Teenager with DCS, mother in denial, treatment delayed

[boulderjohn]

a) every dive is a decompression dive.

By strict definition of the term, that is true, but as we really use the term, it is not true.

With the tremendous assistance of Dr. Simon Mitchell, I wrote this article on the then latest thinking on ascent profiles for decompression dives. (Not much, if anything, has changed.) When I was done, I was stoked to do the same thing for NDL diving, and I asked Simon if he would help as he had for the decompression diving. He politely refused, saying there was not much of any good research on different approaches, and he frankly did not have an opinion. Undaunted, I did my own research, and when I was done, I concluded that there is not much of any good research on different approaches, and I frankly do not have an opinion.

But I did conclude strongly that there really is a significant difference between dives where we have incurred required decompression stops and true NDL dives, with kind of a fuzzy no man's land in between (the realm of required optional safety stops).

This explanation will be overly simple. When you have required decompression and take longer than the optimal amount of time to ascend from depth, you incur a penalty that you must pay in added decompression time. With an NDL dive, if you begin your ascent within NDLs, you can take your sweet time heading up, taking as long as you want as long as you don't violate NDLs. You should still be able to go directly to the surface, although a safety stop is recommended to be on the safe side.

If I do a 90 foot dive using EANx 32, the NDL on the PADI tables is 35 minutes. If I start my ascent at, say, 32 minutes and then stop at, say, 75 feet for a while, and then maybe go to 60 feet, etc. I could easily end up with an 80 minute dive, and it should still be OK for me to go straight to the surface. (I pulled those numbers off the top of my head, but they are reasonable.)

 

[SlugLife]

That's what you get for shelling out all those bucks on a computer with a shiny oled screen: now you have to worry that others can see it.

"The first rule of solo-diving is you do not talk about solo-diving."

Many "rules" of diving are a simplified version of skills, experience, or equipment students don't currently have. I'm no expert in the area discussed, but if you know what you're doing and/or aware of any risks involved, it's not really anyone else's business.

 

[Belzelbub]

Does anyone have an update on how he is doing now?

Nothing real current. Last update I saw was in mid May. Motor skills improving, can walk slowly without a walker. Neuro & sensory functions still slower than before. He drove the boat in mid May, and was able to prepare the fish for the ever so important tacos.

 

[Belzelbub]

.

 

[Marie13]

I saw a post from the mother in late May lamenting that neither of her sons got to walk at graduation. Eldest was due to Covid and the DCS kid due to well, having issues walking.

But you know, tacos.

 

[Kay Dee]

But you know, tacos.

Lets all just hope they were really really great tacos then!

 

[Esprise Me]

If I do a 90 foot dive using EANx 32, the NDL on the PADI tables is 35 minutes. If I start my ascent at, say, 32 minutes and then stop at, say, 75 feet for a while, and then maybe go to 60 feet, etc. I could easily end up with an 80 minute dive, and it should still be OK for me to go straight to the surface. (I pulled those numbers off the top of my head, but they are reasonable.)

Interesting. I never gave this subject much thought because I used a computer from the beginning. But I've always been a little hazy on the concept of "bottom time" as opposed to dive time. Sure, on a square-ish profile like a wreck dive from a boat it seems clear enough; even if you drop to the sand and work your way up to the top of the wreck, your bottom time ends when you start up the anchor line. But most of my dives aren't like that--most of the time, there's stuff to see and linger over at least most of the way to the safety stop depth. My favorite local night dive is at Veteran's Park in Redondo Beach. We usually surface swim out to about the end of the pier (which still puts us in only about 20-30 feet of water), then follow the slope down into the canyon. Sometimes we go to the monument (60-65 ft); sometimes to the sailboat (80-90 ft), sometimes just out into the abyss (we stop at 130 but one can easily go deeper.) Twice when going to the sailboat, I've actually incurred one minute of deco while I was already on the way back to shore. And I was pretty far along on the way back, too; it wasn't as though I waited until my NDL counted all the way down before turning the dive. Both times, I began swimming straight back up the slope toward shore with at least 5 minutes remaining. But I've discovered that, if I don't want to come up off the bottom to where I can't even see it, and I don't want to go into deco, I need to turn the dive with more like 10 minutes NDL remaining. (Of course, both times the 1 minute of deco disappeared before I reached the stop depth, and by the time time I hit 30 feet I was back to 99 minutes NDL. The safety stop countdown begins at 20 feet, and even though I don't stop, the timer clears before I get to 15 feet.) So what the heck even is bottom time vs. ascent? And how do you properly account for it without a computer?

 

[boulderjohn]

So what the heck even is bottom time vs. ascent? And how do you properly account for it without a computer?

Bottom time as originally defined by table users started when you began the descent and ended when you began the direct ascent to the surface. It had to be that way, because that was the only way to read the tables. Multi-level diving, such as you describe, was a problem. Once you realize that, and when you realize that you are using a computer and not a table, then traditional "bottom time" becomes meaningless for a dive like that. If you are logging the dive, just put in total dive time.

 

[Bob DBF]

Oh, they have chambers.

They reserve them for scheduled hyperbaric medicine patients (wound care, etc.), and the chambers are staffed for that schedule. DCS patients screw that up.

There are chambers, and then there are chambers. There are hyperbaric chambers in our local hospital, however they are soft sided, and if they could take 10# (about 20') I would be surprised. Great for wound care, but couldn't do a table 5 on a bet.

 

[Akimbo]

There are hyperbaric chambers in our local hospital, however they are soft sided, and if they could take 10# (about 20') I would be surprised.

I have not seen soft-sided chambers in HBOT (HyperBaric Oxygen Treatment) centers. Most that I have seen are rigid one-person "torpedos" that are limited to 2 ATA or less.

Most either have acrylic tubular hulls or have very large view ports to reduce claustrophobia and allow the operator to observe the patient for OxTox Symptoms. AFAIK, soft-sided chambers are primarily used for air-evac and very remote operations.

You are quite correct that the vast majority of these chambers are less than ideal for DCS treatment, bordering on inappropriate. Multi-place chambers are important to allow for an inside tender since DCS patients may not be conscious and to do neuro exams at treatment depth. In addition, DCS treatment chambers should have a minimum operating depth of 165'/50M.