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Originally Posted by cebaztian
I have a feeling that our main problem is:
1) Tracheasqueeze and that the bloodspecks mainly comes from the throat and bloodvessel inbetween (?) the cartilage. The throat I believe goes deeper down into the lungs than we generally percieve as "the throat".
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Yes, Sebastian that is possible, and can be one of the sources of blood spiting, but if diver suffer shortness of breath and his/her pulse oximetry is lower than normal, the problem has to be in other place. The trachea goes a little deeper in the thorax and subdivide in the two main bronchi, the intrathoracic trachea is more affected by pleural pressure, and extra-thoracic trachea by atmospheric pressure. And as You and I said before contractions can reduce dramatically the pressure in the airway, making a big gradient pressure when comparing it with the atmospheric.
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Originally Posted by cebaztian
I do not believe that the small increase of pressure from let say 60-70 causes bloodvessels to break in the alveolis.
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Nobody knows exactly what is the pressure breaking point for stress failure in pulmonary vessels
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Originally Posted by cebaztian
But the chest area is not exposed to vasoconstriction, is it?
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Yes it happens, hypoxic pulmonary vasoconstriction is a reflex mediated by Oxygen reactive species and it produces vasoconstriction in the blood vessels of low oxygen alveoli, when all or most of the alveoli are low in oxygen the reflex can led you to extremely high resistance. Some persons develop extreme vasoconstriction with little exposure to alveolar hypoxia.
About slow descent, it's quite difficult to know the depth where the descent has to be the slowest, the first part where biggest changes in pulmonary volume take place, or the deepest part where the vessels can be reaching the breaking point.
By looking the descent profiles of deep divers like Coste, Stepanek, Nitsch, Nery, Molchanova, the slowest part is the deepest one. And the profile of deep diving mammals like weddell seal, the profile is the same.
Thatīs why I think that a personalized approach is the rule.
