In-Water Recompression, Revisited

[Duke Dive Medicine]

Hello all,

At Pete's behest, I am posting this here. You may have seen the article in the latest issue of an online diving magazine that advocated an in-water recompression profile similar to a U.S. Navy Treatment Table 5, i.e. the diver with decompression sickness is advised to descend to 60 feet and breathe 100% O2 from an open-circuit SCUBA regulator, then follow the O2/depth/time profile of a U.S. Navy Treatment Table 5. It is not my intent to publicly belittle a publication or an author so I will not name either.

I believe (and it is Duke Dive Medicine's position) that in-water recompression has its place. The pros and cons have been thoroughly discussed in other threads in this forum. However, the procedure and recompression profile advocated in the article place a diver at grave risk of serious injury or death and should not be attempted. Treatment Table 5 is designed for use in a hyperbaric chamber, not for in-water recompression. For a number of reasons, divers under water are at much higher risk of CNS oxygen toxicity than patients in a hyperbaric chamber, and a TT5 exposes divers to an inspired partial pressure of O2 of 2.82 ATA, far higher than the generally accepted safe immersed exposure limits of 1.3-1.6 ATA . The consequences of a seizure under water while breathing from an open-circuit regulator are obvious, and the article only mentions a full-face mask as a consideration, not a must.

For those interested, I've linked Rubicon Foundation's excellent summary on the subject, and also the SupSalv website where the U.S. Navy Diving Manual can be downloaded. In-water recompression is a reasonable part of a dive team's safety plan when that team is equipped to do so and is made up of individuals who are trained and experienced in decompression diving and treatment of diving injuries. It should never be undertaken without a thorough risk/benefit assessment by, and advice from, a knowledgeable medical professional.

In-water Recompression | Rubicon Foundation

Naval Sea Systems Command > Home > SUPSALV > 00C3 Diving > Diving Publications

Best regards,
DDM

 

[oya]

Excellent post.

IWR: Valuable tool.

IWR as recommended by that article: Godammed idiotic.

 

[northernone]

Exceptional post.

Thank you,
Cameron

 

[emoreira]

I've found the article that was referenced.

 

[CuzzA]

So @Duke Dive Medicine, I looked at the different tables a while back. I even started a thread on it about a year ago.

I came to the conclusion that if given enough gas and a support diver (perhaps a cheap full face mask too) that the Australian Table seemed like the safest table and simplest to execute for the above average/advanced diver. Any thoughts on the common table options?

 

[Duke Dive Medicine]

So @Duke Dive Medicine, I looked at the different tables a while back. I even started a thread on it about a year ago.

I came to the conclusion that if given enough gas and a support diver (perhaps a cheap full face mask too) that the Australian Table seemed like the safest table and simplest to execute for the above average/advanced diver. Any thoughts on the common table options?

I would avoid the ones with deep air stops for the same reason that they've fallen out of favor for surface treatment - high risk of additional on-gassing and bubble growth, plus gas supply and tender exposure issues, with the added complication that the diver may incur a decompression obligation and can't be surfaced immediately in the event of an emergency. Beyond that, I would probably trust the US Navy's the most since that's my own background but I'm sure there's bias there. They're roughly similar to the Australian tables; I don't know if enough data exist to state definitively which is safer or more effective.

Best regards,
DDM

 

[jseyfert3]

As a new diver who is still doesn't know a lot of what he doesn't know, it seems pretty telling that in the US Navy dive manual, rev 7, they don't recommend doing treatment table 5 for emergency in water recompression. In water recompression is not recommended unless you cannot reach a chamber within 12-24 hours. If it's the only option, they recommend air treatment table 1A (less preferable) or 100% O2 if available (preferable). If using 100% O2, the procedure is 30 feet for 60 minutes for type I or 90 minutes for type II symptoms, then ascend to 20 feet even if symptoms are still present, finishing with 1 hour stops at 20 and 10 feet, and 100% O2 on the surface for 3 hours. At this point if there are symptoms, they don't say to go back in the water but rather arrange for transport to a chamber regardless of the delay.

 

[CuzzA]

I would avoid the ones with deep air stops for the same reason that they've fallen out of favor for surface treatment - high risk of additional on-gassing and bubble growth, plus gas supply and tender exposure issues, with the added complication that the diver may incur a decompression obligation and can't be surfaced immediately in the event of an emergency. Beyond that, I would probably trust the US Navy's the most since that's my own background but I'm sure there's bias there. They're roughly similar to the Australian tables; I don't know if enough data exist to state definitively which is safer or more effective.

