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Scuba Forum / General / February 2007Narcosis Explained
"The next depth related danger occurs around 100 feet, and effects different people differntly. Now you start talking about "partial pressures" and other complex interactions of the gases that make up "air". Basically, air contains a lot of nitrogen, which is normally a safe harmless gas. As the pressure increases, however, nitrogen and oxygen combine to form "nitros oxide" which can have a dramatic effect on you." Care to comment? :-) > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 5 lines] > > Care to comment? :-) Sounds like a troll to me! > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 3 lines] > oxygen combine to form "nitros oxide" which can have a dramatic effect > on you." > Care to comment? :-) Where did you get that doozy? http://www.scuba-doc.com/narked.html http://www.sfu.ca/~jmorriso/kin485/inert_gas_narcosis.doc http://www.anesthesia-analgesia.org/cgi/content/abstract/96/3/746 > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 5 lines] > > Care to comment? :-) Firstly, you need to stop sniffing cans of whipping cream ;-) Secondly, you're wrong. Nitric oxide (NO) is a common component in our bodies which plays a central role in numerous things, ranging from neurotransduction, to bacterial clearance, to giving you an erection. It's only known synthesis pathway within our bodies is via enzymes called "nitric oxide synthetase" - AKA NOS. None of these use nitrogen as a reagent, as nitrogen is simply too chemically inert for our bodies to convert it into anything. Instead, the nitrogen is stripped from L-argine, an amino acid. The anesthetic effect of NO appears to be due to its absorption into neural cell membranes, where it interferes with the transmission of neural impulses. Bryan >> As the pressure increases, however, nitrogen and oxygen combine to form >> "nitros oxide" which can have a dramatic effect >> on you." > Secondly, you're wrong. Nitric oxide (NO) is a common component in our > bodies which plays a central role in numerous things, ranging from [quoted text clipped - 8 lines] > neural cell membranes, where it interferes with the transmission of neural > impulses. Seems to me that he's not the only one that's wrong. Everything I've seen says that Nitrous Oxide, also known as dinitrogen monoxide, is N2O, not NO. As for interfering with the transmission of neural impulses, doesn't that describe nitrogen narcosis as well? Lee >>> As the pressure increases, however, nitrogen and oxygen combine to form >>> "nitros oxide" which can have a dramatic effect [quoted text clipped - 19 lines] > > Lee Oops, my mistake. I actually was intending to write about N2O (he mis-spelled the word, not sure what he was talking about). Regardless, had I put in the last sentence it would have made a lot more sense: our bodies breakdown NO into several components, including N2O, NO2, peroxynitrate, nitrosylated proteins, etc. This breakdown of NO into N2O is the only natural way N2O is produced in our bodies. Regardless, nitrogen is simply too stable to be biologically reacted into N2O, NO2, or any other similar product simply by increasing pressure. Only a few biological organisms have the ability to fix N2, and they require tremendous amounts of energy to do so - far, far more energy then is provided by increasing the partial pressure of N2 during a dive. Bryan > Oops, my mistake. I actually was intending to write about N2O (he > mis-spelled the word, not sure what he was talking about). Yes he did. I considered what he might mean and decided it had to be nitrous oxide, N2O. > Regardless, nitrogen is simply too stable to be biologically reacted into > N2O, NO2, or any other similar product simply by increasing pressure. > Only a few biological organisms have the ability to fix N2, and they > require tremendous amounts of energy to do so - far, far more energy then > is provided by increasing the partial pressure of N2 during a dive. This is the first post in the series that indicates a reason why the original post is probably incorrect. Interestingly, though, you state that "Nitrogen is too stable to be biologically reacted." The implied process in the original post did not appear to be a biological process, but rather, a purely physical one resulting from the increased pressure. The rest of the sentence, however, implies that simple pressure, at least at a few BAR, is also inadequate to result in N20 from a purely physical process. So, assuming you're information is as