My visit to the chamber!!!!

[Phil Ennis]

Originally Posted by ChrisP

As I understand it what Peter Wilmshurst has said is that because during all (most?) ascents we produce microbubbles, which are easily filtered out by the lungs and do not result in problems, if one coughs then the bubbles can be pushed through a PFO, these then enter the arterial blood system and do not get filtered by the lung. If you continue to ascend these bubbles will enlarge and could cause symptoms.
These is also part of the idea behind doing deep stops during ascents.

I seemed to remember reading or being told that sneezing, coughing can cause a cavitation. It makes its own bubbles, a bit like a propeller underwater.

But then again this could be total bollocks.

[Phil Ennis]

Sorry, I meant to quote the last post from Janos.

[Lee B]

Originally Posted by ahar

Hi Lee, how's it going ? Managed to get much diving in after Swanage ?

PFO stands for Patent Foramen Ovulae (spelling?). Instead of having a solid bit of flesh between the two sides of the heart (one going to the lungs and one going from the lungs) there is a flap that may open during stress - this could be when the heart is working hard, or if you sneeze, cough or clear your ears. PFOs will be different between people in size and their propensity to open. The problem with diving is that the venous blood filled with bubbles on the way to the lungs from the muscles will escape through the PFO if it is open and the bubbles will go back towards the muscles and other tissues, potentially getting trapped in the small capilliaries, possibly causing a bend. Ordinarily the venous blood with bubbles in it would travel to the lungs and be 'filtered out' as the blood passes through the lungs.

I seem to remember that 1in10 of the poulation are thought to have a PFO of some degree, but a small number of those will have a PFO that could cause a problem diving. As babies in the womb, we all have a PFO to aid in oxygen transfer from the umbilical cord, it's just that in some people it doesn't see up properly after birth

I think this is all correct, but I'm sure that more knowledgable people will be around to correct any mistakes

Hi Andy thanks for the answer, had a few more dives after swanage in the UK waters but about 12 dives in Hawaii, Fantastic, Im ready for some more cold water though just give me a shout if you want a buddy. Sorry for hijacking and back to the thread

[ChrisP]

Originally Posted by ahar

I seem to remember that 1in10 of the poulation are thought to have a PFO of some degree, but a small number of those will have a PFO that could cause a problem diving.

It depends what you mean by a PFO.
1 in 4 people have a "probe positive" PFO. What this means is that if you routinely check the hearts of people who are having a postmortem you find that you can easily push a probe through in a quarter of all adults. However many of these are not significant as far as diving is concerned. By the time you get to a hole approx 1cm across then this becomes a high risk for diving. In between the situation is more difficult, especially if you have a hole say 0.5cm or less. These ones probably don't need closing but it would be wise to dive conservatively. You would need to seek the opinion of a Cardiologist who is interested in Diving Medicine about this first though.

[Janos]

Originally Posted by ChrisP

As I understand it what Peter Wilmshurst has said is that because during all (most?) ascents we produce microbubbles, which are easily filtered out by the lungs and do not result in problems, if one coughs then the bubbles can be pushed through a PFO, these then enter the arterial blood system and do not get filtered by the lung. If you continue to ascend these bubbles will enlarge and could cause symptoms.
These is also part of the idea behind doing deep stops during ascents.

Ah. Cheers.

Originally Posted by Phil Ennis

seemed to remember reading or being told that sneezing, coughing can cause a cavitation. It makes its own bubbles, a bit like a propeller underwater.

And again cheers.
Both explanations make sense. I do cough underwater occasionally (big retching coughs, can scare the crap out of my buddy), and will be a bit more concious of this in the future

Laters,
Janos

[DIVE BUDDHA]

i just wanted to reply to the comments askin me if i was darting about dureing the dives absolutely not mate i always skull nice and steady and chill underwater

[Neil M]

Leigh...

Small question.. have you calibrated your o2 analyser against air/pure o2?? just to check the readings??

have you checked the final mix agianst another analyser?? and your entered percentage??

Just a thought....
Cheers
Neil

[Forest Diver]

I am glad your both OK. I am interested in your comments on the sunnto as i recently did a 39m (very short bottom time slow ascent to 23m) dive at Chepstow and after slow ascent did my 6m saftey stop (during which I did drop to 8m briefly). On the ascent it gave me a deco ceiling of 3m - as I was ascending I didnt stop immidiatly and it cleared BUT when i descended to 3m it gave me 3min at 3m. The point is had I not descended it would have given me an error free dive despite missing the 3m stop.

My shortest no deco time was 4min

Net result I'm glad I'm doing adv-nitrox/deco so I don't blindly follow a computer in almost total ignorance.

My buddy was diving the same profile on a vyper and had no penalty?

I would be interested by others experiences as we rely on these things to keep us as safe as poss??

[DIVE BUDDHA]

regarding the analising of the o2 content within the cylinder that was done on the one thats in the air bar at stoney cove

[Dave Crampton]

Take care Yippee diver. I like others, would advise on having a PFO test. A member of my dive club had a very minor (if very slight) bend diving in Mull in April. He choose to go private and was found to be free from a PFO. He's a lot more secure now knowing he is clear. He went private with BUPA and it cost around 300 pounds. He also told me that had he gone on the NHS he would have only had to wait another 3 weeks. After the private doctor had eventually sent the PFO test results to his GP and they were passed to the local Diving Doctor, he thought that it would have been just as quick on the NHS

Good luck, but don't just leave it to luck!

Dave C
-----------------------------------------
as an after thought, Although I don't have any deco/diive plan software I had a look through my BSAC air tables. I know they are air tables and that the algorithms for the tables are unpublished, but all the same. After looking through them with your dive profiles, on your dives you went past the last recomended max dive time, for the depth, on both the second and third dives. I used Mark Chase's EAD of 18m for all three dives, and took 2 hours for surface interval. I used table C for the second dive and the table stopped at 50 minutes, giving at least 21 minutes at 6m. Looking at your second dive profile, you did nowhere near 21 mins at 6m!. I used Table C for the third dive, working back from the surface interval table, and this was for a longer surface interval than you said you did. I know as some will say these are for flat bottom profiles, but looking at your profiles, you were pretty constant in your depths.

Take care, D