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new theory about risk in freediving (dcs/airtrapping)

Discussion in 'Freediving Training & Techniques' started by wolleneugebauer, Jul 13, 2006.

  1. wolleneugebauer

    wolleneugebauer tekknoapnoist

    Local Time:
    6:05 AM
    by too much packing it will be possible to get an arterial embolism. this symptomatic is calling "airtrapping". I heard roumors that several unnamed freedivers have accidents by this symptoms... after deepdives, after dynamics and dry statics too.

    my incredible theory is:
    many bos after deepdiving are causally by this.

    I viewed a lot of freedivers (incl. micro-bloodspitting or coughing) with symptoms like dcs after deepdives. I thought this wear dsc-symptoms alltimes.

    but now, I dont believe all theories in dcs after deepdives (without scuba/freedive mix).

    why? benjamin franz owns 2 serious expertises from 2 different instituts that his accident was definitiv no dcs. in this expertises you can reasoned: "dsc in freediving is not really possible!" (...or you can dive more than three -130m in less than 4 houres). long times I thougt this expertises wear only good for the insurances, but now I know that fact was not important for this (sorry benjamin!).

    furthermore I know 3 examples that freedivers had symptoms like dsc without deepdives. the symptoms are comming directly after or while performances with over-packing!
    fortunately all symptoms (blindness, hemiplegia, syncope, kaleidoscope viewing, tachycardia etc.) wear gon after 20 minutes...

    a doctor from a german institut of navy told us that the pressure in our lungs while packing will be not possible without micro-ruptures (theoretical).

    since 3 weeks a have new experiences with blood spitting (micro) after statics and dynamics... (and I know I am not the only one) ([ame="http://forums.deeperblue.net/showthread.php?t=66854"]packing and buoyancy[/ame])

    ok, this theory is in opposit off all knowledges in freedivers world. I am not sure and I will not be a scaremonger or a prig. I would like to have a serious discussion about the theory and I will have facts. one of my friends broks his freediving career after his bad "airtrapping" experience (yes, he is anxious!)

    before you think: "wolle is stupid", please think a while about the facts...

    greetings wolle

    my own knowledge in freediving medicin is definitly better than my badly english... (i hope that (?)
     
    immerlustig and DeepThought like this.
  2. naiad

    naiad Apnea Carp Supporter

    Local Time:
    5:05 AM
    Interesting. I don't pack heavily, hardly ever to much more than 100% volume.

    Certainly heavy packing can increase residual volume, not good for deep dives.

    Thanks for sharing, I hope someone with more experience can add to this.
     
  3. laminar

    laminar Well-Known Member

    Local Time:
    5:05 AM
    Hi Wolle,

    Thanks for sharing your theory and ideas about the further dangers of packing.

    I would like to say that based on Eric's recent experiences with DCS on both inhale/packing dives and exhale/FRC dives, that DCS in freedivers is definitely possible.

    But that's another topic altogether.

    Can you explain more about the theory of how exactly the increased pressure causes an embolism? What's the etiology?

    Thanks,

    Peter
     
  4. efattah

    efattah Well-Known Member

    Local Time:
    5:05 AM
    Since July 2005 I have suffered freediving DCS at least 7 times. On the worst occasion I went into the recompression chamber. Upon entering the chamber and going to 18m on 100% O2, my symptoms disappeared.

    This year I was doing nothing but FRC diving, starting each dive with about 4-5L of air. I still suffered DCS at least 4 times (i.e. NO packing, not even full inhale!)

    After analyzing the data, I concluded that the primary risk factor was the ascent rate. Ascending over 1.15m/s, especially in the last 10m, dramatically increased my risk of DCS. With ascent rates of 1.20m/s, I could suffer DCS after just two dives to 40m.

    With this information, I changed my dives to do 'deco stops' in apnea at 6m at the end of each dive. I would ascend at 1m/s, stop at 10m, ascend very slowly to 6m, stop for 5-15 sec, then ascend slowly to the surface. Using this method, I have eliminated my DCS problems, despite doing 'worse' profiles than before.

