Triggers of Dive Accidents

[Garth]

Can someone please explain to me the issue with AGE and rapid accent while either holding their breath or not breathing properly...
I can see the barotrauma risks with holding your breath or not allowing enough air to escape while on a rapid accent. I can also see subcutaneous emphasema (little air bubbles beneath the skin). But... i don't see why you are at a heightened risk because you are "holding your breath" while ascending... as it pertains to AGE.
My understanding of the physiology would be that rapid ascents can cause AGE. I dont see the breathing component in it for AGE as I understand that the breath holding may cause other things.
Do you see my question?
Do you have an answer?

 

[spoolin01]

Spoolin,
I am not thrilled at the way you are twisting my words..... I tried to make it abundantly clear that the issue of DCS not being an issue, was with a slow continuous ascent to the surface on a dive fitting No Stop / NDL parameters...I even shortened the duration by 5 minutes in my example...

DanV, I hope you'll understand across the digital ether that I don't mean to twist your words, I just wish to argue them a bit. I'm... proposing, that you're making an unproven assumption about when all risk related to DCS ends. Since I expect it tapers off, rather than ending abruptly, I still see a trade-off with coming to the surface any sooner than necessary. You don't acknowledge that, that I can see - you present it as taken care of, as you described any thought of trading any remaining air for off-gassing time as 'insane', etc. Just to complete the thought, I haven't understood what your great concern is about low air stops or ascents from 15' with low air, though you and others seem to think it is a serious problem.

I am beginning to think your instructor trained you to believe that DCS is some insideous threat, ready to pounce on you the moment you exceed your table by a second or two--or the moment you miss a "SAFETY STOP".

No, I don't recall his particular take on DCS relative to other risks. He was more interested in grandstanding to his captive audience about his derring-do in the edge-of-death world of scuba. He wasn't big on detail over much, if I recall.

But based on some reading and common sense, I do contemplate the prospect that DCS is indeed insidious, that tissue changes can occur that may be damaging even when they don't nearly sum up to an acute incident, and that damage (as commonly is the case, pick your vice or stress) may accumulate. If you know of epidemiologic or post-mortem histologic studies that are adequate to disprove that hypothesis, I'd love to know of them. Until then, it colors my dive planning.

If this is the case, you need a fresh perspective. I'm sure Thal or Bob or Peter can explain this in a more traditional manner, but you need to look at how bubbles form in your body durring a dive, and how well most bodies get rid of the bubbles as you ascend ( and later on the surface) ... There was a time the George Irvine, Bill Mee, myself and a few others had a Doppler study done [on us, or for us --?? ] , and the objective was to show how quickly our personal physiologies were able to deal with what "should" have been hypersaturation, according to the typical PADI tables...
We did a 125 foot dive, for about 27 minutes. It was a high crusiing speed dive, a spearfishing dive for me, the other guys keeping pace. They wanted us to do an ascent with no stop, just 60 foot per minute climb to surface--then get out, and get dopplered. And then again in about 15 and then 30 minutes.
Again. No Deco stop. No Safety stop.


< note to Spoolin......this is considerably beyond the 60 foot dives with 45 min duration, and my suggestion for blowing off the stop if very low on air>


UNique for my situation, was that I had been in a bicycle race crash 4 days earlier, and had almost separated my shoulder--not quite, but there was still swelling and the expectation was that blood flow would be compromised, and this would hurt offgassing/lead to more bubbling in the area of my shoulder.
Also unique, was my speargun..a huge 60 inch double barrel Ultimate Speargun made by Pat Frain, it was nearly as heavy as a Nato Assault Riffle. This I had no concerns over at all...but....
most of us had minor bubbling, nothing of any concern at all...when they did my injured shoulder, I expected the doppler to show some serious bubbling..but it was completely insignificant...however, the arm holding my speargun throughout the dive was bubbling at a considerably significant level..not enough for me to want to administer O2, but clearly, having a heavy muscle load throughout a dive like this, leads to very constricted muscles, meaning poor blood flow, meaning bubbling will become a problem...in recreational diver "speak", if you are pushing a big two strobe housed camera around, you are getting bubbling issues far beyond your evel twin without a camera....this could easily explain the arthritis seen in many of the older big name photographers ...
In any event, even my speargun arm cleared fast in the first 15 minutes, once the muscle constriction was over.

