Scuba diving and sickle cell trait

[Samson]

Hi everyone, my name is Sam and I'm new to this forum.

I'm just recently getting into scuba diving (going through my online course before actual classroom and then water) and I'm very excited and can't wait to start diving.

I have one issue though. I have sickle cell trait (NOT anemia). For those who don't know, the trait causes a certain percentage of my red blood cells to become oddly shaped when lack of oxygen occurs (such as at very high altitudes). This is deadly because it inhibits the ability to efficiently take in oxygen and can cause organ damage if oxygen isn't provided.

I can find almost nothing on sickle cell trait with regards to scuba diving except for a very old thread on here and a few other sources but nothing seems to be definitive nor can I find any research done on this matter.

I went to get my level of HbS tested (which is the % of cells in my blood that would get out of shape due to lack of oxygen) but my primary doctor had no idea what I was talking about Unfortunately I don't know what my HbS percentage is yet.

Now I'm still new to all of this but aren't there circumstances in diving where oxygen levels aren't ideal? Would increased depths/pressure play a role in the uptake of oxygen by cells and would that be an issue for someone with sickle cell trait? Anyone know of any recent findings on all of this? Any know of divers with sickle cell trait?

**If it helps at all I'm extremely athletic, 28 years old, total health nut

 

[Protondecay123]

Hi everyone, my name is Sam and I'm new to this forum.

I'm just recently getting into scuba diving (going through my online course before actual classroom and then water) and I'm very excited and can't wait to start diving.

I have one issue though. I have sickle cell trait (NOT anemia). For those who don't know, the trait causes a certain percentage of my red blood cells to become oddly shaped when lack of oxygen occurs (such as at very high altitudes). This is deadly because it inhibits the ability to efficiently take in oxygen and can cause organ damage if oxygen isn't provided.

I can find almost nothing on sickle cell trait with regards to scuba diving except for a very old thread on here and a few other sources but nothing seems to be definitive nor can I find any research done on this matter.

I went to get my level of HbS tested (which is the % of cells in my blood that would get out of shape due to lack of oxygen) but my primary doctor had no idea what I was talking about Unfortunately I don't know what my HbS percentage is yet.

Now I'm still new to all of this but aren't there circumstances in diving where oxygen levels aren't ideal? Would increased depths/pressure play a role in the uptake of oxygen by cells and would that be an issue for someone with sickle cell trait? Anyone know of any recent findings on all of this? Any know of divers with sickle cell trait?

**If it helps at all I'm extremely athletic, 28 years old, total health nut

@Samson I’m not a Diving Physician but can orient you to some literature Sickle cell trait and diving: review and recommendations. - PubMed - NCBI
DAN | Medical Frequently Asked Questions
The Real Risks of Sickle Cell Trait - Johns Hopkins Center for Innovative Medicine

 

[Samson]

@Samson I’m not a Diving Physician but can orient you to some literature Sickle cell trait and diving: review and recommendations. - PubMed - NCBI
DAN | Medical Frequently Asked Questions
The Real Risks of Sickle Cell Trait - Johns Hopkins Center for Innovative Medicine

Proton, thank you for these. I've read the Johns Hopkins article as well as the one from PubMed but I didn't see the one from DAN which seems to indicate there is no correlated risk between diving and sickle cell trait. Finding a diving physician would be great!

 

[tmassey]

I have no experience with your exact condition and SCUBA. I do not want to make *any* statements related to that. But you stated that 'in SCUBA there are conditions under which oxygen conditions are not ideal'. I thought I might expand on that for you a bit. By the way, this is stuff that will be heavily covered in a decent initial Open Water certification class.

In open-circuit recreational SCUBA (i.e. what most people think of as SCUBA), there are no circumstances under which you will be exposed to *less* oxygen than you will experience on the surface. In fact, it's always a lot *more*.

When diving, we are breathing compressed gas; for a beginner usually compressed air. That means that, at worst, the percentage of oxygen in the gas you will be breathing will always be at *least* the percentage on the surface. Yet even then, the *amount* of oxygen you are exposed to is much, much higher. In fact, for divers, over-exposure to oxygen is a danger, not under exposure. (Again, leaving non-recreational SCUBA out of it.)

For example, while diving at 33 feet and a cylinder filled with air, the percentage of the oxygen within the cylinder is the same 21% as it would be as when we are on the surface. (The atmosphere is very close to 21% oxygen.) But because the gas we're breathing out of that tank is twice as dense (or under twice the pressure) as it would be at the surface, the amount of oxygen (what we call the partial pressure) is actually double that of on the surface.

So yes, as divers we have to be aware of oxygen levels because they are not always ideal. But it's always because we have too much of it, not too little.

Now, what effect does elevated O2 levels have on your condition? I certainly can''t hazard a guess. DAN seems to indicate that there is no correlated risk according to your reply. Intuitively, that makes sense to me, and maybe it will to you once you understand how diving affects oxygen levels (by always increasing them).

