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Message no. 1
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Underwater breathing
Date: Thu, 28 Nov 1996 11:28:42 +1100
Just a thought...

Most marine mammals actually collapse their lungs when they go underwater.
This prevents the problems with resurfacing such as gas expansion or gas
coming out of solution. What if a bioware or cyberware structure could be
developed to do this.

BTW, humans can't do this - collapsing the lungs for a human has disastrous
effects. We're not very good at reinflating them. I know someone is going to
mention babies breathing once they born. But, I'm referring to both the
physical processes referring to the lungs as well as the lack of stimulus
from the nervous system!

Shaman
Message no. 2
From: Glenn Robertson <Glenn.Robertson@***.EDU>
Subject: Re: Underwater breathing
Date: Wed, 27 Nov 1996 21:36:36 -0700
On Thu, 28 Nov 1996, Calvin Hsieh wrote:

> BTW, humans can't do this - collapsing the lungs for a human has disastrous
> effects. We're not very good at reinflating them. I know someone is going to
> mention babies breathing once they born. But, I'm referring to both the
> physical processes referring to the lungs as well as the lack of stimulus
> from the nervous system!

Just FYI, babies before they are born do not have collapsed lungs. The
lungs have some fluid in them. Hence the risk of having babies gestate
for too long of a time, they may pass their first bowel movement in their
amniotic fluid and subsequently end up with some of it in their lungs,
where it remains at birth and causes serious problems. At birth, air
rushes in as the refill after being squeezed somewhat thru the birth
canal.

Just some info.

Glenn
Message no. 3
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Re: Underwater breathing
Date: Thu, 28 Nov 1996 21:56:39 +1100
At 09:36 PM 27/11/96 -0700, you wrote:
SNIP!
>Just FYI, babies before they are born do not have collapsed lungs. The
>lungs have some fluid in them. Hence the risk of having babies gestate
>for too long of a time, they may pass their first bowel movement in their
>amniotic fluid and subsequently end up with some of it in their lungs,
>where it remains at birth and causes serious problems. At birth, air
>rushes in as the refill after being squeezed somewhat thru the birth
>canal.

Yeah, I knew that. Just wanted to keep my email brief. Recall the creation
of the lung surfactant starts during the 28th week from memory... Actually,
a major component of amniotic fluid is recycled fluid from the urinary
system (mesonephros and metanephros) and not really from the gut. Remember
that the gut has to undergo canalization!

Sorry about this anatomical info, I can't help myself!

Shaman

>
>Just some info.
>
>Glenn
>
>
Message no. 4
From: Peter Coxon <coxoff@***.COM>
Subject: Re: Underwater breathing
Date: Wed, 27 Nov 1996 15:17:33 UT
>Just a thought...
>
>Most marine mammals actually collapse their lungs when they go >underwater.
>This prevents the problems with resurfacing such as gas expansion or >gas
>coming out of solution. What if a bioware or cyberware structure could be
>developed to do this.

>BTW, humans can't do this - collapsing the lungs for a human has >disastrous
>effects. We're not very good at reinflating them. I know someone is going >to
>mention babies breathing once they born. But, I'm referring to both the
>physical processes referring to the lungs as well as the lack of stimulus
>from the nervous system!
Just a thought use a internal air tank (cyber) then fill the lungs with liquid
and then go diving, then use the air in the tank to reinflate your lungs???
(flame away I am not quite consious and what I just said might be a loada...)
>Shaman
Tim (ntoo)
Message no. 5
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Re: Underwater breathing
Date: Fri, 29 Nov 1996 12:06:01 +1100
On Wed, 27 Nov 1996, Peter Coxon wrote:
SNIP
> Just a thought use a internal air tank (cyber) then fill the lungs with liquid
> and then go diving, then use the air in the tank to reinflate your lungs???
> (flame away I am not quite consious and what I just said might be a loada...)
> >Shaman
> Tim (ntoo)
>
I thought about this. However, let's envisage this from a physiological
point of view. The alveolar of the lungs (where gas exchange takes place
between air and blood) expand against resistance and surface tension. It
uses surfactant to reduce this and also (most importantly) allow small
alveoli to reinflate before bloating up the larger ones. Removal of
surfactant with liquids has a devastating effect. So, in order to
include this idea, we have to incorporate a surfactant excreting
cyberware as well.

