Excess carbon dioxide and severe narcosis?

[markovcholesky]

I was recently acting as the divemaster trainee (supervised by an instructor) guiding 3 highly experienced tourist divers at Nusa Penida in Bali. The first dive was something of a nightmare, with none of the tourist divers following proper buddy procedures and one displaying very poor buoyancy control while trying to take pictures. I was therefore highly stressed about the second dive (at Crystal Bay).

We entered the water from the boat and within seconds it was evident another dive group had spotted a Mola in the distance at depth...so the chase was on. The divers I am supervising took off at high speed. I was swimming hard to chase them and descending fast. The water temperature dropped to around 18C, and I am used to tropical diving in much warmer water. So...stressed already + physical exertion + likely not breathing deeply enough + quickly chilling = trouble.

At around 25m I was suddenly hit by a sensation of being unable to breath, as if each inhalation was pure CO2. Straight away I also experienced severe vertigo, tunnel vision and related loss-of-control symptoms all resulting in a realisation I was in a serious situation (nb. I was diving on Nitrox (30% O2)).

I was near a rock wall and struggled to grab on to that and drag myself hand over hand up the wall. The first 5m of the ascent were slightly too quick. I slowed down and monitored my computer (although struggling to read it) and ascended to around 15m...all the time wondering if I should risk it and go straight to the surface, given I could not breath properly. I managed to stay in control and after around 1-2mins at 15m my head cleared, and breathing returned to normal. By this time I had been absent from the group for about 4-5mins, so they had come looking for me (I had veered off in a completely different direction given I needed something to hang onto to try to maintain control).

I re-connected with the group and ascended, completing a much longer than normal safety stop in the process. I was likely in a very mild state of shock on the boat...nausea, some dizziness, shivering. Not surprisingly I skipped the third dive of the day.

I'd be interested in people's thoughts on what happened. I believe this was a result of excess carbon dioxide, which in turn aggravated the narcosis effect (I definitely did NOT get narc'd, panic and then short of breath). I distinctly recall the inability to breath and the severe narcosis were simultaneous...it was like a dumb teenager downing 20 vodka shots in quick succession and going from fine to on the floor incoherent in a heart beat. And of course all of this driven by, as mentioned above, stress + cold + exertion + (likely) shallow breathing. I knew before I started the 2nd dive that I was not comfortable given stress. If it had been a simple fun dive I would not have entered the water. Lesson learned. Don't dive if it does not feel right.

 

[Ryan Mcshane]

You’re right, sounds like a co2 hit. Improving your physical fitness and getting more efficient with finning techniques is the best prevention.

 

[johndiver999]

Why cling to a wall? If you were down a few minutes, why not come straight up? Glad you were OK.

 

[markovcholesky]

You’re right, sounds like a co2 hit. Improving your physical fitness and getting more efficient with finning techniques is the best prevention.

Yes, perhaps finning technique improvement might help. My physical fitness is, by any objective measure, high. I'm middle aged but in v good shape, healthy eating and frequent exercise, low resting heart rate, etc. I suspect the biggest mistake was not breathing deeply enough (I was trying to minimise air consumption) while finning hard, resulting in the rapid CO2 build up.

 

[markovcholesky]

Why cling to a wall? If you were down a few minutes, why not come straight up? Glad you were OK.

You are absolutely right. I could have come straight back up. However, I was on the verge of blacking out, the world was spinning around me and I could barely see. So there was simply no way I could think straight. I had lost all sense of time and couldn't be sure that a direct ascent was safe. I also wasn't sure that I could control a direct ascent. However, by pulling myself hand over hand up the wall I had a sense of ascent rate.

 

[DandyDon]

I suspect the biggest mistake was not breathing deeply enough (I was trying to minimise air consumption) while finning hard, resulting in the rapid CO2 build up.

We did that on the school bus as a kid - hyperventilating, then holding our breath to pass out. We survived our childhoods fortunately. I would think a DM trainee would know better, but I guess it depends on the instructor.

I could have come straight back up. However, I was on the verge of blacking out, the world was spinning around me and I could barely see. So there was simply no way I could think straight. I had lost all sense of time and couldn't be sure that a direct ascent was safe. I also wasn't sure that I could control a direct ascent.

Bali may not have the best medical facilities for treating a bent or embolism incident, but your chances are much better alive on the surface, whatever it takes, than dead with weights attached on the bottom. When in doubt, ditch & float.

 

[BRT]

If you ever do that again try breathing out completely, as empty as you can empty your lungs, take a full breath and repeat. That does it for me.

 

[okvij]

If you ever do that again try breathing out completely, as empty as you can empty your lungs, take a full breath and repeat. That does it for me.

I once read about a similar technique for averting panic caused by increased CO2.

Recall from memory:
1. Stop
2. Exhale forcefully twice
3. Take a deep breath and expand your belly so it becomes like a basketball
4. Hold breath as long as you can

Maybe there was repetition, I don't remember well.

 

[drk5036]

I once read about a similar technique for averting panic caused by increased CO2.

Recall from memory:
1. Stop
2. Exhale forcefully twice
3. Take a deep breath and expand your belly so it becomes like a basketball
4. Hold breath as long as you can

Maybe there was repetition, I don't remember well.

Maybe this would be good on the surface, but taking a breath so big it extends your stomach then holding it is a huge no no for scuba.

 

[BRT]

I once read about a similar technique for averting panic caused by increased CO2.

Recall from memory:
1. Stop
2. Exhale forcefully twice
3. Take a deep breath and expand your belly so it becomes like a basketball
4. Hold breath as long as you can

Maybe there was repetition, I don't remember well.

All good except the breath hold. I'm not so worried about it for blowing up my lungs but I don't want to stop ventilating CO2 at that point.