Mailing List Archive

Mailing List: techdiver

Message Display

>
>
>>shifted from head-down to head-up, I was overcome by strong 'cold'
>>narcosis (tunnel vision, paranoia,no sense of time passage).  Not
>>until I ascended to 60 ft did the symptoms go away.
>
>Symptoms of cerebral hypoxia
>
>>I told the University's Diving Safety Officer about this and he thought
>>it was due to what he called 'blood pooling'. As I was decending head
>>down and kicking strongly, the blood vessels in my head constricted
>
>plausible
>
>>to ensure an adequate blood supply to my legs.
>
>Nonsense, blood supply to the brain is always given priority over blood
>suplly to every other organ (except the myocardium).
>
>>When I went head-up
>>the combination of constricted vessels and gravity caused a low
>>blood pressure condition in my head, causing (along with the depth)
>>the extreme narcosis.  Does this sound reasonable or has anyone
>
>Yes, it sounds reasonable.
>
This latter is not reasonable as the effects of venous pooling in 
the legs in a head up position are due to the hydrostatic 
pressure of the column of blood below the heart.  This effect, very 
obvious on land, is conteracted by in water by, among other things,
the increased ambient pressure around the legs compared to the 
heart in the head up position.  I find it hard to belive that 
cerebral perfusion will be compromised.

David Doolette
ddoolette@me*.ad*.ed*.au*

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]