Question Panic in the experienced diver?

It would seem to me that, as we gain experience and go through some minor glitches on dives, we should increase our capacity to tolerate issues underwater. I'm wondering what could cause an experienced (say, more than 200 lifetime dives) diver to become distressed enough to lose rational thought. Has anyone here (who meets those criteria) been through a panic event? What caused it, and what did you do?

 

[Dr. Lecter]

So all I can, for sure say, is that at depth, one has more available O2 to make CO2

Be that as it may, the metabolic rate remains constant regardless of depth and thus one is not making more CO2 just because there's a higher PPO2 present.

That CO2 has a "much stronger effect at depth" is no more unusual than noting that nitrogen is increasingly narcotic, O2 increasingly toxic, and helium increasingly HPNS-y with depth. For whatever it's worth, there is anecdotal evidence that CO2 + depth can play a significant role in what's generally termed "dark narc". Having experienced a CO2 hit at 240' on CC, I can say it definitely has the potential to cause a uniquely unpleasant sense of imminent doom.

 

[TSandM]

I'm getting very confused reading these posts.

Everybody needs a certain amount of oxygen to stay conscious. At sea level, that's said to be about 16% O2 in the breathing gas. Obviously, as you go deeper, the percentage can be lower because the density increases -- that's how hypoxic trimix can be used safely. But your CO2 production is a function of metabolism, not how much O2 is present. Once you have the amount of oxygen you need to support your metabolic activity (which is obviously affected by your rate of exertion) then having more doesn't make you make more CO2. Having too LITTLE oxygen can reduce your CO2 production, but it does it by limiting cell metabolism, and by the time you get to where oxygen is in that short supply, you are in a world of hurt.

Laryngospasm is horrible. I've seen one bad case of it in the ER, and I thought I was going to have to cut a hole in the lady's neck to keep her from dying. I can't honestly imagine experiencing it underwater, but my friend NW Grateful Diver did. He aspirated water when finishing up an air-sharing drill in a cave, and his throat closed on him. He sat there, knowing it would either open up or he would die, because no way was anybody getting him from where he was to any kind of help before that happened. He didn't bolt or panic, which I find astonishing. But there are many stories of people who continued to try to solve problems far beyond what one would believe. Some of the stories in Sheck Exley's Caverns Measureless to Man gave me goosebumps.

 

[Puffer Fish]

Be that as it may, the metabolic rate remains constant regardless of depth and thus one is not making more CO2 just because there's a higher PPO2 present.

That CO2 has a "much stronger effect at depth" is no more unusual than noting that nitrogen is increasingly narcotic, O2 increasingly toxic, and helium increasingly HPNS-y with depth. For whatever it's worth, there is anecdotal evidence that CO2 + depth can play a significant role in what's generally termed "dark narc". Having experienced a CO2 hit at 240' on CC, I can say it definitely has the potential to cause a uniquely unpleasant sense of imminent doom.

Thanks for posting, and would agree it is obvious it should be different.

Regarding the usable amount of O2 present...while not asked before, here is the detail:

I was doing some extremely physical work trying to hold myself still on a vertical wall with heavy surge. Left hand holding myself, right hand with a large camera setup (with two strobes).

A much larger surge hit me (pushing down) and twisted me (left hand hold was fairly small). When I got sideways, as I exhaled, water was going thru the exhaust, and held the exhaust flap open, so when I stopped the exhale, water filled the second stage. I started to inhale, but stopped asap, but a small amount of water must have made it to the cut in my trachea. Suddenly it closed.

Note: I can, on the surface hold my breath, if relaxed, around 2 minutes (maybe 10 or 15 seconds longer), but since this, I have tried doing it while climbing a hill (we have lots of them here). As my wrist computer is doing lots of calculations on breathing, heart rate, I tried to match the air flow rate I was using at the time. Might not have been perfect, but it was close. I cannot do 30 seconds..and while I did not do it for minutes, I doubt I would be awake if I tried to do it for minutes. This is a guess, but it would seem I was going thru O2 at something over 4 times my resting rate.

At first, I let go, got away from the wall and did nothing..for just under 1.5 minutes..then, as there was no change, and wow, the drive was incredible, and was very difficult to control.

I know I cannot surface without getting air out of my lungs, I'm still in some surge and have now passed into the feeling of dying.

Note2: TSandM, if panic is the action, I never panicked. If panic is the feeling, well, then I was going thru hell.

