In Water Recompression

[Charlie99]

I am curious what protocol was being followed?

The report cited shorter stops as the diver was ascending, this is niether IWR nor ommitted "D" protocol.

On another note it would seem even within this discussion there is some difference in opinion as to what IWR is and what ommitted decompression is...

IWR - In water recompression protocols are methods of conducting recompression treatments on divers that require treatment when there is no chamber available...

Ommitted "D" - If you can get the diver back down to the depth of the missed stop within five minutes you can continue decompression.......
<snip>

Again this is something that must be planned for, not conducted off the cuff... <emphasis added>

It looks to me like the diver spent about 70 minutes at 20' on O2, after doing 30', 40', and 20' stops on EAN60 and/or EAN50. It also appears that they were ready to stay at depth on O2 until the helicopter arrived -- if the event times are correct, they only surfaced and got on the boat about 10 minutes before the helo arrival.

As to the confusion between omitted deco and IWR, this one kind of falls in both side. He did go back down at around 5 minutes after surfacing. OTOH he was experiencing minor DCS symptoms.

Yet another way of looking at this incident is that 20' on 100% O2 time was a good place to stay while waiting for the helo.

 

[rmediver2002]

Brian reports that Rob has spent about 20 minutes at 40 feet, 10
minutes at 30 feet and about 8 minutes at 20 feet where he was at the time
of the report

This was the portion I was refering to. He then spent another 45 minutes at 20 FSW it would seem.

Much of the confusion comes from not being able to talk to the diver and tender.

It looks to me like the diver spent about 70 minutes at 20' on O2, after doing 30', 40', and 20' stops on EAN60 and/or EAN50. It also appears that they were ready to stay at depth on O2 until the helicopter arrived -- if the event times are correct, they only surfaced and got on the boat about 10 minutes before the helo arrival.

As to the confusion between omitted deco and IWR, this one kind of falls in both side. He did go back down at around 5 minutes after surfacing. OTOH he was experiencing minor DCS symptoms.

Yet another way of looking at this incident is that 20' on 100% O2 time was a good place to stay while waiting for the helo.

 

[SeaJay]

Just checking, what's your missed stop protocol?

Same as yours... Well, sorta... Head to the stop and extend the stops above 40' by 2x (seems easier to do the calculations on the fly). When he surfaces and announces that he's missed a stop, he's given fresh gas and then descends while accompanied by one or more divers. Wherever possible, he's given EAN32 or EAN36. Since we typically dive with 21% or EAN32, EAN36 is a good choice here. In addition to doubling his stops, great care is taken for him not to exceed an ascent rate of 10' per minute.

If the diver was symptomatic of DCS prior to his descent, then once he's done, he's fed 100% while on the deck and medical attention is sought immediately.

A situation where the diver became unexplainably symptomatic after his dive was over (ie: No missed stop, but symptomatic anyway), then we place him on 100% and seek immediate medical attention; our protocol is not to perform "true" IWR. "Missed stops" are a different story, and was what I was talking about above.

Of course, we've never had to employ any of the procedures in real life, but that's the protocol.

 

[HammerNoMore]

If the diver was symptomatic of DCS prior to his descent, then once he's done, he's fed 100% while on the deck and medical attention is sought immediately

....

our protocol is not to perform "true" IWR. "Missed stops" are a different story, and was what I was talking about above.

If the diver is symptomatic of DCS and you send him down you are performing IWR. And based on this description you are not doing it right. This is what I and others have said above:

IWR can save lives, but only if performed by propery trained people using the right eqipment.

I think you should re-evaluate your protocol such that you are either prepared for proper IWR or you remove it from the protocol.

James

 

[rmediver2002]

When a diver has a symptom you have to begin attempting to identify the cause of the symptom.

The specific symptoms alone may not provide enough information to determine the type of injury. The size of the blockage or "bubble" is going to be in large part dependant on the type of injury, the type of injury will also determine the composition of the "bubble" itself.

All of these issues are going to play a role in whether or not IWR is likely to be effective... You are limited in IWR, especially when dealing with POIS injuries. In a chamber if the initial compression to 60 FSW on 100 % O2 is not effective you have the option of taking the diver deeper and "crushing" the bubble.

I have a photo at work of a AGE at work that makes the concept easier to understand... When dealing with DCS your talking about "bubbles" the size of those seen in a draft of Guinness.

