34 dives to 15 feet in 4 hours - symptoms

[chillyinCanada]

Not in 2 hours as op described. Skin rash starts lightly as well until you acknowledge it, it will intensify and disappear.

I'm well aware, very well aware of how they look, feel, evolve and abate.

 

[scubaozy]

I'm well aware, very well aware of how they look, feel, evolve and abate.

Sorry to hear that. I have seen more than 20 cases of C. Marmorata in my diving past. It is the easiest one to deal with because it is something you can see and it is probably most common. In each case I have seen there was enough insult in dive profile such as multi-day diving or diving > 45 feet.
General algorithm to look at dcs is very basic:
Dive profile, is there any (or enough) insult?
Symptoms will start short after dive, the later it starts less likely it will be dcs (80% within 8 hours), not the case for OP
After onset they will worsen
Breathing 02 will improve the symptoms
......

Btw, DCS related itching is generally around lymphatic nodes, like ears, armpits, groins. Exposure to the cold will make you tired and itchy as well. You have to understand that unexplained fatigue is a bit stronger than feeling tired.

 

[beester]

Depth and bottom time are just some of the factors in decompression stress. Multiple ascends, or depth changes are another.

There are these famous cases of norwegian fish farmers using scuba to clean the nets underwater, and doing multiple very shallow dives per day (taking 6-9m depth) and getting bend. I can't find the source now but I'm sure someone will post it before I have time to look for it.

Same can be said for example of OW instructors teaching a lot of pool sessions, very shallow but a lot of ascends in a day.

 

[Hoyden]

As far as I am aware, there are no peer reviewed studies that support DCS in the circumstances listed by the OP. I am a dive safety officer at a public aquarium and the kind of up and down profile the OP describes is not uncommon in aquarium diving. I am confident that I have dozens (if not hundreds) of dives with more than 20+ ascents/descents without incident (beyond wrecking my ears). I have a few dives of more than 4 hours that involved lots of up and downs, but they are all warm water dives in wetsuits. Generally, we don't have one diver doing 4 hours in a single go, but it has happened. Also, generally, our coldest exhibit is around 50 degrees F and we limit how much time one diver can spend in it so I don't have direct experience with the exact conditions. Having said that, I am here to say that if I spent 4 hours doing up and downs (or frankly just sitting on the bottom) I would expect to be exhausted afterwards. It is also not uncommon to have mild rashes after that amount of time in the water.

If anyone has anything other than ancedotal information that supports DCS in this circumstance, please share it.

YMMV,

Jackie

 

[scubaozy]

Depth and bottom time are just some of the factors in decompression stress. Multiple ascends, or depth changes are another.

There are these famous cases of norwegian fish farmers using scuba to clean the nets underwater, and doing multiple very shallow dives per day (taking 6-9m depth) and getting bend. I can't find the source now but I'm sure someone will post it before I have time to look for it.

Same can be said for example of OW instructors teaching a lot of pool sessions, very shallow but a lot of ascends in a day.

Could this be because symptoms of DCS and AGE are similar and rarely distinguishable? They both are often classified as DCS and then you do not need the depth and time.

 

[boulderjohn]

While I know it is not common, I have read of shallow water DCS around 20 feet or above, so it seems while not likely, still possible. Or maybe the reports and such were simply incorrect

Do some looking at Steve Bogaerts, it happens. Since his leaving diving, many have reached out to him with very similar stories.

We just had a long and very informative thread on this a few months ago. Like this one, it started with a lot of "I heard that..." and "I once read about a study that..." comments. About halfway through it had some real information.

Here is the thread: Is DCS possible under 20fsw, or 100% impossible?

Here is one of the studies mentioned: Bubble formation and decompression sickness on direct ascent from shallow air saturation diving - PubMed

The gist is that you don't get bent shallower than 20 feet.

 

[beester]

I did a quick check and the only thing I could find regarding to fish farm bounce diving actually points in the same direction. That there is no statistically significant evidence showing increased risk in shallow water bounce dives.

Field validation of Tasmania's aquaculture industry bounce-diving schedules using Doppler analysis of decompression stress - PubMed

These data suggest bounce diving was not a major factor causing DCI in Tasmanian aquaculture divers. Analysis of field data has improved industry productivity by increasing the permissible number of bounces, compared to earlier empirically-derived tables, without compromising safety. The...

pubmed.ncbi.nlm.nih.gov

So I stand corrected ;-)

 

[boulderjohn]

That there is no statistically significant evidence showing increased risk in shallow water bounce dives.

...and just in case people don't read the study, the "shallow water" dives studied were up to 21 meters/70 feet deep.

 

[ginti]

We just had a long and very informative thread on this a few months ago. Like this one, it started with a lot of "I heard that..." and "I once read about a study that..." comments. About halfway through it had some real information.

Here is the thread: Is DCS possible under 20fsw, or 100% impossible?

Here is one of the studies mentioned: Bubble formation and decompression sickness on direct ascent from shallow air saturation diving - PubMed

The gist is that you don't get bent shallower than 20 feet.

From the same thread you mentioned:

Is DCS possible under 20fsw, or 100% impossible?

Bubble formation and decompression sickness on direct ascent from shallow air saturation diving - PubMed It seems that 8m is minimum depth where you can get DCS. And this is for saturation diving...

scubaboard.com

I wonder if the data @Duke Dive Medicine mentioned are published or not. The situation in that thread looks very similar to the one in this post

 

[Subcooled]

Could something like this happen:

1. Nitrogen dissolves in blood at depth.
2. When one later ascends and the ambient pressure drops, that nitrogen wants to get out.
3. There are always bubbles in blood but they do have a surface tension that stops nitrogen from getting into them (unless the pressure gradient is high - hence, depth).
4. Bigger bubbles have smaller surface tension and can grow more easily, but there are less of them.
5. Deco algorithms contain lots of parameters and constants that are set based on dive statistics.
6. Those bubbles that can grow more easily are not a problem as we have seen from dive statistics (all of which are max 3-4 dives per day)
7. Frequent ups and downs could, however, pump those bigger bubbles and possibly case some harm.

This is a divers attempt to understand what is going on. I am not a decompression theorist.