factual as you make it sound, congratulations, you've busted the myth. Lee > This is the first post in the series that indicates a reason why the > original post is probably incorrect. Interestingly, though, you state that [quoted text clipped - 3 lines] > sentence, however, implies that simple pressure, at least at a few BAR, is > also inadequate to result in N20 from a purely physical process. Nitrogen will have more of an effect when it is eaten in form of more complkexe moleculkes... Otherwise a diver who got busted would also get combusted. > So, assuming you're information is as factual as you make it sound, > congratulations, you've busted the myth. Were it otherwise, a diver who got busted would also get combusted. Matthias > This is the first post in the series that indicates a reason why the > original post is probably incorrect. Interestingly, though, you state that > "Nitrogen is too stable to be biologically reacted." The implied process in > the original post did not appear to be a biological process, but rather, a > purely physical one resulting from the increased pressure. Based on the OP I guessed he was referring to a non-biological fixation method, as humans simply do not fix N2. Nitrogen is an inert gas, meaning that it is not chemically reactive. Converting N2 into other nitrogen-containing molecules (called nitrogen fixation) requires tremendous energy - for example, here on earth the major source of non-biological nitrogen fixation is lightning. Biological fixation accounts for the majority of nitrogen fixed here on earth; but still requires huge amounts of energy. Only a few species of bacteria are known to do this - for example, the bacteria which colonize the roots of some plants. > The rest of the > sentence, however, implies that simple pressure, at least at a few BAR, is > also inadequate to result in N20 from a purely physical process. Yes. If you put N2 under enough heat/pressure you can get it to react, but those conditions would never be seen in a diver - not even in the deepest of dives. Commercial nitrogen fixation is done by compressing nitrogen & hydrogen, along with a catalyst, at 250 atmospheres, 450-500C. Assuming my memory of my into scuba is still good, that's a pressure equivalent to ~2,500m (8300'?) depth. Since the catalyst doesn't exist in our bodies (or free hydrogen for that matter) its a good bet that even this is a gross underestimate of what kinds of pressures & temps you'd need. > So, assuming you're information is as factual as you make it sound, > congratulations, you've busted the myth. The bio stuff is accurate - I work for one of the labs which uncovered several of NO's biological effects and secretion mechanism, so I'm pretty familiar with that end of things. The rest is just high school (or by todays educational standards, 1st year college) chemistry. Bryan > > Oops, my mistake. I actually was intending to write about N2O (he > > mis-spelled the word, not sure what he was talking about). [quoted text clipped - 20 lines] > > Lee When I read the statement about nitrous oxide forming due to pressure increase on the body being the cause of NN. I looked up how nitrous oxide is made commercially. And based on what I read (it can be a rather explosive process) I realized the partial pressure method could not be true or no one would bother making it any other way. > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 3 lines] > oxygen combine to form "nitros oxide" which can have a dramatic effect > on you." Care to comment? :-) Interesting. First, Bill's been around for a long time. Hi Bill. Nice to see you back. Second, he's not a troll, unless your definition of troll includes on topic comments intended to stimulate interesting discussion. If this is a troll, we could use more like it. Several people pointed out that nitrogen narcosis is a form of inert gas narcosis, sure it is, but that does not mean that the nitrogen causing the inert gas narcosis isn't nitrous oxide, N2O rather than N2. Personally, I haven't a clue, but it's an interesting idea. Lee > capt.bil...