Anyone else have some decent photo's they could post?


In treating these injuries several important factors are at work.

100% O2 saturating the diver tissues will allow some amount of cellular transfer that can bypass the injury site keeping the downstream tissue from becoming hypoxic.

100% O2 being inspired makes the pressure differential between the divers tissue and the inspired air greatest as far as inert gas is concerned and allows the greatest amount of off-gassing.

Increasing pressure during the treatment can decrease the size of the blockage "crushing" the bubble and allowing mre blod flow to the effected tissues.

High ppO2 treatment have also been shown to increase the bodies healing response, this is the reason for some hyperbaric treatments not involving diving injuries and the reason we conduct repetative treatments in the days following a severe injury...

Jeff Lane

 

[SeaJay]

If the diver is symptomatic of DCS and you send him down you are performing IWR. And based on this description you are not doing it right. This is what I and others have said above:

<snip>

Well, don't just stand there telling me I'm wrong... Tell me what your protocol is. What do you consider the "right" way to handle a missed deco stop?

What would you do?

 

[Bob3]

... "right" way to handle a missed deco stop?

It's all in the definition, in a "skipped stop" situation the diver is not displaying any symptoms (asymptomatic), there is "usually" no more than a 5 minute surface interval.
If/when problems are observed, gears shift & then you slap the 100% O2 w/demand mask on the guy while evaluating the situation.

 

[rmediver2002]

I think the point was that if the diver has a symptom they have DCS, it is no longer omitted decompression. This is not a time for a missed stop protocol...

I think part of the confusion comes from sometimes from a mis-understanding of what is happening to a bubble once formed.

Missed stop or "ommitted D" protocol is to get the diver back down to the depth of the missed stop within 5 minutes and then multiplying the stop times by 1.5 (10 minutes at 40 feet will now be 15 minutes...) This same time frame of five minutes is used for surface decompression when moving the diver to the chamber. Testing and field experience has shown that under most conditions divers returned to pressure inside of this five minute window have not had enough time for bubbles to form in the tissues. Decompresion can be safely completed...

The problem comes when bubbles have formed or do form in the tissues, when the diver is not returned to pressure within five minutes there is a much larger chance that bubbles will have formed whether or not they are currently presenting symptoms. In other cases the bubbles have formed and they manifest themselves as symptoms within this five minute "safe" period. In these cases returning the diver to the depth of the missed stop is not going to be effective in "reversing" the bubble formation... It may stop additional bubbles from forming but the original symptom will still be present. It may also further compound the problem depending on mixture because the diver may be absorbing more N2 during the time spent at depth...

Another issue is the cause of the bubble, if it was due to AGE (suspect an AGE more than DCS when the diver has blow-up from depth unexpectedly and even more so if a neurological symptom presents within those first 5 to 10 minutes of surfaceing...) then there is in comparison to DCS bubbles a very large bubble in the diver circulation. Further compounding problems, it will be within the divers arterial circulation...

Once the gas has come out of solution just sending the diver to depth does not cause bubbles to go back into solution...

Recompression treatment or IWP flood the body with high ppO2 for an extended period of time (the shortest being over two hours / longest are several days) this does not force the bubbles back into solution either but does allow the body to slowly absorb the nitrogen out of the bubble due in large part to the pressure gradient of inert gas in the inspired gas and subsequently the diver tissues (100% O2 is used for treatments...)

You can follow one of the links already posted to see some examples of IWP, do some of the math on times and gas consumption (you must figure for two divers as the patient must always have at least one tender in the water) This type of protocol must be very well planned as complicating factors include progression or worsening of symptoms, gas supply, environmental conditions, divers tolerance (temperature for a long duration treatment while not moving), gas toxicity problems, a method for gas switching, etc...


Jeff Lane

Well, don't just stand there telling me I'm wrong... Tell me what your protocol is. What do you consider the "right" way to handle a missed deco stop?

What would you do?

 

[pipedope]

It may be important to consider the depth of the dive as well. In some cases you may need to recompress to dive depth (or even greater) so if the dive was to 300 feet then many chambers are not going to do the job.

Darn, it just keeps getting more complicated......

 

[rmediver2002]

This discussion provides a good example of the fixation on DCS even when AGE should be obvious...

http://www.scubaboard.com/t43602.html