My personal experience getting bent...

[fsardone]

Wow, amazing story and glad that you seem to be doing great! Thanks for sharing this...

A newbie question: You showed the profiles for your dives, and I understand that the red area was your deco ceiling, right? And so the theory is that you shouldn't ascend into that area, but the closer you get, the faster you off-gas. So, in your profiles, you ascend right up to that depth and do a long stop there. But here's my question: there's that quote about deco theory being drawing a bright line through a field of gray; you extended your stop for extra safety, but would it be safe to do your stops further below the deco ceiling, to have some extra margin of error? You'd have to decompress longer, but you wouldn't ever get quite as close to the ceiling. (Sorry if this is a dumb question. I have zero training in decompression, but was just curious...)

Hi Seymour,
in my quest for knowledge I always been told there is no such a thing as a dumb question but only dumb answers ... with this I will try not to make a fool of myself and answer concisely to a question requiring a book to be answered.

What you have stated would be entirely correct if it was possible to exacly determine a ceiling. In fact the ceiling is calculated by imposing the maximum inert gas overpressure in the most critical tissue. This would require to 'know' exactly how much gas there is in each tissue and to exactly know how much overpressure each tissue can bear before becoming symptomatic. This is not the case the best we have few tissues and a guesstimate based on a bunch of hypotesis (situation is not too bad but many 'undeserved' DCS cases are reported: people that dove by the book and got bent anyway)

So we (tech/deco divers) try not to skim too close to what we assess being the ceiling introducing conservativisms (such as gradint factors or different ongas offgas speeds) which will keep us longer and lower in decompression. Unless, of course, we need to get out of the water quickly: if you are bent you can get a tour in the pot, if you drown well, that is kind of a permanent status once achieved :angel2:

Also understanding this concept will also help understand why oxigen enriched decompression helps: the bubble formation is affected by the pressure differential between ambient pressure and tissue dissolved gas pressure but desaturation speed is affected by the inert partial pressure in the breathed mix versus tissues dissolved gas pressure. Enriching the mix with oxygen will allow to decompress deeper without slowing down desaturation. In fact decompressing at 6 meters in 100% keeps inert partial pressure at 0 and ambient pressure at 1.6 bar .... and it is the reason why a rebreather diver can spend the surface interval at 10 meters and desaturate faster than his oc buddies can on the boat

Hope it helps rather then confuse!

Fabio

 

[victorzamora]

Wow, amazing story and glad that you seem to be doing great! Thanks for sharing this...

A newbie question: You showed the profiles for your dives, and I understand that the red area was your deco ceiling, right? And so the theory is that you shouldn't ascend into that area, but the closer you get, the faster you off-gas. So, in your profiles, you ascend right up to that depth and do a long stop there. But here's my question: there's that quote about deco theory being drawing a bright line through a field of gray; you extended your stop for extra safety, but would it be safe to do your stops further below the deco ceiling, to have some extra margin of error? You'd have to decompress longer, but you wouldn't ever get quite as close to the ceiling. (Sorry if this is a dumb question. I have zero training in decompression, but was just curious...)

Message me for more detailsif you'd like, but to not derail the thread I'll simplify that the deco ceiling he showed is only theoretical. Not only that, it's already including a safety factor he selected. Different algorithms have different ways of doing this. Gradient factors are one such way. However, the important thing to understand about deco is how flawed our current methods really are.

Deco theory was described to me as measuring with calipers, marking with chalk, and cutting with an axe. Computers use incredibly precise calculations using very precise instruments to make very precise mathematical determinations of our deco obligations.....but that is no guarantee of accuracy. Divers get bent on the far conservative end of the theories and other divers perform tons of dives at the more aggressive end.

The two sources I recommend if you're curious are "Deco for Divers" by Mark Powell (well worth the price) and the explanation of Gradient Factors on Dive Rite's site. Whether you dive Buhlmann GF or not, it's good theory to know.

 

[kensuf]

Hi John,

Been there, done that. I took a pretty nasty type 2 hit after a 120 minute bottom time in Indian Springs outside of Tallahassee (max depth 150, average 130) 18 months ago. About a month later I was diagnosed with a small PFO.

I had it closed with an Amplatzer Septal Occluder in September 2014 and I was cleared to dive six weeks later. My resumption to diving started by teaching a full cave class that began on Halloween 2014.

Since having the bionic heart installed, and being cleared to dive almost exactly one year ago, I've done almost 300 dives including over 150 decompression dives, and dives to depths of 290'. Three weeks ago I did a 180 minute bottom time at an average depth of 140' (390 minute run-time), this weekend I'm planning on a 150 minute bottom time at an average depth of a 150' (anticipated 300-330 minute run-time). I have had ZERO niggles since the closure.

Prior to the closure, I used to get a case of skin bends every couple of months, and considered that normal.

Let me restate, I've had ZERO niggles. No skin bends. Nothing.

Now I feel pretty damned good after diving. I even went for a run Monday night after wrapping up a full cave course that I had been teaching (8 deco dives over 4 days).

Best of luck to you,

Ken
ps - if you've got any questions about the post-procedural return to diving, recovery (bruising, omg), please feel free to PM me.

 

[KevinNM]

I wonder how much of our deco theory is confused by the test divers containing an unknown mix of divers with a PFO and those without?

 

[WetRocks]

Great presentation, thanks for sharing.

I had the Amplatzer placed by Dr Ebersole in September...procedure was a piece of cake.

