"Patent Foramen Ovale Influences the Presentation of Decompression Illness in...+

[DocVikingo]

....SCUBA divers."

Not a news flash type of study, but it is done collboratively by a respected diving research institution and a known cardiac center, involves a modestly large subject sample culled from a nine year period, contains a reasonbale control group, examines a fair number of variables, bases the diagnosis of PFO primarily on trans-oesophageal echocardiogram (TOE) (aka transesophageal echocardiogram (TEE)), is written in relatively non-technical & easy to understand language, and is up front about study limitations.

The finding that the presence of baseline spontaneous, unprovoked right to left shunt is more common in patients with DCI when compared to other patient groups suggests that a subset of divers with PFO may be primed with bubbles before they even start a dive, the implications of which are interesting to consider.

Hope you enjoy.

Patent Foramen Ovale Influences the Presentation of Decompression Illness in SCUBA Divers

Cheers,

DocVikingo

 

[danvolker]

When George Irvine and Bill Mee were working with Dr Bill Hamilton in the 90's, on their own special WKPP trimix tables, the thinking from all available research plus anecdotal/experiential accounts of the Cave community.....was that roughly a quarter of all divers ( those statistically expected to have PFO's) "should not" be tech or cave divers doing deco dives---and any modifications of a set of tables to accommodate this PFO group's special needs, would be destructive to the optimal profile planning needs of healthy exploration level divers--where artificially increasing deco stop times for a fudge factor would actually introduce more deco, for your deco, and increase logistical dangers by requiring massively more deco gasses

And this is one reason I prefer to consider the accepted agency tables today ( what PADI, NAUI and most others use), as too full of fudge factor to be something I want to pay undue attention to.....and it is another reason I will NEVER use the extra deep stop ideas that became in vogue about 2 or 3 years ago( which I see as more fudge factor deco than as useful to a fit diver without a PFO)

 

[dreamdive]

It may be prudent to have a "bubble" study done prior to planning on going tech. Granted, this would be an out of pocket expense, but worth it. Shop around and you will get different prices.

A diver who experiences repeated skin bends, or other "undeserved hits" when their buddies on the same dive are asymptomatic, may want to consider getting checked out for a right-left shunt. One diver had a small ASD (atrial septal defect) and was asymptomatic for years until.......

 

[DocVikingo]

A diver who experiences repeated skin bends, or other "undeserved hits" when their buddies on the same dive are asymptomatic, may want to consider getting checked out for a right-left shunt. One diver had a small ASD (atrial septal defect) and was asymptomatic for years until.......

Amen, Sister dream'

Cheers,

DocV

 

[danvolker]

I've often wondered if there is some similarity between the way the Dive Industry views PFO'S and potentially losing 25% of it's Diving population and new sales.....to how the Tobacco Industry viewed the suggestion that smoking could be bad for your health....and then moved to discredit studies linking cancer and smoking, and continued to push for smoking as being good for everyone.


The loss of at least 25 % of divers would be almost certain, if the cost of deciding to become a new diver included the cost for PFO screening, as well as the loss of most of the PFO population as new divers each year. I think such a prospect would be horrifying to the Dive Industry In fact, it would probably force many in the dive industry to close their doors--they can't afford to lose 10% , so this would be catastrophic.

 

[TSandM]

I think everybody would agree that across-the-board PFO testing for recreational divers is unwarranted. Since roughly 25% of the population carries a PFO, and FAR less than 25% of the divers get DCI (in fact, the problem is actually extremely rare in people who haven't exceeded some limit) it's difficult to make the argument that a PFO alone should mandate staying topside. The quoted study suggests that those who have rest shunting may be the high risk group, but until someone does a study identifying such a cohort of divers and following them to see what their DCI rate is (I suspect it's STILL quite low) you can't really argue for routine screening.

 

[dreamdive]

I agree, even the latest statement from DAN in one of their articles this year, stated that the incidence of DCS in recreational divers (in warm waters) was rediculously low (something like 0.1 %). That is why right to left shunt testing should be reserved/considered for those planning diving deco dives.

Incidentially, I don't think that a new incoming diver has even heard the connection between PFO and DCS. Those terms are still quite alien to him/her. Interestingly, there are quite a number of people out there with asymptomatic PFO's doing long trimix dives. Just because you have a PFO does not guarantee you a hit!

 

[tomfcrist]

And this is one reason I prefer to consider the accepted agency tables today ( what PADI, NAUI and most others use), as too full of fudge factor to be something I want to pay undue attention to.....and it is another reason I will NEVER use the extra deep stop ideas that became in vogue about 2 or 3 years ago( which I see as more fudge factor deco than as useful to a fit diver without a PFO)

Concerning Deep Stops, it is worthwhile to note that deep stops on No-Deco dives has little evidence to support the idea that they are helpful or not. On longer decompression dives, there is evidence showing a significant reduction in size/frequency of bubbles if staged stops are started earlier in the profile.

 

[DocVikingo]

I think everybody would agree that across-the-board PFO testing for recreational divers is unwarranted.

Indeed.

Informational is DAN's latest take on the topic --> When to refer a diver for PFO screening? | The Dive Lab

Cheers,

DocV

---------- Post added August 21st, 2014 at 08:56 AM ----------

I agree, even the latest statement from DAN in one of their articles this year, stated that the incidence of DCS in recreational divers (in warm waters) was rediculously low (something like 0.1 %).

Among the latest DCS incidence figures for rec divers in the DAN membership population are: (1) 1.55 per 1,000 dives based on self-reported DCS & (2) 5.72 per 100,000 dives based on treated DCS.

Cheers,

DocV

 

[Duke Dive Medicine]

The finding that the presence of baseline spontaneous, unprovoked right to left shunt is more common in patients with DCI when compared to other patient groups suggests that a subset of divers with PFO may be primed with bubbles before they even start a dive, the implications of which are interesting to consider.

Doc, can you elaborate on this?

Best regards,
DDM

---------- Post added August 21st, 2014 at 01:53 PM ----------

It may be prudent to have a "bubble" study done prior to planning on going tech. Granted, this would be an out of pocket expense, but worth it. Shop around and you will get different prices.

A diver who experiences repeated skin bends, or other "undeserved hits" when their buddies on the same dive are asymptomatic, may want to consider getting checked out for a right-left shunt. One diver had a small ASD (atrial septal defect) and was asymptomatic for years until.......

I think it's worthwhile to note too that an ASD is an absolute contraindication to diving, while asymptomatic PFO is not.

Best regards,
DDM