+ Reply to Thread
Page 3 of 3 FirstFirst 1 2 3
Results 21 to 29 of 29

Thread: PFO's and CC diving?

  1. #21
    New Member Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell's Avatar
    Join Date
    May 2005
    Location
    New Zealand
    Posts
    683
    Hello Pete,

    I have no problem with the course of investigation etc that you have opted for. However, in the interests of promoting the correct objective interpretation of the results of PFO tests, you cannot be "satisfied" that your episode of decompression illness was caused by your PFO. Many cases of serious "undeserved" DCI occur in divers without PFOs, and it follows that the occurrence of such an event in someone who does have one can never be attributed to the PFO with any certainty. Why am I making a fuss about this? Mainly so that you don't make any assumptions about your future risk being reduced by having the PFO fixed. It may be, but then again it may not. As I have said many times before, commentary on this issue should be made with very careful attention paid to avoid invalid conclusions.

    Warm regards,

    Simon M

  2. #22
    I finished it once, but.. PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS is a name known to all PeteS's Avatar
    Join Date
    Jun 2005
    Location
    New Zealand
    Posts
    562
    Inspiration Vision

    Inspiration Classic

    Quote Originally Posted by Simon Mitchell
    I have no problem with the course of investigation etc that you have opted for. However, in the interests of promoting the correct objective interpretation of the results of PFO tests, you cannot be "satisfied" that your episode of decompression illness was caused by your PFO. Many cases of serious "undeserved" DCI occur in divers without PFOs, and it follows that the occurrence of such an event in someone who does have one can never be attributed to the PFO with any certainty. Why am I making a fuss about this? Mainly so that you don't make any assumptions about your future risk being reduced by having the PFO fixed. It may be, but then again it may not. As I have said many times before, commentary on this issue should be made with very careful attention paid to avoid invalid conclusions.
    Hi Simon,

    Future risks, as always, are unknown. Who knows what tomorrow will bring.

    But in general, I agree with you. I do feel that if it is possible to remove a risk factor, then it should be removed. But as you point out, it is only one risk factor in a whole pile of unknowns, so my present risk factors may or may not have changed. I did however fit the pattern of Bends/PFO's/Deep diving seen by the Doctors at DDRC Plymouth and Shrewsbury in many other divers, and so I still lean towards "the PFO caused my bend" theory.

    Since my bend, and subsequent PFO fix, I have become very aware that decompression diving is not a race to get out the water as soon as possible, but to get out the water safely! Even if I have arrived back on the boat to find all the biscuits gone. Bastards, they know who they are.

    Spending a week in a chamber does tend to help you focus your mind like that.... On the biscuits that is....

  3. #23
    hell is in the details Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T is just really nice Marc T's Avatar
    Join Date
    Sep 2005
    Location
    FRANCE Carcassonne
    Posts
    836
    JOKI/rEVO/HOME MADE

    EDO04 Ray

    Its very difficult to know if a PFO isreally dangerous or not. or if you are safe if you havent PFO
    And certainly a non dangerous PFO can sudenly became dangerous.
    Listen this story of a young lady diving instructor: after several years of serious diving without any problem she suddenly had two very serious DCI problem after a 40 m dive then after two years witout diving an other neurologic accident after the first 20 m dive.
    I see her on echograhy after the second accident, the communication between right and left was so big and the artificial bubbles flow so enormous that you can be sure its impossible she dive again without accident.
    So?? certainly this PFO became lager after several years of diving no?

  4. #24
    New Member Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell's Avatar
    Join Date
    May 2005
    Location
    New Zealand
    Posts
    683
    Hi Marc,

    Since you did not investigate this patient prior to her diving / problems, I don't think you can be "certain" of anything. However, I do agree that the history provides circumstantial evidence of altered behaviour on the part of her PFO over time. Interestingly, I have just spent a week in South Africa with Sandro Marroni (head of DAN Europe). He and several colleagues published a paper in the American Journal of Cardiology earlier this year in which they present data suggesting that the behaviour of PFOs can change over time in divers. If you have not already seen this it would be worth having a read. This is an area of current interest and no doubt it will receive more attention in the near future.

    simon m

  5. #25
    Cave nut!
    Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris is a jewel in the rough Richard Harris's Avatar
    Join Date
    Jul 2005
    Location
    Adelaide, South Australia
    Posts
    174
    rEVO

    KISS, Flex, Satori, Mk15.5, ++

    The natural history of Atrial Septal Defects (ASD's, which are a more "abnormal" form of PFO if you like) is that they grow bigger with age and tend to produce symptoms in patients' 5th decade of life if not detected. There is some evidence to suggest that PFOs also get bigger with age. Some of the autopsy studies I mentioned earlier show smaller numbers of PFO in older subjects, but they tended to be bigger when they did exist.