The point of this big story, is that a group of us, all into cardio sports outside of diving, could on a given day, blow the daylights out of the tables, and not have it maim or kill us.
Bubble theories give divers with math backgrounds ideas on how to prevent DCS.
Each day I go out, I have a table based plan for my dives....and I take the plan seriously. That being said, if my buddy needs to come up because of an emergency, I KNOW that I can blow off huge parts of a real deco dive, and still survive or have even no bad effects--and to save your buddy, this is the behavior to utilize. On a No Stop/No Deco dive, I think this point should have been well "overstated"

Regards,
DanV

So... you didn't suffer acute symptoms thankfully. The possibly more sensitive imaging method showed lots of tissue change due to gas absorption, but you dismiss it as inconsequential and transient. Is there some foundation for the prognostic value of these results or the method generally in the context of chronic effects? "It didn't kill you so it didn't hurt you" and its corollary "it's only harmful in large doses" is not compelling to a sceptic. You know of arthritis in photographers - doesn't that complicate the simple theory of DCS avoidance? You don't appear to take the risk of damage very seriously even in the face of contrary evidence - I don't see that I twisted your words on this subject much at all. If bubbles have been proven inconsequential, if it's known there are no low level and cumulative effects from staying within NDL, and I just don't know about it, I apologize in advance.

I believe it was Ross Hemingway who put it most appropriately regarding decompression ... "We're all lab rats". That's a simple summation of the fact that there's just too many variables to come up with anything resembling hard and fast rules that apply in all cases.

That said, I think you've been either mistaking Dan V's comments or using them to set up strawman arguments. I don't think Dan has said or intended to say that safety stops should be taken lightly. I read him as saying that if you have to make a choice between DCS or OOA, DCS is fixable ... death is not.

LOL, what was that straw man crack again?

Therefore, don't get so fixated on the safety stop that you run yourself out of air and therefore put yourself in an even worse place ... because in any case, running out of air greatly increases your risk of a bad outcome.

Well this 'running out of air' is a pretty slippery straw man itself. It's a loooong ways from 500/400/300/200... psi to being 'out' of air, esp at 15', which is what the last few exchanges have been about. I'm truly dumbfounded by the persistence with which making it to 15' with air, but choosing to breathe some or even most of that air down to get some more off-gassing time, is characterized as some crazily dangerous act. C'mon, who dies at 15'?

I'm a firm believer in the concept that the best divers are those who don't put themselves in a situation to have to make that decision ... and a good foundation in gas management will give most divers a better set of tools to achieve that goal. But if you should find yourself in a position to have to make that choice, choose the lesser of two evils ... which in this case would be to surface before your air supply runs out.

So long as you'll permit me to define 'out' in the way that balances risk to my satisfaction, we're in agreement! If you have some particular insight into that other evil - I'm all eyes, it can only help me re-assess my current take on the balance.

 

[Ayisha]

C'mon, who dies at 15'?

Unfortunately, too many people die even afer reaching the surface, where you would think safety has been reached. Often OOG, very overweighted, and couldn't or didn't release their weights.

I think everyone agrees to save some air for the surface, in varying amounts. How much to surface with is probably really immaterial as long you do not put yourself in an OOG situation. If some divers want to save only a few hundred psi after their safety stop and some want to save 1000 psi, it should only matter to the diver and their buddy or buddies.

 

[lamont]

DanV, I hope you'll understand across the digital ether that I don't mean to twist your words, I just wish to argue them a bit. I'm... proposing, that you're making an unproven assumption about when all risk related to DCS ends. Since I expect it tapers off, rather than ending abruptly, I still see a trade-off with coming to the surface any sooner than necessary.