Of course, it's much wiser for you to do the research and find out for sure! But hopefully this explanation might help to understand why SCUBA may not need to be an issue.

And like I said, my 30 second explanation will be covered in *much* more detail in an Open Water class; and when you take a class to use a gas called Nitrox (which is probably the next class someone should take after Open Water!), it will go into all of this in even more detail.

If I only confused you more, please let me know: I'd be happy to try to answer any questions I might have just created!

 

[RyanT]

@tmassey beat me to the explanation I was going to provide. Definitely get some real medical advice first. We do have a few of our community members here with actual medical training, so perhaps they can steer you in the right direction. @Duke Dive Medicine.

 

[Samson]

Thanks guys! @tmassey you didn't confuse me at all, you've offered some great clarifications.

Sickle cell trait is only concerned with lower than normal levels of oxygen. I don't think there's any complications with elevated levels of oxygen that would be any different from someone without the trait.

I know I'm getting WAY ahead of myself but would the dynamics change with closed circuit diving coupled with elevated pressure and how would that effect someone with sickle cell trait?

 

[tmassey]

I know I'm getting WAY ahead of myself but would the dynamics change with closed circuit diving coupled with elevated pressure and how would that effect someone with sickle cell trait?

Again, I can say nothing about the dynamics of sickle cell trait. I *can* say something about the dynamics of oxygen in different types of diving.

To make it very simple up front: oxygen levels below atmospheric only occur with gasses designed for dives below 200 feet or a very advanced device called a rebreather. These are very advanced dives and you will need years of classes and experience before this is even a possibility.

As I mentioned, too much oxygen is dangerous. The deeper you go, the more oxygen is in your gas. (EDIT: the more oxygen you are exposed to.) Below something in the neighborhood of 200 feet or deeper, the oxygen in even normal air can become toxic. To avoid this, divers start removing oxygen (and nitrogen) and replacing it with helium. This is called Trimix. This means that divers might need to use a gas that has a smaller fraction of oxygen than in even normal air. At depth, this is not a problem: the compression we experience bumps the oxygen levels way, way up. BUT, while you're *descending* to those depths, the partial pressure (the "amount") will be lower, and on the surface it literally might be too low to support life.

In those circumstances, you would need to be careful to make sure that you had a gas with enough oxygen for your needs. This is usually accomplished by bringing another cylinder of gas -- called a travel gas -- to breathe until they're deep enough to safely breathe their main gas. (It is extremely likely that they would need to carry that same gas for other reasons, too: to accelerate the decompression (EDIT: off-gassing, called "deco") process on the way up from their very deep dive.)

HOWEVER: for convenience, many divers who need to do a dive with only 18% oxygen will simply use that as they descend, without a travel gas. For people with normal blood cells, 18% oxygen is enough to support life and for the short time they're doing so it won't make a difference. It's like being at altitude for a few minutes. For YOU, however, this may not be possible: you may need a travel gas any time you're using a gas with an oxygen percentage below 21%.

To repeat: this is only an issue with dives below 200 feet! This level of diving is called Hypoxic Trimix, and it's literally the most advanced level of SCUBA.

I mentioned that there is also an issue with a rebreather. With rebreathers, there are circumstances (such as if you ascend too fast) where the partial pressure of oxygen (again, the "amount") can drop, so much and so fast that even people with normal blood cells will pass out nearly instantly. Rebreathers are again a very advanced device (and pretty crazy expensive), and it will be a very long time before you will need to even be aware of this, let alone worry about it.

But now you know!

Again, if you have any questions, ask. If other more experienced divers have any issues or nit-picks, please feel free to let me know. But if it isn't a true safety issue, how about a PM? I don't want to derail the thread with technical minutiae that is highly unlikely to be relevant to the OP, who is *miles* away from any of this... Having said that, I'm interested in the minutiae! But if I said something you think is unsafe, by all means correct it in public!

 

[Samson]

@tmassey you are a wealth of information, thank you so much!

I have heard of rebreathers. No safety issues now, this is all just my curiosity and excitement getting the better of me.

Thank you again. You've taken concepts that are way ahead of what I'm learning now and simplified them and you have answered many of my questions (some I haven't even asked yet )

 

[tmassey]

@tmassey you are a wealth of information, thank you so much!

Thank you, but you only say that because you haven't taken your Open Water class yet! 80% of what I wrote will be covered even better (and no doubt more concisely!) in your course materials... "In the land of the blind, the man with one eye is king..."

There shouldn't be a certified diver that *couldn't* have explained all of that -- and *certainly* any Nitrox-trained diver. Maybe not the Trimix and rebreather stuff, but they darn well better cover the rest!

 

[michael-fisch]

My Samsung smart phone has a health app which among other features measures O2 saturation. As long as it, or any other O2 saturation monitor, shows O2 saturation above 97%, you're good to go, if it shows O2 saturation below 90% it's time to see a hospital ASAP.
The last time I messed my lungs up breathing a caustic liquid, I drove 30 miles to the hospital myself and had an O2 saturation of 43-45% on admission, but I was still concious.

Michael