@verizon.net wrote > [quoted text clipped - 19 lines] > > Lee Thanks Lee for the "welcome back". I got that off a boating forum that I visit. They just started a diving section and a discussion on NN came up. Some one posted that ditty as fact. :-) When I called him on it he said when he got certified his instructor claimed that was the cause of NN. Scary what gets passed on as fact in some course classes. This is more like what I understand the cause to be: "Scientists aren't sure, but most now accept what's called the Meyer- Overton hypothesis, that narcosis happens when the gas penetrates the lipids (the fatty structures) of the brain's nerve cells. Here it apparently interferes with the transmission of signals from one nerve cell to another and disrupts your central processor. It's a little like spilling a Coke onto your computer keyboard." <capt.bill11@verizon.net> wrote> "Scientists aren't sure, but most now accept what's called the Meyer- > Overton hypothesis, that narcosis happens when the gas penetrates the > lipids (the fatty structures) of the brain's nerve cells. Here it > apparently interferes with the transmission of signals from one nerve > cell to another and disrupts your central processor. It's a little > like spilling a Coke onto your computer keyboard." Here's what Wikipedia says about nitrous oxide. "Nitrous oxide is relatively non polar, has a low molecular weight and high lipid solubility. As a result it can quickly diffuse into phospholipid cell membranes. Like many classical anesthetics, the exact mechanisms of action is still open to some conjecture. It inhibits the NMDA receptor at partial pressures similar to those used in general anesthesia." Not all that different, is it? Like I said, we're pretty sure that nitrogen is the culprit, but I still haven't seen anything that makes it clear that it's N2 and not N2O that carries the nitrogen to brain cells . . . and visa versa. Lee > <capt.bill11@verizon.net> wrote> "Scientists aren't sure, but most now > accept what's called the Meyer- [quoted text clipped - 19 lines] > > Lee The problem is that you can't make nitrous oxide in a scuba tank. You need a very different process. If yer filling yer tanks with nitrous, there might be a significant narcotic effect at relatively shallow depths. esg > "Scientists aren't sure, but most now accept what's called the Meyer- > Overton hypothesis, that narcosis happens when the gas penetrates the > lipids (the fatty structures) of the brain's nerve cells. Here it > apparently interferes with the transmission of signals from one nerve > cell to another and disrupts your central processor. It's a little > like spilling a Coke onto your computer keyboard." There are studies which indicate a 1/6 narcotic potential for oxygen with repect to nitrogen. Anyhow, the Meyer-Overton hypothesis does not count for the oxygen window, and thus not for the loss of partial pressure due to metabolism. Matthias > Several people pointed out that nitrogen narcosis is a form of inert gas > narcosis, sure it is, but that does not mean that the nitrogen causing the > inert gas narcosis isn't nitrous oxide, N2O rather than N2. Personally, I > haven't a clue, but it's an interesting idea. Claiming that it is nitrous oxide instead of just the nitrogen doesn't explain why argon, xenon, and krypton also have increased narcotic effects at higher partial pressures... There's no reason that nitrogen would be a special case... >> Several people pointed out that nitrogen narcosis is a form of inert gas >> narcosis, sure it is, but that does not mean that the nitrogen causing >> the >> inert gas narcosis isn't nitrous oxide, N2O rather than N2. Personally, >> I >> haven't a clue, but it's an interesting idea. > Claiming that it is nitrous oxide instead of just the nitrogen doesn't > explain why argon, xenon, and krypton also have increased narcotic effects > at higher partial pressures... There's no reason that nitrogen would be a > special case... Since why argon, xenon and krypton are not part of the question, I made no attempt to explain them. For that matter, I didn't make any attempt to explain N2 versus N2O. As for why nitrogen might be a special case, let me see, now, N2O is made up of nitrogen and oxygen. Nitrogen and Oxygen are the two most common gases in air, the breathing stuff we're talking about. Other inert gases are present in such miniscule amounts that we don't even mentioned them individually. Hmmm, seems like that might make a difference. What do you think? Nobody, including me, has claimed that it was anything other than Nitrogen that is responsible for the effects. The only discussion is about what molecule carries the nitrogen into the body's tissues. Since both N2 and N2O are soluble in lipids, and since both are known to have the same effects once there, by the same means, almost certainly because of the nitrogen content, what makes you choose one medium over the other? So far, not one person, including me, has said a word about why we should expect it to be one