Of course the risks with decompression are fuzzy. But for single incidents you can point to people doing 20 min @ 150 foot dives that blow off 10 minutes of shallow stops entirely and walk away. The risks of blowing off a single NDL dive is minimal.

You don't acknowledge that, that I can see - you present it as taken care of, as you described any thought of trading any remaining air for off-gassing time as 'insane', etc. Just to complete the thought, I haven't understood what your great concern is about low air stops or ascents from 15' with low air, though you and others seem to think it is a serious problem.

Unless you're doing every single dive such that you're low on air, you're simply not going to get injured from a single NDL direct ascent. That was, in fact, how everyone used to dive, and the tables were generated assuming 60 fpm ascents, and the DCS rate was still extremely low.

No, I don't recall his particular take on DCS relative to other risks. He was more interested in grandstanding to his captive audience about his derring-do in the edge-of-death world of scuba. He wasn't big on detail over much, if I recall.

Yes, he's actually got some experience to fall back on, unlike you.

But based on some reading and common sense, I do contemplate the prospect that DCS is indeed insidious, that tissue changes can occur that may be damaging even when they don't nearly sum up to an acute incident, and that damage (as commonly is the case, pick your vice or stress) may accumulate.

How often are you planning on going low on gas? If its a typical practice of yours, I suggest that you plan your gas better so that you have enough to be able to do deco/safety stops without going low on gas.

If you know of epidemiologic or post-mortem histologic studies that are adequate to disprove that hypothesis, I'd love to know of them.

How about the way that everyone was diving prior to like 1980?

Until then, it colors my dive planning. So... you didn't suffer acute symptoms thankfully. The possibly more sensitive imaging method showed lots of tissue change due to gas absorption, but you dismiss it as inconsequential and transient. Is there some foundation for the prognostic value of these results or the method generally in the context of chronic effects? "It didn't kill you so it didn't hurt you" and its corollary "it's only harmful in large doses" is not compelling to a sceptic. You know of arthritis in photographers - doesn't that complicate the simple theory of DCS avoidance? You don't appear to take the risk of damage very seriously even in the face of contrary evidence - I don't see that I twisted your words on this subject much at all. If bubbles have been proven inconsequential, if it's known there are no low level and cumulative effects from staying within NDL, and I just don't know about it, I apologize in advance.

There's a big informal epidemiological study that has been going on with divers for decades, and there's no evidence that divers who did what we'd consider to be rapid ascents on a routine basis had sufficient damage to affect their lives. I'm definitely not going to worry about doing one single recreational rapid ascent (in fact, I've done one before -- I'm sure one of your "histological studies" would find all kinds of hidden damage and destruction just waiting to be unleashed on my physiology....). I'm also not going to worry about advising people that they should skip a safety stop if they are low on gas. There is a significant risk of actual *death* if a diver goes out of gas and blows their lungs heading to the surface -- in comparison, by skipping a safety stop -- YOU ARE DIVING THE WAY EVERYONE USED TO DIVE FOR THAT ONE DIVE. People used to dive that way for decades.

Seriously, while your appeals for "epidemiological" and "post-mortem histological studies" do establish that you may be intelligent enough to know what the word "epidemiological" means, but you have absolutely no background in actual scuba diving, or you wouldn't be asking for that kind of information.

 

[Ken Kurtis]

I'm sure you would agree that there's a lot more to be known about those fatalities . . .

Yes to that part of the sentence.

. . . before the causes are sufficiently understood.

No to this part.

I think that sometimes, in trying to make sense of all of this stuff, we over-complicate the analyis when it doesn't need to be over-complicated.

Case in point (sadly, a true story - this is one I investigated for the LA County Coroner): 15 year-old gets certified. Diving with his dad a week or so later. Descends to about 10 feet, mask floods, can't clear water out of mask, panics, does rapid ascent, embolizes, drowns.

(Bear in mind when I say "trigger" I'm talking about what went wrong on the dive that then caused everything else to spiral out of control and resulted in a fatality. In this case, the trigger was the mask flooding.)

