Intersting question, Possible medical problem?

[MikeR]

I have a friend who I've been diving with for a very long time. He is OC Trimix certified and we dive at least a couple deep wrecks a month together. Well he decided to give CCR a try so I am instructing him.

Here is the problem. He does very well to 60'. Beyond 60' he gets dizzy spells. He says they come on sudden and are very disorienting. He terminated a dive on OC bailout and I could see the disorientation on his face. I initially thought maybe it was a scrubber issue, mushroom or WOB issue, but after further inspection and diving the unit myself it works flawlessly. He is not a high stress person and I dont suspect anxiety to be an issue, his breathing rate appears to be quite normal. We gave it a try again and same problem....any ideas. We did a 1.5 hour dive to 40' no problems, go to 60' dizzy again. We have terminated the CCR training for the time being as its got us both abit concerned. Has anyone experienced or heard of anything similar? If so what was determinied to be the problem?

 

[madmole]

Skip breathing from OC habits leading to CO2 buildup on the RB? I was very aware when I first swapped that I had an irregular breathing pattern from OC days and had to make a real effort to breath more normally

Also check the bite radius of the mouthpice, if narrow, his teeth could be blocking gas flow and leading to CO2 retention

Maybe he is just a CO2 retainer and the lower gas flow of CC is showing this up

Dissorientation and dizziness I have seen in a dive partner about 4 times. It was due to duff sofnolime that would cope to a certain point and then at a certain depth or if work increased WAM! I dived his unit with no problems to rule out bypass (but filled it with my sofno) so after 4 hits we finally ruled out the unit and threw away his sofno tub, no problems after that

 

[apitkin]

It would be useful to know whether this is true vertigo (i.e. does the dizziness have a rotatory component where he feels that he or the environment is rotating) or just a non-specific feeling of being "fuzzy" in the head. If it is vertigo, I'd be interested to know if he ever experiences it when OC diving, particularly on ascent. One possibility is that his middle-ear spaces are not being equalised equally (sorry for the clumsy language) and this is sending mixed messages to his brain which are experienced subjectively as a sensation of turning.

If it is not true vertigo then, well, the list of possible causes is quite long, and hypercapnia is certainly one of them, as madmole points out.

 

[MikeR]

The mouthpeice is fine, and his breathing appears to be quite regular with no skips. I think that the CO2 retention is probably the culprit. It is as he describes a "vertigo" type of spell. above 60' no issues below 60' spells. Thats the part that has me a little baffled. When we did all the confined water and shallow dives everthing went off without a hitch, below 60' is the only time he has any issues.

He never has this issue OC, I have been on many sub 200' dives with him and OC he is fine.

 

[madmole]

You could test for CO2 retension. Go to a depth near to the depth it happens but before it does, then swim hard on the level to build up CO2, if he gets a hit, its CO2

If this is the case, try cinching the lungs down to the waist harder. Some of us also use the inner D rings to pull then in and down as well. Make sure they are not free to move away from the bidy in any way. Try smaller lungs

Also try a dil flush when it occurs to see if this stops it

Normally vestibular problems arise on the ascent rather than descent (I know cos I suffer badly from vestibulal vertigo on ascent and have for years due to unequal clearing of my ears (too many dives and plane flights))

 

[MikeR]

Just a little update. The person in question after visiting a couple docs found out he has some lung damage. Apparantly asbestos related. Sadly he wont be able to dive any longer. Thankfully it is minimal and should not affect his life otherwise.