Mailing List Archive Mailing List Archive
Richard Pyle wrote
>There's also the issue of initial bubble growth after switching to 100%
>O2, and the problem of recompressing bubbles trapped in a not-so-damaging
>place, allowing them to lodge in a somewhat-more-damaging place. I'm not
>sure if this is really a serious theoretical problem, after your extremely
>...
>Additionally, if anything other than pure O2 is included in protocols
>(and, all liability issues aside, I believe air/nitrox has a place in some
>IWR situations), then we have to wrestle with the risk of additional inert
>gas loading.
You are thinking of Hyldegaard et al (1991) reporting on studies in which
they injected air bubbles into spinal white matter in rats. They found that
during air breathing all injected bubbles began to shrink and one of them
disappeared and during breathing of heliox (80:20) bubbles constantly shrank
and disappeared from view. In contrast, during breathing of 100% oxygen,
most bubbles initially grew and began to shrink and disappeared at about the
same time after decompression as during heliox breathing.
Stationary bubbles in tissue are not going to move about the place when
recompressed. I can't see that for bubbles in the circulation some slight
regrowth is going to matter much since the DCI process has already begun.
In fact, if they are stuck in the lung, making them bigger may be a good thing.
It takes about an hour for the stationary spinal cord bubbles to start
shrinking during oxygen breathing but this may not matter either if
symptoms don't get worse. Of course the rub is that IWR seems to work,
suggesting that under the circumstances it is being used DCI is more common
than spinal DCS.
I am unaware of any similar studies using nitrox instead of heliox.
/rat
reference
Hyldegaard O, Moller M, Madsen J (1991) Effect of He-O2, O2 and N2O-O2
breathing on injected bubbles in spinal white matter. Undersea Biomedical
Research 18:361-371
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shelps@ac*.ma*.ad*.ed*.au*|Stephen Helps PhD Ack! ___/|
FAX (08)232-3283 |Anaesthesia & Intensive Care \O.o|
Voice (08)224-5495 |University of Adelaide =(___)=
|ADELAIDE, 5005, South Australia U
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's not denial. I'm just very selective about what I accept as reality."
--- Calvin ("Calvin and Hobbes")
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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]