narc'd

[MantaRey]

I've been diving for a long time, never with any issues. I took some time off of diving for whatever reason, and on my return I had two bad experiences:

the first dive I went jumped in, was fine, until about 40 feet I got the chills and became disoriented. so I signaled one of the divemasters and he took me up. on the way up we paused, to see if I had just lost my breath or something, but when descending the same thing happened. I didn't think anything of it, because the water was pretty chilly and all I had on was a long sleeve shirt skin and regular trunks. which is what I used to always wear.

about a week or two after that I attempted to dive again. this time I had a shortie wetsuit with my long sleeve skin under, the temperature was definitely not a factor. even then a much more serious problem occured. we were doing a 95 foot wreck dive. I've been to this same site many times, it used to be a cake-walk for me. however this time I had really lost it. I became really narc'd. signaled the dive master, too keep an eye on me, than grabbed a hold of some debris to rest and try to recollect myself. I would calm for a little bit, but in no time I was disoriented again. it was bad, I realized that I was totally unresponsive to my divemaster, my brain seemed like it couldn't put it together to signal back, but I still somehow managed to surface normally.

the only good thing is that she told me that I handled it very well. when most people panic and quickly surface, I remained calm. but it didn't seem calm to me! my heart was racing, and it seemed no matter what I did, I felt oxygen deprived as if I was holding my breath. but really it felt like I was breathing normally. not a cool experience, I was close to blacking out. throughout that day I had slight chest pains, and for a couple days after that my throat hurt, it felt as if it had collapsed under pressure or something. but that I'm not too sure, because with my luck, the next night I got food poisoning :-/

I still have no clue as to what it could be. I left my regulator for service. but I have a feeling that it was a bad mix of air. because on both dives it was the same air, I just had it topped off on the second dive. I think this because on the second dive I was able to go deeper. is it possible that the first fill gave me little oxygen, and topping it off on the second dive added more? or could it be from me taking time off? or is it that I'm just out of shape? because man college racks on the pounds lol.

I haven't had a chance to dive since, because I got food poisoning last week. but hopefully it's a fluke and not a health issue.

 

[fins wake]

Hi, MantaRay, guess this belongs in the Dive Medicine section and not with the eminent Dr Deco, but here goes anyway:

I had a similar experience to you many, many dives ago on a reasonably deep tropical reef dive. Apart from the black-out fears you mention, I had almost all the symptoms you describe.

The main suspect as you mention would likely be narcosis, which can manifest itself as angst and anxiety as well as euphoria. However, in the first case you mention you were at a depth not normally associated with narcosis. In the particular case I'm referring to, I was at 30m+, but I habitually go deeper in tropical waters and have never experienced any similar sensations before or since in tropical seas.

I have, however, once or twice, experienced similar sensations (on OC) in the cold low-viz waters where I usually dive. And then at the depths you had your problems at.

This is why I think CO2 retention is an issue, something that can be exacerbated by badly serviced regs. In my case, the (top-quality) regs hadn't been serviced for nearly two years and nearly 150 dives and you mention that you've left your regs in for service as well (indicating you might not have serviced them for a while?).

Now, it is my strong belief that regs overdue for service retain more CO2 than well-serviced regs. It is a fact that high levels of CO2 exacerbate the effects of N2 narcosis (Lowry et al, Bennet & Elliot etc). If we also assume that you're a bit out of shape or have anything else out of the ordinary - in my tropical example I was dehydrated and fatigued due to a very bad and unusual case of diarrhoea the previous night with only two hours of sleep. I probably shouldn't have dived. :book2:

Anyway, I've serviced my regs now, and the problems haven't occurred since, despite far more challenging dives at extremely cold temperatures in no-viz environments at all depths. So I think it was a case of CO2-enhanced nitrogen narcosis, or pure carbon dioxide retention problems as such, exacerbated by other factors, physiological or perhaps psychological ("This is not going to go well, this isn't going to go well, this isn't going well ...").

As such, you should be fine with your new serviced regs, just start at shallow depths in good conditions again (good viz, low currents etc) to work up your self-confidence and get back into the habit. You need to be "dived-up". If you feel out of shape, it won't hurt to work out a bit either. I've just started doing that again and it certainly has helped me in the water. :lifter:

Incidentally, I've only experienced these sensations (and only two or three times prior to my regulator service over many, many dives) on open circuit. Theoretically it should be worse on a rebreather. I've never, however experienced anything similar on SCR or CCR. This is consistent with what I've read from other RB divers' accounts. Perhaps due to good CO2 washing from the scrubbers ...

I think it all points to CO2 retention, but hopefully one of the medical regulators would care to comment ... :doctor:

(Oh, and perhaps move this to the Dive Medicine section as well ...)

K.
/with apologies for the length of the post :geek: /

 

[MantaRey]

awesome, that does make sense. because I figured that it has been about a year since I've serviced my reg. and also it has been set for that time.

thanks for the insight.

 

[trheeltek]

Hmm...it could possibly be CO2 retention, as noted above - I've sometimes felt disoriented/dizzy in relatively shallow water (50-60fsw) if exerting. However, the symptoms you describe also sound a lot like the bad fills I've seen - in both cases you'd be hypoxic, so I don't know. But, I'd definitely smell and taste the air from that tank before I dove it again if I were you. Also, if the air was significantly contaminated, it may have left traces on the first stage filter - when they pull it for service, maybe see if it's discolored.

 

[fins wake]

... but this wouldn't lead to hypoxia , but again, to hypercapnia. Any contamination in the bad air fill would likely contain elevated levels of carbon dioxide (CO2) or - rather more immediately fatally - of carbon monoxide (CO). So I think the CO2 retention hypothesis still holds its own. Please note that this is merely a hypothesis although a reasonably well-founded one IMNSHO ...

Checking the first stage filter for undue discolouration is a good tip. It is actually very probable that one or more bad air fills (accumulation over time?) may lead to some degradation of regulator performance. But again, this is a hypothesis, I haven't seen any papers published on this.