Further investigation revealed that the kid always had problems clearing his mask in class. In fact, he may never have cleared it well. However, the instructor (prepare to cringe) issued the card to him anyow basically telling him to keep working on it and he'd get it eventually.

(Sidenote: Yes, the instructor was reported to his training agency. I have no knowledge of what, if any, disciplinary action was taken. I have no knowledge of any lawsuit that might have come out of this tragedy.)

So from my perspective you've got (1) mask floods, leading to (2) inability to clear mask, leading to (3) panic, leading to (3) rapid ascent, during which (4) breath was held, causing (5) embolism, which resulted in (6) drowning (listed by the Coroner as the official cause of death).

Now you can nitpick and drill down and talk about standards violations or lax instructional oversight, or bad judgement or whatever, and while those would be contributing factors, when you try to understand JUST the mechanics of the accident, it all starts with the mask flooding and then the inability to react to that and solve that problem. If the kid had cleared his mask, we wouldn't be using this as an example.

As just one of the simplest considerations, I'm betting that once you experience AGE, DCS damage is no longer of interest to anyone.

I wouldn't agree with that either. Although the AGE is immediately life-threatening and has to be dealt with, so does DCS if they both happen at the same time. While DCS likely won't kill you, it can certainly cause permanent neurological problems if left untreated or ignored.

You won't be dead, just crippled.

The conclusion I was more interested in was the damage from DCS, not just fatality.

DAN actually has some stats on this dealing with divers suffering from severe neurological problems (and it underscores the value of oxygen in the field prior to treatment):

If they received emergency oxygen prior to chamber treatment, 67% had full resolution.
If they received NO oxygen prior to chamber treatment, only 56% had full resolution.

For those with mild symtoms:
If they received emergency oxygen prior to chamber treatment, 73% had full resolution.
If they received NO oxygen prior to chamber treatment, only 49% had full resolution.

How quickly you get to a chamber makes a difference too. Of the divers who had residual pain following treatment:

4% were treated w/in 4 hours of surfacing
19% were treated 4-12 hours after surfacing
77% waited 12 hours or more hours to seek treatment

The take home message: The longer you wait to get treated, the more likely it is that it won't fully resolve.

You're in a better position than I to have an idea of what kind of traffic those chambers get - are they sitting idle, deaths being as rare as they are?

The Catalina Hyperbaric Chamber gets a treament roughly every other week, so about 26 a year. However, there have been times when there have been treatments four days in a row. (There was one time when they dealt with four AT ONCE.) There have also been times where months have gone by without a treatment.

Also bear in mind that these chambers (not just Catalina) get what are called "no treats." These are people who may be brought to the chamber, but are not treated because (1) it wasn't a diving accident, (2) it was diving but they're not bent or embolized, or (3) they've already been pronounced dead. So even though Catalina may do a treatment every other week, the actual traffic is more frequent when you factor in the "no treats".

I'd still like to know the answer to the question, which group of divers fares better health-wise over the course of their diving careers, those who push the limits of reserve gas planning or those who push the limits of absorbed gas management?

Old saying but appropriate: There are old divers, and there are bold divers, but there are no old bold divers.

- Ken

 

[drdaddy]

Unfortunately, too many people die even afer reaching the surface, where you would think safety has been reached. Often OOG, very overweighted, and couldn't or didn't release their weights.

I think everyone agrees to save some air for the surface, in varying amounts. How much to surface with is probably really immaterial as long you do not put yourself in an OOG situation. If some divers want to save only a few hundred psi after their safety stop and some want to save 1000 psi, it should only matter to the diver and their buddy or buddies.

A few years ago I came to the surface, from a 40 foot crab dive. I had a full load of dungeness crabs and was low on air because I had stayed down after that "one more crab" I had seen (and got!). I had not begun my dive overweighted, but I sure was when I surfaced. I have vowed never to come up from a dive without sufficient air - for me it is about 800psi. That gives me enough to mess around at the surface with overweighted issues (due to game) and recovering my dive flag, and maybe being washed off the jetty rocks and tumbled a bit before crawling out again. And I dive with a 19cf pony (which I hope I never have to use) on all my dives.

