I don't breathe enough! Options

[jo_c]

As there isn't a medical type section, I guess this is the best place to post and it will be a long one..

As many of you may know, I have been diving a Megalodon rebreather for the best part of 3 years. I've done most dive types on it - deep, shallow, cave, high flow, high current dives and I've survived them all with no problems. The worst situation I had encountered was a self created CO2 build up (not hit) issue having to haul my ass down a shot line that was about 20m too long in a current. So, I stopped for a minute at the bottom of the shot and was fine. I've also stuck a BOV on there before which noticeably affected the WOB but I still dived the unit fine.

Things started back in September 08 (read about it here: http://www.tecdivers.co.uk/index.php?showtopic=5). That was not a very nice experience that I put down to CO issues, but I was never truly convinced.
Anyway, after that incident I took some time off diving. This was due to having some girlie hormonal problems (it may be relevant, ok) and I also noticed some changes in my metabolism at the same time.
When I went back to diving, I did a 30min dive in Wraysbury with no issues, then I did a day at Vobster. The first dive was fine (30mins) but on the second dive I had an incident 5 mins into the dive. The "incident" is a sudden big panicky feeling, possibly with nausea as well or as a precursor. The panic also causes an increase in breathing rate. As soon as I ascended it disappeared. Often I had a headache on getting out of the water that would go in 5 mins or so.

So, I kept diving at Vobster trying to work out the issues, because I was convinced it was a psychological problem that I just needed to get over. However, I would have a day of diving and it would be fine, no problems, then the next time I would have an incident again. I was preparing for a trip to Scapa and the last dives I did before I was fine, so I assumed I was "over it". I got to Scapa and it was pretty manky weather. Rough seas and everything. Every dive I did, at the bottom of the shot I would have a big panic hit. I would stop, hold on to the wreck until the feeling passed (maybe a minute tops) then swim off again fine. But then 10mins later, it would happen again. I think I did 4 dives in the whole week and I wished I had never gone.

All signs were pointing towards a CO2 bypass/hit issue, so maybe I should mention that my meg was stripped down and checked about 4 times while this was occurring, my sorb was sent for testing (it was fine), my gas bottles were emptied completely then filled, using several filling stations. My meg has also subsequently been sent to Meg UK for checking and it was fine.

I was due to go cave diving in November and I decided to stick to my plan, as I was going there with my instructor who knew all about the issues I was having. The caves in mexico are all pretty shallow, and the first dive was a cavern shakedown. This was a fairly short dive (30-40mins) but when I surfaced I had a headache. We then traversed to another exit and I decided to call it a day. I had a big headache that disappeared in 5 mins. After talking this through with my instructor, she suggested that my breathing might be a factor and to focus on taking long deep breaths- so on the next dive, I spent the whole dive breathing in, breathing out, breathing in, breathing out. I spent 2 hours underwater with no problems whatsoever.

The next day, we were following some OC divers into a cave, and I was working hard to keep up with them. As I followed, I could virtually feel the CO2 building up in my body and I knew it was going to hit. Sure enough, I had a CO2 hit, so I stopped and hung round for 5 minutes, not moving. I turned the dive and headed out, but every time I even slightly exerted myself I had a hit. I had to crawl out at snails pace to avoid getting a hit.

The conclusion: Something had changed in me, and I was getting CO2 hits from the meg. I've heard stories of people having the same problem, but these have been people brand new to the Meg. They have had a hit on their first or second dive, then had to bail on every subsequent dive.

So, my instructor suggested trying a back mounted CL unit as CO2 build up tends to occur because of resistence on the exhale. Back mounted units tend to help you exhale (but you might have to work a bit harder on inhale). I tried a Revo (because that was all I had access to and I've always liked it) an as soon as I put it on, it felt easier to breathe than the meg. I then did a 30 min swim, working fairly hard to see if I would get a hit. I didn't.

So, I have my answer. Kind of. The meg has been sold (a previous meg user, who knew all about the problems I'd had) and he is diving it fine. Has no problems. My instructor also dived my unit and didn't experience any problems.

The question is: What the hell has changed? I have dived it fine for 3 years, and as of November I could not dive it at all, because I couldn't even lightly exert myself. The reason I had so many big hits in Scapa was because the sea was very rough, so I was working hard to get to the shot and on the descent.
It doesn't make a lot of sense that after 3 years, my breathing has suddenly changed. Or does metabolism play a part in it? Do metabolic changes suddenly mean I'm susceptible to CO2 build up?

I doubt anyone can answer these questions, but people should probably be aware of these issues that can appear. Although I doubt its a common occurrance

[Rob Dobson]

Nice write up. I knew some of it but not all of it and hadn't realised how long this had been going on for. I hope this really is a resolution - but if it isn't at least you have your chest area back and you can save a bit of money on sorb!

After a year or so of being on OC my breathing got so relaxed that I simply wasn't breathing enough. Whilst I felt fine underwater I would get killer headaches as soon as I surfaced. It took a while to work out that I was getting too relaxed in the water and by consciously increasing my breathing rate the problem disappeared. I know it isn't the same thing but it sounds like it might be related.

So are you having to put up with the rEvO Dreams or have you managed to buy one without the native electronics? That was the only thing that ever stopped me from buying a rEvO II. Now with JJ due next week I guess I'll probably never own one.

[MartyC]

Jo, Interesting read, hope you have it sorted now! thanks for sharing

[gordon mackie]

Good read - thanks
I have had that a few times..I once chased a bait ball of fish to get a photo...got completely out of breath and wanted to either A) take my reg out and take a good breath leg it for the surface like a loony!
I have also had a few after a haul down a line..just need to stay still and breathe for a minute and then I am fine for the rest of the dive

I have spoken to a few folk and had the "oh, thank god for that... I thought I was the only one and didn't want to be slagged off for panicking and being a wee wimp"

I only do OC and have good regs but still seem to have a habit of not breathing deeply on descents and letting CO2 build up when I drag down a line in a current

[The Duck]

Good read - thanks
I have had that a few times..I once chased a bait ball of fish to get a photo...got completely out of breath and wanted to either A) take my reg out and take a good breath leg it for the surface like a loony!...

I had one of those once - at the surface there wasn't much of a current so down the shot, but at the bottom the current was running like a train. What was worse was that the wreck was nowhere in sight! However we spotted a dark shaddow off in the distance in the direction of the shot's drag marks and set off into the current - we hand to fin furiously and scrabble with our hands . Five min later we were on the wreck but panting like fu*k & I had a banging headache, classic CO2.