    So I have a feeling that this may partly explain why some people get a PFO related hit after years of uneventful diving.

    Regarding deco dives vs non-deco dives and DCI risk. I had always held the belief that a well conducted NDL dive has the same incidence of DCI as a well conducted deco dive. Obviously the the risk for a deco dive is higher because the margin of safety is lowered I.e. if you have to bolt to the surface you are far less likely to get away with it. But now I suspect that a deco dive is riskier because of a higher inert gas load and higher bubble grade on doppler (need to check my facts there) so if a shunting PFO is present it would more likely play up. Also we dont dive close the the NDLs whereas we often get pretty close to the curve to get out of the water in a reasonable time with a deco dive. Remember also the prolonged immersion with a deco dive (dehydration, cold, exercise etc). This is all conjecture and opinion on my part.

    To DrMike, I agree coughing, valsalve etc is a bad idea in theory during deco because of potential for shunting. I often catch myself forcefully exhaling on ascent to active the OPV instead of through my nose. Then I sit there and wait for a niggle! After a big dive (say >100m) I imagine the bubbles would be really firing up around the 6m stop.

    Finally a word about DCS in dives less than 10msw. In one survey, 10% of divers with DCS diagnosed at the Hyperbaric Unit in South Australia performed dives to 10m or less. You do not need a PFO for this to happen. But multiple ascents like in fish farm divers and SCUBA instructors helps!

  6. #26
    RBW Member Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike's Avatar
    Join Date
    Feb 2005
    Location
    tokyo
    Posts
    4,504
    Quote Originally Posted by Richard Harris
    To DrMike, I agree coughing, valsalve etc is a bad idea in theory during deco because of potential for shunting. I often catch myself forcefully exhaling on ascent to active the OPV instead of through my nose. Then I sit there and wait for a niggle! After a big dive (say >100m) I imagine the bubbles would be really firing up around the 6m stop.

    !


    This has got me wondering something else;

    When doing O2 flushes at 6m I usually alternately suck out of the loop as hard as I can down to vaccum and exhale before injecting O2.

    Do you thing potentially such a strong alternate bottoming out of the lungs/enhale could also lead to a shunt? or does this action not result in a differential?


    I guess in hindsight there isnt a need for such a strong action anyway.

  7. #27
    RBW Member Gregv is on a distinguished road Gregv is on a distinguished road Gregv's Avatar
    Join Date
    May 2005
    Location
    Tutukaka, New Zealand
    Posts
    34
    Megalodon

    In case anyone was interested in the paper in the American Journal of Cardiology mentioned by Simon earlier, here is the reference:

    Germonpre et al, "Evidence for the increasing patency of the foramen ovale in divers", Am J Cardiol. 2005;95:912-915

    Only small numbers (40 divers, 16 with a history of DCI, 24 without) but this is supposedly the first prospective followup study to document the increase in PFO size in humans using transoesophageal echo.

    As noted by others already, this could be an interesting area of research.

  8. #28
    not RBW staff. EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT's Avatar
    Join Date
    Feb 2005
    Location
    UK, Brighton
    Posts
    2,720
    Classic Kiss

    Sports kiss, dolphin

    Excellent thread guys, particularly for the links/references.

    My contribution in this are could be written on the tip of a fairys... erm.. yeah. Happy to read anyway :)

  9. #29
    A Prismer in Megland Underwaterbear has a spectacular aura about Underwaterbear has a spectacular aura about Underwaterbear has a spectacular aura about Underwaterbear has a spectacular aura about Underwaterbear has a spectacular aura about Underwaterbear has a spectacular aura about Underwaterbear's Avatar
    Join Date
    May 2005
    Location
    Seattle, WA
    Posts
    254
    I had always held the belief that a well conducted NDL dive has the same incidence of DCI as a well conducted deco dive. Obviously the the risk for a deco dive is higher because the margin of safety is lowered I.e. if you have to bolt to the surface you are far less likely to get away with it. But now I suspect that a deco dive is riskier because of a higher inert gas load and higher bubble grade on doppler (need to check my facts there) so if a shunting PFO is present it would more likely play up.
    Hi Harry, I think your new view is the correct one. But understanding how rates vary between these two arbitrary groups (non-deco and deco dives) is very tough and goes to the heart of selection and validation of the so called NDLs using any particular deco model. Interesting to think about - but a bit hard for me right now I have to admit!! Where's my coffee!?

    Cheers

+ Reply to Thread
Page 3 of 3 FirstFirst 1 2 3

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts