Oh Dear - You're "bent" and a long way from home.. IWR Anyone?

[keri.lewis]

Clare asked me to post this following a comment I made about undergoing In Water Re-compression (IWR). I'm not saying right/wrong and I am trying to illustrate issues in dive planning with the potential impact. Try as I might – I can think of no real ways to avoid this in planning – most deco planning would have come up with similar profiles (give or take a few minutes). I've put what I learned at the end of the post.

From Feedback - Apologies for the long post I wanted to be as informative as possible.

Background to my experience with IWR
I was on a liveaboard boat – more than 20 hrs direct steaming from the nearest land-based working chamber.
There was no air-evacuation where I was diving in international waters.
Everyone on the boat was diving in a very conservative manner (considering the depths/exposures)
We were all VERY conscious of hydration – air temp was 32 deg C water 28 deg C – you need to drink water all day to stay hydrated!
For those that don't know me – although a little plump (BMI 26) I do go to the gym 3-4 times a week and do 40 mins to 1hr of cardio plus some weights . I occasionally run half marathons and consider myself reasonably fit.
I drink moderately – and when diving is no more than 1 (or at most 2) can of beer a day. (don't you find it cleans out the taste of a regulator better than anything else?? )
I've done more than 150 Deco dives before the trip.

Profiles and exposures
I got my suspected “hit” on day 4 of the liveaboard. This was after the 8th dive. All dives were in the 50-55M range with bottom times of 35 minutes. With Water temperatures and conditions being almost ideal (20-30M viz light currents – scooters) – all divers were diving 21/35 as potential narcosis issues were quite light. Deco was planned on 50% and Surface supplied O2. Sufficient 50% was carried on all dives to surface on only this gas should it not be possible to make the surface supplied O2.

Deco Profiles were calculated on VPM-B with conservatism +2. This was compared to Ratio deco and the curves were manipulated to the following -

Bottom time at average depth 52M 35 mins

Slow ascent / deep stops
First Stop 33M
30 M 1 Min
27 M 1 Min
24 M 2 Mins

Switch to 50%
21M 5 Mins To allow gas circulation
18M 3 Mins
15M 3 Mins
12M 3 Mins
9M 6 Mins Total 50% Time 20 Mins

Switch to O2 – Managed with Standard CNS Break pattern 12/6 = 15 Mins

6M 20 Mins first dive (Pattern 12/6/5) 22 mins 2nd dive (Pattern 12/6/7)

Ascent to surface – 6 mins

Total O2 time 26 Mins first dive 28 mins 2nd dive

The planning gave dives with a RT of about 90 mins after faffing about with gas switches/backgas breaks etc.

It was felt that this gave a lot of padding to the standard VPM-B table because of the following factors.

• Extended Gas Switches - we tried to offload the helium at the early part of the decompression. This gave us N2 to manage at the top of the curve.
• Padding to the curve – whilst making it easy to remember..
• A long enough time on O2 – with a slow ascent to minimise the gradient change at the top of the ascent.

The dive in question..
It went without a hitch. We left the bottom on schedule, and made it to the upline comfortably. Everything was smooth on the ascent – gas switches were OK – Stage/deco bottle juggling was OK – no real issues. Everything in the happy place contemplating the dive completed.. as so many times before..

Symptoms as experienced
Everything was fine until I got to the bottom of the weights on the SS O2 bar at 9 M depth. We did the switch to back gas for the ascent and got to the 6M Bar to start O2. On the ascent to 6 I noticed a VERY slight nagging in my left wrist. I put it down to hanging on a deco line in current – possibly a niggle – we've all had them.

At 6 M it was just “there” slightly sore.. a little tingle here and there.. signs I guess. As I said I was sure it was from hanging on the rope. It wasn't painful. There was no loss of feeling or movement (you have a lot of time to figure these things out on a 20+ minute stop.. ) so it was "OK"..

On the final ascent it started to hurt and I figured I was “bent”. I thought “Damn” or words to that effect... I got to the surface – notified the skipper and we decided on getting me to depth while the action plan was figured out.

Action Plan
We had been the first team in the water. There were still divers in the water with >1 hr of runtime to go. So moving the boat wasn't an option.

