CO2 build-up at depth - what to do?

[Teamcasa]

Thanks for the info!

The reg was balanced. I mentioned "sucking" because at a certain point, when vision and hearing started fading, awareness of air (that felt toxic) moving in and out of my body was all I had to hang on to.

Having a balanced regulator or not, does not assure you that the regulator is functioning properly at depth. Having it serviced is also no guarantee it will work properly at depth either. In fact, the highest probability of having a regulator issue is directly after having it serviced.

As a 30 year mechanic I tell people to get their car serviced a month before they make that long vacation trip or just wait until they return. Same goes for your regulators, camera housings and other dive gear. I would never take or advise anyone to take a newly serviced regulator on a dive vacation until it has been tested by diving locally first.

 

[Nismo]

I'm wondering if this was more of a case of anxiety than CO2 retention. Not everyone has the same response to being narced. If it caused a slight amount of anxiety which some people get instead of the drunk like symptoms. Anxiety has a tendency of making itself worse. You start to panic so you breath a little harder, The feeling of anxiety does not reduce so you breath even harder. It's a nasty cycle. A lot of people who who have anxiety attacks feel like they are not getting enough air when they are. It would be very easy at that depth to be too low in CO2. They actually have too little CO2 in their system and start to have muscle spasms mostly in the hands but often in the feet and their mouth will feel numb. Put that on top of breathing for a reg and you could be heading for something down right nasty. Unknown if this was the problem or too high CO2. Either way you did great to realize there was a problem and surface. Narcosis can present itself in different ways and can cause different reactions. Again great job on recognizing a problem and calling it. Theres a lot being mentioned about swimming into current which you do not actually say you were doing. If you were, then it could be that your metabolic demands were not being met by the amount of oxygen being provided. Sometimes I think the work of breathing a reg while exerting can cause this or at least be a combination of anxiety and high CO2.

 

[TSandM]

If you were swimming into current, you may well have had CO2 retention. But I have had precisely the symptoms you describe from pure narcosis. I became convinced my regulator was malfunctioning, and I was short of breath and anxious, and only held onto my composure by focusing on a slow, rhythmic breathing AND telling myself, "You doofus, you're NARCed!"

CO2 is additive with nitrogen in causing narcosis, though, so the two together are a bad combination.

Yes, you will have enough oxygen in your bloodstream at depth, if you are breathing much at all; the oxygen partial pressure of air or Nitrox at 100 feet is so very high. However, elevated CO2 is not to be dismissed. CO2 is tightly regulated by the body in order to keep the blood pH within very narrow limits. Significantly, acutely elevated CO2 is also associated with acidosis, and acidosis means muscles don't work well, and neither do nerves . . . and neither does the heart. Because the body needs to keep CO2 so carefully controlled, you have some powerful urges built in to increase your breathing when CO2 starts to rise -- along with them comes a feeling of anxiety and suffocation. Heightened anxiety is NOT good for divers, because it puts you closer to panic, and panic kills.

As said before: If your shortness of breath is associated with having to do too much physical work, you need to stop working. Drift, or stabilize yourself on some feature of the environment, and rest, while maintaining a deep, rhythmic pattern of inhalation and exhalation. If you are short of breath and anxious WITHOUT exertion, check your gauge to make sure it isn't oscillating with each breath (indicative of a valve which is not completely open), and if it's OK, try ascending ten or fifteen feet to see if the symptoms abate.

BTW, I, too, have read that rapid descents make narcosis more noticeable. I think it's because you don't have any time to get slowly used to being stupid . . .

 

[Thalassamania]

Another thing to consider is how tight was your wetsuit jacket?

 

[Colliam7]

Because of current we dropped down really quickly that day. I have heard that a very rapid descent rate can amplify narcosis. Is this true?

Interesting question, and I hope others will comment. I have not personally experienced this. But, my dive buddy insists that a rapid descent rate leaves him feeling more narc'd at depth than a slow rate.

 

[Thalassamania]

Interesting question, and I hope others will comment. I have not personally experienced this. But, my dive buddy insists that a rapid descent rate leaves him feeling more narc'd at depth than a slow rate.

I'd agree. But is it the rate of descent or the CO₂ built up by working to get down fast? I don't know.

 

[Walter]

I am a little confused by this statement. You will get substantially MORE oxygen through the regulator at depth than you get breathing on the surface due to the increased partial pressure.

So you agree she's not getting less oxygen.

 

[AbyssalPlains]

Because of current we dropped down really quickly that day. I have heard that a very rapid descent rate can amplify narcosis. Is this true?

In my recently completed decompression diving class I learned that this is indeed true. I haven't looked up any specific literature myself, though.

 

[String]

Dropping fast definitely increases my narcosis compared to a slow descent.

 

[Plumb bob]

I can vouch for the amplification effect of rapid descent, I've had a chamber dive down to 55m (180 feet) that was done very very rapidly (something like 35 secs) and had much more intense narcosis than similar depths at a slow rate of descent.