Nitrogen bubbles and air bubbles

[triswebb]

OK, here's the simple version of what happens, from a physiologic standpoint. As previously mentioned, what gas forms an embolism is irrelavent, WHERE the bubble goes is what is important. in the case of DCS bubbles form almoast exculsively in teh venous circulation becuase the gas that forms them is comming out of tissue like muscle, or fat, and blood leaving these tissues enters the venous circulation. The lungs are pretty good at filtering out most bubbles - up to a point. DCS happens when the bubble load in your venous circulation either exceeds the lungs ability to filter, or the bubbles find another way into arteries. Once in the arterial circulation bubbles are forced into ever smaller vessels, ultimately into capillaries where gas exchage with tissues takes place. Sometimes bubbles get stuck here, but not usually. What happens is the bubbles change shape so they can fit through the small capillaries - you end up with thin, VERY long bubbles that interupt the oxygen and nutirient supply of vulnerable tissues like nerves for such a long period (becuase the bubble is so long) that the tissue begins to starve and suffocate (sort-of).

I'll try to attach a picture here to explai things a little better. If this works, it is a photo of blood vessels in the retina of the eye. All the bright white areas are bubbles

OK, I have th photo in a powerpoint slide. I'll try to post it as a jpeg when I get to a computer that can convert it to jpeg format.

Cam

Thank you for this - very informative. I have attatched the picture as a JPEG incase anybody else wanted to take a quick look !

Thanks again,

tristan

 

[Charlie99]

However, in the venous system, vessels get bigger and bigger until you move through the heart and go to the lungs, which are a pretty good filter for bubbles.

DCS happens when the bubble load in your venous circulation either exceeds the lungs ability to filter, or the bubbles find another way into arteries.

One way for bubbles to get into the arterial side is via a PFO defect in your heart, which allows those bubbles to bypass the lung and get into the arterial system.

 

[Rick Murchison]

As has been mentioned, what's in the bubble isn't important so much as where the bubble is and what it does. In AGE we're generally talking about relatively large bubbles that enter directly into the pulmonary circulation via a tear in the lung tissue. The really dangerous ones travel through the pulmonary veins to the heart where they are then pumped out into the peripheral arteries - if one enters a coronary artery, you can get a heart attack; if it's the corotid artery (and the corotid is particularly vulnerable as it comes off the top of the aorta and bubbles like to rise) then you can have a stroke. Either can kill you, quick.
DCS is a different animal. And it isn't the bubbles that form in the veins that are usually the problem, as these are usually easily filtered out in the lungs. Remember, nitrogen diffuses out into all the tissues during a dive - the longer and deeper the dive the more nitrogen gets into the muscle, the bone, the tendons, the nerve cells, the interstitial fluids etc. That nitrogen must be given time during ascent to diffuse back into the bloodstream and be carried away for elimination in the lungs, or it can form bubbles deep in the tissues, where you have a double whammy. First there are the mechanical effects - interference of the foreign body (the bubble) with cellular processes, physical separation of things that ought not to be separated (tiny rips and tears in the tissue), and blockage of things flowing where they ought to flow. Second, the body reacts to the bubble as an invader, producing antibodies, hystamines and chemical agents to attack the foreigner; white cells move in to try to engulf the bubble - and this is a problem because these defensive measures are damaging to our own cells there too. The longer the bubble remains the more damage is done - sometimes even permanent. Timely recompression is important not only to reverse the mechanical effects, but also to get the body to stop its defensive assault.
Rick

 

[triswebb]

As has been mentioned, what's in the bubble isn't important so much as where the bubble is and what it does. In AGE we're generally talking about relatively large bubbles that enter directly into the pulmonary circulation via a tear in the lung tissue. The really dangerous ones travel through the pulmonary veins to the heart where they are then pumped out into the peripheral arteries - if one enters a coronary artery, you can get a heart attack; if it's the corotid artery (and the corotid is particularly vulnerable as it comes off the top of the aorta and bubbles like to rise) then you can have a stroke. Either can kill you, quick.
DCS is a different animal. And it isn't the bubbles that form in the veins that are usually the problem, as these are usually easily filtered out in the lungs. Remember, nitrogen diffuses out into all the tissues during a dive - the longer and deeper the dive the more nitrogen gets into the muscle, the bone, the tendons, the nerve cells, the interstitial fluids etc. That nitrogen must be given time during ascent to diffuse back into the bloodstream and be carried away for elimination in the lungs, or it can form bubbles deep in the tissues, where you have a double whammy. First there are the mechanical effects - interference of the foreign body (the bubble) with cellular processes, physical separation of things that ought not to be separated (tiny rips and tears in the tissue), and blockage of things flowing where they ought to flow. Second, the body reacts to the bubble as an invader, producing antibodies, hystamines and chemical agents to attack the foreigner; white cells move in to try to engulf the bubble - and this is a problem because these defensive measures are damaging to our own cells there too. The longer the bubble remains the more damage is done - sometimes even permanent. Timely recompression is important not only to reverse the mechanical effects, but also to get the body to stop its defensive assault.
Rick

Again, thank you so much for all this valuable information.

Thanks to you all,

Tristan

 

[DepartureDiver]

A bubble is a bubble. As others have said, the content does not matter. Bubbles are also not separated into different kinds such as air, nitrogen, oxygen, or helium. A bubble may contain any of the gasses depending on your breathing mixture, but the off-gassing will not result in different and distinct bubbles such as some being nitrogen bubbles and others being helium bubbles. The gasses will all be combined into one.