Narcosis

[diligaf]

In the general spearfishing section, I read posts by Chad Carney & Bucket One discussing the effects of narcosis. Being one of my favorite subjects… I must put in my 2 cents, but since the discussion was getting off topic from the thread, I thought it might be better to reply here. Here is a link to the original thread-

http://www.spearboard.com/forum/showthread.php?s=&threadid=7186&perpage=15&pagenumber=2

I agree with what Chad said and thought I might add a little more. Like drinking alcohol, we build both a physical and learned resistance to narcosis. The physical resistance to narcosis, only last about a week, so if you haven’t been out in some time, you’ll need to have a learned resistance.

First and most importantly, the diver needs to be relaxed. When diving deep, never ever rush. This is when accidents happen. Many experienced deep divers will always take a minute to relax and visualize the task at hand. If you’re a little out of breathe… wait a minute (or be a good buddy and wait if your teammate needs a minute) before entering the water. Besides being safer and more relaxed… you’re less likely to spook the fish!

Entering the water in a relaxed state automatically lowers your heart and air consumption rate. And the more you practice, the more efficient you become at lowering your bodily functions… again, another big plus when approaching fish!

As you near the bottom, make sure your head is clear. If you feel that little twinge… stop, relax, breath deeply into your diaphragm, check your gear and gauges, and get your concentration. If you don’t feel well… don’t be afraid to call the dive. No one always feels 100%. The effects of narcosis can vary day-to-day and individual-to-individual… there is no shame in being safe.

Having good in water skills will also decrease the effects of narcosis… so don’t overload yourself with gear, have the right gear, and work to be efficient, streamline, and properly buoyant.

On the other side of the coin, is O2 toxicity. In my experience, pushing your O2 limits has a much greater effect on bodily functions and the ability to rationally think. The effects of O2 tox are very real and unforgiving… whether you’re pushing the limits of deep air or the MOD of your nitrox mix… it doesn’t matter who you are, it will eventually get you. Choose the right mix for you and the dive you are making.

[dagodiver]

Originally posted by diligaf


First and most importantly, the diver needs to be relaxed. When diving deep, never ever rush. This is when accidents happen. Many experienced deep divers will always take a minute to relax and visualize the task at hand. If you’re a little out of breathe… wait a minute (or be a good buddy and wait if your teammate needs a minute) before entering the water. Besides being safer and more relaxed… you’re less likely to spook the fish!



Perfect...!!!!
On my deep stuff that is all i think, relax relax relax relax.
Makes a huge difference.
Also plan your dive and dive your plan..!!!
I know for spearfishing this is hard but atleast try.
Dago

[fishspearit]

I usually start to feel the effects of narcosis around 105-110' feet. I don't ever do it, but I'm pretty sure I would know if I dropped below 120' without looking at a depth gauge. When I was learning deep air the way my instructor put it to me was that everyone is narced at 130', people who don't think they are just don't know how to recognize the symptoms in themselves, and don't have any business going deeper. Deep air is not about ignoring narcosis, but learning how to recognize it, and with training,practice and experience you can learn to handle the effects. I also think it should be clear that peoples first dives below 130' shouldn't be spearfishing dives, but that they should always be comfortable diving whatever depth they're at before they take on the distraction of hunting at that depth. Just my opinions.

[Reaperspear]

I have what may seem a strange question concerning narcosis. I would like to know if narcosis could be countered by pain or the lack of pain in my case. As I said this probably seems strange to most people, but even at 130' I am very aware of my surroundings my buddy and my own equipment. This is just a question and I am not foolish enough to think I am immune to narcosis.

[zds3488]

Im fine at 130. However on a dive in the MG, I hit about 140 and started to feel it.

[dagodiver]

Originally posted by zds3488
Im fine at 130. However on a dive in the MG, I hit about 140 and started to feel it.

I'm sure you are fine at 130, i ment that just like i said it.
I would still like to dive with you and give you the narc test..:D :D
Dago

Please dont take this into BS land i ment I'm sure you are
fine at 130fsw.