    When I had DCS, the symptoms I had were:
    - Numbness/tingling on one half of my big toe(s), or thumb(s), or other finger(s), which would occur about 15-20 minutes after getting out of the water (my feet/hands would warm up, become very warm & normal, suddenly part of a finger(s) or thumb(s) or toe(s) would go numb, usually the left or right side)
    - Then, the next day I would get pain in my joints, usually elbows, knuckles, and ankles. These pains would be very annoying, switching between dull aches, and occasional spikes of pain. They would last about 2-3 days.
    - On the worst DCS case, on the next day I became extremely exhausted, so much that I could barely walk.



    I think it is possible to have strange problems from packing, but I think that DCS is also possible. Packing or not packing didn't seem to affect my DCS incidences, therefore it is safe to say that the problems/symptoms I experienced were not caused by packing.

    I also know that many of the spearfishermen who get DCS at the world championships, do NOT pack....
     
  5. wolleneugebauer

    wolleneugebauer tekknoapnoist

    Local Time:
    6:05 AM
    @eric:
    how do you know that your symptons wear dcs and no arterial embolism? they have the same symptoms. an if you are coming to fast with bloodshift from the depht is it not possible to have a "high pressure lung damage" (without packing)?

    two years ago (after the dsc-ulm-workshop), i had "dsc"-symptom very often. since the accident from rasmus (he has the worst experience after a maximum dry packing) i am in doubt about the dcs-theory and ...I had no dcs-problems further... I am diving deeper, longer and ofttimes then before.

    in all cases without bloodshift and without packing have you ever made the bubble-test? (i dont know the right word for that in english. only i know that you can check the size of the bubbles in your blood with a special test).

    do you know benjamin`s expertises? what do you think about this?

    what do you think, what are the reasons for the "dcs"-symptoms without deepdiving?

    sorry, I wouldn’t like to make you angry...
    I would like to have answer. what is my own risk?
    greetings wolle

    and have nobody for that theme in germany (yes I have to learn english, i know)
     
  6. jome

    jome Well-Known Member

    Local Time:
    7:05 AM
    Eric, how much did you dive on those sessions?

    I find if very disconcerting that you would get DCS symptoms even after FRC diving...

    But certainly I think Wolle is onto something. And we've heard before some very disturbing things about extreme packing. My worst experiences have been 2 severe "cardio vagal problem" attacks (for the lack of a better term). Never spat blood and I would be scared witless if I did. But in any case, I try to avoid extreme packing. Besides, recently I've made my depth pb's without packing at all :)

    Who is Rasmus and what happened to him? Is it the same case Sebastian N was describing some time back?

    Scary stuff and it would be nice to have some actual research done into this...
     
  7. bolts

    bolts New Member

    Local Time:
    12:05 AM
    Freaked out!

    I'll add my 2 cents here after my weekend's 'experience'... :head

    Here's the post I made an hour or so after the dive in question:

    [ame="http://forums.deeperblue.net/showthread.php?p=604822#post604822"]Depth, pressure and squeeze - Page 2[/ame]

    It should be noted that all the dives were pulldowns followed by finning back to the surface...the rate of ascent was faster than the rate of decent, which may reinforce some of the ideas in this thread.

    A few hours later my right ear of all things went numb for about 20 minutes. Very freaky. I didn't think much of it at the time, until later that night when I started to really do some poking around the internet after thinking what could have caused it. As well, I felt really fatigued.

    The next day I still felt fatigued, and had very slight tingling in my extremities. I played it safe and checked myself into a local ER with a hyperbaric chamber, in case treatment was needed. After 5 hours of doctors looking over me, they concluded that it probably wasn't DCS, because I was freediving, not using compressed air.

    My experience leads me to believe that there's a lot misunderstood about this phenomena... :head

    I'm still not quite 100% after nearly 48 hours after my dive, there's some slighty achiness in my knee and slight tingling, plus fatigue. I'm hoping these symptoms eventually go away...
     
