How to safely ascend with Spare Air

[fisherdvm]

So I think I have came to a conclusion, it doesn't matter what depth you are at, you should try to breath from your empty tank or regulator. Or from the spare air. Snowbear has shown me that you can reflexly or unconsciously shut down your larynx.

So maybe the spare air might not save you from DCS, it might cut down your anxiety enough to prevent breathholding????

 

[MikeFerrara]

WOW! What a thread. On ascent you can get a little more gas from a tank because the ambient pressure is dropping. I think some one mentioned that. A reg is designed to work on a pressure equal to ambient + IP. Once you get below that the reg doesn't work right. Once you get down near ambient you won't get gas at all.

Niether the reg or a stupid spair air is there to help you keep your airway open. They are there to give you gas to breath.

Don't run out of gas.
If you do switch to an alternate.
If you can't and you muct do an ESA, do it like you were taught. Keep the reg in your mouth (because you can get a little more on the way up) and, in the mean time, exhale a little to keep the airway open.

Did I miss something?

 

[Don Burke]

Did I miss something?

Yes, the part where someone explains the wisdom of going in the water knowing your independent air source is not going to get you out of an OOA without a bunch of luck.

It is a basic problem of bringing a Nerf bat to a gunfight.

 

[OneBrightGator]

Just kidding, I very much appreciate Snowbear for making me think ..... and possibly might save my life in the future.....

Please keep in mind the advice hinted at in her last paragraph has a much better chance of saving your life then any discussion on larnyx control or any other medical gobly-gook you two have been discussing.

 

[wedivebc]

To be very honest, I have dived only 13 times, and that was 10 years ago. It is very refreshing to read about these topics here and get input from the veterans. I am planning to get a refresher course and restart diving. It is amazing what a medical residency and having a family can do to your diving hobby.

I am obsessive about science, so I would like more input from other medical folks or engineering types. As for my name, the dvm does imply a veterinarian. I do hold both a DVM and an MD. But it is worth S...T when one is diving. I have intubated hundreds of dogs and cats, about 10 or so infants, and 1 cardiac arrest human . So I believe that I understand the anatomy of an airway from the vocal cord up very well.

I still strongly believe that a conscious person with a regulator in his mouth can not have a closed upper airway.

The use of a rigid airway is to keep an unconscious person who is still breathing from shutting down his upper airway with his tongue. A rigid airway is not needed in ACLS or ATLS if the patient is conscious and breathing.

Please correct me if I am wrong, I will always be the first to admit it.

Based on the first sentence in this post I think you would do well to take an OW scuba course. This material is covered in detail in OW 101 and you may find all the answers you need.

 

[Snowbear]

By the way, Snowbear, what would a firefighter be doing intubating a horse? Were you trying to tube its stomach and got it in the wrong pipe?? Intubating a live horse is an extremely difficult task, and I have done it only about 3 times in vet school. As for the dogs, cats, and other animals - I think you must be a very wonderful firefighter to help them creatures......

I wasn't a firefighter at the time.

There was a time when my goal in life was to be a DVM. I was offered and took a job as a "veterinary assistant" to the local DVM who was the primary and emergency care provider for all of our farm and house critters. There were multiple occasions when it was just not possible for him to make it all the way out in the boonies to treat the beast, so he would talk me through whatever it was over the phone. Or if it was a case of follow-up care, he would leave the stuff and show me how to use it. Once I turned 16 and was legally able to work for him, he offered me a job in the clinic as his assistant and usually took me on farm calls (he no longer does the farm calls, unfortunately). I learned a tremendous amount of stuff I still use to the point I rarely need an actual DVM to treat my own critter problems (he still gives me the Rx I need or sells me the drugs I need to keep on hand)

Anyhow, among other things, he taught me how to intubate the cats and dogs coming in for whatever surgery was required. I learn best by doing stuff hands-on. I practiced on other people's pets

As for the horse - it was a colt that was born as a twin to my own mare ~5 years ago. His lungs were not fully developed and he ended up unconscious in respiratory distress. While waiting for the vet to come, I used a human ETT I keep in my "first aid" kit and successfully nasally intubated him. Needless to say, the responding vet was surprised not only by that, but by the warmed saline I had running into him via IV in the EJ. Unfortunately, that beautiful big colt died at less than 24 hours old :frown: His sister, whose lungs were fine but had a puny body, died 3 months later when she had to be put down due to a badly fractured hock. :frown:

Anyhow... as a firefighter/Paramedic, although I have actually attempted resuscitating a couple of canine fire victims, most of my medicine is now practiced on plain ol' humans

 

[StSomewhere]

If your first stage fail, and dump 3000 psi into the second stage, you would lose all your air in a few seconds. ... Now your second stage is filled with water, why keep it in your mouth.

The interesting thing here is that to move that much air (3000 psi) through that little connector is going to take a lot longer than a few seconds. In our confined and open water dives we all (no matter what agency did our open water certs) actually simulated this type of failure by holding the purge button (equivalent to the fastest that air would dump out of your second stage) and then "sipped" the air going past without actually having the regs in our mouths.

The amazing takeaways for me from these skill demos was:
1. You get an amazing amount of breathable air with this technique.
2. Regs are built to freeflow in a failure (instead of not delivering air) so this scenario is the most realistic and common air situation for anyone who pays regular attention to their SPG.
3. In my open water drills, even at 1000 psi from a depth of 40 ft, I had plenty of air to safely surface at the normal rate of 30ft/minute.
4. All that air escaping looks far worse than it really is.

