Diving with Stevie Wonder

Hydro Atlantic

Deck of the Hydro Atlantic













Enter the villain, Carbon Dioxide.












15 Responses

  1. Jeff Raffa
    Great arrival as usual. I really enjoy your blog.
  2. Manuel Garcia
    Hey John, Been following your blog fro some time now, great stuff. I am a little vexed at your explanation of CO2 toxicity though. CO2 is a metabolic waste product, which is vented out of the body when breathing, unless a diver is holding his breath. I don't understand how it could be retained in the body at a partial pressure greater than normal since it depends solely on the metabolic output of the muscles, normal breathing in an open circuit system will dump all excess CO2 out. As far as being narc'ed... There is consensus that it is responsible, at least in part because of the saturation of N2 in the neural cells. N2 is very lipid soluble, (which is why it is used to make whipped cream at coffee shops) and so it can penetrate and saturate the cell surrounding neurons. This saturation alters the natural volume, and chemical properties of these cells making, which causes an interruption in normal neural signaling. I dive out of SFDH with the FIU program regularly, we just finished doing a photo shoot on their new boat the Black Pearl. Hope to see you out on the water sometime! -Manny
    • John Chatterton
      Manny, Thanks for the feedback. Yes, the science about what elevated levels of N2 do is developing, and I am not an academic researcher, but I do not believe anyone has all the answers about how narcosis happens? However nothing I am aware of with regards to N2 narcosis explains why today, and not tomorrow? Why Steve, and not me? Why 90', or 80'?? As far as the buildup of CO2, it has to do with the lag time between producing CO2, and eliminating it through the lungs. If you increase production, and you do not increase elimination, you get more systemic buildup of CO2, not unlike someone with COLD. When you work, you consume O2, and produce CO2. Your body senses the increase in CO2, and your respiratory rate increases. But if you are diving, you have to overcome the Work of Breathing from the use of the scuba delivery system, as well. So, your work increases CO2, which increases respiration, which increases CO2. It can be a snowball, even in shallow water, and impacts more than just narcosis, IMHO. They still need some people to go and dive the Rodeo25 tomorrow? What are you going to do, that is more important than that? Cheers JC
  3. Mike Walsh
    Good 1 & it's true how to exausting C02 .. It's the main problem with getting narked !! Thanks to dives like John his buddy came back ...........
  4. Gas exchange between the atmosphere and the blood takes place at the alveoli, which line the lung. During shallow breathing, the alveoli in the lower lung collapse for lack of use. This is called atelectasis. Periodically taking a deeper breathe, as you suggest, will open the collapsed alveoli and improve gas exchange during both inhalation and exhalation. Some degree of atelectasis is normal even out of the water, even though it can be associated with various medical conditions and procedures. My experience with atelechtasis is limited to general nesthesia. Long periods of shallow breathing cause atelechtasis which limits gas exchange, raises CO2 levels, and lowers the blood pH (more acidic). Anesthesia causes all of this; none of it is good. "Bagging" - firmly squeezing the inhalation bag to force a deep breathe - will open the alveoli (relieve atelectasis) and improve gas exchange. Once every 5 minutes is sufficient. Taking a deep breathe periodically, as JC suggests, by relieving atelectasis would improve gas exchange. Taking a deep breathe periodically is NOT a license to hyperventilate.
  5. Good post John. Nitrogen will certainly have an affect at depth, but it is often misunderstood. CO2 is a big contributor and when someone, especially those with tons of experience at depth, suddenly has a much stronger response to relatively shallow depths, it is best to look at CO2 as the additional gas in the equation. They can also look at the feeling of the narcosis. CO2 narcosis tends to come on hard and is much less pleasant than N2 is. This of course is not a data point, but does seem to ring true. For lack of a better explanation, it can feel more aggressive. Narcosis will tend to extend whatever mental state you are in. So, if you are excited about the dive, you may become giddy or laugh. If you feel apprehensive about the dive, narcosis can lead to greater feelings of stress and even panic. CO2 being added in can turn a pleasant sensation into one of great discomfort or even terror. John, you also point out another important aspect of the situation, at greater depths it does not go away from the ascent of