[bgbill]

People have different levels that they get narced at, one day you may be fine at 130' the next you may get narced at 100', I notice it generally around 150' and below, or if I am working real hard.

Sometimes it has been shallower, but it usually is when I did not have enough rest the night before, or when I am not hydrated properly, or when I am on a MG trip and it is towards the end of the second day when I am getting tired.

You can have someone write some simple math questions and word problem questions on a slate, go to depth and answer them, see how long it takes, and when you surface see how well you did, and see how your handwriting is, that will let you know to some extent how narced you were.

You can build a tolerance to it, but it takes a while and you can lose it pretty quickly if you aren't diving regularly.

[Reaperspear]

I would never dive beyond my ability. I am taking advanced nitrox thru extended range now. Your point about Goofy boy is a good one and thats what I hope to avoid. Since I have not noticed any changes to a depth of 130', I have no experiance with narcosis to help me identify it when it begins. I have no doubt that I will be effected by narcosis as I go beyond the 130'. My concern is identifying the symptoms before I become goofy boy.

[kitefisherman]

Brokenspear:

The symptoms that I notice the most when I am narced is the failure to concentrate and remember (e.g., checking my PSI every other minute because I am not exactly sure how long it has been since I last looked) and the tendency to obsess over things that I know to do any way as if I might otherwise forget (e.g., "don't drop your gun, don't drop your gun" or "be careful where you point the gun, be careful where you point the gun"). I guess my mind is working on overdrive to manage the control that it senses that it is losing. I usually don't notice mild symptoms until about 145 fsw and they progress as I go deeper. I think that you build sort of a tolerance to it the more frequently you dive deep - your speargun accuracy certainly improves. I am much more relaxed and confident at depth than I once was although I still check my PSI and deco status every couple of minutes (which is a good thing). Last year I saw a presentation by a local deep diver who lineshafted big fish on the 200+ fsw wrecks here. He said that every time before he took a shot he would first check his PSI to make sure that he had more than enough gas to deal with the fish (apparently he didn't trust his memory either). I think that you can also do things like freeshafting and lift bagging your fish to enhance your safety in what you must recognize is an impaired state (no matter how confident you feel at the time).

I'm no expert at deep air diving, but maybe this will help you know what to look for. Good luck!

[Nikki]

bgbill - your observation of an increased tendency to get narced after being tired, dehydrated, etc.

AND

BucketOne - your statement that focusing on something helps

Both very good suggestions and things to keep in mind. Thanks!

[Divin' fool]

At 125' or so I start to feel it coming on.... but by 140 I start to feel "mentally uncomfortable".....esp when things don't go the way I have it planned. Ditto on what Kite said.

I'll do the deeper stuff once in a while, but generally I leave the deep stuff to the "young turks":D

[HDrider]

Narcosis north verses south

This may or may not be of interest to warm water divers. But could be worth reading, while I have never experienced a major thermocline (20 degree) while diving in Tropical waters I have heard of bottom temperatures on deep dives being mid 40’s occasionally on deep wrecks in SE FL.

In my experience I have found narcosis to be enhanced greatly by water temperature or lack of it! This could be due to a number of things that have been mentioned above. First relax and be comfortable, this is great advice given by Diligaf. Cold can make this difficult at best. Task loading becomes a real issue, something as simple as turning a reel handle can become quite a chore when you cannot feel your hands because of the cold this adds stress. The things mentioned above all add up to increased narcosis level. In my experience diving in cold water and warm water on air or nitrox it would be safe to say one could add somewhere from 1 – 2 ATA to your nitrogen partial pressure. In other words a 130’ dive in cold water (mid 30 degrees) would have the same narcosis effect as a dive of 170’ – 190’ in warm water. At 150’ in water 33 degrees I have experienced pretty severe narcosis (with drysuit). Much more than 180’ in warm ocean (68 bottom temp 3mil wet). Multiple dives seem to reduce the narcosis quite a bit so the “getting used to it” rule applies in my experience. This may be useful if you ever experience this cold water on a deep wreck I have heard of if for no other reason than you will at least be expecting it.

Very good information here from the post’s!

