gas for a dive I do not use END butbrather EADD (Equiv. Air Density Depth). I aim for an EADD of <50msw (taking into consideration HPNS issues for deep dives (100m+).

It would be interesting to know how many of the people who have suffered from this also snore at night.

Andrew

PCDiver

Andrew,

thanks for taking time to post. Have some green.

I snore sometimes.

Peter

RichClark

I think I have a big eyes kicking around somewhere, so will give it a go. You could aways simulate yourself; use your hign volume mask and when you start to 'snor' hold your nose.

Cheers

Rich

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