DCS hit 4 days later

[Larry7895]

I know little technically about DCS, but in terms of other issues to investigate, I suffered virtually the exact same symptoms following a 20 hour flight. Turns out dragging my carry on luggage had aggravated a degenerative neck condition (that I was previously unaware of) that impinged on a nerve and somehow the flight set it off. Took a month of physiotherapy to sort it out. Oh by the way, I'm pretty sure it wasn't DCS.......as I hadn't been diving


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[boulderjohn]

I'm afraid the reference is a personal communication. A friend took a hit, called DAN, and they told him that. It was some years ago and I do not remember any details. Burt may have been doing deco dives (he did that a lot), I don't remember, but at the time the issue was he did a pre-flight surface interval of 24h, flew to Denver for work (it was not his usual flight home), and called DAN after the pain began. They told him he should have spent 48h pre-flight because of flying to altitude, not flying to sea level.

So they have decided that this critical piece of safety information should be kept as a closely guarded secret. Interesting policy.

Here is one reference that recommends 48 hours before going to elevation.

http://www.imca-int.com/media/72854/dmac07.pdf

That was published in 2001, before the published results of the DAN study. To my knowledge, no actual research had been done before that. The reference to 48 hours is after saturation diving, more than 4 hours under pressure.

---------- Post added January 18th, 2014 at 10:18 AM ----------

One more thought.

Colorado has among the highest percentage of divers per capita in the nation. We have very little local diving of any quality, so almost all of them do all their diving in other countries. That means many thousands of divers are flying back to altitude within that 48 hour window every year. I think it would be very strange that DAN would not issue a public warning on that one.

 

[Akimbo]

…However, I have long held the view that heavy repetitive diving of the type people do on a liveaboard creates risks that are not adequately covered by existing decompression theory, particularly with divers who don't have a history of heavy diving...

I couldn’t agree more <bracketed comment added for context>. Quoted from another interesting DCS incident discussion.

http://www.scubaboard.com/forums/ask-dr-decompression/467632-dcs-treatment.html

…
Agreed, 2 hour surface intervals are pretty rare <on liveaboards>. To make matters worse, there isn’t all that much quantitative data on repeds… yet. The world’s Navies (the source for most historic data) really didn’t do that many repeds deeper than about 40'. When they did, they would rotate through the entire dive team before a sailor’s turn was up again. I would guess that typical surface intervals deeper than 40' probably was 4-6 hours.

DAN is collecting a lot of data from recreational computers now, but I don’t believe it has been going on long enough to really affect computer algorithms on repeds much. Aside from repeds; age, physical conditioning, meandering dive profiles, and gender are variables that distances “typical” recreational Scuba divers farther from the data collected from Navies that influenced dive algorithms. I am not suggesting the gender is a negative or a positive… we just don’t know for conclusively.

By meandering profiles I mean that military working dive profiles are usually spend all at the max depth (a square profile) where recreational divers typically vary their depth a lot. This probably generally works in our favor but the effects on 1-4 repeds a day might surprise us one day. I think that most hyperbaric physiologists recommend that dives start near the maximum depth for the dive and gradually work shallower rather than the reverse...