Tom

[diligaf]

Tom ~ Good points… another factor is visibility. The need to keep your bearings is very important to some divers. Some people I’ve dive with prefer or need to go down a descent line to limit the effects of narcosis… and feel so strongly about this technique that they’ll fight a strong current. Others prefer to free-descend to the deep wrecks of SE Florida… they feel an effortless descent helps limit the effects of narcosis for them. Divers should choose what works best for them.

The part I’ve always hated about the summer up-wellings is during the ascent. When I come out of that mid-forty degree water and instantly hit that mid-eighty degree water, I always want to throw-up. It can be very nauseating!

[Reaperspear]

I would like to thank all of you for sharing your knowledge with me. I will keep all of this information in mind.

[Mobile Diver]

All,

Terrific discussion. The benefit of all this experience is priceless.

[Steel Shootin']

I personally start to notice narcosis in myself anywhere past 100fsw on some dives, and I can almost always feel it's presence at 130. One thing I noticed is at 130 or deeper, if I shine my light into a hole or under structure of any kind, I get somewhat of a wierd sensation. Mild vertigo I would call it. The effect goes away when I stop looking inside the hole.

Darkness can increase narcosis (i.e., "dark narc"), as can cold. The most narced I have ever been in my life was in a mere 100fsw, with a water temp of 55 and complete darkness. Cold + Dark is a double wammy, and almost guarantees narcosis.

[Nikki]

I thought that a "dark narc" was simply an unpleasant - opposite the giddy - experience of being narced.

An unpleasant narc happened to me once at 126' - lots of factors (new dive location, new group diving with, heavier wetsuit so overweighted, first dive in couple months, etc.) contributed to create some anxiety plus depth of dive equaled (in this case)uncontrollable hyperventilation at depth. Was so strong that I felt that if I didn't hold the regulator against my mouth that the forcefulness of my exhale would shove it out of my mouth! :O Wasn't a panic and was thinking clearly, but my body just wasn't cooperating to control my breathing rate. It was one of those experiences that certainly shook the "cocky" confidence of invincibility right out of me! Anyway, went up about 30' and everything returned back to normal. It was weird though how quickly and how strongly it came on though - within 10 seconds dive went from pleasant to "dark". I do believe that this experience gave me a much needed respect for the sudden "challenges" that can happen when diving.

[swimndive]

These are all good points. Here are a few links to abstracts on narcosis, which underscore some of the other risks for divers. Narcosis wouldn't be such a problem if its first casualty weren't judgement/perception. Without an ability to accurately judge or measure one's own level of impairment, things often go from bad to worse faster than can be managed. In addition divers often mistake the perceptual narrowing and task fixation that comes with increased narcosis levels for concentration and focus. These are two of the most insidious of the symptoms.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=2741255&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=7742709&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=8180569&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=7665424&dopt=Abstract

In addition to the inert gas component (N2), temperature, anxiety, medications and visibility all influence a divers level of narcosis on a dive. The metabolic gas components (O2 and CO2) can also significantly affect these levels. All of these gasses (N2, O2 and CO2) are potentially narcotic at depth, with CO2 being extremely so, at 130 times that of N2.

Studies show that divers breathing nitrox at 4 ATA (99 fsw), had normal arterial CO2 levels while at rest, indicating that respiratory ventilation was sufficient to eliminate CO2 while resting. Under exertion the increase in lung ventilation was shown to be less than occurs at 1 ATA (due primarily to gas density), and arterial CO2 levels were shown to rise to significantly higher levels than during exercise at 1 ATA. The higher arterial CO2 levels reduced the test subjects ability to perform mental skills (arithmetic and color naming), as well as physical skills (manual dexterity and eye-hand coordination) significantly.

Physical responses to CO2 loading in the form of ph buffering in the bloodstream can also vary from individual to individual, and might explain why certain divers routinely record higher than normal levels of arterial CO2 during tests. Lamphier termed these divers retainers in his early studies. The navy sought methods to identify these retainers because they were shown to experience higher levels of hyperoxic seizure (oxtox),CO2 blackout and narcosis levels during subsequent tests. Why is this important? Freedivers, spearfishermen and sleep apnea sufferers are often retainers. The good news is this spearboard and not the navy and you can reduce all these risks with training.