    Last edited: Jul 31, 2006
  8. Sommerlund

    Sommerlund New Member

    Local Time:
    6:05 AM
    Just a little of my opinion to Wollen...,
    the diving theory I have learned statest that the symptons of DS and AGE are the same, however, after 10 min. you can rule out AGE.
     
  9. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    Hi,

    if you are convinced that you've suffered from dcs (I am not and rather tend to go for the air embolism), you should read the following two articles (if you haven't already done so):

    http://jp.physoc.org/cgi/content/full/537/2/607?ijkey=07968c786bee54f0c91006f88297fc55f7cad094

    http://jp.physoc.org/cgi/content/full/555/3/637

    to give a quick summary:
    gas bubbles which are the cause of dcs can only form from so called gas nuclei which are gas-filled bubble precursors (~1µm) attached to blood vessel endothelium. the amazing thing is that the number of these nucleation sites may be influenced by exercise. In the first article above the most noticeable protective effect of exercise against dcs was seen after a single bout of exercise 20h before decompression (in rats).
    Same thing in humans after a single bout of exercise 24h before decompression (second article).

    so, maybe it is worth a try next time you go free diving. you exercise as described in the second article 24 hour before going down. if you still get dcs symptoms, well that might indicate that dcs may not be the culprit after all and that one has to focus more on the air embolism due to lung squeeze theory, which btw. I find very intriguing. I mean if I hear these blood coughing stories it seems plausible to me that alveolar gas may enter the blood stream even through the smallest ruptures of the alveolar-capillary membrane especially in a hyperbaric condition. Although most of the blood coughing originates from upper respiratory tract vessels I wonder if this may not be an indicator for a possible rupture of the much more fragile alveolar-capillary membrane (0.6 µm). Also, it would be very interesting to see if there is a correlation between blood coughing and the occurrence of dcs symptoms which would also argue for micro air embolisms due to lung squeeze.

    Considering frc-diving, lung squeeze should occur much earlier then in “normal” free diving because sub- residual volume volumes are reached much earlier. However, packing might cause micro ruptures even before going down which, in combination with pressure equalization techniques (valsalva), should worsen the risk for air embolism even more.

    bube
     
    DeepThought likes this.
  10. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    after 10 min of what you can rule out AGE?
    do you have a references for that?

    according to Francis and Denison (Pulmonary Barotrauma, The Lung at Depth, Ed. C.E.G Lundgren and J.N. Miller, Volume 132, page 334-337) one has more or less abandoned to discriminate between the two in favor of a unified diagnosis (DCI) because symptomes and treatment are very similar.

    bube
     
  11. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    I want to withdraw that statement please...:duh

    bube
     
  12. cebaztian

    cebaztian Well-Known Member

    Local Time:
    5:05 AM
    This is what I think is the main reason for lung and/or trachea squeeze. Add prior packing and contractions to the effect of a fast ascent - thats when it happens - at least thats my latest theory after "playing around" with myself.

    http://www.fridykning.se/freediving/features/squeeze.html

    Sebastian
    Sweden
     
  13. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    everybody is way too much afraid of pressures in the lung.
    VOLUME damages the lung NOT PRESSURE!!! at least as long as the pressure in the lung does not exeed the perfusion pressure of the capillaries, specially in the airways (could lead to necrosis of the cells there due to the cut off blood supply resulting in hypoxia - but only after several minutes. this mechanism is also irrelevant in freediving).

    so, in my oppinion, the answer is NO, no high pressure lung damage due to a too fast ascent. even if it takes the shifted blood longer to leave the chest cage again refusing the air in the lung to "claim" its appropriate volume (according to the ambient pressure), the remaining blood still restricts the available volume in chest cage. so ,YES, the gas pressure in the lung may be a bit higher than expected (according to the ambient pressure) because of the "slow returning blood", but this will cause no damage since the higher pressure cannot be translated into a greater VOLUME.
    or, in other words, do you think all trumpet players suffer from lung damage every time they play (or you sitting on the toilet "squeezing one out")?

