Air2 / octo inflators

[beanojones]

You don't have pulmonary barotrauma from insuffuciently breathing. You only get it from holding your breath, medical defects aside (See: why asthma and diving are not such a good mix).

You can hum the star spangled banner if you want. Just as long as you do not hold your breath. There is a reason we teach un-assisted, out of air swimming ascents in OW class. (Why does everyone seem to forget those?) And they are done with no breathing at all: just keeping the airway open. You don't exhale (or you will involuntarily inhale), you just keep the airway open.

You do not get AGE from fast ascents (aka fast pressure changes). If you did OW instructors (and students) would be dropping like flies.

Faster rate of pressure change is where? OW water students train where? OW instructors do rocket ascent with students where? Answer to the above: in the shallowest part of the ocean or the pool.

Rate of pressure change is highest in the shallowest water. If rate of pressure change had anything to do with AGE, we'd be dead.

Someone being an ER doc (who is the ER doc, BTW?) gives them experience in the ER. The ocean is not like anywhere else. No expertise or knowledge or experience from anywhere else helps anyone here. Because the land based experience (knowledge, etc) is useless at best and actually dead wrong at worst.

Diving in general (and especially pressure related issues) is strictly empirical. And it is completely counterintuitive to all our previous experience. Because we are quite simply not made for diving, we just have to see what works. Being an ER doc (or an Olympic swimmer, or a physics PhD) gets you nothing.

If you try and slow a panicked OOA diver, you will endanger their well-being for no reason (See the above mentioned Puget Sound story, where the divers separated in shallow water, where the pressure change was greatest). Take them to the surface, at their pace. Slower is better. (But then again checking on gauges is better.) It's not going to be slow though. And trying to make it so will just result in them abandoning you. They don't need hand gestures, they need air. And they will do what is necessary to get to it. You should do what is necessary to get them to it.

 

[victor]

Well said beanojones
The only think I would add is
AS SOON AS YOU GET THEM TO THE SURFACE DROP THEIR WEIGHTS SO THEY STAY ON THE SURFACE.

A few $ worth of lead is not worth a panicked diver sinking back into the depths. It's amazing how many times a panicked diver makes it to the surface only to sink and be lost.
Hopefully they are positive without their weights even with an empty BC.
p.s. This is why I like weight belts, everyone knows how to release them.

 

[Thalassamania]

I think beano and you are assuming that's what was said. IIRC, the point was that a diver who suddenly (and possibly needlessly) ascended in an OOG situation suffered an embolism.

So far so good.

As I understand it, and feel free to correct me if I'm wrong, gas embolisms in divers are usually due to pulmonary barotrauma where the lung sacs burst due to overexpansion (introducing air bubbles into the blood stream), which is caused by a diver holding their breath or not breathing sufficiently during a rapid ascent.

An AGE results from the inability of gas to be vented from the "lung sacs." The rate of ascent is irrelevant, for practical purposes. There are several ways to keep air from venting from the "lung sacs." Involuntary ways such as a mucus plug or "voluntary" ways such as holding your breath whilst ascending.

If that's true (and checking my notes from a course I took, I believe it is) then you are technically correct that its its not the rate of ascent, but insufficient breathing during the sudden change in pressure (brought on by the rapid ascent).

I am not quibbling about the cause, the rapid ascent is irrelevant, it has nothing to do with a "sudden" change in pressure, the only relevant point is that the diver held his (or her) breath. This is time independent. If you were to take a fulll breath at 5 feet and hold your breath whilst surfacing at, say, 10 fpm ... you'd likely embolize. Conversely, if you were to take a full breath at 100 feet and keep your airway open whilst surfacing at 300 fpm (about terminal velocity for a buoyant human in water), you'd likely not embolize.

Which at the end of the day is really an unimportant distinction in the case of the person who died during a cluster**** of an airshare with some dual-use gimmick that this diver and her buddy probably never practiced using. That, plus a healthy dose of gas management might've gone a long way toward making this particular incident a non-event.
As always, YMMV.

The distiction is important only if you want to avoid an AGE. Divers are afraid to make a ESE because they are afraid of getting DCS and/or AGE. If they understood more about the difference they'd be less hesitant to go ESE. As far as dual-use "gimmicks" vs. octos vs. necklaced auxiliaries vs. buddy breathing ... they all work with training and practice and they all fail without training and practice, and you are right that none of these techniques are often required when divers exhibit competent gas management.

The same could probably be said for using a separate inflator and alternate air source.

This is where we part company. Over what part the selection of one or another type of back up regulator system plays in the situation. Training and practice have been shown to make virtually any approach work. Perhaps one way or another may be better for a completely naive diver, or easier to master, but I submit that all work given training and practice.

Besides, if I recall the accident that is being used as an exemplar here, it was the OOA diver (the receiver) who bolted and embolized, not the diver with the AIR II type device.

 

[John_B]

Thanks beano and Thal.

The only point I would quibble about (as a musician and erstwhile vocalist) is that it is entirely probably that you could be humming TSSB, Dixie, Dixie Chicken, or whatever and still not be guaranteed to have a completely open airway. I would rather people were just taught to just breathe vs. the whole humming thing. My own opinion, worth what you paid for it.