I agree that the emergency ascent training gives the newby diver a false sense of security that it is alright to run out of air. It's not!!! I think more emphasis should be put on air management from the very beginning.

 

[Ken Kurtis]

Can someone please explain to me the issue with AGE and rapid accent while either holding their breath or not breathing properly . . . My understanding of the physiology would be that rapid ascents can cause AGE. I dont see the breathing component in it for AGE as I understand that the breath holding may cause other things.
Do you see my question?
Do you have an answer?

I don't mean this cruelly, but I think I do understand your question and if I do, I'm a bit concerned. (And please free to post a follow-up for anything I've gotten wrong about what I think your understanding is.)

Let's make sure we understand that AGE stands for "Arterial Gas Embolism," also referred to many times simply as "Embolism." It's an air bubble (or bubbles) in your blood. It can kill you.

Where does the air bubble come from?

Very simply, it comes from when your lungs burst and release air bubbles directly into your bloodstream. This happens when your lung (think of a balloon) over-pressurizes and breaks. The air bubbles enter the bloodstream and go to your heart or brain, can stop blood flow, and end up killing you.

How do your lungs get so big they burst?

Hopefully you remember Boyle's Law relating to pressure and volume. When pressure increases, volume descreases. When pressure decreases, volume increases. It's an inverse relationship. In other words, whatever you multply one by, you divide the other by that same number.

In the ocean, the pressure increases as we go down and decreases as we go up. On the surface, we are under 1atm (14.7psi) of pressure. In the ocean, the pressure increases 1atm for every 33 feet of depth. So at a depth of 33 feet, we are under 2 atm of pressure vin the ocean.

Back to Boyle, if the pressure doubles, the volume decreases by half. So your balloon lung, at 33 feet, is half it's normal size. However . . .

We are breathing off of a scuba tank at depth and the scuba tank is pressurized. The regulator is designed to deliver air at ambient (surrounding) pressure. This means that at 33 feet the pressurized air from the scuba tank re-expands your lung to 100% capacity and a pressure of 2atm. In fact, the regular is designed so that no matter what depth you are diving at, your lungs will always be at 100% capacity and at ambient (surrounding) pressure.

Let's say, for whatever reason, you spit your regulator out at 33 feet right after you took a breath of air from your tank. Your lung is at 100% capacity. (Also, just for the sake this example, let's assume you lung cannot expand beyond 100% without bursting.)

You decide to head for the surface 33 feet away. Boyle tells us that in that journey, the pressure will decrease as you go up which means the volume of air in your balloon lung will increase. In fact, since the pressure will be cut in half, from 2atm at 33 feet to 1atm on the surface, that means the volume of air in your balloon lung will double during the journey.

If you decide to hold your breath all the way up and never let out a bubble, the air in your balloon lung will expand (to 200% volume), and your balloon lung will burst, releasing all of that air into your bloodstream.

This has NOTHING to do with how fast you go up. You could go up at 1 foot/minute, 1 foot/second, or 30 feet/second. It is a law of physics that the air will expand based on the pressure change, not matter the amount of time the pressure change takes. Reagrdless of speed, the volume of air will be 200% when your surface.

If you hold your breath all the way up, because of the expanding air (not because of the speed of the ascent) your balloon lung will burst, the air will go into your bloodstream, and you will embolise.

That's how holding your breath AND ASCENDING will cause embolism. However . . .

If during this same ascent, you are continually exhaling, and never allowing the air in your balloon lung to exceed 100% of capacity, your balloon lung with NOT burst, you will NOT embolise, and you will live to dive another day.

In fact, you can do a rapid ascent and not get embolised. As long as the volume of air you exhale exceeds the expanding volume of air in your balloon lung, and you never allow the balloon lung to get beyond 100% of capacity
(DISCLIAMER: I AM NOT ADVOCATING YOU DO RAPID ASCENTS)
you can go as fast as you like. As long as you never let your balloon lung capacity exceed 100%, you will not embolise.

