Welcome to the Cave Diver's Forum.
  • Patent Foramen Ovale

    By Brad Starks 2002-11-26

    Normal Circulation

    PFO

    As you can see from the above illustrations, blood normally travels from the body into the right atrium (Venous circulation), then into the right ventricle and to the lungs. From the lungs blood travels to the left atrium and into left ventricle and lastly to the rest of the body. In a normal individual, If a bubble were to form in the venous circulation (i.e. air embolism) it would travel back to the right atrium and into the right ventricle and to the lungs. If the bubble is too large to pass through the pulmonary capillary bed then it would become lodged there and cause a pulmonary air embolism. If it was small enough to pass through the pulmonary capillary bed it would next travel to the left atrium, into the left ventricle, and into the systemic circulation. If the atmospheric pressure continued to decrease the bubble would enlarge and become lodged somewhere en route. It may be in the systemic circulation or it may be in the venous circulation. Where the bubble will lodge is purely dependent on its size and the size of the vessel it is passing through.

    In the case of a PFO, the process is similar. In this case, however, if the bubble formed in the venous circulation and was small enough to continue to the right atrium, it MAY pass into the left atrium and bypass the lungs thereby entering the systemic circulation. If the atmospheric pressure continued to decrease, while the bubble was in the systemic circulation, then the bubble would enlarge and become lodged. If it continued to be small, it would then travel back to the right atrium where again it MAY pass into the left atrium or it may go to the lungs. The point is....in either a normal individual or an individual with a PFO, the bubble will lodge somewhere and cause blood flow to cease thus causing hypoxia.....then anoxia...and finally cell death.

    The possibility of a bubble traveling from the right atrium into the left atrium ( in the case of PFO) is increased only when there is an increase in the right atrial pressure ( as in the case of pulmonary artery atresia, stenosis, or an obstructive lung disease. Normally, even with a PFO, the right atrium has an equal or lower pressure then the left atrium so if anything blood will be forced into the right atrium from the left.

    As you can see, PFO's do not increase the risk of an air embolism. It may have an effect on where the bubble lodges, but the result is the same. I hope this clears up any confusion. If anyone disagrees with my synopsis, please feel free to refer me to a research article that states the contrary. I am always interested in learning new ideas. Thank you!

    Brad Starks MSII
  • Recent Forum Posts

    Germie

    Input on Books needed.

    I got 3 second hand books last week:
    Tom Mount-Mixed Gas Diving. A little bit outdated, but still a nice book, and I dove with Tom.
    Rob Palmer-Deeper into blue holes.
    Guy de Laveur-Caves and...

    Germie 11-21-2017 02:04 PM Go to last post
    rddvet

    Cave CCR certification required at Ginnie Springs

    Such a silly turn. You can make up 50 different calculations but you're never gonna know ginnie's annual income on divers. All you need to know is we arent special cause we're dumb enough to swim...

    rddvet 11-21-2017 12:54 PM Go to last post
    Adler

    Cave CCR certification required at Ginnie Springs

    Far too simple of an analysis to convince me of anything.
    Sure the OW divers matter. Even Intro divers who pay more.
    How many Ann pass holders are out there? I wouldn't even hazard a guess....

    Adler 11-21-2017 12:28 PM Go to last post
    Jim Wyatt

    Cave CCR certification required at Ginnie Springs

    Yes, many times.

    Jim Wyatt 11-21-2017 12:09 PM Go to last post
    Jim Wyatt

    Cave CCR certification required at Ginnie Springs

    Yes, many times.

    Jim Wyatt 11-21-2017 12:08 PM Go to last post
    hunabku

    Green Cove Springs?

    Wow, they really put a lot of effort into making it look even less natural than id did before. Its a really nice facility though. I guess it just makes me sad to see a spring so domesticated.

    hunabku 11-21-2017 11:34 AM Go to last post
    IowaCaveDiver

    Green Cove Springs?

    I just stopped by Green Cove spring on my way through town for work. The renovation of this park and Facilities is absolutely amazing... Definitely worth stopping through especially if you have...

    IowaCaveDiver 11-21-2017 11:22 AM Go to last post
    MORGAN

    Ginnie Fatality?

    My cave DPV instructor (Paul Heinerth) and my mentor on my early DPV cave dives (FW) both emphasized that when you add a DPV to the plan, gas planning needs to become more conservative, not less.
    ...

    MORGAN 11-21-2017 10:54 AM Go to last post
    bullfrog

    Ginnie Fatality?

    rddvet and ofg Both of you have excellent post worth reading, which is more than you can say for most of the rest.

    bullfrog 11-21-2017 10:48 AM Go to last post
    rddvet

    Ginnie Fatality?

    I will say as a new scooter diver (took class a few months ago) that my perception of what a scooter can and can't get me has changed. Going in I thought with a scooter I'd be able to go farther and...

    rddvet 11-21-2017 10:25 AM Go to last post
    OFG-1

    Ginnie Fatality?

    Thanks Ted. My thanks also to all involved with recovery, and condolences to friends and family.

    I have a personal bias against "accident analysis" as its practiced online. It is almost always...

    OFG-1 11-21-2017 10:22 AM Go to last post
    tbone1004

    Ginnie Fatality?

    @nitrogenius, the argument against not being able to go farther on a dpv is hilarious.

    In Ginnie, call it avg depth of 90ffw.
    I budget 5.2cf/100ft for entry, and 10.4cf/100ft for exit when doing...

    tbone1004 11-21-2017 09:34 AM Go to last post