In Water Recompression

[BenjaminF]

@Kevrumbo , if diving in the tropics, maybe also find a sandy lagoon without Bobbit-worms hiding in the sand?

 

[100days-a-year]

Kevrumbo,I am talking of actual empirical evidence from several dozen divers over 50 years plus of commercial diving.Most of the divers are well over 10,000 dives.I am considered a junior with 8000+.They have been doing this for a long time.
They were using nitrox since the 70s and since tables and classes were largely unavailable other than second hand from Navy and commercial divers,they developed their own protocols.I remember bringing tanks to a shop in 88 with 200 psi 02 for deep and 500 psi for shallow dives.Most still dive EDGE or Skinny Dippers and end up with a lot of multi day multidive experience.
I understand you are trying to relate best practice,I am sharing my observations more as an example of our incomplete knowledge of what IWR really entails.

 

[Kevrumbo]

Kevrumbo,I am talking of actual empirical evidence from several dozen divers over 50 years plus of commercial diving.Most of the divers are well over 10,000 dives.I am considered a junior with 8000+.They have been doing this for a long time.
They were using nitrox since the 70s and since tables and classes were largely unavailable other than second hand from Navy and commercial divers,they developed their own protocols.I remember bringing tanks to a shop in 88 with 200 psi 02 for deep and 500 psi for shallow dives.Most still dive EDGE or Skinny Dippers and end up with a lot of multi day multidive experience.
I understand you are trying to relate best practice,I am sharing my observations more as an example of our incomplete knowledge of what IWR really entails.

@100days-a-year , @Akimbo , @Duke Dive Medicine , @thin_air :

Look -->We really don't have anything more objective than Pyle/Youngblood's and Carl Edmonds' original articles on IWR anecdotal case studies from the South Pacific Underwater Medical Society (SPUMS) Journal (IN-WATER RECOMPRESSION AS AN EMERGENCY FIELD TREATMENT OF DECOMPRESSION ILLNESS and Underwater Oxygen Treatment of Decompression Sickness: A Review ), and a UHMS IWR Workshop -all twenty years ago or older, so looking forward to David Doolette Ph.D's IWR presentation and @Dr Simon Mitchell 's attendance at the April TekDiveUSA conference, as well as updates on their own workshop/conference back in 2004: (Management of Mild or Marginal Decompression Illness in Remote Locations ).

The only informal anecdotal and empirical study since then that IMHO, I find somewhat "reassuring" has to do with CO2 retention, Oxygen Toxicity Seizure risks @ 1.3 to 1.6 bar ppO2, and what that may imply for anyone having to make the choice of O2 IWR Therapy (see article: Advanced Knowledge Series: Carbon Dioxide Retention | Dive Magazine )

 

[Akimbo]

Does anyone know what kind of studies that the US Navy did for their IWR-O2 procedures? See US Navy Diving Manual, Revision 7, Page 17-17, Acrobat Page 867.

17‑5.4.2.2 In-Water Recompression Using Oxygen. If 100 percent oxygen is available to the diver using an oxygen rebreather, an ORCA, or other device, the following inwater recompression procedure should be used instead of Air Treatment Table 1A:

• Put the stricken diver on the UBA and have the diver purge the apparatus at
  least three times with oxygen.
• Descend to a depth of 30 feet with a standby diver.
• Remain at 30 feet, at rest, for 60 minutes for Type I symptoms and 90 minutes for Type II symptoms. Ascend to 20 feet even if symptoms are still present.
• Decompress to the surface by taking 60-minute stops at 20 feet and 10 feet.
• After surfacing, continue breathing 100 percent oxygen for an additional 3 hours.
• If symptoms persist or recur on the surface, arrange for transport to a recompression facility regardless of the delay.

 

[100days-a-year]

Love the abstract from that first study, Kevrumbo.
"theoretical risks"
"overwhelming majority of cases in which the conition of DCI victims improved after attempted IWR"
It then goes on to infer it is lunacy to do it anyway?????

