Anemia and Air Consumption

[Viv]

I have been trying to figure out how to improve my air consumption recently. I am an "air hog" supreme. It is not unusual for me to suck an aluminum 80 filled to 3000 psi down to 500 psi in 20 or 30 min. I can't figure out an obvious reason for this. I am a small female who is reasonably fit (work-out regularly, avid runner, non-smoker, pulse rate of 60, etc.). I have all of my own well fitting, well maintained gear which I have streamlined as much as possible. I have been diving for 5 years and I feel as if I am reasonable relaxed in the water.

Now here are the questions. Am I too anemic to dive? Is the anemia altering my air consumption? Is it increasing my DCS risk? After doing some research on the internet I was surprised to learn that "normal" blood counts for diving are considered to be a hemoglobin of 12 and a hematocrit of 37%. I tend to run in the 11/35 range (which is considered "within normal range" for the lab that my GP uses so she doesn't consider me anemic).

 

[scubadoc]

Hi Viv:

People generally breathe about as much as their body needs for the right amount of oxygen - even though the main stimulus for breathing is an elevated CO2.

Your hemoglobin level (and hematocrit) are borderline low. It may be that your body has been compensating for the slightly lowered oxygen carrying capacity with an increased respiratory rate. Or, you might have a slightly elevated thyroid function - again with an increased metabolic rate and need for increased respiration.

You mention that you are relaxed, ruling out the possibility of anxiety being a factor; this will cause an increased respiratory rate and air consumption.

There are several threads on this board that will help you. Just search for anemia, blood or donation for some interesting discussions.

Our web page about anemia and diving might be interesting at http://www.scuba-doc.com/overview.html

Hope this is helpful!
scubadoc

 

[pipedope]

Hi Viv,

What is your breathing pattern like underwater?

What regulator are you using?

What does it feel like when you are breathing underwater?
What does it feel like when you inhale?
What does it feel like when you exhale?

What are you doing underwater when you do your 'air hog' imitation? Anything strenuous or just hanging out?

Do you know how to calculate SAC, surface air consumption? There is at least one thread on this on the board if you look for it. Giving air consumption in SAC can be helpfull as it adjusts for depth.
There is a wide range of *normal* air consumption rates for divers but I think all of us would like a tank of gas to last longer.

I am not a doctor but I am a commercial diver. I could tell you more if I could listen to you breath underwater but the answers to these questions may point me to a way to help you.

 

[Viv]

Scubadoc,
Thanks for the references. They were helpful and quite interesting. By the way, I was concerned about my thyroid as well since I am one of those small, thin people who can eat a horse and still not gain weight so I had it tested and the results were normal.


Pipedope,
Here are the answers to some of your questions:

Breathing pattern - I try to use a pattern of inhale/slight pause/exhale but I am not exactly certain what I am doing when I get busy or distracted.

Regulator - AquaLung Titan LX
I have tried changing the venturi adjustment but it doesn't seem to make a difference.

What does it feel like when I am breathing? - This may sound stupid but I'm not sure. I am not particularly aware of it. Maybe exhaling a little hard?

What am I doing?
I can suck a tank down pretty fast just hanging out. Obviously if I am more active (like fighting a current) it is worse.

Surface air consumption:
I got .667 and .775 for my two most recent warm water, low stress dives.

Thanks again for your help,
Viv

 

[Liquid]

Reading your message gives me the impression that an Al 80 tank should be enough for you for a lot longer than 20-30 mins, even considering the factors of your anemia. I am probobly thrice as big as you, and can use an al 80 for over an hour ana a half (on shalow dives). But it took me a lot of practice to reach this level. How many dives have you loged by now? and how long since you started to dive?

If youd answer the folowing questions, I'd probobly be able to offer some help on improving you consumption rate:

How calm are you in the water?
How good do you consider your bouyancy?
Do you tend to bounce up and down unintentionaly?
Do you tend to use your hands from time to time, maibe for pushing yourself from the ground?
are you comfortable with an AL 80 tank? seems to me it's to big for you, and may couse you stress that leads for more breathing.
How much led do you use?
Do you usualy dive from shore or from a boat?
do your legs tend to float/sink when you stop?
Do you consider yourself a "fast" diver or a "slow" diver?
Is your buddy faster/slower than you during the dive?

oh well- enough questions. It's hard to help you without seeing how you actualy dive, but if you'd answer these question I may be able to offer some advice. For some of these questions, maibe you'd need to ask you buddy.

 

[pipedope]

Viv, those SAC numbers are well within the normal range. The do sound just a little high for a fit, petite, lady diver but they are not so high as to indicate any real problem.
It certainly doesn't put you in the 'hoover' category. Incidentally, the cat on my shoulders in my profile photo is named "Hoover", for the way he sucks down bowls of food.

Now for some meat and potatoes of what you might do.

I first thought that you might be breathing shallow and thereby pushing up your CO2 causing you to overbreath. This can also be caused by a poor performing regulator.

What to do?
Do a pool dive where you do nothing but sit on the bottom and concentrate on breathing slowly and deeply. Carefully check the tank pressure and time the dive to make a very accurate measure of SAC.
Remember that a standard AL80 is actually closer to 77 cuft. Make note (write it down on a slate if you need to) of what the breathing feels like. Things you are looking for are;
Do you have to suck to get air, or does it seem to flow in effortlessly.
Do you first have to suck and then the reg seems to stuff your lungs full of air.
When you exhale, do you have to push the air out or does it just flow?
Does the air flow feel harder or easier anywhere in the breathing cycle.

The ideal is when almost no effort is needed to breath in or out as long as the reg does not free flow.

From the last study I have seen (by the US Navy) resistance on exhale was more work to overcome than on the inhale. There may be newer research on this now though.

Perversely, often the more you try to improve your air consumption the worse it gets. The more you just accept the rate you use gas and just plan your dives to fit the better it gets, to a point.

On working dives we don't get concerned until the SAC gets over 1.4 or 1.5 which indicates the diver is working too hard. We then have the diver just slow down enough to get back to about 1.4. Most dive planning uses 1.4 as the rate for normal work and we make sure to have gas available for this and also much more for emergency and backup. We also have it easy in most cases as we don't have to carry our gas on our backs so the supply becomes virtually unlimited.

My advice, just relax and enjoy the diving even though you use more gas than some other people.
Remember too that some divers don't do better than you on gas usage but they lie about it.

 

[Viv]

Thanks for the additional tips guys. I am planning a trip to the local quarry next weekend and I will certainly try to be a little more observant of what my breathing feels like and how much effort I am expending.

Liquid, that's a good point about the tank size. I don't own a tank so I am at the mercy of the LDS and what they have for rent (which are AL 80's). They are really big for me since I am only 5ft tall so they tend to hit my thighs when I am swimming. I may consider purchasing a steel 80 since it is shorter.

By the way, I don't want to sound as if I am obsessed with air consumption rates. As far as I am concerned if the dive lasts 20 min. and it was a good dive I am happy. It is just that I have had some bad experiences on group dives on dive vacations. I have had the group get angry with me because the DM had made a rule that when the first person reached 1000psi the group would have to return (and guess who that happened to after about 20 min.) I have also had people refuse to buddy with me because they said being with me would cut their dives short.

 

[Liquid]

Viv- it might be, that you'r in a situation that you dont feel comfortable, becouse you think you may ruin the dive for others. This couses you to get exited, and therefore breath more. Try finding a buddy you'r comfortable with, and take with him a few easy dives. Try working on being relaxed, It may work wonders on your consumption when you'r with a more simpathetic envirment.

Try also working on you bouyancy with the use of your lungs, and strive to reach a point, where you inhale/exhale only to control yourself in the water.

I can also think of several more reasons that may couse it, such as too much led (It alwais acompanies high consumption rates, since your average size of the lung is bigger), or tending of legs to float or sink. it may also be that since you'r small, you lose heat faster, and breath more in order to heat yourself (in which case a thicker wetsuit would help). I've had several divers with relatively high consumption, which I helped to improve drammatically. If you can give some more information (see the questions at my former post) I may give more specific advice.

Like I also said- it is possible to improve your consumption by working on it. I did it, and now I dive with people half my size and breath less than them even though they'r experienced divers.

 

[Viv]

Thanks for the support Liquid. I have been feeling a little bad about my consumption rate because of "peer pressure." I have been diving for 5 years and have about 100 dives. The funny thing is that my air consumption was much better when I started and seems to have gotten slightly worse instead of better.

Concerning your questions:

I feel calm when I am in the water. Then again I am not a very calm person I can't even take a yoga class because I won't sit still very long!

My bouyancy could use a little improvement, but I don't tend to bounce all over the place or use my hands a lot. I usually swim with my arms at my sides or folded across my abdomen.

My legs tend to float so I use ankle weights to keep myself more horizontal in the water. I am always working on getting my weighting right because I tend to be naturally neutral in water.. When I am wearing a 3mm in salt water I usually wear 5-7lbs (3 of which are the ankle weights). If I take weight off then I tend to get very light at the end of the dive (with the tank that I have sucked empty!)

I am always cold. Since I do most of my diving in the northeast US I am always cold - even with a 7mm jane/jacket, hood and gloves. My next thought is a dry suit and steel tank.

Thanks again for the suggestions.

 

[Liquid]

From your answer, I think it cn be concluded that there are 2 reasons that maibe be helped-

1- the pressure you feel from other divers, that is the only logical explanation, for your consumption to worsening instead of improving.

2- your 'jumpiness'.

About the pressure- you need to dive more with friends that will suport you instead of groups of people you dont know, this will help your self-confidence and may contribute towards improvement.

And about the jumpiness- well, the slower and calmer you are, the less air you take. If you can be slower it may help. When I dive, if I speed up, I suck the air extremely fast.