So I try to breath..not much is going in or going out, but there is some. However, I am using a lot of energy to pull and push air, so I doubt this is making things better, except there is some are movement.

And then, as I now cannot stop moving my legs, I deflate my vest and use the slow kicking to slowly go up.. took several minutes to get this to be effective in the up and down water motion.

While I was unaware at the time (as it all felt the same), at just past 3.5 minutes into this, my trachea opened, but by now I had sucked fluid into my lungs and they still did not work.

Note3: Dr Lecker, please feel free to try this on land...get into heavy exercise and then hold your breath for 3.5 minutes, and see what will happen. As I have been told, I would not have been awake, had this been on the surface. As was explained to me, that extra O2 was a major help, and a major terror, as I now could go to higher levels of CO2. And I was on 32% nitrox.

Once on the surface, I still could not breath and was coughing up pink foamy blood. That changed to brown foamy blood and after some time (not that good at this point on time passage) it stopped. When I got on the main boat (only a short way away), I was told I was white (was not personally aware) and was given some O2, and the condition gradually passed in maybe 10 more minutes.

This was nothing like the classic panic feeling one can get, that feeling of wanting to bolt to the surface, the adrenaline rush, that will pass in a short time and you can practice and manage. This is an internal chemical issue. I had people say that breath holders can get used to higher levels, but this is way past what any breath hold could ever experience.

TSandM. This is just about what happens when you cannot breath...you will continue to metabolise O2, until you get to the point where you pass out. But starting at 32% and needing a lower % at depth means the O2 will not be an issue. What now is an issue is how much CO2 is gradually being made. It is possible to make enough to be toxic (which cannot easily happen on the surface, or perhaps better stated, happens around the time that one runs out of O2).

What was lost on me, and seems difficult for others, is that given that you have a ton of extra O2, you now can experience levels of CO2 that no one on land can get to, and that will bring with it effects that don't exist on the surface.

Take that 16% number, that would mean one can only get a level of CO2 of half the difference between 21% (as some CO2 will make carbonic acid), so one could get up to 2.5% max. Not a toxic level. Terrible feeling at that point.

At say 66 ft, with 32%, one can now go down to around 6% O2.. but lets say it is higher..8%. That now, over time, with no breathing, would allow you to make up to 13% CO2 (assuming half went into Carbonic acid). There would be the toxic effects of CO2 and the effects of acid on you....and not something one would ever experience on the surface.

I sure did not understand this, and is meaningless, unless your lungs don't work. No wonder the effect is so strong if it does happen and why people act the way they do.

I've been told that people even experience PTS from going thru this (and to expect this).

---------- Post added May 13th, 2015 at 01:54 PM ----------

After this happened I went on a search to find out what happened and if I was going to have it again (in which case I was not going to dive). I talked with DAN, talked with local diving doctors..none even knew what I was talking about, and could not imagine it happening. That is, until a friend suggested I talk to a Dr Meekin.

What a surprise, he stopped me from explaining, and then proceeded to go thru the steps I went thru, without me telling him...it was a very normal and should have been expected.
But then he had been involved in actually testing this effect while in the Navy.

What particularly bothered me was when I asked some "what if" questions..most of which end up with you dying, and many are not a good way to die.

I also learned that a rebreather diver is far safer from this effect, than someone using Nitrox.

The fluid in my lungs, for example, is to be expected, partially because of the toxic effects of CO2 (higher blood pressure for example) and trying to get air in and out of your lung. Have even partially clogged arteries, and it can lead to uncontrolled fluid build up.

While mine was not the normal larynx spasm, there have been recorded deaths from it on the surface, and people passing out on the surface. The longest one I could find was around 10 minutes, underwater you would dead. Pass out with closed lungs and you are dead.

Anything that can cause your CO2 level to rise, can make a runaway event, that would not happen on the surface (never knew that). A regulator that breaths hard on the surface, can, at depth cause CO2 build up, and as you go down, the sensitivity to it goes up, while the regulator gets harder to breath. Was hard for me to believe that such a small thing could have such terrible effects. Breathing harder, might make this better, but if your breathing harder is making more CO2 than you can remove, it makes it worse.

Obviously if you bolt to the surface, you may die from several events, and DAN knows what to do with those (if you live).

I learned a lot of things I wish were not true...and I need to avoid any buildup of CO2 at depth (like don't twist sideways in a current). I'm lucky, I don't have cholesterol build up in my arteries (genetics), but if you do, then living thru any type of spasm is unlikely, so avoiding one should be a major goal.

