Underwater Wakulla- March 28, 2019

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I Can’t get Bent! By GREGG STANTON

I Can’t  get Bent!

Whenever we expose ourselves to a greater pressure than one-atmosphere, or within 1000 feet of the ocean (elevation) we are subject to a remote chance of Decompression Sickness. When we dive underwater, that pressure differential increases considerably, in fact, doubling in 33 feet in depth. The deeper you go the greater the chance of suffering from the challenges of off gassing the accumulated inert gasses that are part of what we breathe. We do follow decompression tables to calculate the safe off gassing of these gasses, but since we are all built differently, there are no guarantees. We often refer to good judgement when planning a dive, not unlike planning for anything in life.

I got a picture of a rash on the back of a friend who said I can’t get bent, so why do I hurt?  Everyone agreed he had a skin bends, indicative of a high decompression stress that could (and later did) result in worse symptoms.  All his profiles and steps he took during the dive were within the expected terms of good risk management = he did “nothing wrong”. Decompression Stress (sickness) is not a crime! Anyone can get it and for no particular reason.

So, what can we gleam from his case.  One obvious feature that jumps out is that, while he is in excellent cardiovascular shape, he weighs in excess of 300 pounds. Usually, a person that large is in poor cardiovascular shape, thus reducing his body’s ability to off gas. His sheer size may be a factor.  He is diving a rebreather, which normally improves decompression stress because he can breathe much higher concentrations of oxygen, which reduces the inert gas in the body faster. But he might be asking the rebreather to run a lower concentration of oxygen causing the problem.  Rebreathers are awesome mix-masters that let the user dial in their optimal blend, when treated correctly.

Or it may be how he is diving that has created his challenge. He loves to take people out on open circuit diving in Hawaii. They go off the beach and have a great time. The water is always warm, and usually clear. But there is nearly always surf that the diver must penetrate to get out to and from the dive sites.  He often gets tumbled in the surf zone, which at the beginning of the dive is no problem physiologically speaking. Throughout the dive his body is concentrating nitrogen, a gas it does not use, and must off gas at the end when he returns to the surface.  In this case, as he is crossing the reef and tumbling through the surf, again! The now supersaturated gas in his blood system gets agitated, and can come out of solution forming bubbles that cause the skin rash that he experienced, even though he followed the dive tables to the letter.

He is frustrated because when he guides people, he must keep up with them to help them out of the water to minimize their injury from the surf.  In doing that, he stresses himself beyond what he might otherwise do at the end of a long day. We rebreather divers are a lazy crowd that appreciates a slow exit from the water. And surf never is so accommodating. My advice has been to either dive with open circuit limiting his capabilities, or dive his rebreather much more conservatively.

You can get Bent and for no apparent reason, so dive conservatively and don’t get caught out. There are Bold divers and there are Old divers, but there are no OLD BOLD divers.