In Water Recompression

[Duke Dive Medicine]

I don't understand the back and forth. Is someone questioning the efficacy of IWR? I didn't think that was questionable. Safety, procedures, and consequently whether you're better off doing IWR vs. waiting for a ride to a chamber are valid topics of discussion and contextually dependent.

I don't think anyone has questioned its efficacy. There are some indirect indicators that it's not as effective as chamber treatment - some of the therapeutic effects of hyperbaric oxygen are not activated until inspired pO2 rises above accepted safe parameters for O2 breathing under water, but I'm not aware of any literature that directly compares the two.

Best regards,
DDM

 

[Michael Guerrero]

While I think that makes sense, it strikes me as something of an academic argument. The whole point, at least as I understand it, about doing IWR is that a chamber is unacceptably far from the dive site to render timely aid. So even if IWR is less effective, if it's your only choice then who really cares?

 

[Duke Dive Medicine]

Seems simple enough, right? ;-)

 

[Kevrumbo]

David Doolette might. I also wonder about various thermal conditions. Colder = slower offgassing, so I wonder if 60 min per stop accounts for that.

This is the procedure I have memorized in case it's needed--but need to start bringing more spare O2 with me.

On a gear note, I was glad to see OTS roll out the Spectrum FFM. You can use your own reg and it's compatible with comms equipment. This, combined with some quick connects, is part of my IWR kit.

You need a wetsuit or drysuit undergarment heater system as well.

Even in 80°F/27°C tropical waters, you will get chilled after more than an hour, which can also impact efficacy of the treatment. (Especially the last 135 minutes on the slow ascent to the surface from 9msw of the modified Australian O2 IWR method. It was nice to flip the switch and have heat on demand under my skinsuit. . .)

 

[Michael Guerrero]

That's one of those planning factors that is really important I think, depending on the profile and if you intend to do the entire course of treatment.

I tend to think of IWR as a spectrum of recompression. On the more benign end, you've done your schedule, approach the surface, and maybe feel some niggles. This may not merit an entire 3-hour treatment schedule. Maybe you just need to head back down and do another 15 or 30 min to clear it, with some surface O2 for good measure. On the other hand, maybe you start developing some clear, significant symptoms that merit a 3.5-hour recompression. That's a different beast entirely. And which one will it be on any particular dive is a difficult guess. Moderate dives (couple hours) have the potential to induce significant symptoms. So now that comfortable couple hour dive in warm water with a thin wetsuit and a couple deco bottles necessitates a drysuit, heater, lots of O2, a drop line, FFM, block, etc., and don't forget to stay hydrated, both pre-dive and during IWR.

Who doesn't like a challenge ?

 

[Kevrumbo]

While I think that makes sense, it strikes me as something of an academic argument. The whole point, at least as I understand it, about doing IWR is that a chamber is unacceptably far from the dive site to render timely aid. So even if IWR is less effective, if it's your only choice then who really cares?

I believe it's just as much a controversial medico-legal issue as well -which is why no hyperbaric physicians are responding to this thread as of yet, nor do I think there will be a consensus agreement -let alone a full endorsement- on use of O2 IWR by DAN or the UHMS Adjunctive Treatment Committee.

It will be IMO officially stipulated as elective and optional treatment AMA ("Against Medical Advice"), and signed off as such if a Hyperbaric Physician happens to be involved in a particular case -especially if the case goes bad (i.e. Oxygen Toxicity Seizures at depth)- given the decision to undergo O2 IWR by the patient or persons acting on behalf of the patient.

Otherwise if your team is isolated & alone, but prepared, trained and has the necessary proper equipment & Air/O2 gas supply to handle DCS -good luck & go for it.

 

[Kevrumbo]

. . .I've personally never seen a DCS case go to 165 feet, though some facilities use deeper tables and swear by them. The one time it happened at Duke (before my time) is still legendary there. The old protocol for gas embolism used to involve a 165 foot spike and the option is still there if the diver can be placed in the chamber immediately or doesn't respond to initial treatment at 60 feetc. . .

The Hyperbaric Treatment Center at the University of Hawaii, John A. Burns School of Medicine, as an option has deep table treatments, and "swear by them", and have data to back it up @Duke Dive Medicine:
http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/4054/16457085.pdf?sequence=1

The anecdotal history and experiences of Hawaiian Spear Fisherman and Black Coral Divers (as well as ichthyologist Richard Pyle ), have produced the deepest and most controversial IWR profiles currently attempted:

(See also discussions in IWR as Emergency Field Treatment in DCI and 1998 UHMS IWR Conference)

The only other protocol just as risky or more so than the above is Bret Gilliam's Oxygen IWR at 2.8ATA. . .