The reason we associate rapid ascents with embolism is that the faster you go, the more rapid the gas volume increase will be inside your balloon lung, and the more difficult it will be to keep your balloon lung volume below 100%.

Now this is an over-simlified explanation. Your lungs are NOT balloons with a single compartment. The gas exchange actually takes places in the alveoli inside the lungs. The alveoli looks more like a head of broccoli. You could, in theory burst some alveoli during a breath-holding ascent even though your lungs arer not at full capacity. If you have asthma, it makes it even more complicated. But the simple answer is as I stated above.

Additionally, a rapid ascent, because the ascent rate is really a form of decompression, can cause a bends hit in what should have been an otherwise uneventful dive. But that's for a different remedial lesson.

Does this help out and have it make more sense to you????? Or have I totally confused you?

- Ken

 

[Ken Kurtis]

I spent three years in Vidalia, Georgia, running a radio station and since UDTFIRE hails from GA I figured I'd give this a shot. I'm not one to pass the Buck, and much as I like a good troll . . .

ken really do you believe what you are saying or just pulling my leg not teaching ooa drill is like telling a fighter pilot you dont need a parachute if you dont run out of gas

That's not what I'm saying at all. If you'd re-read the initial post, you'd comprehend that.

But to use your analogy, it would be like telling a fighter pilot that since they have a parachute that they don't need to worry as much about running out of gas becaue they can always pop their chute and get another plane.

What I have said is:

1. Based on the DAN study, we seem to have an inordinate amount of fatalities caused by OOA.
2. But we constantly tell people running out of air is bad.
3. At the same time, we tell them there are options if they do run out of air.
4. We present those options as reasonable solutions.
5. Is there a connection/correlation between the fact we give them options to solve something we tell them never to do?
6. Would it change behavior NOT to give them options and better drive home the point of "Don't ever do this?"
iiiiiiiiii(Note that that's a hypothetical thought, not a call to action . . . or inaction.)
7. Should we add to the message something about going OOA greatly increases your chances of becoming a statistic?
8. Can this be solved with better training alone?
9. Is this not really a problem?

training solves that problem

If training solves the probem then why does the problem exist? Are you suggesting (1) that people aren't currently being trained not to run out of air, &/or (2) that people aren't currently being trained on OOA options?

not the stupid yes i said the s word stupid idea we dont teach ooa drills

What's stupid is to stick your head in the red Georgia clay and insist there can't possibly be a problem instead of really stepping back and taking a good, critcal look at things to see if the underlying premise has any validity to it and, if it doesn't, to make cogent arguments against it.

- Ken

 

[danvolker]

DanV, I hope you'll understand across the digital ether that I don't mean to twist your words, I just wish to argue them a bit. I'm... proposing, that you're making an unproven assumption about when all risk related to DCS ends. Since I expect it tapers off, rather than ending abruptly, I still see a trade-off with coming to the surface any sooner than necessary. You don't acknowledge that, that I can see - you present it as taken care of, as you described any thought of trading any remaining air for off-gassing time as 'insane', etc. Just to complete the thought, I haven't understood what your great concern is about low air stops or ascents from 15' with low air, though you and others seem to think it is a serious problem.


But based on some reading and common sense, I do contemplate the prospect that DCS is indeed insidious, that tissue changes can occur that may be damaging even when they don't nearly sum up to an acute incident, and that damage (as commonly is the case, pick your vice or stress) may accumulate. If you know of epidemiologic or post-mortem histologic studies that are adequate to disprove that hypothesis, I'd love to know of them. Until then, it colors my dive planning. So... you didn't suffer acute symptoms thankfully. The possibly more sensitive imaging method showed lots of tissue change due to gas absorption, but you dismiss it as inconsequential and transient. Is there some foundation for the prognostic value of these results or the method generally in the context of chronic effects? "It didn't kill you so it didn't hurt you" and its corollary "it's only harmful in large doses" is not compelling to a sceptic. You know of arthritis in photographers - doesn't that complicate the simple theory of DCS avoidance? You don't appear to take the risk of damage very seriously even in the face of contrary evidence - I don't see that I twisted your words on this subject much at all. If bubbles have been proven inconsequential, if it's known there are no low level and cumulative effects from staying within NDL, and I just don't know about it, I apologize in advance.

