Immediate CESA Vs. looking for your buddy...

[Bigeclipse]

I just want to reiterate to everyone that I do NOT plan to do CESAs unless forced to. I always dive doubles OR with a pony 40cu slung on my side, no matter the dive. I was just thinking that it takes a lot of muscle memory in an emergency to remember to signal your buddy for OOA and then for them to help donate their air to you...seems like a lot of moving pieces when maybe a CESA would be faster/better (assuming you had a lung full of air to do so).

 

[Marivan377]

From my very novice perspective the cesa took place when the buddy needed his reg back after not locating his octo. Why did the ooa diver not reach for the octo that was in his sight before he took off. Easier said I guess. Or even locate for the donor.

 

[nolatom]

You were the non-problem buddy pair, so you're relying on the problem-pair to tell the story straight. Did they fully understand what happened?
I'm having trouble with both of OOA's regs (which he'd just used during all his recent AOW cert dives) malfunctioning at same time--are we sure that was true for the alternate reg, or did he just maybe not purge it before inhaling (and getting water, and "hitting the panic button" instead of the purge button)?
And the CESA--did he bleed off his BC as he ascended, and "swim", or did he just go zoom-zoom on a nearly-full BC? Since it seems this happened real early after descent, he probably got away with it since not much nitrogen yet absorbed. But 90 feet in 20'vis sounds scary to me nevertheless. And his donating buddy I understand why he got flummoxed but this is where he should have dug his alternate out and donated it while purging it.
Easy for me to say from a desk, I know. But zooming up to the blue sky and the seagulls I don't think I'd consider doing from that depth unless there was no other way.
Glad it had a happy ending.

 

[Lorenzoid]

. . .
This all got me thinking...unless you have OOA procedures basically burned into muscle memory, would it just be better to do a CESA? The reason I say this is what if the OOA person didnt find that buddy right away, thus spending a little more time down below and when they go to do a CESA end up drowning on the way up? What if as soon as they had a failure, instead of looking for a buddy just start immediately doing a CESA?

The question seems to be worded from the perspective of a diver who is presumed to be thinking, before diving, what he will do in the event he goes OOA and can't immediately find his buddy. The hypothetical diver is contemplating, in effect, burning into muscle memory (or at least what we might call mind memory) whether to spend more time searching for his buddy or to immediately do a CESA. But as far as this hypothetical diver is concerned, what happened in the actual incident you related or other such incidents is moot. No matter what we say here in response to the question, if someone has never thought about this before the dive, then he's just going to do his best to think about and solve the problem as it occurs, which is exactly what the recently certified diver in your story did. For a hypothetical diver thinking BEFORE diving how he will handle that situation, then as you clearly recognize, there are better options than a CESA:

. . . For me, I only have one dive buddy that I trust. We do many drills all the time. If he is not available to dive and I dive with others, I treat it like a solo dive and prepare as such. (Honestly, I tend to dive sidemount doubles OR sling a 40cu on rec dives. I like to be overly cautious)

 

[rsingler]

Keep in mind that at 95', you have four times as many oxygen molecules in your lungs as you did at the surface. That means that whether you started with a half breath or a full one when you made the decision for a CESA, you still have lots of oxygen, and are not likely to pass out.
CESA's have been done repeatedly from these depths with no difficulty by many divers.
That also means that you have a few seconds to look around for your buddy before you make a decision that may have offgassing consequences.
No, I wouldn't "just do a CESA". But I also wouldn't sweat it if I had to. The expansion of gas on ascent will fill your chest, and you'll still need to breathe out.
The breathlessness that you feel upon breaking the surface will be due to increased CO2, and likely not hypoxia.

Diving Doc

 

[Storker]

at 95', you have four times as many oxygen molecules in your lungs as you did at the surface.

Immediate problem is, you also have four times as many CO2 molecules in your lungs. And it's the CO2 that triggers your breathing reflex (or, as it's more colloquially known as, the "damn, I need a breath!" feeling).

Now, if you're a trained apnea freediver that doesn't mean that you're in any kind of immediate emergency. But I'm pretty certain I'd be somewhat freaked out.

 

[rsingler]

Immediate problem is, you also have four times as many CO2 molecules in your lungs.

I'm not sure that's really true, @Storker .
Keep in mind that before the OOA, you were breathing in gas with 0% CO2 (i.e., tank air). And when you stop breathing, you only produce CO2 at your body's metabolic rate. It is not ambient pressure dependent. And the trigger for respiration is not lung CO2, but blood pCO2.
Therefore, while you'll certainly have a real "urge to breathe", the increased CO2 should only be about 10 mm Hg over the 90 sec that it takes to make a non-rocketing CESA. Yes, a huge respiratory stimulus, but exhaling helps with that urge, and it's not more than just about any diver can do.

 

[yle]

seems like a lot of moving pieces when maybe a CESA would be faster/better (assuming you had a lung full of air to do so).

Just my two cents: a CESA attempt can create two problems. First, if a diver is panicking or close to panicking, such that getting assistance from a buddy seems to complicated, that diver is more likely to forget to exhale on the way up. Second, if a diver makes the decision to CESA, they necessarily leave their buddy alone... so the CESA-ing diver (as well as the buddy) is now solo, with no one able to to render aid (which they are likely to need.)

All round the best option is to get assistance from your buddy. This is why a pre-dive briefing should include 30 seconds of discussion as to how an OOA situation will be handled. It would be interesting to find out if this was addressed in the briefing of the two divers in your story.

 

[Zef]

...assuming they had the last breath of air to do so.

If one finds themself in an OOA situation it typically is not when they receive a last breath of air form their tank...it is when they go to get a breath of air and find there is nothing left.

Everything you described in your post begs one to pay attention to their buddy and their pressure gauge. While a CESA is a good technique to know, it is inherently dangerous. One should have an innate awareness of how to share air and how their life support equipment is setup/situated on their body to avoid having to employ such a technique.

In my opinion, If you are diving and your buddy is more than 2 arms lengths away, you are doing it wrong. If you descend as a group and half the group goes one way and the other half another, and you were not expecting that, then the dive brief you gave or received was insufficient. If you run out of air, barring a catastrophic failure of your 1st stage or an LP hose, it is because you are negligent about managing your own gas supply. If you can't find your octo when you or your buddy needs it then you are a danger to your self and/or of no help to your buddy when the s&%t starts hitting the fan.

It is ridiculous how often I see people's octos and pressure gauges dangling or trailing behind them. The instructors I have come across who teach basic OW tend to not correct this and so their students don't know to care.

Go back and review your OW manual. You would be surprised that just about everything that you mention is addressed in one form or another.

-Z

 

[Vicko]

CESA from 30 meters with a inflated BCD and swimming hard takes you around 30 seconds. With all the bubbles likely blowing around you, your BCD over pressure valve blowing and the gas you are exhaling you don't really have time do something else, and you probably won't pass out for hipoxia. The gasping at the surface is from a massive swell of adrenaline your system just took.
You could also try and do it by the book and do a calm CESA, it takes almost 2 minutes from that depth so good luck with that...

Personally I would use up around 15-20 seconds (remember at the bottom your lungs are empty, not a pleasant feeling) to try to locate and establish eye contact with my buddy (tank bangers don't work, you can't scream at him as you have no gas in your lungs) , if he is swimming away from me I would CESA.
Better bent than dead.