I de-kitted my doubles and bottom stage – and got back into the water on 50% (side slung) at 9M (the bottom of the deco bar assembly) while arrangements were made. The last dive team waved-off their dive and I was accompanied to the line by one of the divers.

I was expecting to sit in the water for 30 mins or so while the chamber was prepared.. Unfortunately, and I didn't know this at first, the chamber on the boat was found to be missing the communications and breathing masks... much to the skipper's chagrin! They were back in storage – having being offloaded in error.

I was greeted by a communication on a page of wetnotes stating that the chamber was “unavailable” (Another euphemism).. and we'd do an IWR cycle as a precaution. I must say I was a little “apprehensive” (don't you just love PC language).. my drysuit was in danger of being soiled.. the communications diver had brought down a full-face mask to attach to the deco bar with the adjustable spanners to change from a reg..

All the while I had plenty of company... lots of concerned divers asking how I was.. and me responding with the universal signal for “bent”... for Brits reading this I felt an awful lot like Larry Grayson..

To top it all after 15 mins of faffing around getting set-up (breathing 50% at 9M) the symptoms had disappeared.. I was committed to the IWR cycle. After some initial difficulties putting on and clearing the full-face mask.. I am told it was funny to watch.. I settled into a pattern of

1hr O2 at 9M
1hr O2 at 6M
30 Minute Ascent

There were regular Backgas breaks provided off the doubles of the communications diver.

I must add my thanks to the last dive team (Ferg and Adrian) who shuttled down to me on a 40 minute cycle to keep me company as the afternoon passed.. the wetnotes included one classic where Ferg handed me a note saying...

“No Luke... I am your father!”


I must say it's a good job it was a full-face mask or I would have completely spit a reg! Clouds of bubble ensued..

I surfaced at sunset feeling fine.. and proceeded to “on-gas” some N2. I also added a little C2H5OH..for good measure!

Wash-up/Follow-up
I sat out the next day – looking for symptoms and feeling quite nervous.. everything was fine except for my temper. I was irritable as hell watching everyone else dive. We'd been planning the trip for 15 months and I was so frustrated watching everyone doing the dives.

So – and I'm not sure this shows good judgment – I dived on Day 6 and Day 7. Go on – tell me off – but you need to have been there!

We made a few adjustments to the profile..

We added 1 min to the 18/15/12/9 stops and we extended the O2 to two full cycles before the ascent (12/6/12/6).

I was fine for the dives and thoroughly enjoyed the last 2 days. I am fully recovered – and expect to dive more of the same again. I am in the middle of a full medical cycle Just-In-Case, but nobody expects to find anything..

Lessons Learned
Planning
We all know that you can be well inside the tables and still get a “hit”. I guess that the incident brought it home to me in living colour. We had several minutes of spare time built into the profile and I still got hurt.

Gas Choices
I think I'd like to do the dives on a little richer mixes – not because of narcosis, which is barely noticeable in those conditions – but to get more Helium for faster off gassing. I certainly would have a deeper mix in UK conditions!

“Listen to Your Body”
It doesn't matter how many times it is said – I guess you need to feel it to understand what the statement means. I think if I had a similar niggle – I'd stay at 9-12 M for a bit longer say an extra 5 mins. It saves a lot of time in the long run.

IWR Works – and is a fair emergency procedure
If you've got the gas supply and the full-face mask IWR is a workable procedure. I seemed to have good Ox-Tox tolerance that day – no symptoms during the IWR – and I know that's no guarantee for the future. I wouldn't want to try it on a standard regulator the risks are too high – I would want to head for the exit by the fastest means possible.

IWR is not a trivial procedure
I was lucky that the skipper on the boat is a trained decompression chamber operator (a nice little side skill to ask about on your next trip.. go on I dare you ask the skipper! ). His knowledge enabled us to try this procedure. Otherwise it would not have been an option as even though we were all experienced divers we didn't know enough.

READ the IWR Posts in RRR
Everyone trying remote diving NEEDS to know this stuff!
I would also ask all people reading to contribute to support Rubicon Foundation in their efforts to spread knowledge. It is essential that more knowledge is spread to help people avoid these sorts of problems. I was lucky in this situation - good back-up and a good team. I'm reasonably experienced but I was still lacking in knowledge.