ten or twenty feet. Unlike the techniques suggested in the recreational texts. Impairment can last to significantly shallow depths often near the surface. As much as trimix is becoming a crutch for narcosis avoidance, it is no assurance that narcosis will not show up. So, narcosis tolerance training is still needed even with trimix at any depth. I have seen divers on high helium mixtures narced out of their minds very shallow because of hard work and CO2 build up. So, those that are out there believing that trimix will save them from narcosis need to think again. I would suggest that those that think CO2 is not an issue read some medical texts. It is a metabolic gas, but gas densities at depth, breathing equipment, technique, and workload among other things can all lead to increased levels. The assumption that all the CO2 produced is breathed out on every breath is not how things work. It also does not take massive amounts of extra CO2 to begin to have effects. Proper technique means a lot. But, good technique is not going to eliminate narcosis. Here is a post on breathing techniques. http://precisiondiving.com/2011/03/18/breathing-for-scuba/
  6. This is an excellent informative post. I am a long way from being a tech diver, though I hope to be some day, but this is good information for recreational divers to. Thank you John Tláloc
  7. Don Sack
    Hey John; Great information which, as an RN, makes darn good sense. I'm a novice diver on Cape Cod (you may remember the short piece I posted some few years ago along with photos of Seeker when I found her land locked near New Port)and am fortunate to dive with the "crew" out of Dive Locker in Hyannis.It is the season around here but this 61 year old is in half butt shape so there will be a lot of dives at Hathaway's Pond before I follow the guys off the back side;Jiu Jitsu training sees to that! I never did understand why some divers insist on kicking like mad and going no where. Get a grip! Crawl when ever you can is my motto!
  8. Great post, John. I think the increase in CCR use has significantly contributed to the understanding of CO2 effects. This is of benefit to all divers, open and closed circuit. I was taught that different gases have different narcosis effects: helium is slight and others worse. Some consider oxygen to be only slightly less narcotic than nitrogen. I don't know where CO2 ranks on the scale, but anecdotally it appears to be bad. Does anyone have a link to a narcotic relativity table? Cheers John.
  9. Jeff McPhate
    Good suggestion for possible cause. Historical note: C02 has been used as anesthesia gas in veterinary applications. It is quite potent at high partial pressure. Perhaps there's also a link with depth and rate of exertion together. Certainly whatever traces exist in the breathing mix are going to have proportionally higher partial pressure at depth, just like every other component.
  10. Robert H. Hughes
    John, All of these parameters have an effect on our bodies and minds while diving. Every divers own physical conditions also have an effect regarding narcosis. Depth, task load, physical activity, general health, etc. I have to agree with the comment that "recreational" tri-mix and rebreather use has begun to be looked at as a "magic" solution to narcosis and I feel that is becoming a very dangerous assumption. Another thing that I feel is getting overlooked by a huge portion of divers is gas quality. In saying this I am referring to CO2 levels in a tank fill. I realize that all of us diving on blended gas other than compressed air are testing our tank fills for content percentages. However- I would like to bring up a situation that even the most seasoned divers never saw coming! While cave diving in Mexico on tri-mix rebreathers the group all had air fills done. Two days of stage bottle placement in the cave system was carried out along with in depth planning and safety considerations. The day of the mapping research project had arrived and all systems were a go. Each diver meticulously went through pre-dive checks, numerous re-checks and pre-breathing and the dive was a go. All entered the water and the project was underway. Six divers entered the cave system with slow deliberate actions and all looked to be going great. Approximately twenty minutes into the penetration one diver started to pick up speed unexpectedly and break away from the group quickly. This was a very experienced cave diver who was young, in great physical shape and a seasoned rebreather diver. What had caused this sudden dangerous burst of speed? He was located approximately one hundred and fifty feet ahead of the group after a slow and methodical continuation of the dive plan. He was found to be unconcious floating at the cave ceiling with his breathing loop hanging out of his