Undeserved hit

[DivingDoc]

Re: the SOB -- John's CXR was wnl except for what was probably an artifact in the RLL. Following treatment, his O2 sat was 98% on room air. So I doubt the SOB was due to bubbles in the lungs. It was probably on a non-organic basis.

Petra probably caused her ear drum rupture when she put her finger in her ear to scoop out the plankton that she thought got inside. This was on the ascent. She probably created a temporary vacuum and also increased the pressure differential between her middle and external ear, since she probably rose a couple of feet during the time that her finger was in her ear.

I've attached a download of John's dive data for the few days that he dove. It is in Excel format. You can get an idea of the profile.

It looks like he ascended a little fast, but did not go into the red on his computer.

 

[DocVikingo]

I receive regular figures from inside sources among the dive & medical community on Coz.

The number of dives for the past several years has been about 750,000 per year. The number of cases of DCI treated by the 3 chambers on the island is about 180 per year.

This would place the DCI percentage within the ballpark figures reported by DAN & Bove.

Best regards.

DocVikingo

 

[DivingDoc]

DocVikingo once bubbled...
I receive regular figures from inside sources among the dive & medical community on Coz.

The number of dives for the past several years has been about 750,000 per year. The number of cases of DCI treated by the 3 chambers on the island is about 180 per year.

This would place the DCI percentage within the ballpark figures reported by DAN & Bove.

Best regards.

DocVikingo

For those who don't know, DocV is correct about the chambers. There are 3 chambers -- but all in one facility. There is one 2-person chamber (the one my SIL was in), one 1-person chamber, and even one chamber that can hold 9 people at one time!

I'm confused about the statistics. I just looked at the DAN report for 2003 and found this paragraph regarding incidence:

"Figure 3 shows the number divers who volunteered for PDE since
data collection began in 1995 through 2001, the number of dives
they made, and the number of divers who were recompressed for
DCI. To date, there have been more than 36,000 dives by 3,750
divers, of whom 22 were recompressed. There has also been one
fatality."

This would give an incidence of one case of DCI per 1636 dives. DocV's Cozumel data would put the incidence in the 1 in 4000 range. And I don't know whether I am just remembering wrongly the 1 in 250,000 figure that I thought I read in some position paper about asthma and diving.

Oh well.

ET

 

[leadweight]

PDE includes a group of cold water wreck divers who have a much higher incidence of DCS than the recreational diving population. There is also a group of professional divemasters who have a somewhat higher rate of DCS than their clients.

For the liveaboard divers there were no cases of DCS in about 4000 dives. A move general group of recreational divers had 2 cases in about 4000 dives. Combined, that yields about 1 case per 4000 dives.

Incidence of DCS in cold water wreck divers was about 15 times higher.

The Cozumel statistics no doubt include professional divemasters who are at higher risk due to their having to lug tanks around and chase divers who are shooting up to the surface.

Some divers in Cozumel intentionally go deeper than 130 feet. By definition that takes them out of the recreational diving category.

It is also possible that not all of the 180 divers who were recompressed needed it.

Perhaps all of this would put the incidence of DCS in Coz recreational divers at around 1 case in 10,000 dives.

 

[DivingDoc]

I have finally found a way to save John's graphical data as jpg files. The zip file I have attached contains 3 jpg's -- one for each dive that day. Dive 3 is the night dive -- the last one he had before he developed DCS.

BTW, was wondering if anyone has an explanation for people on liveaboards having such a low to non-existant incidence of DCI. Don't they usually do around 5 dives per day? I suppose they get less exercise because they don't have to carry their equipment anywhere.

 

[dtdiver]

i wonder if the symptoms could be temporally related to his vomiting

the valsalva with a pfo (or opened a non-patent pfo) could have shunted venous bubbles

thusly resulting in his acute symptoms assoc with vomiting and diarrhea

dt

 

[leadweight]

DivingDoc once bubbled...

BTW, was wondering if anyone has an explanation for people on liveaboards having such a low to non-existant incidence of DCI. Don't they usually do around 5 dives per day? I suppose they get less exercise because they don't have to carry their equipment anywhere.

The explanation is easy. The liveaboard divers play it safe. The much more interesting question is why is the accident rate so high for the cold water wreck divers.

 

[raviepoo]

I know local (NY/NJ) divers who regularly do deco dives without having deco training. Do you think that might have something to do with it?

leadweight once bubbled...


The explanation is easy. The liveaboard divers play it safe. The much more interesting question is why is the accident rate so high for the cold water wreck divers.

 

[DocVikingo]

As for the figures, they vary by agency & sample. The PDE is a special, self-selected cohort, and may well not be representative of the diving population as a whole.

For the population at large, DAN has given a figure of 1.5 DCI incidents per 10,000 dives & Bove of 3.4 per 10,000. This puts my figure of 1 in 4,000 in the obviously imprecise ballpark as advertised.

A point of clarification on the chambers, as both of us have been misleading. I should have been clearer. I was referring the 3 recompression facilities on Coz, and they have more than 3 chambers total.

There are 3 chambers at the Sub-aquatic Safety Services/Buceo Medico Mexicano (SSS/BMM), managed by Mauricio Moreno, which is the one you went to.

There is also a recompression facility, managed by Heidi Piccolo, RN/operated by her husband, Pascual Piccolo, M.D., the Hiperbarica De Cozumel (HDC), that has one chamber.

Finally, there is a little used satellite facility with a single chamber down at one of the southern beaches.

Best regards.

DocVikingo

 

[Dr Deco]

Dear Readers:

The Recreational Dive Planner and DCS

In 1986, we finished testing the PADI/DSAT tables (The Recreational Dive Planner) for their use with multilevel dives,; this involved up to three dives a day for one or possibly two days. At this time, liveaboards were coming into vogue. By the time the DSAT tests were completed, it became clear that they would need to be repeated with several, sequential days of diving. I was concerned that so many days of diving would lead to big gas loads and the carryover of decompression gas bubbles. Thus, a six-day dive series was planned.

The Doppler monitoring indicated that the Doppler bubble Grades were not high. In addition, decompression bubbles were not being carried over from day to day. This was good news from the laboratory for liveaboard divers.

Liveaboards and DCS :scuba:

I now suspect that a large part of the answer lies in the lack of physically stressful activities on the boats. I doubt it is the gas loads or bubbles.

My finding at NASA that the primary reason that astronauts were not getting DCS in space as predicted from ground-based studies indicated that physical activity plays a very large role in DCS risk. In some cases, the reduction in DCS incidence between simulated 0-g and 1-g decompression was almost ten fold. That is what musculoskeletal stress can do for you (or against you).
Liveaboard and Sitaround :relaxing:

The worst activity following a dive is heavy physical activity. This has been known since the 1940s to precipitate DCS. In the selection process, physical activity (stair stepping, running in place, etc) was found to be necessary as simple decompression could be efficiently determine who was the DCS-resistant and who was DCS-susceptible aviator.

Dr Deco :doctor:

Please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm