Buoyancy & CO2 Poisoning

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OP
mrGaribaldi
Messages
2
Reaction score
5
Location
Los Angeles
# of dives
0 - 24
Hi all,

TL;DR I learned to use my lungs as a BCD instead of using a BCD at all when learning scuba and accidentally CO2 poisoned myself repeatedly. I don't know how I should approach trying to learn a better way and stay safe while doing it.


A couple months ago I got scuba certified abroad via a PADI center with excellent reviews online. I did about half the online classes in advance and half during the 3 day course itself. I must have misunderstood the section on how to use your BCD appropriately or it wasn't detailed enough for someone with as thick a skull as mine because I never once touched my bcd except to deflate fully at the surface and then inflate fully again after the dive at the surface during the course or in my ~9 dives after. I really just thought it was a fancy life vest (sorry!!!).

During the course, when we were practicing buoyancy in the pool, I had a really hard time staying below the water. It felt like as soon as I breathed in, I went shooting to the surface. My assistant instructor explained that I was breathing too deeply and that I should exhale sooner, more quickly, and fully. I asked if that meant I should be taking short, shallow breaths with my lungs mostly empty the whole time so I wouldn't float away as much. She said yes. When I adopted this sort of approach, I nailed neutral buoyancy. It felt really awkward and uncomfortable, but it wasn't terrible and it wasn't a new feeling either.

A short aside is that a few years back I had a massive pulmonary embolism, so I have a lot of experience with awkward and uncomfortable breathing (the first thing I did after getting cleared was cry a bunch in relief, then sign up for a scuba class). If anyone's ever taken a spirometry test, you know exactly what I mean. During that sort of test, they have you take a deep breath and then "blow out the candles" and keep exhaling as much as you can, past the point where it seems reasonable, past the point where your brain is screaming at you to please for the love of god stop. After the class, I told my partner that scuba diving felt just like spirometry, and that I felt extra prepared for this because of all the lung **** I went through.

Also after the class, I had a splitting headache. I basically went straight to my hotel room and laid down in the dark, waiting until I could fall asleep and work off the headache. I got headaches basically every time after diving, which became more brutal and intense the longer I dove. I asked my instructors if this was a common side effect of diving and they said no, not really, but it can take time for new divers to get used to breathing under water and with more practice I would become more comfortable underwater and that would stop happening.

Well, I actually felt really comfortable underwater and I was killing this "lungs empty + small breaths" approach. It was pretty annoying to have to keep my lungs super empty though, and it seemed like it'd be a lot more comfortable if I could keep my lungs at like 50% full and whatever amount of breath I needed to go up and down. I mentioned to my instructors that sometimes I even had a really difficult time getting to the bottom of the dive site. I said I couldn't touch the bottom if I wanted to, even with my lungs as empty as I could make them, and that maybe more weight would help me. I said that of course I know I'm not supposed to touch the bottom (I just wanted to give some reference), but they said not to worry because I shouldn't touch the bottom anyway.

Anyway, we passed the course and the instructors said we were some of the best students they've seen (woo!) and went off to go dive more elsewhere. On my final dive, I just had the worst headache known to man. The site was gorgeous - manta rays - but I felt wicked. It was normal though? Like, worse than usual, but I got headaches every time I dove, so I didn't think anything bad was happening? I was so happy when my buddy ran out of air and we surfaced though.

On past dives, I started to feel a little better after surfacing. Not this time though. There are no words for how god awful I felt. I noticed at the surface that in addition to the splitting headache I felt weak and deeply nauseous. I used my remaining strength to climb the ladder to the boat, and then crawled on my hands and knees to the side of the boat. I felt like sobbing but didn’t have it in me. I did have vomit in me, though, and I soon hurled over the side into the sea repeatedly. Felt less nauseous after that but my head still hurt like crazy.

After puking, the divemaster from this dive said not to worry, that I probably just had CO₂ poisoning. New divers often take rapid shallow breaths because they’re more anxious underwater and that with time I’d learn to breathe underwater more normally like I do on land. I was too out of it to have a full conversation, but I immediately put together that I was doing what he said on purpose because that’s how I thought scuba diving worked.

He also explained in more detail about increased dead space in the breathing passageways and all that jazz. See, while I knew in theory about the increased dead space, I just didn’t understand well enough what that meant practically. I wasn’t actually getting a whole lot of new air when I breathed in, because the air from my tank was just getting exhaled without actually making it down my bronchial tubes.