My point is while you might think you'd lose all your air in a few seconds that is actually not the case, not unless your tank failed catistrophically (i.e. burst like in the ending of "Jaws"). Of course, having practiced this so you'd automatically know to handle it and you'd be less likely to panic. And the reality is that your spare air/reg is in your buddy's tank/octo (and even the most clueless buddy should notice the sound/sight of all that air escaping), so you shouldn't actually ever have to surface using this method, but you could if you needed to.

As I understand, please teach me again, my scuba instructors, I should try to ascend with by lips pursed open and allowing bubbles to blow out.

Not just that. Also make a little humming or quiet singing note (if you've ever played a kazoo as a kid, just like that) with your vocal cords as you blow bubbles. That insures your airway is *REALLY* open. You can actually blow bubbles and not have your airway open, by blowing bubbles from captured air already in your mouth. That's not good enough. Remember if you ascend even semirapidly your lung volume doubles in every 33 ft seawater/34 ft freshwater.

I do not see a difference between this act and one which a person has a dry regulator in his mouth, and is not purposely holding his breath aside from not inhaling. The only resistance to letting the air escape at this point is the resistance from the exhaust valves of the second stage.

Ironically enough, this is the EXACT same problem as the air tank at 3000 psi. The air volume can expand so fast in your lungs that it can't overcome all the resistance to a closed airway in time to prevent your lung air sacs from exploding. Without an existing airflow, the air sacs in your lung will give way first, before the airway opens.

So is it the wording that I am using that is getting people all upset? Or by not inhaling, I am shutting my airway down?

No, no, no. It's because I had an excellent instructor who went through this exact same argument you are making as the #1 mistake people who wind up with embolisms and DCI make. Whether you realize it or not, what you are advocating is a form of skip breathing. And the #1 rule of scuba is to always breathe and never hold your breath.

If I were you, when I interviewed my scuba instructor (and you should interview your scuba instructor!) I'd make sure I had someone who could adequately explain this to your satisfaction.

 

[fisherdvm]

You know, I never presented myself as an experienced diver. You are probably right about retaking an OW course. I have read enough to see that my training in 93 is different than some of the more conservative OW programs. I also have seen how much I did not learn the first time - either through my own omission or to my instructor.

I am glad that enough people here are understanding enough to go through my thought processes. I think that the more you understand a situation beforehand, the better you would manage it if you were narced out or having a panic attack.

So I appreciate the folks who don't ask stupid questions like "where is your buddy", or "why is your tank pressure not observed", and focused on answering my question and concern. But I can see the machismo attitude that comes with this sport.

Thank you Snowbear for making me think. And thank you for our Japanese colleages who are much more pleasant and thoughtful than the macho divers who just wants to leave their attitude signature behind.

When I think of DCS sickness, I think of tiny little nitrogen bubble that doubles its volume every 33 ft. I am inclined to think that the advocacy of decompression at 1/2 of maximum depth for 1 minute, and then repeat at 15 ft for 4 to 5 minute is better than just at 15 ft. In the same way, a slow descend at 30 ft / min is better than 60 ft/min - as it would give you a steady 3 minute of decompression as you rise from 100 ft than just 1.5 minutes (just in case you overshoot the 15 ft mark). But if you did overshoot, you can just descend and shrink those little bubbles (an instant decompression chamber).

 

[derwoodwithasherwood]

I am inclined to think that the advocacy of decompression at 1/2 of maximum depth for 1 minute, and then repeat at 15 ft for 4 to 5 minute is better than just at 15 ft. In the same way, a slow descend at 30 ft / min is better than 60 ft/min - as it would give you a steady 3 minute of decompression as you rise from 100 ft than just 1.5 minutes (just in case you overshoot the 15 ft mark).

Sorry, I'm lost here. Are you still talking about safe ascent on a Spare Air? I really don't think a 3 cu ft cylinder has enough air to allow those luxuries. I did my own calculations and for me, at my worst SAC rate, I would consume at least 8 cu ft of air during the ascent* you just described. Did I screw up the math or am I just a "hoover"?

(*you actually typed "descend" but I believe you meant the other way, right?)

 

[bwerb]

So I appreciate the folks who don't ask stupid questions like "where is your buddy", or "why is your tank pressure not observed", and focused on answering my question and concern. But I can see the machismo attitude that comes with this sport.

Sorry dude, I was the one that asked that question...no machismo here. What you were clearly failing to realize in your posting and your responses is that frankly you totally missed at least half of the first day of the first class in OW. When someone comes on a board with one of their very first posts asking about a piece of gear which is beyond useless and starts going on wanting to discuss the physics of using it (after acknowledging that it is a questionable piece of gear) and you have the adacity to start putting limiters on what type of responses you want...sorry, I'm not listening.

Your initial post demonstrated very, very clearly that you have little to no idea of what you are talking about. Your last post here still indicates that you don't get it. Here this loud and clear...I don't want to read about someone "testing his theory" in the DAN report.

You are spending far too much time working out the physics and not looking at the primary end of the equation. Why would this event occur? If you are in the medical field...sign up for DAN and start doing some reading.

The strength and tone of my response was guaged to get you to THINK for a minute, that hmm...perhaps I'm concentrating on the wrong thing. I can also see a real sense of dare I say, arrogance in you postings. Your lack of knowledge comes across clearly but your insistence on debating it and whining about how you are being responded to isn't exactly demonstrating a move towards the light here.

Good luck...come ask the question again after you've listened during your OW class...oh...you won't need to ask the question then and you won't be considering using a Spare Air anymore either...(unless the shop sells them... )