Mailing List Archive

Mailing List: techdiver

Message Display

Tom,

The problem is that these bubbles effectively block normal capillary
plug flow.  Plug flow is the phenomenon of red blood cells lining up
behind each other and moving through the capillary in unison. If you get
a tiny bubble forming at a capillary junction or a cross channel it can
physically stop the flow and lead to ischemia in the tissues downstream.
The same thing happens sometimes while filling your gas tank when you
get an air pocket.  At any instant the blood flow in about a quarter of
the vessels is either stppped or sluggish. When you observe
microcinematography of capillary beds you can see this process. Once you
have these bubbles formed you need to both get rid of the bubbles
(shrink them) and try to get oxygen to the tissues deprived of
perfusion.  This is one of the arguments against using the 80/20 mix
because when you really need the o2 at 20 ft you are not getting the
full partial pressure you would get if you used pure O2.

You and Will are of course correct in assuming that there are always
bubbles.  The trick is not to let them get to the point where they begin
occluding flow to sizeable areas of tissue.

Bill

Thomas A. Easop wrote:
> 
> To go off on a tangent to this discusssion momentarily, since micro bubble
nuclei  are
> indeed "an a-priori fact of life" wouldn't it make more sense to include the
10ft/3m 02
> deco stop in your schedule since these "bubble seeds" will then have more
surface area
> to offgass, as oppposed to a higher inner bubble preasure at 20ft/3m?
> 
> Also, Will, do you find the texts of Yount, etc? I still can't find any in
the usual
> places.
> 
> Bill Mee wrote:
> 
> > <snip>
> > > On Mon, 23 Mar 1998, Bill Mee wrote:
> > >
> > > > The more surface area for gas exchange, the better able for the
> > > > system to transport dissolved gas to the alveolar pulmonary circulation
> > > > and hence the critical level of dissolved inert gas, where bubble
> > > > nucleation occurs, can me minimized.
> > > >
--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.

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]