I couldn’t believe how stupid I had been. My symptoms were getting worse as I kept diving, because I kept getting better at keeping my lungs empty and not breathing. Not only had I been repeatedly poisoning myself for nearly ten dives, but I also didn’t learn how to dive safely. I was super scared and canceled the last dive I had planned for the trip, and haven’t been diving since.

It’s been long enough since that bad experience and I love ocean wildlife enough to want to try to start diving again, but I have no idea where to start. I’m technically certified, and in theory I know what to do now, but this is a dangerous activity and I do not want to die. I almost want to start from the beginning and take another course, but it’s not like that worked the first time around. Any thoughts on how to move forward?

Thanks :)
 
You're not the only one - I also used to get terrible, day-long headaches after every dive. The solution for me was to get my weighting just right. When your weighting is perfect, it lets you breath more freely since there's less air in your BCD, and small changes in depth don't cause as much of a difference in buoyancy. I almost never get headaches now that I'm not overweighted.

I had this happen diving in the ocean on Saturday. I rarely dive in salt water, so I just guessed how much weight I needed. Surprise surprise, headache. I suspect that some people are just more sensitive to CO2 than others.

Shameless plug to my blog
 
Using your lungs to make adjustments in buoyancy is overrated. Oh, it may work for small buoyancy adjustments when diving with a single aluminum tank; say, you inhale a bit more to rise as you swim over a rock, and exhale a bit more to sink back down on the other side. I got pretty good at it and was proud of my "skill" of not having to use the BC so much and thereby conserving my air supply. Then I started learning to dive heavy double steel tanks and found it was more difficult. My instructor saw me and said quit trying to do that--"that's what the BC is for." Nowadays, even with a single Al 80 I don't hesitate to use the inflator and dump buttons on the BC for anything but the smallest adjustment. You don't want to be constantly adding and dumping, but they are controls that are there to be used when it makes sense.
 
I use my wing on 3 occasions- descending, when on the surface, and anytime I level off at a new depth for a while during a dive. Doing breathing control for the rest is fine. Never had a heartache or light headed. If you find yourself breathing too deep or too shallow, you put too little or too much air in the BC when leveling off at that depth.
 
As your story reveals, you shouldnt use shallow breathing for buoyancy control -- maybe just for an instant, or on occasion, but not throughout the dive. Take full breaths, especially when you're at depth, and buoyancy is easier.

New divers have problems with buoyancy. Continue to work at it, it will improve. However, if you have trouble staying down at very shallow depths, adding a couple pounds of lead is not the end of the world, despite what some of the scuba gods say here. Make sure your BC is empty, make sure your not unconsciously kicking/sculling up, and if all else fails, add a few pounds.
 
The proper breathing pattern is to take a long, slow, full inhalation (not exaggerated) and then a long, slow full exhalation, again not exaggerated.

Do not hold your breath between in/out cycles.

Use your BCD to adjust your buoyancy, use your lungs to breathe and to oxygenate your body and equally importantly to prevent CO2 buildup.
 
I used to get headaches like you do and research pretty much confirmed it was co2 driven. All it took was adding a couple of pounds of lead and actually using the bcd for bouyancy rather than never adding any air to it. Probably a thousand dives since without a headache.
 
WOW the OP describes exactly the situation I envision when the "challenge" to use as little lead as possible is taken to the extreme. Having a little extra ballast should never be an issue or problem to a skilled diver. When I say a little extra, I mean like 2-8 lbs or so. For the instructor to recommend a deliberately shallow and inefficient breathing pattern, simply to avoid adding some lead is very disappointing and super dangerous. A diver who is way over stressed from co2, is also much more likely to "bolt" and that could be fatal.

Yesterday I was all ready to splash and realized that I forgot my weightbelt. I figured that I don't really need it, but with a full 5mm suit and a 3-5 mm hooded vest I am cutting it close with a aluminum plate, 13 pony, 85 steel and zero ballast/lead. Did the dive fine, although getting the descent started was a little slow and I may have hung on the scooter (which is a few lbs heavy) on the deco stop, but it was not an issue.

I forgoed the weightbelt primarily because I was lazy and I knew the current was mild. If/when the current is strong, I NEED that extra 6 lbs of lead to comfortably work on the bottom. If/when, I dump all the air from my BC and I am below 100 feet, I am quite heavy with that weightbelt. Technically, according to some people's definition of optimized weighting/buoyancy I am always diving 6 lbs over weighted and even more when I use a bigger, heavier steel tank. Managing a slightly larger bubble in my BC/wing is not an issue for me, at all.

Some of the "games" people play, when diving seem really silly to me.
 
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