    italic = wrong info

    in terms of packing, if one assumes that you won't loose or gain any gas volume during your dive (which is not exactely the case) then packing would have already caused lung damage while doing it at the surface.

    as explained above, in my oppinion this cannot be the reason. in terms of trachea squeeze i think it is much more probable that the injury happened during the desend because of developing shear stress of the less compliant trachea structure.

    bube
     
    Last edited: Aug 14, 2006
    DeepThought likes this.
  14. naiad

    naiad Apnea Carp Supporter

    Local Time:
    5:05 AM
    I have thought of that. I'm sure that it is possible to create considerable pressure in the lungs like that. Maybe it is volume and not pressure that causes the damage. Excessive volume could be caused by heavy packing, and then made worse by a fast ascent from depth with no release of air, so the volume is increased suddenly.

    I think it is possible to have a "high pressure lung damage", because changes of pressure cause a sudden increase in volume.

    Lucia
     
  15. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    as I have explained above, a decreasing ambient pressure causes an increase in volume ONLY if the decreasing pressure can be translated INTO a greater volume. normally, your lung will not be damaged when breathing at vital capacity (VC). thus, in the case of the ascending freediver who has not packed, there is NO risk of volume trauma while ascending. However, depending on the compliance of the tissue, a very rapid (abrupt) decrease of pressure with a rapid (abrupt) increase of volume from whatever baseline value may in fact cause ruptures. but I doubt that you can be that fast on ascent considering that the volume/pressure increases/decreases with a factor of 2 as max. on the last 10 meters (if you are healthy and a bit trained, it should be no problem to inhale to your VC in a second or so more than doubling your lung volume in a very short amount of time without causing any damage. the freediving equivalent would be to ascend the last 10 meters in less then a second) .
    please keep in mind that i always refer to a healthy lung. certain pathological situations can of course change the variables (compliance for instances) increasing the likelihood of injury that ,under healthy circumstances, should not occur.

    bube
     
    Last edited: Aug 11, 2006
  16. naiad

    naiad Apnea Carp Supporter

    Local Time:
    5:05 AM
    But the available space may have decreased due to blood shift, so there is still a problem of increased volume for the amount of space available.
     
  17. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    no! since the available (non compressible) space is reduced due to blood shift the air has no other option (cause air IS compressible) than to not increase volume as desired maintaining
    a higher pressure (pressure x volume = constant) even though ambient pressure (water pressure) is already lower. in other words, you now have a relative postive pressure situation (in relation to the baseline
    - the moment after you took your last breath)
    in your lungs, just like the trumpet player. if you wait at the given depth and give the blood time to exit the chest cage
    space becomes available for the air to expand into, thus reducing the relative pressure to zero again.

    so, to rephrase your sentence :
    But the available space may have decreased due to blood shift, so there is still a problem of increased PRESSURE.


    italic = wrong info


    but as already mentioned, pressure is not a problem at all.


    bube
     
    Last edited: Aug 13, 2006
  18. trux

    trux ~~~~~

    Local Time:
    6:05 AM
    Bube, I am afraid you have it wrong. Say you have 5 liters lung capacity at surface, and residual capacity of 1 l. At -50m, the residual capacity is reached, and it is then filled due to the blood shift, further compressing the air in the lungs to the ambient pressure. So far you are right there is no pressure problem (assuming the blood shift really works, and that it works as fast as you descend).

    At -100m, you have only 0.5 l of air in the lungs compressed to the ambient pressure of 10 bars, and the remaining 0.5 l of your residual capacity is filled with blood plasma. So far, so good.

    Now you start ascending, but faster than the reverse blood shift can receive the plasma from the lungs. Let's say you are now at -50m but still have 5 liters of atmospheric air compressed to 5 bars (it means to 1 l), but you also have 0.5 l of plasma in the lungs. Still, there is no problem - it takes all together just 1.5 l - much less than your 5 l lung capacity.

