Need Help with Article on Getting Bent

[boulderjohn]

If you can't, don't or won't figure it out, you're bound to repeat it. If it were me, I would be checking myself for a PFO, and if that was negative, I would never go into deco again.

Is it? John indicated that he did 3 times the deco that was required. That's a lot of padding, n'est pas? He hasn't indicated that he was inordinately cold, tired, sick, hungover and so on, and knowing how thorough John is, I doubt that any of these other vectors existed.

As I said earlier, for unrelated reasons I have had the test used to detect PFOs. In fact, I have had it twice. I don't have a PFO. I have done a ton of decompression dives over the years without a hint of a problem. If I have a regular physiological problem that caused it, it should have reared its ugly head long ago. I was in fine health for those dives, and they were really wonderful dives, among the most enjoyable recreational dives I have done in a long time.

I haven't got a clue what I would do differently in the future.

 

[Dominik_E]

I do not read out of his postings that John did 3 times the deco his plan would have mandated? I thought the "three times" part of the comment was in response to the Chatterton quote, to say that there is an amount that is surely enough, but there is also a grey area?
Anyhow, as said, he also posted that he does not have a PFO, so this can not be the cause.

I think there are basically two points where I personally have a different view:

1.: Why search for a PFO and not for a ton of other physiological reasons that may have been at play on this day? It just puzzles me to single out the one thing that is getting the most publicity in the diving community, and which one third of all humans have, so there will in one's individual case never be a strong proof that it was even causal (even if it was present).

2.: I understand the strong will to find a reason behind all accidents. And often this can be done and will prevent future accidents. But I think that at some point we have to accept that there are processes at play (bubble formation) that start from tiniest scales. It is a bit like having a humid and hot afternoon. Clouds are forming. Why did the first lightning bolt strike this one tree and not the one next to it? Why would one assume that if a rate of 1 hit in 10 000 dives is "built into" the models we always have to be part of the 9999?

Of course just idle thoughts...

 

[stuartv]

If you can't, don't or won't figure it out, you're bound to repeat it. If it were me, I would be checking myself for a PFO, and if that was negative, I would never go into deco again. If I still got bent, I would restrict myself to free diving. There's nothing down there worth getting hurt over.

This seems a bit hyperbolic, to me. It implies that "bent is bent" and any bend is so bad that it merits stopping diving if you can't prevent it from happening again.

If John's incident were identical in all regards except that his DCS hit was solely in the form of very mild skin bends, would you be saying the same thing? You would quit diving to avoid ever getting a slight, mild rash again?

If what you really meant is that you would quit diving if the DCS hit were particularly bad, well, that wasn't very clear to me. Particularly since John has not given a lot of details (that I recall, anyway) about exactly what his symptoms and treatment were.

At the end of the day, one data point does not a dataset make. DCS is FAR from as straightforward as a car that is overheating. Car engine thermal management is a pretty dang well-understood field. It is reasonable to assert that overheating has a cause that can be identified and fixed. Deco theory and the physiology of DCS is not completely understood at all.

Having one problem with a car and making concrete decisions based on that can be entirely reasonable. Having one DCS hit and making concrete decisions based on that does not seem reasonable at all. When it comes to DCS, we don't know everything and we probably don't even know all the things that we don't know.

One negative outcome among many, many positive outcomes does not seem like a good reason to quit, even if it can't be explained.

 

[stuartv]

Of course.

Question: How do you know you have had enough? If you triple the deco your computer computer said to do, then, sure, you didn't do enough deco. But how do you know before the symptoms set in?

I know I'm not telling you anything when I say that our understanding is incomplete, so we CAN'T (yet, anyway) really KNOW when we've done enough deco.

My takeaway from the Chatterton quote is simply that, when we dive, we should be generous to ourselves with our time spent doing deco. As you were, and you took a hit anyway!

Rather than "I've done this same profile 100 times. My computer says I'm good. I'm getting out" we should remind ourselves, "I've done this same profile 100 times. My computer says I'm good. But, you never really know, so I'm going to hang here a while longer, just because I can."

You did that. You got bent anyway. That sucks. Hopefully, what happened to you will at least serve as a good example to me and others for why we should "be generous to yourself with your deco time." Because you never really know for sure. You might only lower your risk of a hit from 0.2% to 0.1% - but you still cut your chances in half!

 

[boulderjohn]

I do not read out of his postings that John did 3 times the deco his plan would have mandated? I thought the "three times" part of the comment was in response to the Chatterton quote, to say that there is an amount that is surely enough, but there is also a grey area?

That comment echoed my earlier description in which I did say that I had done triple the required deco time. I was supposed to do a whopping 2 minutes of deco. I did that on oxygen and then did another minute on oxygen. I then switched back to my nitrox back gas (so I could stow the O2 rig and made it easier to get back on the boat) and did a slow and leisurely swim from the ascent line to the back of the boat before ascending near the ladder. On both dives I did a total of four minutes of deco after the two minutes that were required. That means I did triple the deco time.

Once on the surface, I continued to breathe nitrox while I handed my deco bottle up to the DM, removed my fins, draped them over my wrists, climbed the ladder, walked to my seat, and settled in. that means I had an additional couple of minutes on nitrox on the surface.

 

[Dominik_E]

OK, I mis-read then, sorry for this. However, 6 minutes versus 2 minutes is mathematically a factor three, sure. But the difference of 4 minutes may easily be within any margin of error in any model, no?

 

[JonG1]

Mild rash and skin bends are what I first experienced back in the mid 90s, my last experience was a helicopter ride to the nearest chamber when I couldn't see properly.

Soon after that a PFO was diagnosed.

I'd sooner have a mild pain only hit to nudge me in the right direction from a DCS management perspective than a skin bend as they seem to be more symptomatic of more serious issues.

 

[The Chairman]

Why search for a PFO and not for a ton of other physiological reasons that may have been at play on this day?

I would be going after any and everything that might be a cause.

John knows John. Pete knows Pete. Each of us, Dominik included, must react to their specific situation. I told you how I would react to me getting bent. However, since I've never ever been bent, I have no reason to research other venues. Until I figured it out, or had a reasonable belief that I might have figured it out, I wouldn't dive. There's nothing, and I mean absolutely nothing down there worth getting bent over. Know your limits. Dive your limits. If you're getting hurt, modify those limits so you can stay safe. You and only you can make the decision for you to dive. Staying safe and having fun is your responsibility.

 

[Dominik_E]

The Chairman, to that I wholeheartedly agree!

 

[bakodiver391]

I would be going after any and everything that might be a cause.

John knows John. Pete knows Pete. Each of us, Dominik included, must react to their specific situation. I told you how I would react to me getting bent. However, since I've never ever been bent, I have no reason to research other venues. Until I figured it out, or had a reasonable belief that I might have figured it out, I wouldn't dive. There's nothing, and I mean absolutely nothing down there worth getting bent over. Know your limits. Dive your limits. If you're getting hurt, modify those limits so you can stay safe. You and only you can make the decision for you to dive. Staying safe and having fun is your responsibility.

From what I've observed, in most cases you're simply not going to get an explanation. Why someone gets bent on one dive and not another is, barring obvious mistakes, largely a matter of chance, at least among our client base, which includes some very experienced tech divers and more than a few hyperbaric physicians.
Everyone is free to do as they please, but I would concentrate on having a plan in place to deal with DCS when it happens, not avoid risk altogether.