Best regards,
DDM

Thanks. It would be interesting to know. Simply because it appears the Australian table would require less gas, which of course is a concern for a non commercial/military diver at a remote site without the resources typically available to the commercial/military dive operation, but then I wonder if it would be as effective as the Navy table.

 

[DocVikingo]

For some additional lively discussion of this topic, see the comments section beneath the following Undercurrent blog > Bret Gilliam’s Protocol for In-Water Recompression at Remote Dive Sites | Gilliam

Cheers,

DocVikingo

 

[Kevrumbo]

The modified Australian IWR Method as taught by UTD has either 30, 60 or 90min choice of prescribed O2 breathing therapy at 9m/30ft depth (10min O2:with 5min Air Break); and then a very slow 0.1mpm/0.3fpm ascent to surface (same breathing 10minO2:with 5min Air Break).

So choosing 60 minutes of O2 time at 9m for example, you breath 10min on Oxygen, and then take a 5min break on Air for a total bottom time of 90 minutes (Air Breaks do not count or accrue credit into the O2 time at 9m), and on the slow 0.1mpm O2 breathing ascent you have to hold at every 1 meter of ascent for the 5min Air Break - a time-to-surface of 135 minutes. So the total treatment time would be 90min bottom plus 135min ascent equals 225 minutes. Can be done with an AL80/11L cylinder of Oxygen and another of Air on Open Circuit. . .

Modified Australian IWR has a lesser ppO2 exposure of 2.0 at a longer time & shallower depth of 30'/9m, while still squeezing/off-gassing pathogenic DCS bubbles to at least 80% of their original size; while Bret Gilliam's Navy Table 5 modification in the article has ppO2 of 2.8 at a shorter time but deeper 60'/18m depth and reducing bubble size to 70%. The risk of Oxygen toxicity is still there though in both IWR methods. . .

For those worried about Ox-Tox seizure potential in IWR might be feel somewhat better with this article:
End tidal CO2 in recreational rebreather divers on surfacing after decompression dives. - PubMed - NCBI

". . .We found no general tendency to CO2 retention during decompression. It is plausible that breaching oxygen exposure limits during resting decompression is less hazardous than equivalent breaches when exercising at deep depths. Mitchell SJ, Mesley P, Hannam JA. End tidal CO2 in recreational rebreather divers on surfacing after decompression dives."

So @Duke Dive Medicine, I looked at the different tables a while back. I even started a thread on it about a year ago.

I came to the conclusion that if given enough gas and a support diver (perhaps a cheap full face mask too) that the Australian Table seemed like the safest table and simplest to execute for the above average/advanced diver. Any thoughts on the common table options?

Thanks. It would be interesting to know. Simply because it appears the Australian table would require less gas, which of course is a concern for a non commercial/military diver at a remote site without the resources typically available to the commercial/military dive operation, but then I wonder if it would be as effective as the Navy table.

I had three separate type I DCS incidents experienced on Truk Lagoon Trips in Oct-Nov 2014 -all were upper Right arm/Shoulder classical acute "pulsing" symptoms with increasing pain within 90min time post-dive, and occurring within three to four days of starting Open Circuit Deep Air bottom mix dives with 50% & O2 deco (two tech deco dives per day with a 3 hour SIT). Possible contributing factors were dehydration, insufficient "acclimatization" to the tropical environment, and no prior "work-up" practice deco dives to sensitize the body's immune/inflammatory response system to high FN2 saturation & resultant residual bubbles in slow tissues & venous blood vessels (first early AM deep dive with deco of that trip was SF Maru at 51m ave depth, 45min BT and over two-and-a-half hours runtime, after long trans-pacific flight from Los Angeles arriving late in the night before).

All DCS type I Pain Symptoms at that time in Oct-Nov 2014 were resolved with In-Water-Recompression (IWR) sessions which were performed off the end of Truk Stop Hotel Pier. Lying prone & relaxed at 9m depth breathing standard open-circuit non-face mask regs, on a sandy bottom in 28 deg C water temp, the modified Australian Method IWR as taught by UTD was used -with either 30, 60 or 90min of elective prescribed O2 breathing therapy at 9m depth (10min O2:with 5min Air Break); and then slow 0.1m/min ascent to surface (same breathing 10minO2:with 5min Air Break). Went with 60 minutes O2 time at 9m as outlined above. . .