Air Embolism and Patent Foramen Ovale

[Saturation]

Question ... My friend says that it's not that doing deco dives puts you significantly more at risk of having DCS if you have a PFO (properly done deco does not) but that it's the increased frequency of your diving that puts the risk higher, if you dive often, then you should be tested for one
... sorry if the answer is already in the info posted

Any dive that generates bubbles after a dive would put the PFO or shunt diver at risk for AGE. However, its not just the bubbles, its the size and volume of bubbles, and the likelihood of forming bubbles depends on the gas load at the end of each dive.

It doesn't depend on how many dives one does, it depends on how cleanly one surfaces after any dive.

That cleanliness depends on doing the safety stops, decompression, ascent rate, motion before in- and after a dive, one's choice of gases, and finally if possible modified to that diver's physiology [ age, fitness, diseases, etc.,]

The PADI RDP has been tested to generate a small amount of bubbling in most normal subjects, if at all. I cannot say about other tables as survey of such tables [ See Lippman and Mitchell's Deeper into Diving V2] often shows it has not been as heavily tested as the RDP.

 

[kbuschmann]

"The PADI RDP has been tested to generate a small amount of bubbling in most normal subjects, if at all. I cannot say about other tables as survey of such tables [ See Lippman and Mitchell's Deeper into Diving V2] often shows it has not been as heavily tested as the RDP.[/QUOTE]"


The DCIEM tables were generated with extensive doppler bubble testing. They are probably the most empirically based tables we have.

 

[Saturation]

The DCIEM tables were generated with extensive doppler bubble testing. They are probably the most empirically based tables we have.

Yes, and so did the PADI RDP, of which Dr. Powell was a team member in the design, mirrored the DCIEM protocol [ now DRDC] closely for their methods. In recreational diving, RDP has more relevance given the distribution of experimental subjects and the field trials for recreational level dives. The tables are similar for the first dive, but differ in repets, given the DRDC tables were clearly designed for Canadian cold water diving.

 

[kbuschmann]

Yes, and so did the PADI RDP, of which Dr. Powell was a team member in the design, mirrored the DCIEM protocol [ now DRDC] closely for their methods. In recreational diving, RDP has more relevance given the distribution of experimental subjects and the field trials for recreational level dives. The tables are similar for the first dive, but differ in repets, given the DRDC tables were clearly designed for Canadian cold water diving.

Yes, the DCIEM tables are more conservative than RDP for rep dives. I think the jury is still out as to whether or not that is a more beneficial or justified approach - as always, the answer is context dependant. Unfortunately, DRDC (as you say, DCIEM's new name) does not have the funding or manpower to pursue further empirical studies. I'm currently at DRDC and look across to that big chamber wishing.....maybe in a few years.

 

[D_B]

I thought doing the proper ascent rate, exertion level, safety stops, and/or deco time .. only lessons your likelihood of DCS ... maybe lessoning the risk down to statistically insignificant levels for someone without a PFO .. but someone with a PFO, the risk is still much higher, no matter what kind, or how perfect the dive, and is a risk because you dive at all, and not because the type of diving per say

 

[TekDiveGirl]

I believe that a PFO is a ticking bomb just waiting to go off on any dive. I had a PFO and took my first hit on a 60' - 40 minute dive. This was my open water dive number 4. My second hit was after a 130' - 30 min bottom time - 43 minute total dive time dive. This was a simple decompression dive compared to the dives I had been doing.

I have seen divers time and time again with PFOs take hits on dives that are in the recreational range that should NEVER give them problems. If a person has a PFO and its their day for that bomb to go off --- when it comes right down to it I don't think it matters what tables they are using --- the bubbles are going to migrate through that hole and dcs is going to occur.

 

[Saturation]

I thought doing the proper ascent rate, exertion level, safety stops, and/or deco time .. only lessons your likelihood of DCS ... maybe lessoning the risk down to statistically insignificant levels for someone without a PFO .. but someone with a PFO, the risk is still much higher, no matter what kind, or how perfect the dive, and is a risk because you dive at all, and not because the type of diving per say

PFO increase the risk of DCI by 3-5x that of a normal diver. If, taking your logic, the proper procedures reduce risk for normal folks to near zero, then 0 times 5 is still zero.

The issue presumed with PFO is gas emboli. Without gas emboli there is far less problem. Any process that can reduce inert gas forming bubbles thus, reduces problems with PFOs. I say presumed because its still not entirely clear what causes the increase risk of DCI, its just associated not causally related with PFOs.

 

[Saturation]

I believe that a PFO is a ticking bomb just waiting to go off on any dive. I had a PFO and took my first hit on a 60' - 40 minute dive. This was my open water dive number 4. My second hit was after a 130' - 30 min bottom time - 43 minute total dive time dive. This was a simple decompression dive compared to the dives I had been doing.

I have seen divers time and time again with PFOs take hits on dives that are in the recreational range that should NEVER give them problems. If a person has a PFO and its their day for that bomb to go off --- when it comes right down to it I don't think it matters what tables they are using --- the bubbles are going to migrate through that hole and dcs is going to occur.

When a diver receives an unexpected hit, such as the dives you describe, this is wake up call to find out if there is something physical that puts said diver at higher risk. This is the best way to find a PFO: if you have an unexpected hit, start looking or pay heed to risk reduction methods to "safen" your dives.

However, there is still the very problematic physiologic lung shunt, which occurs with exertion, and has yet to be proven to occur intra-dive. If it where to occur on the surface after a dive, it would be far worse than any PFO as it allows bubbles through the lungs without mercy, this physiologic phenomenon happens to normal folks under physical stress.

Sonographic detection of intrapulmonary shunting o...[J Clin Ultrasound. 2007] - PubMed Result