Great Teams and Buddies Make Everything Possible!
Again I thank the guys that babysat me while I was in the water.
For the record – I paid a section of their gas bill for the trip – and an extra share of the O2 bill (shared as it was Surface Supplied) – as well as quite a few beers..
It's only a good team concept that allows us to do these things.. 1-up for the team!

[graham_hk]

Quote: (Originally Posted by keri.lewis)

Clare asked me to post this following a comment I made about undergoing In Water Re-compression (IWR). I'm not saying right/wrong and I am trying to illustrate issues in dive planning with the potential impact. Try as I might – I can think of no real ways to avoid this in planning – most deco planning would have come up with similar profiles (give or take a few minutes). I've put what I learned at the end of the post.


Background to my experience with IWR
I was on a liveaboard boat – more than 20 hrs direct steaming from the nearest land-based working chamber.
There was no air-evacuation where I was diving in international waters.
Everyone on the boat was diving in a very conservative manner (considering the depths/exposures)
We were all VERY conscious of hydration – air temp was 32 deg C water 28 deg C – you need to drink water all day to stay hydrated!
For those that don't know me – although a little plump (BMI 26) I do go to the gym 3-4 times a week and do 40 mins to 1hr of cardio plus some weights . I occasionally run half marathons and consider myself reasonably fit.
I drink moderately – and when diving is no more than 1 (or at most 2) can of beer a day. (don't you find it cleans out the taste of a regulator better than anything else?? )
I've done more than 150 Deco dives before the trip.


Profiles and exposures
I got my suspected “hit” on day 4 of the liveaboard. This was after the 8th dive. All dives were in the 50-55M range with bottom times of 35 minutes. With Water temperatures and conditions being almost ideal (20-30M viz light currents – scooters) – all divers were diving 21/35 as potential narcosis issues were quite light. Deco was planned on 50% and Surface supplied O2. Sufficient 50% was carried on all dives to surface on only this gas should it not be possible to make the surface supplied O2.


Deco Profiles were calculated on VPM-B with conservatism +2. This was compared to Ratio deco and the curves were manipulated to the following -


Bottom time at average depth 52M 35 mins


Slow ascent / deep stops
First Stop 33M
30 M 1 Min
27 M 1 Min
24 M 2 Mins


Switch to 50%
21M 5 Mins To allow gas circulation
18M 3 Mins
15M 3 Mins
12M 3 Mins
9M 6 Mins Total 50% Time 20 Mins


Switch to O2 – Managed with Standard CNS Break pattern 12/6 = 15 Mins


6M 20 Mins first dive (Pattern 12/6/5) 22 mins 2nd dive (Pattern 12/6/7)


Ascent to surface – 6 mins

Total O2 time 26 Mins first dive 28 mins 2nd dive


The planning gave dives with a RT of about 90 mins after faffing about with gas switches/backgas breaks etc.


It was felt that this gave a lot of padding to the standard VPM-B table because of the following factors.

• Extended Gas Switches - we tried to offload the helium at the early part of the decompression. This gave us N2 to manage at the top of the curve.
• Padding to the curve – whilst making it easy to remember..
• A long enough time on O2 – with a slow ascent to minimise the gradient change at the top of the ascent.

The dive in question..
It went without a hitch. We left the bottom on schedule, and made it to the upline comfortably. Everything was smooth on the ascent – gas switches were OK – Stage/deco bottle juggling was OK – no real issues. Everything in the happy place contemplating the dive completed.. as so many times before..


Symptoms as experienced
Everything was fine until I got to the bottom of the weights on the SS O2 bar at 9 M depth. We did the switch to back gas for the ascent and got to the 6M Bar to start O2. On the ascent to 6 I noticed a VERY slight nagging in my left wrist. I put it down to hanging on a deco line in current – possibly a niggle – we've all had them.


At 6 M it was just “there” slightly sore.. a little tingle here and there.. signs I guess. As I said I was sure it was from hanging on the rope. It wasn't painful. There was no loss of feeling or movement (you have a lot of time to figure these things out on a 20+ minute stop.. ) so it was "OK"..


On the final ascent it started to hurt and I figured I was “bent”. I thought “Damn” or words to that effect... I got to the surface – notified the skipper and we decided on getting me to depth while the action plan was figured out.


Action Plan
We had been the first team in the water. There were still divers in the water with >1 hr of runtime to go. So moving the boat wasn't an option.


I de-kitted my doubles and bottom stage – and got back into the water on 50% (side slung) at 9M (the bottom of the deco bar assembly) while arrangements were made. The last dive team waved-off their dive and I was accompanied to the line by one of the divers.


I was expecting to sit in the water for 30 mins or so while the chamber was prepared.. Unfortunately, and I didn't know this at first, the chamber on the boat was found to be missing the communications and breathing masks... much to the skipper's chagrin! They were back in storage – having being offloaded in error.


I was greeted by a communication on a page of wetnotes stating that the chamber was “unavailable” (Another euphemism).. and we'd do an IWR cycle as a precaution. I must say I was a little “apprehensive” (don't you just love PC language).. my drysuit was in danger of being soiled.. the communications diver had brought down a full-face mask to attach to the deco bar with the adjustable spanners to change from a reg..


All the while I had plenty of company... lots of concerned divers asking how I was.. and me responding with the universal signal for “bent”... for Brits reading this I felt an awful lot like Larry Grayson..


To top it all after 15 mins of faffing around getting set-up (breathing 50% at 9M) the symptoms had disappeared.. I was committed to the IWR cycle. After some initial difficulties putting on and clearing the full-face mask.. I am told it was funny to watch.. I settled into a pattern of


1hr O2 at 9M
1hr O2 at 6M
30 Minute Ascent


There were regular Backgas breaks provided off the doubles of the communications diver.


I must add my thanks to the last dive team (Ferg and Adrian) who shuttled down to me on a 40 minute cycle to keep me company as the afternoon passed.. the wetnotes included one classic where Ferg handed me a note saying...

“No Luke... I am your father!”



I must say it's a good job it was a full-face mask or I would have completely spit a reg! Clouds of bubble ensued..


I surfaced at sunset feeling fine.. and proceeded to “on-gas” some N2. I also added a little C2H5OH..for good measure!


Wash-up/Follow-up
I sat out the next day – looking for symptoms and feeling quite nervous.. everything was fine except for my temper. I was irritable as hell watching everyone else dive. We'd been planning the trip for 15 months and I was so frustrated watching everyone doing the dives.


So – and I'm not sure this shows good judgment – I dived on Day 6 and Day 7. Go on – tell me off – but you need to have been there!


We made a few adjustments to the profile..


We added 1 min to the 18/15/12/9 stops and we extended the O2 to two full cycles before the ascent (12/6/12/6).


I was fine for the dives and thoroughly enjoyed the last 2 days. I am fully recovered – and expect to dive more of the same again. I am in the middle of a full medical cycle Just-In-Case, but nobody expects to find anything..


Lessons Learned
Planning
We all know that you can be well inside the tables and still get a “hit”. I guess that the incident brought it home to me in living colour. We had several minutes of spare time built into the profile and I still got hurt.


Gas Choices
I think I'd like to do the dives on a little richer mixes – not because of narcosis, which is barely noticeable in those conditions – but to get more Helium for faster off gassing. I certainly would have a deeper mix in UK conditions!


“Listen to Your Body”
It doesn't matter how many times it is said – I guess you need to feel it to understand what the statement means. I think if I had a similar niggle – I'd stay at 9-12 M for a bit longer say an extra 5 mins. It saves a lot of time in the long run.


IWR Works – and is a fair emergency procedure
If you've got the gas supply and the full-face mask IWR is a workable procedure. I seemed to have good Ox-Tox tolerance that day – no symptoms during the IWR – and I know that's no guarantee for the future. I wouldn't want to try it on a standard regulator the risks are too high – I would want to head for the exit by the fastest means possible.


IWR is not a trivial procedure
I was lucky that the skipper on the boat is a trained decompression chamber operator (a nice little side skill to ask about on your next trip.. go on I dare you ask the skipper! ). His knowledge enabled us to try this procedure. Otherwise it would not have been an option as even though we were all experienced divers we didn't know enough.


READ the IWR Posts in RRR
Everyone trying remote diving NEEDS to know this stuff!
I would also ask all people reading to contribute to support Rubicon Foundation in their efforts to spread knowledge. It is essential that more knowledge is spread to help people avoid these sorts of problems. I was lucky in this situation - good back-up and a good team. I'm reasonably experienced but I was still lacking in knowledge.



Great Teams and Buddies Make Everything Possible!
Again I thank the guys that babysat me while I was in the water.
For the record – I paid a section of their gas bill for the trip – and an extra share of the O2 bill (shared as it was Surface Supplied) – as well as quite a few beers..
It's only a good team concept that allows us to do these things.. 1-up for the team!

Keri

I have pretty much experienced the same niggle as you on the same boat several years ago (right wrist). I got mine after a 45min dive to 65+ on the Prince of Wales. Following that dive I reckon (based on a true scientific wild ass guess) that its related to the shape of the 50% and not having enough Helium in the bottom gas. After the dive I put it down to a scooter strain (first sign of DCS is denial) after second dive I know it was a bubble and just wanted to get out of the water (weird eh) in case it got worse - asprin at the surface and a bit of O2 and I felt the bubble dislodge Yikes.

I don't like the square profiles in the 50% and would rather shorten 18 and 15 (there is no point in riding the deplenishing oxygen window particularly if you've spent longer at 21m) and then lengthen the 9 accordingly - works for me and I feel better after the dives.

For these longer bottom times and multi day trips I feel one really needs to step up the Helium or you start to have problems with Nitrogen. I would dive minium of 55% on Repulse now.


Sitting in FL waiting for EE to open

Graham

[keri.lewis]

Graham

Hope the Jetlag is OK..

You're right - but as I said a very minor hit.. possibly not one at all but 95% likely it was.

For the profile - I just got lazy with the memorisation.. 3s is easy to remember. I would say we were over the original table by some minutes on both the O2 and the 50%.. I guess we added some slow N2 on the 3s.. but not enough to be outside the table at any stage as they were plugged into Decoplanner as planned stops..

A few minutes more on 50% would probably be a good idea. We all know it's in-exact though!

Ho Hum! Put that one down to experience and make sure I "listen" harder..

Hope you have a blast in Florida - maybe next year I can go with you..

[Hugh]

Quote: (Originally Posted by graham_hk)

Keri

I have pretty much experienced the same niggle as you on the same boat several years ago (right wrist). I got mine after a 45min dive to 65+ on the Prince of Wales. Following that dive I reckon (based on a true scientific wild ass guess) that its related to the shape of the 50% and not having enough Helium in the bottom gas.

I don't like the square profiles in the 50% and would rather shorten 18 and 15 (there is no point in riding the deplenishing oxygen window particularly if you've spent longer at 21m) and then lengthen the 9 accordingly - works for me and I feel better after the dives.

For these longer bottom times and multi day trips I feel one really needs to step up the Helium or you start to have problems with Nitrogen. I would dive minium of 55% on Repulse now.


Sitting in FL waiting for EE to open

Graham

Arent GUE teaching squaring the profile now?

What do you mean, felt the bubble dislodge?


Hugh

[Alastair]

Hi Keri,

Thanks for posting - very interesting read. I've read about the different IWR protocols in the past so it's useful to read about it being put into practise.

Thanks
Al

[speedlime]

Thanks for sharing, very interesting read. Good team work saved the day. Also now we can ask the right questions in the dive/trip planning in the future.

[Cyrille]

Hi Keri,

Thanks for sharing your "real-life" experience on IWR.

I remember reading an article from DIVE about 5 or 6 years ago which featured a pretty extensive article on this topic.

The method was a stay of 30-60-90 min (depending on the symptoms mild-med-severe) at 9 m, breathing pure O2, then ascending 1 meter every 12 min. There was a recommendation to use a Full Face Mask (in case the casualty would vomit), to use a harness (to ensure the casualty is attached to the line), to have a diver accompanying the causalty during the deco.

When we look into it, this is a procedure that needs to be known, with a good planning to ensure sufficient gaz is available for one or multiple causalties (unless a pure O2 rebreather(s) with FFM is/are available)...

But for expeditions far away from any deco chamber (or when that one is out of use...), it makes a difference between life and death or avoiding remaining the rest of one's life in a wheelchair.

I recall a technical dive instructor in France who did a 30 min O2 IWR because he felt a pain in his shoulder after a dive. Was it really a decompression accident or was it an injury prior to the dive? I don't know. All I can say, he is still carefull and healthy.