One of the reasons I have a love/hate relationship with PubMed is that too many studies seem to contradict themselves.It is nice to to have access to such a resource to call ******** when there are clearcut outcomes.

 

[Kevrumbo]

Love the abstract from that first study, Kevrumbo.
"theoretical risks"
"overwhelming majority of cases in which the conition of DCI victims improved after attempted IWR"
It then goes on to infer it is lunacy to do it anyway?????

One of the reasons I have a love/hate relationship with PubMed is that too many studies seem to contradict themselves.It is nice to to have access to such a resource to call ******** when there are clearcut outcomes.

Well @100days-a-year , @thin_air , @Akimbo , @Duke Dive Medicine -I think the best historical resource to reference for now is the UHMS In-Water Recompression Workshop (1998), with more relatable practical issues and an interesting Pros & Cons and famous Who's Who panel discussion of administering O2 IWR Therapy. Interestingly, this conference did not produce a consensus for a prescribed O2 IWR regimen at that time. . .

Does anyone know what kind of studies that the US Navy did for their IWR-O2 procedures? See US Navy Diving Manual, Revision 7, Page 17-17, Acrobat Page 867.

17‑5.4.2.2 In-Water Recompression Using Oxygen. If 100 percent oxygen is available to the diver using an oxygen rebreather, an ORCA, or other device, the following inwater recompression procedure should be used instead of Air Treatment Table 1A:

• Put the stricken diver on the UBA and have the diver purge the apparatus at
  least three times with oxygen.
• Descend to a depth of 30 feet with a standby diver.
• Remain at 30 feet, at rest, for 60 minutes for Type I symptoms and 90 minutes for Type II symptoms. Ascend to 20 feet even if symptoms are still present.
• Decompress to the surface by taking 60-minute stops at 20 feet and 10 feet.
• After surfacing, continue breathing 100 percent oxygen for an additional 3 hours.
• If symptoms persist or recur on the surface, arrange for transport to a recompression facility regardless of the delay.

The only historical mention I found was on p.6 of the UHMS workshop link above, was that the US Navy incorporated their own modification of IWR some 15 years after the Royal Australian Navy developed it:

This [Australian O2 IWR Method] was developed in the late 1960's at the RAN, and by 1970 was employed through many parts of the Indo-Pacific16 - where chambers were not readily available. The origin of this treatment is not in dispute, as no one else was prepared to share the flack when the knowledge of it spread to the USA in 1973.

It was also reported at an international conference in France, in 1978. The UW 02 regime is still employed by many of the divers in remote areas, such as in the Pacific islands, the abalone fields of southern Australia, and the pearl fields of the Australian north. But local variations in technique have developed. . .

. . .The UW O2 treatment is now a part of many national diving manuals. It was included in the Royal Australian Navy manual as tables 81 and 82, but took 15 years and with some modifications, before it found its way into the US Navy Diving Manual.

 

[Michael Guerrero]

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.

 

[100days-a-year]

It's Winter.Wind is blowing.Can't dive.So talk about diving.

And we are hashing it out,just a bit of jumping about on different aspects you mentioned.And about as civilized a discussion on Decompression as one will find.

There will never be a real consensus,as it is "Decompression Theory" not "Decompression Immutable Law" and our experiences,needs and situations are different.But we can help validate/invalidate some theory by discussing our actual experience with or around IWR and possibly help the poor shmuck down the road who has to make the call whether to wait or try IWR on himself,a loved one,crew or a passenger.

Kev and DDM have pointed out well the need for better and more recent data.

 

[cathal]

Love the abstract from that first study, Kevrumbo.
"theoretical risks"
"overwhelming majority of cases in which the conition of DCI victims improved after attempted IWR"
It then goes on to infer it is lunacy to do it anyway?????

One of the reasons I have a love/hate relationship with PubMed is that too many studies seem to contradict themselves.It is nice to to have access to such a resource to call ******** when there are clearcut outcomes.

On this point of who to believe I would always go with the findings of the latest papers published on the topic.

 

[Michael Guerrero]

Does anyone know what kind of studies that the US Navy did for their IWR-O2 procedures?

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.