[Steel Shootin']

Originally posted by Tropicaldiver
I thought that a "dark narc" was simply an unpleasant - opposite the giddy - experience of being narced. Narcosis comes in many forms. While the typical experience is the "Rapture of the Deep" described years ago by Jacques Cousteau, it can also present in any number of ways, including vertigo and anxiety.

[BobK]

I get the "anxiety" version on the first deep dive of the day. Starts around 110 fsw or so. I get a feeling of doom, like something bad is going to happen real soon. I go up to about 90 fsw or so for a minute, and the feeling goes away. I can then go back down to the bottom for the rest of the dive. I never get the feeling on the rest of the dives that day, no matter the depth or the number of dives.

For myself, I'm getting trimix training so that I can run about a 30/20 mix for these dives. I think that will solve the problem for me.

[Marcus]

"Starts around 110 fsw or so. I get a feeling of doom, like something bad is going to happen real soon. I go up to about 90 fsw or so for a minute, and the feeling goes away. I can then go back down to the bottom for the rest of the dive."

Bob,

Have you guys ever tried to slowly ascend so that your brain has time to evaluate and adjust to the "fog". I know this is hard to do when your buddies are racing to the bottom to shoot the biggest fish.

[diligaf]

Originally posted by BobK

For myself, I'm getting trimix training so that I can run about a 30/20 mix for these dives. I think that will solve the problem for me.

Bob - Each of us should choose the mix we are most comfortable with. But beside narcosis... you should consider the deco obligations and the possible need to carry deco gases if you use a 30/20 mix. You may or may not be able to safely deco out on the bottom mix alone... I've never run a table for such a mix, but something to keep in mind. In the end, only you'll know what is best for you.

[biggsy]

What additional affects do you get from smoking and diving at deeper than 100'? I would think the increased CO2 could be a bad mix.

biggsy

[BobK]

Originally posted by diligaf
Bob - Each of us should choose the mix we are most comfortable with. But beside narcosis... you should consider the deco obligations and the possible need to carry deco gases if you use a 30/20 mix. You may or may not be able to safely deco out on the bottom mix alone... I've never run a table for such a mix, but something to keep in mind. In the end, only you'll know what is best for you.

Hence the training. Could be I'll use a totally different mix, or discover it's best to stay on 30/0, or whatever. But I wanted to get Adv Nitrox/Deco training anyway, and I can add shallow TX for not a lot more $$, so I decided to go that route.

[dagodiver]

Originally posted by diligaf
Bob - Each of us should choose the mix we are most comfortable with. But beside narcosis... you should consider the deco obligations and the possible need to carry deco gases if you use a 30/20 mix. You may or may not be able to safely deco out on the bottom mix alone... I've never run a table for such a mix, but something to keep in mind. In the end, only you'll know what is best for you.

I have run 30/30 and 21/35 both of which if used with
"spearfishing" bottom times can easily be deco'd on back
gas.
Dago

[dagodiver]

This is the numbers for a dive to 120 for 20minutes
on 30/30 with a RMV of .8
With a 120cf this dive would be no problem.

Off gassing starts at 69ft

OTU's this dive: 33
CNS Total: 13.1%

84.5 cu ft Trimix 30.0/30.0
84.5 cu ft TOTAL

Dago

[PBDiver]

I am a very in-experienced diver. Just got my open water about 10 dives ago. I really enjoy reading this information. I have been very excited at the prospect of diving and gaining experience. I just wanted to comment about the smoking and diving subject. I smoked for the last 15 years. Since starting to dive ,after about 4 dives, I quite smoking. I noticed considerable anxiety and difficulty in controlling my breathing rate until I quit smoking. I still have anxiety to a degree, but I feel able to get it under control easier. Don't know if they have anything to do with one-other or it is just my confidence level building but I though it was worth throwing it out there. My SAC rates are almost half now being a non-smoker!

Chris
PBDiver