Question Did I get my first CO2 hit?

[johndiver999]

What is your fitness level? Is your aerobic capacity weak? Have you done other dives where you have exerted yourself?

Sometimes I read this forum and I get the impression that many people think diving (and doing it well) is hovering motionless with zero exertion, no kicking and using little air.

I view diving as a little more energetic and (for me) it often involves swimming pretty hard, crawling up current, swimming across a current and chasing fish and maybe even a tiny bit of skip breathing to close on a fish I am trying to impale - or yesterday, holding a scooter and still kicking like hell trying to keep pace with a buddy who has a better scooter.

If you have never been gassed out while underwater from some considerable exertion, you might not grasp how uncomfortable it feels. It might be a good idea to experiment a little and try some moderate exertion and get comfortable with it. This might make you more mentally tough so you don't want to bail on a dive when you first experience some uncomfortableness.

A co2 headache happens rarely on the bottom, often on the ascent and always very soon upon surfacing. It can induce nausea, even.

If you are going to "practice" exertion underwater (with the intent to find out your limits or to make yourself a better, stronger diver) it will be smart to approach this gradually and shallower rather than deeper. Also, it is very import to remember that if you start kicking hard, you want to increase your respiration immediately, even though it is not necessary right away, so that you can avoid getting behind.

You don't ever want to get "behind" where you are gasping to breathe, you want to stay in enough control that rapid inhalations and full exhalations are accomplished. I know I am getting panicky and "behind" when I want air so bad that I start (or want to begin) inhaling again before I have really exhaled fully... that is a strong sign for me that I am losing control of the situation.

If you are in decent shape and you don't try to handicap yourself by trying to "conserve gas", you can probably learn to explore what kinds a physical reserve you have, should something important cause you to want to bust ass on a dive. Like chasing a falling weight pouch, for example.

I find that very short periods of high exertion (maybe 30-45 seconds) - and then resting and recovering my breath, are more realistic than trying to really go hard for 3-4 minutes or longer. Short bursts of high air consumption are not that big of a deal and won't "Waste" that much air, if you keep them to short intervals and not too frequent and you can recover to a normal respiration rate in maybe a minute.

 

[scubadada]

I have had 2 or 3 dives where, after a relatively prolonged period of serious exertion, I have felt inordinately short of breath and could not easily recover. The work of breathing related to exhalation became very evident to me. The solution was to stop swimming, relax, and breathe deeply until the feelings passed or were largely alleviated. Beginning swimming again went without problem. I am reasonably sure that CO2 retention contributed to these episodes. The work of breathing during exhalation is greater than that during inhalation, including with the very best of regulators.

 

[revise]

Ha! Small world. Thank you for the snacks…if that was you! Yeah, hindsight, things were a bit messy. Still had a fun reef dive! Then yesterday got my goal of seeing a turtle!

though it has been a weird weekend. I was supposed to fish yesterday with a buddy. Canceled last Thursday to shore dive. Text him last night and his wife replied he was hit by another boat and tossed from the boat and airlifted as a trauma with 4 fractured ribs. So yeah, whole weekend was….odd!

Yep, that was me! I always have snacks and always happy to share.

It does sound like a very weird weekend all the way. Glad you guys had a good shore dive Sunday, wish I could have made it!

 

[Dsix36]

When I was a new diver, I had similar problems. I soon found that it was my own fault. I would not fully exhale, thus not allowing a complete exchange of lung volume. It would take a little bit, but the CO2 buildup would soon show up every time. New location, deeper dive, new buddies, new boat, harder swim etc. all seemed to be the cause. For some reason I just had a little fear of letting all the air out of my lungs when underwater (even in my first pool dives). Once I got a bit more experience and began to have some faith in my gear, things got better. To this day I am still extremely mindful of both my breathing rate and exhaling fully.

 

[heftysmurf]

When I was a new diver, I had similar problems. I soon found that it was my own fault. I would not fully exhale, thus not allowing a complete exchange of lung volume. It would take a little bit, but the CO2 buildup would soon show up every time. New location, deeper dive, new buddies, new boat, harder swim etc. all seemed to be the cause. For some reason I just had a little fear of letting all the air out of my lungs when underwater (even in my first pool dives). Once I got a bit more experience and began to have some faith in my gear, things got better. To this day I am still extremely mindful of both my breathing rate and exhaling fully.

Rad -- Yeah, I try to be mindful of breathing but I'm certain like others have said, a variety of factors led up to the odd experience I had.

RE: fitness level -- I'm 45 and gym regularly but I'm a cornfed fella...So I'm not light, but I train jiujitsu during the week with lunatics half my age and I can keep up as well as lift weights and cycle when I have time.

 

[johndiver999]

Rad -- Yeah, I try to be mindful of breathing but I'm certain like others have said, a variety of factors led up to the odd experience I had.

RE: fitness level -- I'm 45 and gym regularly but I'm a cornfed fella...So I'm not light, but I train jiujitsu during the week with lunatics half my age and I can keep up as well as lift weights and cycle when I have time.

If you can do that stuff, then scuba should not be a problem; at all.

Being "not light" is actually of little consequence when working underwater. On land the mass is a hindrance, but with the buoyancy of water, some extra weight is not much of an issue at all - especially if the person has developed a good bit of muscle and strength - which is necessary for a heavy person to be active on land.

 

[crofrog]

People underestimate CO2 retention on open circuit. It doesn’t require being deep or working hard although those absolutely make it worse.

I’ve had a bit of co2 build up from a regulator that was turned in to tight, must have bumped or fiddled with the knob, put just peacefully frog kicking into peacock springs and started to have a “I don’t want to be here feeling” and then assed why I was feeling that way and checked the regulator after deciding I wasn’t breathing well. It was screwed in far enough that it was probably about 3-4” of cracking resistance instead of 1”.

Felt similar in a cenote in Mexico at 20ft when I got to light and I was having to constantly stay at the bottom of my lung to stay off the ceiling and not break cave formations.

And seen it in my friends a few times under similar circumstances.

You can replicate the feeling at 1ata at your keyboard. Do a 15-20 second breath hold and then take a quick breath. Either top or bottom of lung is fine to replicate it but it’s easier to feel on the bottom of lung and repeat until you feel bad.

As you go deeper increasing gas density impacts ventilation and the narcotic effects of co2 become more apparent but it’s not required.


My guess is for the op, he increased his metabolic demands through more work, and then picking up the weight he ended up using his lungs for buoyancy more than he would normally because either he added to much gas to offset the new weight and was at the bottom of his lung or added not enough gas and was at the top of his lung, but either way insufficient ventilation increased co2 build up, which doesn’t feel great which added on top of the anxiety and got away from him.

It happens to everyone eventually just understand the feeling and don’t worry about thumbing a dive. The rule that anyone can thumb a dive for any reason exist for a reason.

 

[crofrog]

I also noticed being a bit nervous with higher than normal heart rate on a couple of dives after that, but calm breathing sorted it out

Same same. Took a few “easy” dives to shake the feeling after a particularly uncomfortable dive with a lot of cold water leaking in my mask causing my breathing to be erratic from that cold water on face reflex.