Unknown Woody From “Dive Talk” DCS and Medical Journey

[L13]

The GF only goes above 0% when the tissue pressure exceeds ambient pressure. Off-gassing starts when the tissue compartment pressure exceeds the inert gas equilibrium pressure. If you see this section of the strip here, he was starting to off-gass the fast issues.

It's just a theory... the reality is some times we get bent and we don't have a good explanation fro it.

You start off gassing as soon as tissue inert pressure exceeds inert gas pressure in the inspired gas (well below GF=0%), but bubbles can not form until tissue inert gas pressure exceeds total inspired gas pressure (GF=0%). This is well known Physics/Chemistry, Bubbles/DCS can not occur if tissue inert pressure is < than total pressure.

So, in this situation. the cause of his headaches at 70 ft was not DCS. he was not bent at this point. Given the doctors diagnosis and his response to re-compression, he did get bent latter in the ascent, or after surfacing. However, it is not unreasonable to suspect that the cause of the headache at 70 fee may have also contributed to his becoming bent latter.

Not every dive related symptom is DCS/bent.

 

[grantctobin]

So let's assume their training was spot on.

Assumptions like this are what make accident analysis hard, no?

 

[billgraham]

Assumptions like this are what make accident analysis hard, no?

Sure, let's hear about it then.

 

[Ted Judah]

Do you believe he started the dive "expecting" to get bent?

Were the mistakes obvious at the time?


So, if we assume the answer to those questions is no. We shouldn't apply hindsight bias to the event. We need to ask why it made sense for them to behave in the way they behaved at the time and what we can do to prevent that in the future.

I think there are some interesting questions to ask:

• When he first started feeling a "headache" around 70ft did he think that was a possible sign of DCS?
  • Did he consider slowing, returning to a deeper depth, or extending his deco there?
• Why didn't he increase his "setpoint" on deco from 1.2 to something higher?
  • Did the "CNS Clock" lead to him deciding to run less efficient decompression to stay below the "limit"
• Did they have a plan in place to handle diving emergencies?
  • If so, did they follow it? If not, why not?
  • Does Bahamas Underground have a plan for handling diving emergencies?
• Why didn't they immediately start evacuation?
  • Did they think it was something other than DCS?
  • Did they think it wasn't severe enough to warrant evacuation at the time?
  • Did Brian's background and experience as a Navy diver shape his decisions?
• Was Woody conciously aware that he was dehydrated prior to starting the dive?

I think you are spot on. We need to put more emphasis examining the human factors that shape the decisions that are made.

 

[Nick_Radov]

During my first couple years of diving, there were numerous instances where I surfaced, had a headache, was tired, moving slowly, and not the best conversation partner. When put that way, it sounds quite bad, but was probably mild dehydration and frequent depth-changes. I've since gotten much better about being well hydrated, taking vitamins and electrolytes, avoiding frequent or unnecessary depth-changes, and taking a slow pace. I also remember my Open Water instructor telling us how it was relatively normal to want to take a nap after a couple dives.

Mild hypothermia will also do that to you. It creeps up on you, and even if you aren't shivering the decrease in core body temperature will make you tired and slow.

Not sure what you mean about frequent depth changes. It's fine as long as you equalize properly and don't struggle with buoyancy control.

 

[SlugLife]

Mild hypothermia will also do that to you. It creeps up on you, and even if you aren't shivering the decrease in core body temperature will make you tired and slow.

Not sure what you mean about frequent depth changes. It's fine as long as you equalize properly and don't struggle with buoyancy control.

I'll keep an eye on potential hypothermia as a cause.

By frequent depth changes, I'm talking about a zig-zag pattern along a shore-line going up and down between 10ft to 30ft deep, along with surfacing multiple times to check bearing and nearby surroundings. At that depth, the relative pressure changes are more significant.

Instead, these days I might make a more "oval" pass, first hitting 20-30ft, and then 10-20ft on the way back. If surfacing mid-dive, I really take my time, and avoid doing that too frequently.

Since making changes and avoiding doing that, it appears to have made a significant difference and greatly reduced how frequently I feel bad. The few times I've broken my "rule" since then, I tend to feel bad again. It's of course possible I am misreading the situation or drawing the wrong correlation/causation conclusion.

 

[billgraham]

Mild hypothermia will also do that to you. It creeps up on you, and even if you aren't shivering the decrease in core body temperature will make you tired and slow.

Not sure what you mean about frequent depth changes. It's fine as long as you equalize properly and don't struggle with buoyancy control.

Cave diving often involves a lot of depth changes, and you don't have much choice about it because that's where the passage goes. There are places where you can ascend from 100 feet to 30 feet and back down again, you could possibly need to do decompression in the middle of the dive.

 

[crofrog]

bubbles can not form until tissue inert gas pressure exceeds total inspired gas pressure (GF=0%). This is well known Physics/Chemistry, Bubbles/DCS can not occur if tissue inert pressure is < than total pressure.

Based on my understanding this is not a true statement.

Stable bubble nuclei are likely always present, and bubbles can form under isobaric conditions or in any situation where there is a supersaturation of the dissolved gas.

 

[inquis]

or in any situation where there is a supersaturation of the dissolved gas.

Can you define your understanding of "supersaturation"?

 

[Six Feet Under]

It also shows how even something like a YouTube channel, where they talk about dive-safety, accidents, and incidents all the time ... even they can have their own incidents. And as much as I focus on safety myself, I know I'm not immune either.

I had a friend do a "same cave, same day" dive to 186 feet during my AN/DP class while my instructor and I were gearing up for our last dive of the class. He's been an RN for years and has done critical care transport literally all over the world (Greece, Italy, Australia, the US, South Africa, Brazil, etc). Been a full cave, CCR, trimix diver for at least 10 years now.

He got a severe type 2 hit (nausea, fell down while urinating and couldn't get up or use his arms, vomiting, headaches, tinnitus, altered mental status, etc) and even HE refused to go until almost 2am when his wife basically told him he was either going to let her change him and go to the ER or she was gonna call the ambulance and let them make him go. Took about 18 hours to arrange chamber care (not through DAN, Tampa to Orlando ambulance ride) and he was discharged the next evening. During that 18 hours he was on O2 and IV hydration most of the time.

Was a very close-to-home example of just how "dumb" someone can be when they're in medical crisis, regardless of their knowledge.