form or the other. Bill posted someone else's unsupported opinion that it was N2O. Everyone else has posted their unsupported opinion that it is N2. I posted that, after doing a bit of research, I still don't know. When someone comes up with some evidence, one way or the other, we may actually know the answer. That hasn't happened yet. Lee >>Several people pointed out that nitrogen narcosis is a form of inert gas >>narcosis, sure it is, but that does not mean that the nitrogen causing the [quoted text clipped - 5 lines] > at higher partial pressures... There's no reason that nitrogen would be a > special case... Nitrogen is not a special case. It acts just as predictably and reliably as all the other inert gases. esg >>>Several people pointed out that nitrogen narcosis is a form of inert gas >>>narcosis, sure it is, but that does not mean that the nitrogen causing the [quoted text clipped - 8 lines] >Nitrogen is not a special case. It acts just as predictably and reliably >as all the other inert gases. Are effects the same? I've had nitrous at the dentist but I've never been narced, I don't know. Galen Hekhuis ghekhuis@earthlink.net Illiterate? Write for FREE help > Are effects the same? I've had nitrous at the dentist but I've never > been narced, I don't know. I have been gassed at the dentist, but never narced that hard diving, so it would be hard to say. >>Nitrogen is not a special case. It acts just as predictably and reliably >>as all the other inert gases. [quoted text clipped - 3 lines] > Galen Hekhuis ghekhuis@earthlink.net > Illiterate? Write for FREE help I've been narc'd plenty of times but I've never had nitrous at the dentist. And being narc'd is a bit over-rated - I sure wouldn't want anyone drilling my teeth at 220 fsw on air. esg > I've been narc'd plenty of times but I've never had nitrous at the dentist. I've had it once at the dentist... Maybe I just wasn't breathing deeply enough, but it didn't seem as effective as a *really good* narc... <grin> > And being narc'd is a bit over-rated - I sure wouldn't want anyone > drilling my teeth at 220 fsw on air. I've definitely noticed tunnel vision / task fixation when going deep on air, but it seems a different sensation than nitrous... Of course, maybe I just didn't do enough nitrous... Sounds like further study is recommended... <evil-grin> > > I've been narc'd plenty of times but I've never had nitrous at the dentist. > I've had it once at the dentist... Maybe I just wasn't breathing > deeply enough, but it didn't seem as effective as a *really good* > narc... <grin> > > And being narc'd is a bit over-rated - I sure wouldn't want anyone > > drilling my teeth at 220 fsw on air. > I've definitely noticed tunnel vision / task fixation when going deep > on air, but it seems a different sensation than nitrous... Of course, > maybe I just didn't do enough nitrous... Sounds like further study is > recommended... <evil-grin> To get the full effect, you have to do one of two things; 1) At the dentist, you wait until they settle you in, turn on the gas, then they leave the room to let you get comfy, and then you turn up the flowmeter. 2) You buy the stuff from your local gas supplier (we used it for drag racing, but that was before they were putting sulphur dioxide in it to make you puke), and you inflate clear 10 gallon garbage bags, filled 1/2 with air, and place them over your head. > To get the full effect, you have to do one of two things; > > 1) At the dentist, you wait until they settle you in, turn on the gas, then > they leave the room to let you get comfy, and then you turn up the > flowmeter. No problem there... > 2) You buy the stuff from your local gas supplier (we used it for drag > racing, but that was before they were putting sulphur dioxide in it to make > you puke), and you inflate clear 10 gallon garbage bags, filled 1/2 with > air, and place them over your head. ...but, man, 10 gallons of gas in a plastic bag is gonna take 80 pounds of lead to get off the surface, then at 220 you'll be overweighted better than 70 pounds. That's crazy! Why not just put it in a tank??? I just don't understand west coast dive protocols! esg > No problem there... > > [quoted text clipped - 8 lines] > > I just don't understand west coast dive protocols! Maybe you oughta come on out and dig it, man. We got 7mm wetsuits for you to wear under your leathers while you hit the highway at illegal speeds. >>"The next depth related danger occurs around 100 feet, and effects >>different people differntly. Now you start talking about "partial [quoted