The challenges of the IWR: surface conditions, sharks, shipping lane...

So one technique among others than any serious technical diver must know and be able to apply when there is no other hope in sight.

I only have one remark: why did you plan such a long bottom-time for a 52 m dive: about 35 min. Planning something like 20 min would have been more conservative. 15 extra minutes have a huge deco impact at that depth, adding lots of risk when far from any deco chamber.

Kind regards.

Cyrille

[keri.lewis]

Quote: (Originally Posted by Cyrille)

The method was a stay of 30-60-90 min (depending on the symptoms mild-med-severe) at 9 m, breathing pure O2, then ascending 1 meter every 12 min. There was a recommendation to use a Full Face Mask (in case the casualty would vomit), to use a harness (to ensure the casualty is attached to the line), to have a diver accompanying the causalty during the deco.

The proceudre you suggest is only one of several possible protocols - the link I made to Rubicon Research Repository offers all of the other ones in common use. I agree that it needs to be better known by more people hence my willingness to post the details.

Quote: (Originally Posted by Cyrille)

I recall a technical dive instructor in France who did a 30 min O2 IWR because he felt a pain in his shoulder after a dive. Was it really a decompression accident or was it an injury prior to the dive? I don't know. All I can say, he is still carefull and healthy.

This is definitely my thought too on this instance - better to go through with the IWR treatment than risk a recurring injury - I had at worst a mild instance of injury.

Quote: (Originally Posted by Cyrille)

I only have one remark: why did you plan such a long bottom-time for a 52 m dive: about 35 min. Planning something like 20 min would have been more conservative. 15 extra minutes have a huge deco impact at that depth, adding lots of risk when far from any deco chamber.

Some comments in response - although you may not agree.. I did say - not debating right/wrong in the first post

Motivation - it was at a special place, with a personally motivating objective.. I guess that's why we all do these sorts of dives. 35 minutes was what was required for the dive. TBH it is a dive I have done many times before, with a suitably conservative exit routine with no impact. I would happily do the same dive tomorrow!

Risk Planning was tight - we had thought through a lot of the issues. I addition to standard plans.
We had plenty of gas. Surfaced Supplied O2 plus all of the 50% plus 3*Al80s of bottom mix.
We had a chamber on the boat that everyone believed operational - that was why we hired the boat! Shame it wasn't there when needed - but there was a recompression tech onsite to help.

We always pad the deco schedules to make them more conservative than a fairly conservative setting - either GF85% or VPMB +2 or Ratio deco depending who want to cut the tables - As about 100 dives were done on similar profiles by the teams on the boat and I was the only incident - I guess it's fairly conservative compared to straight Buhlmann FWIW a similar trip 2 years before was completely without incident over 6 weeks of diving by groups of divers. I was there for 2 of the weeks doing 30 min bottom times.

That said, one incident is too many - the lessons I learned will be put into practice - especially the "listen" piece now that I know what I am listening for in greater detail..

I hope from my post that people planning more adventurous T2 type dives like this one - I believe the length of deco qualifies it as T2 along with multi deco-bottles stages etc. - will benefit as well as those thinking about dive planning at the begining of their careers if they are off to more distant places.

Thanks for your interest and the response post.

[Cyrille]

Quote: (Originally Posted by keri.lewis)

35 minutes was what was required for the dive.

We always pad the deco schedules to make them more conservative than a fairly conservative setting - either GF85% or VPMB +2 or Ratio deco depending who want to cut the tables -

Hi Keri,

For trimix dives in the 50-60 meters I usually limit bottom time to 20min, and use vpmb+4. For dives in the 60-80 meters range ... only 15 min bottom time.

Of course, with adequate gaz supplies and surface support extended bottom times are possible.

On this subject, I recall reading an article from Bernard Gardette, former COMEX scientific director, which illustrates the risks of extending bottom time (e.g. doing more than 15 min at 80 meters):

- Article (in english): Rebreather World

- Article (in french): http://www.comex.fr/suite/news/franc...06/article.pdf

Kind regards.

Cyrille

[keri.lewis]

As I said - no right/wrong in my book - you have valid arguments - would love to buy coffee and discuss next time I'm in the Netherlands - will be a couple of weeks until my next trip to Amsterdam - maybe we could do it then.