 

[DCBC]

Regardless of experience, when caught off-guard, it's hard to face drowning passively. For everyone, there is a point of no return. Unless the situation is corrected, experience can only prolong the time available before panic will occur (anyone who has been water-boarded will attest to this) . Experience can however provide enough time to sort the problem out.

 

[The Chairman]

Regardless of experience, when caught off-guard, it's hard to face drowning passively.

While I agreed with your post in it's entirety, I think this point to be incredibly true and disregarded by many.

 

[Bob DBF]

Regardless of experience, when caught off-guard, it's hard to face drowning passively. For everyone, there is a point of no return. Unless the situation is corrected, experience can only prolong the time available before panic will occur (anyone who has been water-boarded will attest to this) . Experience can however provide enough time to sort the problem out.

I have not yet reached the point where I have panicked, but on several occasions I knew exactly when it was going to happen.


Bob
---------------
I may be old, but I'm not dead yet.

 

[mlevsky]

TSandM. This is just about what happens when you cannot breath...you will continue to metabolise O2, until you get to the point where you pass out. But starting at 32% and needing a lower % at depth means the O2 will not be an issue. What now is an issue is how much CO2 is gradually being made. It is possible to make enough to be toxic (which cannot easily happen on the surface, or perhaps better stated, happens around the time that one runs out of O2).

What was lost on me, and seems difficult for others, is that given that you have a ton of extra O2, you now can experience levels of CO2 that no one on land can get to, and that will bring with it effects that don't exist on the surface.

What you're missing is that the chemoreceptors that detect high CO2 levels trigger a long long time before you detect low O2 tension (in normal breathing), and are independent of the O2 tension.

Regardless of what your oxygen levels are, you will trigger the uncomfortable feelings of hypercapnia at the same CO2 tensions.

 

[TSandM]

PufferFish, there are several concepts in your post that I think have been conflated.

It is definitely true that, at depth, you have a higher ppO2 than you ever would on land, and therefore you can tolerate longer periods of apnea without losing consciousness. And during that time, CO2 is building, and CO2 is the panic-inducer.

However, narrowing of the arteries really doesn't have anything to do with this. The blood in your airway was likely due to involuntary attempts to inhale against a closed larynx. In the process, you dropped your intrathoracic pressure enough to rupture some pulmonary capillaries. You can actually put yourself into pulmonary edema doing this. Health or disease of the arteries does not bear on this phenomenon at all.

A rebreather would not help with laryngospasm. It doesn't matter what the gas is that is being provided to you, if you can't inhale it.

I am amazed that you were able to do 3.5 minutes without panicking. I suspect I would have, although the conscious mind knows what the problem is, and that one has to wait it out.

 

[descent]

... I am amazed that you were able to do 3.5 minutes without panicking. ...

Interviewer: "Doctor Einstein, can you tell us about the dilation of time in your theory of relativity?"

Einstein: "When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute and it's longer than any hour. That's relativity."

 

[Akimbo]

… I am amazed that you were able to do 3.5 minutes without panicking…

I have passed out, and witnessed other pass out, during breath holding exercises. All were in the 4-6 minute range. In my case, I was 10-11 years old. One was during static training and the other was in a pool. Fortunately a lifeguard was watching me train. My motivation is explained in this post:

http://www.scubaboard.com/forums/vintage-equipment-diving/326131-your-first-time.html#post5093343

These experiences changed my life in many ways. There is no way to know for certain if it increased my panic resistance or not; though I believe it has. It certainly increased my self-confidence. I learned that there is a long time between the onset of that CO2-induced panicky “must breathe now” feeling and actually losing consciousness. You don’t have to be a genius to figure out it is better to use your time trying to resolve a problem than panicking and guaranteeing a frightening death. The passing out experience itself was pretty serene, for me anyway.

I have also passed out twice from “bad gas” (low Oxygen) — both on deck running pre-dive checks on gas systems that weren’t adequately purged of deep mix. No panic or serenity involved here. I was lying on the deck plates before finishing a full inhalation. I would be dead had the mask been strapped on or if I was in the water. Not much useful to learn here other than being certain of what you are breathing.

I don’t agree that everyone has a panic threshold. There have been too many instances in combat, tragedies, and accidents where people were observed under stressful conditions and died attempting resolution.