    However, as you ascend to the surface, the air goes on expanding to its original 5 l, but there still may be up to 0.5 l of liquid in the lungs (well, probably less - hopefully some got already absorbed in the meantime). Now you are in real troubles - the pressure is indeed higher than it was originally when you started the descent. The difference would make 10% if no reverse blood shift occurred at all yet in that moment. I hope though that the reverse blood shift is faster, hence the difference would be lower.

    If you packed before the descent, the difference in the lungs volume before and after the dive, hence the difference of surface pressures, would be already quite important and could indeed cause injury or embolism.
     
  19. bubestube

    bubestube New Member

    Local Time:
    5:05 AM
    trux, first of all, I think you are mixing a few things up here. I reckon you mean 5 litres total lung capacity and 1 litre residual VOLUME (or did you mean 1 litre functional residual capacity?). Further, at -100m you have an ambient pressure of 11 bar (11 atm) and your lung (gas) volume will be 0.45 l (you just forgot the 1 atm at sea level).
    But anyway, let's stick to you example cause the numbers are even.

    again, let's pretend you meant 90 and 40 meters. apart from that, I am still with you.

    OK, after having read my previous posts I must admit that they are a bit confusing content-wise (even wrong at some points) - thanks for bringing that up. so let's make it as clear as possible:

    Of course, in your extreme example of (permanent) reduced lung volume at depth (lung volume -0.5 l, the shifted blood), the freediver would have a total lung volume of 5.5 litres (5 l gas and 0.5 l blood) when surfacing. Or, if volume expansion were to be restricted to the 5 l, the diver would have a pressure of around 100 cmH2O in his lungs. In other words, another 0.5 l of space is required. That these 0.5 l can be housed without lung rupture is quite propable. It has been observed that lung packing can inrease VC up to 39% (The Lung at Depth, Ed. C.E.G Lundgren and J.N. Miller, Volume 132, page 576). In your example (VC of 4 l) that would be another 1.59 l, so 0.5 l extra should not be problem. However, this VC increase effect due to packing is in all likelihood achieved partly by blood being driven out of the chest cage. In your example you assume that this will not be the case (or only marginally). I on the other hand think that the rate of blood shift into the chest while descending is similar to the rate of blood shift out of the chest while ascending (because the driving force of this blood shift is pressure difference, negative during descent and positive during ascent). Depending on your heart rate on ascent, this extra blood can be pumped out of the thorax quickly. Besides, it has been calculated that a freediver would take up as much as 700 ml N2 during a single dive to 90 m (page 572, same book - thus DCS certainly an option during extreme and/or repeated freediving). Whatever the exact numbers, you will surface with less than 5 l of air after such a dive because there has been some net N2 uptake. So... in summary, your scenario seems very unlikely to me.

    well... it certainly increases the chance of lung rupture but already while doing it at the surface. Or do you have any references for the slowed down return of the shifted blood during ascent?

    so again:

    VOLUME damages the lung,
    PRESSURE influences haemodynamics (bad enough, I guess packing is responsible for many surface black outs).

    bube
     
  20. Mullins

    Mullins Well-Known Member

    Local Time:
    5:05 PM
    I had a lung function test done the other day at a navy hospital here in Auckland. Packing got me an extra 34%, or 3.6L on top of my VC. Based on this I asked about the possibility of lung overexpansion when returning to the surface (one of the dive docs there is reputedly very experienced and has some, though not much, experience with freedivers). He said it should be a non-event, given that a fair proportion of the gas taken down is used for respiration and not exchanged back into the lungs. I guess it might be an issue if a diver aborted at a shallow depth for some reason then came rocketing back up without using much of his/her oxygen.

    What you say about volume, rather than pressure, damaging lung tissue sounds right (to a layman). One thing - do you know whether residual blood shift would affect the whole lung surface area evenly? If not, 500ml or 1L of residual shifted blood might distort the shape of a lung trying to return rapidly to 139% of its VC, creating damaging volume in the area less affected by blood shift. NB: this is just a thought and is quite probably *******s.