mouth. Now this mapping dive had turned into a rescue and any attempt to force a pony regulator into his mouth had failed as his jaws were tightly clamped shut, even an attempt to pry his mouth open had failed. The group turned the dive with the unconcious non-breathing diver and rushed back out of the system while administering CPR, surfaced and started emergency rescue attempts until medical personnel arrived. These attempts along with the attempts by the medical personnel had all failed and the diver was pronounced at the scene. WHY HAD THIS HAPPENED? How could such an experienced, well trained cave and rebreather diver have met such a horrible outcome? Upon investigation of all the equipment he was diving (all was functioning perfectly) and review of his unexplainable actions- there came a shocking answer! His breathing gas was tested- his mix was right on the money and it all looked good. But- when those same tanks were tested for CO2 the levels came back elevated. The cause of his erratic behavior and sudden "bolting" came back to the gas content of his tanks. When his tanks were filled (due to assumed failure of a compressor) the levels of CO2 were elevated and this had caused his demise. What I am trying to stress here is simple. We all test our breathing gas religously, but how many of us test our gas with a CO2 analyzer? Well I can tell you for FACT- that I carry a CO2 analyzer along with my other analyzers and DO NOT take for granted that the level of CO2 in my breathing gas is acceptable!!! I know that I have strayed off the topic of your blog a bit John, however- CO2 is a silent killer and can turn a person who is the safest and most deliberate diver into his own worst enemy. Narcosis and CO2 levels effect us all differently, but an unseen danger that can be seen should not be ignored under any circumstance. My life is well worth the $250.00 cost of a CO2 analyzer and is one more factor I can directly control BEFORE I enter the water! Brendon was a young man in the prime of his life with two young children and because of a "bad" gas fill his children will grow up without ever knowing what a wonderful person he truly was. Hope this makes us all think about what are we truly breathing and don't take for granted anything. This was a very reputable and well known fill location and it could've been a place that YOU got you tank filled recently?
    • Greg N
      Robert, I think you actually mean CO (carbon monoxide) and not CO2 (carbon dioxide). An elevated CO level in the breathing gas will bind to hemoglobins and inhibit O2 transport to your cells. It will also inhibit CO2 elimination as the CO binds very strongly to the hemoglobins and reduces their gas transport carrying capacity. This is one of the main reasons it's not a good idea to have a cigarette before or after diving (or anytime for that matter).
  11. Rick Thomas
    John, I completely agree with you on this one. One tour working a braille dive with an old hat with no o/n mask will teach you the value of correct breathing. The CO2 catches up with you and you are in for a bad day in the office. This lesson best learned by a cherry or pumpkin. rdt
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  13. Greg N
    John, I totally agree about CO2 being the main culprit in narcosis. I think its effects on diving deaths are seriously understated. If one uses the Meyer-Overton gas solubility chart to gauge the relative narcotic effects of a gas - it shows CO2 with about 25 times more narcotic potential than Nitrogen. Wow! is what I said when I saw that. 25 times... Also, as I understand it, the C02 buildup at depth is not the cO2 that is produced by the body's oxidative process (this should stay constant) but as you alluded to in WOB (Work Of Breathing). As we dive deeper the gas is denser and it takes more work to move the same amount of gas through our lungs. This results in less efficient gas exchange and a build up of CO2.-Got your regulators serviced recently? This would make a huge difference at depth. Helium? hell yes.
  14. John, excellent piece. I have had that happen to me. Same dive, once clear-- another time dangerously dopey. I had always wondered what the "difference" was? It makes perfect sense to me if I consider what you are saying. I think of it as "beginning of dive residual in-body gases." (Once, I had an experience where I felt bizarre after a bounce to tie in @ 160) < and when I came up, I realized the boat exhaust was bad, and it had a direct effect. This is a good piece of thinking/writing and it should be shared. Thanks for your professional approach to diving. (*Btw- I read your experience @ WTC. < I was a visitor there only a month before 9-11) The trajectories were on do not belie our orbits ;-) Dave

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