CO2 buildup - Cause, Effects and Solutions

Discussion in 'Basic Scuba Discussions' started by Teamcasa, Nov 3, 2009.

  1. Teamcasa

    Teamcasa Sr. Moderator Staff Member ScubaBoard Supporter

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    This issue was brought up in another thread but I think it needs to be posted here as well.

    Also from that thread:

     
  2. lowviz

    lowviz Great White

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    Newbie OW training headaches are another good sign that you are breathing incorrectly.
     
  3. Cave Diver

    Cave Diver Moderator Staff Member

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    CO2 is thought to be a contributor to "Darc Narc." This is a type of narcosis that gives you a feeling of dread, doom, overall malaise. I've experienced this feeling during an exit in a cave that I'd dove many times.

    Unrecognized and untreated I can see how it could easily build up and lead to feelings of claustrophobia and panic.

    As others stated, long, full exhales are key to getting breathing under control and dispelling the effects of it.

    I've also had a headache that I attributed to CO2 buildup. As someone that used to get migraines, I have to say the CO2 headache ranks as one of the worst I've had and there was no relief from it until it wore off.
     
  4. Bubbletrubble

    Bubbletrubble Regular of the Pub

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    This review article written by Dr. Johnny Brian, Jr., (Associate Professor, Univ. of Iowa) might be of some interest to people. It's entitled "Carbon Dioxide, Narcosis and Diving." Enjoy.
     
  5. CamG

    CamG Loggerhead Turtle

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    Greetings Teamcasa and this is a great thread that would be very useful on the new divers forum as well. The breathing control and or regaining control is priceless. It is right on the money the big exhales allows the built up C02 to escape this is a practice that I have had to implement twice thus far in my time diving. Once at 120' and 137'. The post dive break down was very valuable, over stressed due to junk fins and slightly over weighted. Both were easy to correct but allowed for C02 to build up. Both times I closed my eyes and gained breathing control by using the big exhale method. I find it easier to relax when I breath long in and long out even a little past the all out phase.
    This would be a really great addition to the new diver forum because it goes hand and hand to getting the point of normal breathing patterns under water nailed down.
    Good material and that is what makes Scuba Board awesome!
    CamG Keep diving....keep training....keep learning!
     
  6. TSandM

    TSandM Missed and loved by many.

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    There are a lot of different things that contribute to CO2 retention. Excessive exertion at depth can definitely do it -- I've come out of Ginnie Springs several times sick as a dog from overworking. A poorly adjusted regulator can do it -- a friend bought a new reg, and dove it, and couldn't figure out why she always felt as though she couldn't breathe, and ended the dive with a headache. Turned out the cracking pressure on her second stage was three times what it should have been.

    Diving the wrong mix contributes, too -- gas density at depth begins to play a significant role in alveolar ventilation. I'm not sure whether I like helium as much as I do because of nitrogen narcosis, or because it reduces CO2, but the difference, even at 130 feet, is night and day.
     
  7. B.L. Justice

    B.L. Justice MSDT

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    This is a great thread. I have had that OOA feeling at depth a couple of times. I have overcome it by slowing down and trying to focus on a simple task. Until reading these entries, I didn't realize that CO2 had that big an effect.

    I wonder if doing some deep breathing to purge CO2 before dropping down would help to reduce the build up? Anyone have any thoughts on this?
     
  8. TSandM

    TSandM Missed and loved by many.

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    No -- deep breathing before diving would lower your CO2 for a minute or so, perhaps, but certainly within five minutes, you'd be equilibrated again.
     
  9. ROMO DIVER

    ROMO DIVER Scuba Instructor

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    I am a little confused here (it might be excessive CO2 levels) but I would like to know where the idea that hyperventilation causes an increase in CO2 levels comes from. Every medical book I have ever read states that hyperventilation actually decreases levels. Even Dr. Brian's excellent article states this and nowhere mentions that CO2 levels are increased by hyperventilation. While CO2 buildup can initiate hyperventilation it is not the other way around. If I am missing something please edumacate me.
     
  10. Scott L

    Scott L Giant Squid

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    This is were I break ranks with the High Springs boys. In recreation dives under 130ft while not using using HE I am maximizing FO to a PPO of 1.60 as I feel a heck of lot better at the end of the dive as a consequence. Team concept is not broken down completely as my dive partners are also using the same mix as I fill their cylinders after dive sites are selected and dive planning is complete...Often time when hunting with gusto gas is the limiting factor on such dives which results in less nitrogen loading and consequently greater conservatisim. Please don't tell on me...:)
     
    Last edited: Nov 4, 2009
  11. fisheater

    fisheater Divemaster Candidate

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    The problem is that, in common usage, the term hyperventilation appears to mean two, opposite things. True hyperventilation involves very deep exhales, ridding the body of CO2. The term also can be used to refer to rapid, shallow breathing, which fails to rid the body of excess CO2

    Hence, you could say that "to stop hyperventilation, you should hyperventilate."
     
