Elevated CO2 levels?

[seeker242]

So I found this in another post and didn't want to go off topic so I figured I would start a new one in the new divers section.

Unfortunately, too few divers allow themselves the time to learn the difference between elevated CO2 and the onset symptoms of narcosis. Elevated CO2 is especially a problem among those that obsess over their RMV instead of adequate lung ventilation. The symptoms are often indistinguishable, until you overtly modify your breathing to reduce CO2.

CO2 symptoms can go away with proper breathing and can occur on Trimix or HeO2.

What are the signs and symptoms normally associated with elevated CO2 levels? Shortness of breath? Faster breathing? Vertigo? Does "elevated CO2 levels" mean "hyperventilation" or "hypercapnia"? "Elevated CO2 is especially a problem among those that obsess over their RMV" and that is because they would tend to breathe shallow, to conserve air, instead of full deep breaths? Do slight pauses on the inhale or exhale matter at all, as long as you are not "holding your breath" so to speak?

Proper breathing, to correct elevated CO2 I would assume is normal proper breathing, AKA a full exhalation and a slow deep inhalation? Does the speed of exhalation matter? Is it possible to "overdo" exhalations that would cause CO2 levels drop too low? Is it possible for CO2 levels to drop too low? If so, what would cause that? What effect does breathing too fast have, if any? Even if they are full complete breaths?

Occasionally, I'll experience a very slight vertigo sensation. But if I focus my vision on a stationary object and do one slow long exhale and inhale, it goes away immediately. It only lasts a matter of seconds. It doesn't cause any problems really. It's more like "Hmm, that was weird, what was that about?" I wondering if this is related to CO2? Or perhaps ear equalization? My left ear seems to equalize very slightly differently from my right ear.

 

[dumpsterDiver]

So I found this in another post and didn't want to go off topic so I figured I would start a new one in the new divers section.



What are the signs and symptoms normally associated with elevated CO2 levels? Shortness of breath? Faster breathing? Vertigo? Does "elevated CO2 levels" mean "hyperventilation" or "hypercapnia"? "Elevated CO2 is especially a problem among those that obsess over their RMV" and that is because they would tend to breathe shallow, to conserve air, instead of full deep breaths? Do slight pauses on the inhale or exhale matter at all, as long as you are not "holding your breath" so to speak?

Proper breathing, to correct elevated CO2 I would assume is normal proper breathing, AKA a full exhalation and a slow deep inhalation? Does the speed of exhalation matter? Is it possible to "overdo" exhalations that would cause CO2 levels drop too low? Is it possible for CO2 levels to drop too low? If so, what would cause that? What effect does breathing too fast have, if any? Even if they are full complete breaths?

Occasionally, I'll experience a very slight vertigo sensation. But if I focus my vision on a stationary object and do one slow long exhale and inhale, it goes away immediately. It only lasts a matter of seconds. It doesn't cause any problems really. It's more like "Hmm, that was weird, what was that about?" I wondering if this is related to CO2? Or perhaps ear equalization? My left ear seems to equalize very slightly differently from my right ear.

I won't answer all your questions, but you should learn how to address it in your OW class.

First, when you find yourself in a hole - stop digging... STOP kicking with the big leg muscles. Best to try to stop as much activity as possible. If there is a current and you are not on a drift dive, grab something and hide from the current and rest.

The next thing, is not to breath normally. You need to concentrate on exhaling fully, pushing out more air than normal.. a deeper exhalation. you don't want to go crazy, but you want to push out the air from the bottom of your lungs with a little effort. This helps to vent Co2 and will prevent you from panting. You don't need to try to take in giant inhalations..

As a means to prevent CO2 build up... if you know you are gonna do something stupid and really exert yourself, start this breathing pattern BEFORE it feels necessary. If you got to sprint across the open deck of a wreck in a strong cross current, start blowing some air NOW. Preventing the dreaded CO2 headache is a lot easier than trying to remedy it it afterwards.

 

[seeker242]

I won't answer all your questions, but you should learn how to address it in your OW class.

First, when you find yourself in a hole - stop digging... STOP kicking with the big leg muscles. Best to try to stop as much activity as possible. If there is a current and you are not on a drift dive, grab something and hide from the current and rest.

The next thing, is not to breath normally. You need to concentrate on exhaling fully, pushing out more air than normal.. a deeper exhalation. you don't want to go crazy, but you want to push out the air from the bottom of your lungs with a little effort. This helps to vent Co2 and will prevent you from panting. You don't need to try to take in giant inhalations..

As a means to prevent CO2 build up... if you know you are gonna do something stupid and really exert yourself, start this breathing pattern BEFORE it feels necessary. If you got to sprint across the open deck of a wreck in a strong cross current, start blowing some air NOW. Preventing the dreaded CO2 headache is a lot easier than trying to remedy it it afterwards.

Thanks. I finished my OW class but they only touched briefly on the subject. I learned the "breathe slow and deep" mantra for effective gas exchange, because it was repeated over and over, but no real detailed explanation as to why exactly, with regards to specific gasses. or what effects would occur if I didn't do that. Of course they did mention "overexertion" but they really didn't relate that to "excessive CO2 buildup" specifically, at least not that I remember. But, it seems like the two go hand in hand. I guess the symptoms for "overexertion" would be the same as "CO2 buildup"? Fatigue, labored breathing, air starved, headache, anxiety, etc. Sounds kinda the same. Although, would it be true to say that CO2 buildup generally only happens along with overexertion? I guess it could happen if you are just breathing too shallow in general and not really doing anything strenuous?

