How to conserve air???

[TSandM]

There is some evidence that breathing high O2 mixtures results in some CO2 retention, which would imply that the minute volume would have decreased. But I'm not sure going into CO2 retention is a good strategy for conserving breathing gas -- and I'm also not at all sure that 32% Nitrox is a high enough O2 mix to make this effect noticeable.

 

[Bubbletrubble]

There is some evidence that breathing high O2 mixtures results in some CO2 retention, which would imply that the minute volume would have decreased. But I'm not sure going into CO2 retention is a good strategy for conserving breathing gas -- and I'm also not at all sure that 32% Nitrox is a high enough O2 mix to make this effect noticeable.

@TSandM: In a normal healthy person, wouldn't CO2 retention imply a higher concentration of dissolved CO2 in the blood? And wouldn't the elevated PaCO2 in blood increase the respiration rate (via peripheral and central chemoreceptors)?

I am aware that there may be exceptions to this, e.g., COPD patients, in which the PaO2 actually predominates in driving respiration rate. This phenomenon could explain why providing COPD patients with supplemental O2 might actually decrease respiration rate. Also, IIRC, decreased PaO2 in adaptation to high altitude increases ventilation rate. In this case, at altitude, administering oxygen would slow down hyperventilation (but this is different from decreasing a normal respiration rate). There's also the extreme situation of Type 2 respiratory failure in which escalating PaCO2 levels coincide with diminished respiratory effort...but that's not really relevant to diving.

Just thinking out loud on this. Maybe certain divers live with chronically elevated PaCO2 levels which desensitizes peripheral/central chemoreceptors. Then they might demonstrate a similar "COPD-like" response to breathing gases with higher oxygen concentrations. Any thoughts on this?

 

[drbill]

Start practicing yoga... a well-known diver/scientist friend of mine said it greatly improved his air consumption!

 

[Slonda828]

just for everybodys curiosity, yes i am a ex football player and ex ranger, spent 9 years in the army and loved everyminute of it, yes i do have a beer gut from living in germany but belive me i am solid.ggrrr

Were you just tabbed or did you wear a beret? One thing you will learn about some divers is that they are middle aged, have too much money, and do not do anything exciting outside of diving. Because of that, some of them like to nitpick new divers so they can feel elite. I wouldn't sweat it though, by and large most divers are good, fun loving, beer drinking people. I would find your local YMCA or dive shop and tinker around in the pool. Your SAC will get a lot better just from spending more time underwater, dialing in your buoyancy, and doing things like practicing skills and stuff underwater. The basic 20 diving skills that PADI espouses are a good place to start, but try them while hovering and do not kneel on the bottom. It's just like running man, the more you do it the easier it gets. Let me know if you need a dive buddy, I don't think Tampa area is too terribly far away and I could always use another vet dive buddy. BTW congrats on quitting smoking, as a former smoker I can tell you that the longer you last, the easier it gets (like many things in the military).

 

[MXGratefulDiver]

I'm sure that there are many that will disagree with this.

You can use enhanced air Nitrox. Aside of the acknowledged bottom time extensions, some people including myself have found it useful for reducing gas consumption. Other people who have lung issues from smoking or are older also seem to find it beneficiary.

One doesn't use enriched air nitrox to improve air consumption ... the benefits are to extend your no-decompression limits at a particular depth or to reduce the necessary surface interval between dives on multi-dive days.

Air consumption isn't a factor of how much oxygen you're breathing ... keep in mind that when you're diving air you already expel about three-quarters of the oxygen you are breathing with each breath. Your body only metabolizes about 5% of it. The rest gets wasted.

What makes you breathe isn't the amount of oxygen in your mix, but the amount of CO2 your body produces. So what produces CO2? Well, in divers the most significant factor is the amount of effort you're using to dive. This is why new divers almost always have higher gas consumption rates than more experienced divers ... because they haven't yet taught their body how to relax, and haven't yet developed the skills to move through the water efficiently. Water is heavy stuff, and it takes effort to move it out of the way.

Then there is the breathing pattern ... most new divers have to learn how to breathe properly ... after all, it's the first time in their lives they ever really had to think about it. Slowly and deeply causes the best exchange between the air you're breathing in and the CO2 you want to breathe out.

It comes with practice. The best advice any new diver with air consumption worries can get is to (a) dive as often as possible, (b) check to assure that you are properly weighted ... too much creates buoyancy control issues and too little makes you struggle to stay down, (c) work on developing a horizontal trim so that you don't have to move so much water out of the way to get around, (d) breathe slowly and deeply, and (e) slow down and relax. Stop worrying about how much air you're using ... over time that problem will take care of itself. Just be patient and keep diving.

So remind me why we give DCS victims pure O2?

Not for the same reasons we recommend the benefits of nitrox. The two have nothing to do with each other.

... Bob (Grateful Diver)

 

[islandah]

Aside from understanding dead space and the benefits of longer deeper breaths, by far the biggest factors for consumption for me have always been comfort with my gear, abilities and the conditions. The good news is that the best way to get that comfort is by diving a lot!!

Also, I find that the more I worry about my consumption, the worse it is. Get comfortable with your gear and diving in general, get used to a long, deep breathing cycle, then forget about it! Enjoy your dive and only think about breathing rates when you're doing something strenuous or getting anxious about something.

 

[pushc6]

Just over my check dives I noticed the more comfortable I was the less air I used, and if I took long deep breaths\exhales I also used less gas.

 

[NAM001]

keep in mind that air use is motabolism driven. big guy weight lifter (steel or flesh) muscle bound ....muscle burns o2. next bouyancy bouyancy bouyancy . good bouyancy control little muscle use to stay put less o2 burnt. other thatn that loose 100 lbs to burn less.

 

[Garth]

One doesn't use enriched air nitrox to improve air consumption ... the benefits are to extend your no-decompression limits at a particular depth or to reduce the necessary surface interval between dives on multi-dive days.

Air consumption isn't a factor of how much oxygen you're breathing ... keep in mind that when you're diving air you already expel about three-quarters of the oxygen you are breathing with each breath. Your body only metabolizes about 5% of it. The rest gets wasted.

What makes you breathe isn't the amount of oxygen in your mix, but the amount of CO2 your body produces. So what produces CO2? Well, in divers the most significant factor is the amount of effort you're using to dive. This is why new divers almost always have higher gas consumption rates than more experienced divers ... because they haven't yet taught their body how to relax, and haven't yet developed the skills to move through the water efficiently. Water is heavy stuff, and it takes effort to move it out of the way.

Then there is the breathing pattern ... most new divers have to learn how to breathe properly ... after all, it's the first time in their lives they ever really had to think about it. Slowly and deeply causes the best exchange between the air you're breathing in and the CO2 you want to breathe out.

It comes with practice. The best advice any new diver with air consumption worries can get is to (a) dive as often as possible, (b) check to assure that you are properly weighted ... too much creates buoyancy control issues and too little makes you struggle to stay down, (c) work on developing a horizontal trim so that you don't have to move so much water out of the way to get around, (d) breathe slowly and deeply, and (e) slow down and relax. Stop worrying about how much air you're using ... over time that problem will take care of itself. Just be patient and keep diving.


Not for the same reasons we recommend the benefits of nitrox. The two have nothing to do with each other.

... Bob (Grateful Diver)

Spot on, CO2 is your respiratory drive center not your O2. Higher CO2 levels will cause you to breath faster.

 

[Sharkskin1994]

i had this problem also, my instructor just told me to calm down and slow my breathing and it worked for me