Spoolin,
As Lamont posted, look at the large population that dived from the 60's, 70's, and 80's..all doing 60 ft per min or faster ascent speeds with NO safety stop. If your paranoia was justified, there would be a huge incidence of bonal necrosis, or other related damage. Not only do we not see this problem in that population, most that I run into are in far better physical health than their non-diving peers. I just spoke to Living Dive Legend Frank Hammett 2 weeks ago....He began diving around 1954......he used to suck 72 cu ft tanks dry on the 145 foot deep hole in the wall, free ascend, grab another tank, and do this all over again..he did this for years...even in the 90's and later Frank did not do safety stops. Today, Frank is around 82, in very good health, and showing no signs that your fears of long term bubble damage are as insidious as you suggest.

If you can't shake this "Fear of Bubbles", then perhaps you would be better off just freediving ( which, by the way can still cause a tiny bit of bubbling).
Also, it appears that because you are a freediver, you have an inability to imagine how a new scuba diver can have a problem getting to the surface, and staying there safely, when OOA or low on air....
The skill sets are very different. As a freediver, you also KNOW you can keep your Heart Rate slow, and make it easily to the surface for the 15 feet in question...the new scuba divers will be nervous, heart racing, and have no experience free ascending....they also have far less propulsive efficiency. This list could go on and on. Many will be too negative on their stop, as they have not yet learned proper trim and bouyancy....as evidenced by the way many, many of these swim head up and feet down...
You fail repeatedly to grasp Ken's points about the need to do something to lower the death rate...and the big number of deaths are drowning and OOA related, not bubble/hypersaturation related.

DanV

 

[mdf]

But to use your analogy, it would be like telling a fighter pilot that since they have a parachute that they don't need to worry as much about running out of gas becaue they can always pop their chute and get another plane.

Wait a minute ... ejection seats are the final attempt for the pilot to save their own life. Whether the pilot was reckless or not can be decided later, but I see nothing wrong with telling them "Hey, when the poop irrevocably hits the turbofan for whatever reason pull that handle down yonder..."

What I have said is:

1. Based on the DAN study, we seem to have an inordinate amount of fatalities caused by OOA.
2. But we constantly tell people running out of air is bad.
3. At the same time, we tell them there are options if they do run out of air.
4. We present those options as reasonable solutions.
5. Is there a connection/correlation between the fact we give them options to solve something we tell them never to do?
6. Would it change behavior NOT to give them options and better drive home the point of "Don't ever do this?"
iiiiiiiiii(Note that that's a hypothetical thought, not a call to action . . . or inaction.)
7. Should we add to the message something about going OOA greatly increases your chances of becoming a statistic?
8. Can this be solved with better training alone?
9. Is this not really a problem?

First of all, 41% of all diving accidents being caused by "out of air" strikes me as "reasonable", so to speak. Like saying that most climbing accidents are caused by falling: is it not the nature of the business? If anything, the question should be why are the other 59% dying? Arguably, given someone is to die diving, it ought to be due to a lack of air and no other reason.

In the absence of evidence to the contrary, I also can't find a problem with giving people options to exercise in the unlikely event they do run out of air. Especially if presented in the manner it was to me:

1. running of out air is N'th definition of "stupid" in the OED

2. but if you do, don't panic and try to remember the following solutions ...

The solutions were discussed at some length with the class I was in, and in what you might call a "conditionally reasonable" tone. That is, "out of air" is an absolutely unreasonable situation to be in ("stupid"), but while enduring the situation, the options are entirely reasonable ... given the consequences of not exercising them.

So at best you are helping people potentially escape the consequences of their own mistakes. At worst, risk compensation is happening: despite all the training in the world, the risk-takers will find some other way of killing themselves.