The other point that I think Thal and I are in agreement about is that practicing airshares with whatever equipment you use is the only way to ingrain how you will react in an incident. I didn't mean to imply the Air2 isn't safe for anyone, I just don't think they are safe for new divers. YMMV.

 

[Thalassamania]

If they are not safe for new divers then new divers are not ready to dive, but that's a whole different thread.

 

[beanojones]

The only point I would quibble about (as a musician and erstwhile vocalist) is that it is entirely probably that you could be humming TSSB, Dixie, Dixie Chicken, or whatever and still not be guaranteed to have a completely open airway. I would rather people were just taught to just breathe vs. the whole humming thing. My own opinion, worth what you paid for it.
.

When teaching emergency swimming ascent (taught in OW class, even PADI), students are taught to hum for several reasons:

1. If the student is humming, their airway is open (while you may not be sure about this, the training agencies are. We do this skill with each and every diver we certify. With only humming as a way to verify their airway is open.) Thus ascending without 'breathing' is perfectly safe. The rule is never hold your breath.

2. There is no way to tell if the student is keeping their airway open apart from having them hum, from the instructor's perspective. With a hand on the second stage, it's easy to feel the humming. You cannot otherwise be sure the diver is not holding their breath. Bubbles do not work since the air in the second stage expands and bubbles out by itself, even if the student is holding their breath.

3. If the student just exhales, they will likely exhale too fast and then involuntarily try and breathe in, which defeats the goal of the exercise. In the real world, this is not so big a deal, because if you are 'out of air' at 60 feet, the same tank pressure will deliver some air at 30 feet. But for the porpoises of training, the skilll practice is there to reinforce the idea that one can exhale continuously while ascending because the air in the lungs is constantly expanding.

On a separate note:

In the other thread that was linked above (What would you do?), there was an unfortunate story about a DM who had a gear failure who went to another (non DM) diver for help. IMHO, as a DM/guide/instructor you are always diving solo* (or at least you should consider yourself to be doing so) , and you should never ever ever go to a regular diver for help. DMs who cannot perform skills that OW students have to be able to perform (out of air swimming ascemts) should not be acting in the role of a DM.
http://www.scubaboard.com/forums/accidents-incidents/265854-what-would-you-do.html

Self-rescue should be the primary skill any 'leadership level' diver always has.

* As a DM, you are guiding inexperienced, and even uncertified divers. You do not have a buddy. And in many cases. the uncertified divers do not even have alternate air sources. We used first and second stages only, with only a 6" HP gauge for the intro divers we led. The 6" gauge mounted on a MK2 type first stage puts the gauge where the intructor can always see it on the diver.

As the saying goes: as an instructor teaching OW, who's the person you can turn to for help? This is just as applicable to DMs and guides, since you may well be leading uncertified divers, and thus, divers who are not equipped with alternate air sources, and not trained in how to use them. The only place to turn (in the unlikely event) is to yourself.

 

[Divedoggie]

I use several different systems, depending on what I'm doing. At this point I still use my integrated auxiliary for most diving.

I really feel that any system will work, as long as you and your buddy are comfortable with it and have practiced. As far as embolisms are concerned, it is my understanding that decompression considerations notwithstanding, an ascent of even 300 fpm will not, in and of itself, cause an embolism ... holding your breath is the problem, not ascent rate.

This is a very cool system!

One of my complaints about octo/inflate systems is the possibility of breathing bad air from the BC bladder while venting with inflator in the mouth, or the possibility of the diver holding breath while the inflator is taken out of mouth to vent.
Thal's system addresses both issues. The second stage reg can stay in the mouth while air is vented thru inflator.

I want one!

 

[Thalassamania]

It was sold by MARES in the US about ten years ago. My understanding is that it is still available in Europe. You can attach any second stage that you like, I find that the Oceanic Omega II is best (for me).

 

[beanojones]

The Air-Mic is the same system. Just like the one Thal_____ has, it needs a left handed reg, or a sidebreatther. I bought several trying to use them for my rental gear, but not enough seem to have been sold. Or maybe the people who have them aren't selling them.

I cannot find a picture of one. I have a few but no camera.

The Omega works well because it has no left/right, and it is small. The Micra works because it is left handed, and small diameter.

In playing with other regs on the Air Mic fitting, most second stages are just too chunky to hang right.

I was able to get a number of Sherwood Shadows, which are even better because when the students practice detaching the inflator hose, they don't flood the internals of the reg. But they can be kind of short.

The Air 2 style (or the Oceanic Air XS, or the Atomic SS1, or the Zeagles, etc etc) seem to get the reach right. And the multi-function bit means you save a hose without a lot of bulk. If I never had to teach OW students, I'd only use those. Oceanic (and Aqualung) put a midline dump in their corrugated hoses.

My ideal set-up is the Oceanic midline dump style hose with an Atomic on the end. I will have to see how they hold up to internal flooding. I know Air2's don't do so good getting water in air supply bits. They tend to get leaky and corroded.