text clipped - 15 lines] > inert gas narcosis isn't nitrous oxide, N2O rather than N2. Personally, I > haven't a clue, but it's an interesting idea. Nitrous oxide has been used substituting nitrogen as an agent to induce narcosis because it was believed to act in a similar, if not identical way, and furthermore, did not need to be applied under pressure. However, in the "french" link Scott gave, the scientists point out the physiologic differences between nitrous oxides and nitrogen. Furthermore, most studies were in a chamber, with task different from those in a real dive, at least becuase of the different environment. Because of this, I would question a 101 transfer from chamber findings to real diving, eg. the individual's aptitude to complete a dive successfully. Matthias > Nitrous oxide has been used substituting nitrogen as an > agent to induce narcosis because it was believed to act in a [quoted text clipped - 4 lines] > point out the physiologic differences between nitrous oxides > and nitrogen. Bingo. Anyone who has done both knows that there is a difference. > Furthermore, most studies were in a chamber, with task > different from those in a real dive, at least becuase of the > different environment. > Because of this, I would question a 101 transfer from > chamber findings to real diving, eg. the individual's > aptitude to complete a dive successfully. Also not addressed is the issue of attenuation/aggravation effect of hypervolemia as a result of "weightlessness" and horizontal position. The mechanism of action is believed to be the same for all anaesthetic gasses, which is thought to be reaction of these gasses with the myelin sheath that covers nerve cells, interfering with nerve conduction and "communication". Nitrous oxide is not produced in the body, it is simply that the mechanism of action is believed to be the same as hyperbaric nitrogen. Anyone who has done 3 or 4 air dives in a day should be able to tell you about the "residual anaesthetic effect." I asked The Ole Man, who has been to 300 feet on air in a Mk V, if he was narced and how bad, and he said "Man, you dont even know your name." I have hit 200 on air, and until I started divng helium, I would have sworn that I wasnt narced. It doesnt hit you instantly, like a bong hit or a shot would, it slowly builds. >> However, in the "french" link Scott gave, the scientists >> point out the physiologic differences between nitrous oxides >> and nitrogen. > > Bingo. Anyone who has done both knows that there is a difference. Anyone that has done both at high pressure probably does. Has anyone here? > I have hit 200 on air, and until I started divng helium, I would have > sworn > that I wasnt narced. It doesnt hit you instantly, like a bong hit or a > shot > would, it slowly builds. Sometimes it does, sometimes it doesn't. Jayna's one experience with extreme narcosis came on, and dissipated quite rapidly. I've never had a severe narc. All my experience, down to 175 feet on air, came on gradually and never reached a point where I was severely impaired. Lee >"The next depth related danger occurs around 100 feet, and effects >different people differntly. Now you start talking about "partial [quoted text clipped - 5 lines] > >Care to comment? :-) Why are you postulating a brand new mechanism? Or do you suppose that Argon narcosis is actually due to Argon Oxide? Occan's Razor.  SignatureRon >>"The next depth related danger occurs around 100 feet, and effects >>different people differntly. Now you start talking about "partial [quoted text clipped - 10 lines] > Argon Oxide? > Occan's Razor. Do you mean Occam's (Ockham's) razor? >Do you mean Occam's (Ockham's) razor? Typo aside, yes. SignatureRon (user ron in domain spamblocked.com) > capt.bil...@verizon.net wrote: > >"The next depth related danger occurs around 100 feet, and effects [quoted text clipped - 14 lines] > -- > Ron I was not postulating anything. I just thought it was interesting that someone could be teaching this as true. Especially when you look into the ways nitrous oxide is created. > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 5 lines] > > Care to comment? :-) You really want someoneto dignify that with a comment?????????? > "The next depth related danger occurs around 100 feet, and effects > different people differntly. Now you start talking about "partial [quoted text clipped - 5 lines] > > Care to comment? :-) Well, he's at least partially right. Nitrous Oxide CAN have a dramatic effect on you. ;-) |
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