    Last edited: Nov 4, 2009
  12. B.L. Justice

    B.L. Justice MSDT

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    I think it has to do with rapid, shallow breathing. Ken's post makes a lot of sense. The trigger for hyperventilation is a build up in CO2 but it is also stress or cold related. The first time this happened to me, I was at the surface and had plenty of fresh air. It was my first OW training dive, from a boat and my instructor had failed to mention that the water was in the 50s. I think they call it the mammalian diver response. Rapid pulse and sudden gasping for air. A feeling of being oxygen starved and wanting to climb on top of the first person I saw. Took a little bit to settle down - no thanks to my instructor who was oblivious to it all.

    Could be wrong but it made sense to me.
     
  13. Scott L

    Scott L Giant Squid

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    Hopefully TSandM will chime back in to correct any misinformation received from me but the term hyperventilation is used to describe breathing at a rate faster than your normal breathing pattern. It also occurs when you breathe more, i.e. breathing that is deeper and more rapid than normal breathing. So, a term such as hyper shallow breathing is probaly a more accurate way to describe CO2 inducing breathing patterns. TSandM, please help me! :)
     
  14. lowviz

    lowviz Great White

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    Valhalla, time to drag out Walter's old post again. Your answer is in the next to last paragraph, but the whole post is worth a re-read. (Wish I wrote it...)


     
  15. TSandM

    TSandM Missed and loved by many.

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    Yes, the term hyperventilation, as literally construed, means OVERventilating the lungs, and drives your CO2 down. Symptoms can include tingling around the mouth and cramps in the hands and feet. We treat this in the ER in a very high-tech manner -- we make somebody breathe into a paper bag until their CO2 normalizes!

    Hyperventilation, as commonly used in scuba parlance, refers to a shallow, panting, rapid respiratory pattern that DOESN'T effectively ventilate the alveoli deep in the lungs, where gas exchange actually takes place. Thus the CO2 climbs.
     
  16. Bubbletrubble

    Bubbletrubble Regular of the Pub

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    Physiologically speaking, hyperventilation is usually defined as increased pulmonary ventilation due to an increased respiration rate, an increased tidal volume, or both. We have to be careful about how we use terminology here so that no one gets confused.

    Shallow "hyperventilation" (rapid, shallow breathing) will invariably lead to inadequate ventilation...or hypoventilation. This increases CO2 retention within the body, as reflected by elevated PCO2 in blood (both arterial and venous).

    True hyperventilation results in an actual decrease in CO2 levels within the body.

    As Dr. Brian points out in his article, during exercise, metabolic CO2 production increases and to compensate for this, under normal circumstances, the body will increase minute ventilation (volume of gas breathed per minute). Here's an important point. Brian later writes:
    This is where the density of the gas comes into play. Helium mixes have a lower density than nitrox mixes or regular air and therefore, at depth, the gas can be exhaled more easily. This allows an increase in ventilation to compensate for the increased metabolic CO2 production.

    This is the benefit of helium mixes to which TSandM was referring. Not only is there less inert nitrogen in a helium mix (for the purposes of nitrogen loading) but the mix is also less dense than nitrox or regular air so it is beneficial in protecting against CO2 retention. Also, helium has less of a narcotic effect than nitrogen and oxygen. So I guess that's 3 good reasons to be breathing helium-containing trimix on deep dives.

    Clear?

    [Edited later: I see that TSandM was posting at the same time. I think the info in our posts is complementary so I'll leave the post as is.]
     
    Last edited: Nov 4, 2009
  17. Scott L

    Scott L Giant Squid

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    So what is your term of choice to describe the event? - scuba nomenclature withstanding. In the meatime, hypoventilation is looking pretty good to this layperson.

    "Medical Dictionary

    Main Entry: hy·po·ven·ti·la·tion
    Pronunciation: -"vent-&l-'A-sh&n
    Function: noun
    : deficientventilation of the lungs that results in reduction in the oxygen content or increase in the carbon dioxide content of the blood or both —hy·po·ven·ti·lat·ed /-'vent-&l-"At-&d/ adjective "
     
  18. Bubbletrubble

    Bubbletrubble Regular of the Pub

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    This may be one of those cases in which, to be absolutely clear, the phrase "hyperventilation" should not be used.

    "Rapid shallow breathing" says nothing about tidal volume or true alveolar ventilation. On account of this, it's more accurate than the term "hyperventilation" in describing what we're talking about in this thread. Perhaps that's the phrase we should be using in our scuba discussions.

    "Hypoventilation" would probably work...but it is ambiguous in the sense that it could mean a decreased breathing rate, a decreased tidal volume, or both. In my mind, ventilation refers to moving gas in/out of the respiratory tract.
     
  19. Scott L

    Scott L Giant Squid

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    Gotta agree with you. Hey, can you type slower? I do not like to be beaten time wise as my posts lose their relevance after your thoughtfull responses. The forum is lucky to have you! :)
     
  20. Teamcasa

    Teamcasa Sr. Moderator Staff Member ScubaBoard Supporter

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    I would also add that not adjusting your regulator from pre-dive to dive can also lead to problems. I was at 90+ feet on a dive and began to get the tunnel vision. I did the deep exhale followed by the slow deep inhale routine a few times and the tunneling went away. Only then did I realize my regulator's adjustment was set full on pre-dive.
     

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