I had it closed with an Amplatzer Septal Occluder in September 2014 and I was cleared to dive six weeks later.

Six weeks huh? I was told 12. Hrmm...'bout time to call my doctor and ask for a reprieve!

 

[Superlyte27]

Interesting story. I got bent at Hart Springs a few years ago. You spent some wasted time going to Lake City. The closest chamber to cave country is Tallahassee. Jacksonville is often not staffed. The local EMS would have you choppered directly to a DAN chamber.


Sent from my iPhone using Tapatalk

Actually, the closest chamber to Ginnie is Orlando. It's just under two hours away. Ask me how I know

 

[JohnnyH]

Wow, amazing story and glad that you seem to be doing great! Thanks for sharing this...

A newbie question: You showed the profiles for your dives, and I understand that the red area was your deco ceiling, right? And so the theory is that you shouldn't ascend into that area, but the closer you get, the faster you off-gas. So, in your profiles, you ascend right up to that depth and do a long stop there. But here's my question: there's that quote about deco theory being drawing a bright line through a field of gray; you extended your stop for extra safety, but would it be safe to do your stops further below the deco ceiling, to have some extra margin of error? You'd have to decompress longer, but you wouldn't ever get quite as close to the ceiling. (Sorry if this is a dumb question. I have zero training in decompression, but was just curious...)

What I may add to the responses already provided by others is this. During deco your goal is to take your tissues into supersaturation by reducing ambient pressure (i.e., ascending). You are playing a delicate dance between allowing tissues to supersaturate without allowing the dissolved gas to come out of solution and therefore form bubbles. If you don't allow your tissues to supersaturate (i.e., don't sufficiently reduce ambient pressure) then you either remain at equilibrium or even worse, you will continue to on gas.

Now, this is a huge over simplification, as there are many other factors involved, including the variability of gas mixture available to CCR divers. Plus the human body is very complex and all the various tissues on and off gasses differently. Current deco models typically break the body into 16 different types of tissues, and dynamically switch which tissue group is the "leading" group.

It's actually a pretty interesting subject, one that I try to educate all my divers on. One paper that's good to read and to try to fully understand is a discussion of gradient factors that's available on the DiveRite site (see below). Well worth a read - and a reread...

Gradient Factors

---------- Post added November 4th, 2015 at 06:55 PM ----------

Neither Talahassee or Orlando was taking a bent diver. I don't remember why, though it was July 4th and staffing was definitely in play. I was brought to Lake City just to stabilize me before transport to South Georgia. I was kind of a wreck.

 

[ZephyrNYC]

... After watching it, I'd be happy to answer any questions, as I feel theres some good information in there for us all...

https://www.youtube.com/watch?v=0t8djdervQw

John Hanzl
Author
john h hanzl (author) | official site

Good morning, John.

Happy 2016. Thank you for sharing your video and your experience for us to learn from it. And thank you for being strong enough to live through this. You are a lucky man. Please answer the following:

1. Was this the first time in your life that any symptoms of your PFO presented?

2. Aside from the ECG with bubble test or the presenting of symptoms, do you know of any other ways to test for a PFO? (I had an ECG done a few years ago, but without the bubble test. The doc had no reason to request a bubble test, I suppose.)

3. Do you know of other people with a PFO who didn't find out until later in life as well? If so, did any of them serve in the armed forces (US)?

4. It is now 2016. Have you gone diving yet?

5. Aside from the PFO, would you say that the next major factor leading to your DCS was dehydration?

Btw, I noticed a couple misspellings in the video: "optometrist" and "medevac" (MEDical EVACuation). I think that the way you spelled the latter is slowly becoming accepted, but I think it's another new Americanism or corrupted spelling lol.


Sincerely,
Frank

 

[frontiernurse]

Wow! I'm so glad you are OK! Great job presenting your story and the learning points in such a gripping way! I'm a big believer in learning through story-telling.

I am a PCP and a recreational diver (and I take HCTZ!) and I'm giddy with questions. But mostly just glad you are OK. I can totally see how the denial would happen.

- Would it have been safe for you to fly to Georgia for treatment rather than drive?

- Did they fill you up with IV fluids before putting you in the chamber? How did you hydrate in there? (Sippy cup?)

- HCTZ is a diuretic, but it is so super mild... I wonder if there is any medical literature about not using it in divers? Or anyone else who might be at risk for dehydration? We don't use it in people with low potassium, but we don't always consider lifestyle when prescribing, and lots of providers know nothing about diving in particular. I guess there are plenty of alternatives so why even take a chance (with pro divers), but I never even considered that as a risk factor and I take the drug myself! Although I only do like 30 dives a year (if I'm lucky).

And if I may share a story... I was in a very remote part of the south pacific on a trip and the staff approached me to look at a "rash" one of the guests had. At this place we only dove 2x/day at 10am and 2pm, and this day both dives were quite conservative. The "rash" was a weird marbled looking discoloration on her thighs. She also described feeling "weird" and having tingling fingers. Once she said "tingling fingers" we all looked at each other and ran for 02. There was no chamber for thousands of miles, and she felt totally better after a few hours on 02. Over the next few days she was fine. We were chasing after her with 02 for 2 days. No diving of course. We couldn't understand why she would get a (albeit very mild) hit until she remembered she had a PFO!

I hope your procedure went OK and thanks again for sharing this!

 

[Xaryo]

thanks a lot for the presentation of you incident.