 

[boulderjohn]

I am not sure what Akimbo means by his differentiation. To me, elevated CO2 levels are associated with narcosis--maybe he is saying the same thing. If so, then I also agree with what he says next--by limiting the CO2 buildup, you limit the effect of CO2 narcosis. I will next attempt to expand upon my understanding of what he said AFTER THAT, in the hope he will correct anything I did not say correctly. EDIT: Just to be clear, I am well aware of the fact that Akimbo knows what he is talking about, so I am ascribing any differences to misunderstanding of what he said.

Many people try to extend their dive time by limiting their breathing patterns, resulting in a buildup of CO2. One example of this is something called "skip breathing," in which divers essentially hold their breath at times with the goal of extending their bottom times. I recently dived with highly experienced divers who laughingly said "Hell, yes, I skip breathe!," confident in their ability to do so without going so far as to cause a CO2 buildup problem. (I don't have that confidence.) I think Akimbo is saying that if you get narcosis-like symptoms because you are doing that, then they can be alleviated by stopping it. In contrast, inert gas narcosis caused by the combination of the gas mixture being breathed and the depth can only be affected by getting to a shallower depth.

---------- Post added October 5th, 2015 at 07:30 PM ----------

Although, would it be true to say that CO2 buildup generally only happens along with overexertion? I guess it could happen if you are just breathing too shallow in general and not really doing anything strenuous?

As mentioned above, poor breathing habits are probably more often the cause.

 

[oldschoolto]

John Chatterton has a very good write up on his site "Diving with Stevie Wonder....

Jim

 

[Kevrumbo]

CO2 Retention/Hypercapnia and Narcosis: Deep Air with increased Gas Density & Work-of-Breathing Dyspnea; then throw in Physical Exertion or a Stress Condition, resulting in overbreathing the regulator --all leading to the Vicious Cycle of CO2 Retention and sudden Narcosis (also known as the panicky feeling "Dark Narc"). Can result in severe cognitive impairment at depth or worst case stupor and ultimately unconsciousness. . . In order to break this CO2 build-up cycle, you have to relax with a few minutes of full slow controlled inspiration breathing: --cease & desist all physical exertion that stimulates hyperventilation and abort the dive if indicated.

Taken from Undersea Biomedical Research, Vol 5, No. 4 December 1978 Hesser, Fagraeus, and Adolfson:"Studies on the narcotic action of various gases have shown that the ratio of narcotic or anesthetic potency of CO2 and N20 approximates 4:1, and that of N2O and N2 30:1. From these figures it can be calculated that CO2 has at least 120 times the narcotic potency of nitrogen. Our data would suggest that the narcotic potency of CO2 is even greater, i.e., several hundred times as great as that of nitrogen.

"

Originally Posted by TSandM
Overbreathing the regulator MEANS a CO2 hit . . . It means the increased work of breathing of using a regulator is enough, at the current demand, to prevent you from exhausting all your CO2. All regulators can deliver more gas, faster than you can use up oxygen, but the small increase in resistance involved in trigger the inlet valve and opening the exhaust valve can make the difference between being able to keep your CO2 normal under heavy work loads, and not being able to keep up.

Panic in the experienced diver?

Originally Posted by TSandM
CO2 in the bloodstream is completely determined by minute ventilation, assuming the gas you are breathing does not contain additional CO2. Bailing to open circuit definitely makes it POSSIBLE to reduce the blood CO2 level, assuming you can achieve a higher minute ventilation than what's required to keep the CO2 where it is (which is in part related to level of exertion). It may not, however, be possible to reduce CO2 fast enough to clear your head and get rid of the panicky feeling, in part because the natural tendency when panicky is to breathe as fast as possible. On scuba, this means reducing the efficiency of the ventilation, because too much of it is just going to exchange gas in the trachea and large bronchi, which don't exchange gas. That's why we are taught in OW that, if we begin to "overbreathe our regulator" (meaning the diver feels short of breath despite breathing as much as he can), we are to STOP, hang onto something (reduce exertion) and breathe SLOWLY and DEEPLY. It is then possible to reduce CO2. What may not be possible is to stay rational long enough to do it.

Panic in the experienced diver?

 

[seeker242]

John Chatterton has a very good write up on his site "Diving with Stevie Wonder....

Jim

Thanks! Found that very helpful. Especially the two papers he mentions in his training section, Carbon Dioxide, Narcosis, and Diving, and Mechanisms of Hyperoxic Seizures. This is exactly what I was looking for, detailed explanations. I'm sure the 2nd will come in handy when I go for nitrox training.

 

[TMHeimer]

seeker242, I believe one of my ears may equalize before the other as well on rare occasions. I too have had that slight vertigo when ascending (maybe half dozen times over 10 years). I don't recall ever having any breathing problems, CO2 build up, etc. of any kind. The vertigo just seems to be as you say "what was that about"? Lasts several seconds and vanishes. First time it happened I was ascending from 45 FSW and it was a little disconcerting.

 

[oldschoolto]

Thanks! Found that very helpful. Especially the two papers he mentions in his training section, Carbon Dioxide, Narcosis, and Diving, and Mechanisms of Hyperoxic Seizures. This is exactly what I was looking for, detailed explanations. I'm sure the 2nd will come in handy when I go for nitrox training.

Glad to help .... ;-)

Jim...

 

[dreamdive]

Actually, CO2 is more narcotic than N2. However, I would find it difficult to differentiate if I am narced from CO2 or N2 other than having other signs of CO2 retention (increased resp rate, increased heart rate, headache.......)