The other problem is the gas mixture. From memory (and name) the O2 gas
tank is pure O2. This has serious ramifications if we were to reinflate
with just O2. Hence, a better "air" mixture is needed. If reinflating at
sea level, then an air mixture can be used. If in an underwater city or
something, then the pressure would require another mixture, to compensate
for the partial pressure of O2. So a helium/oxygen mix could be used.

Anyway, I'm blathering. I hope you get the general idea.

Shaman
Message no. 6
From: Glenn Robertson <Glenn.Robertson@***.EDU>
Subject: Re: Underwater breathing
Date: Sat, 30 Nov 1996 08:41:01 -0700
> > Just a thought use a internal air tank (cyber) then fill the lungs with liquid
> > and then go diving, then use the air in the tank to reinflate your lungs???
> > (flame away I am not quite consious and what I just said might be a loada...)
> > >Shaman
> > Tim (ntoo)
> >
> I thought about this. However, let's envisage this from a physiological
> point of view. The alveolar of the lungs (where gas exchange takes place
> between air and blood) expand against resistance and surface tension. It
> uses surfactant to reduce this and also (most importantly) allow small
> alveoli to reinflate before bloating up the larger ones. Removal of
> surfactant with liquids has a devastating effect. So, in order to
> include this idea, we have to incorporate a surfactant excreting
> cyberware as well.

Ahh, but there already is real liquid mediums to aid breathing. Liquid
Perfluorocarbon Ventilation. Check it out. Being a liquid, the lungs
are still inflated, they don't have to collapse. It was primarily used
in premature infants, but recently it has undergone study for application
for adults as well. Just thought I'd let you know, since I just read
about it again last night at work --- I am a registered respiratory
therapist and it was hanging in our break room. :)


>
> The other problem is the gas mixture. From memory (and name) the O2 gas
> tank is pure O2.
No, it doesn't have to be. You can put any mix you want in there. At
the hospital we have varying mixes. Mostly pure oxygen tanks, granted,
but we have two different heliox varieties, various mixes of regular air
and anesthetic, and for machinery even tanks with oxygen, carbon dioxide,
and nitrogen. So, you can put any gas mix you like in a tank.


> This has serious ramifications if we were to reinflate
> with just O2. Hence, a better "air" mixture is needed. If reinflating at
> sea level, then an air mixture can be used. If in an underwater city or
> something, then the pressure would require another mixture, to compensate
> for the partial pressure of O2. So a helium/oxygen mix could be used.

There is nothing wrong with using pure oxygen in tanks as I recall, unless
you are an infant whereby you can get Retrolental Fibroplasia (RLF) and go
blind like Stevie Wonder. Afterall, many patients at the hospital get
pure 100% oxygen. Also, some patients on ventilators get 100% oxygen,
which is important because they don't get any outside air entrainment.
Oxygen doesn't cause alveolar collapse.

Just my respiratory two cents.

Glenn
Message no. 7
From: Tim Cooper <tpcooper@***.CSUPOMONA.EDU>
Subject: Re: Underwater breathing
Date: Sat, 30 Nov 1996 18:04:27 -0800
On Sat, 30 Nov 1996, Glenn Robertson wrote:

> >
> > The other problem is the gas mixture. From memory (and name) the O2 gas
> > tank is pure O2.
> No, it doesn't have to be. You can put any mix you want in there. At
> the hospital we have varying mixes. Mostly pure oxygen tanks, granted,
> but we have two different heliox varieties, various mixes of regular air
> and anesthetic, and for machinery even tanks with oxygen, carbon dioxide,
> and nitrogen. So, you can put any gas mix you like in a tank.
>
>
> > This has serious ramifications if we were to reinflate
> > with just O2. Hence, a better "air" mixture is needed. If reinflating
at
> > sea level, then an air mixture can be used. If in an underwater city or
> > something, then the pressure would require another mixture, to compensate
> > for the partial pressure of O2. So a helium/oxygen mix could be used.
>
> There is nothing wrong with using pure oxygen in tanks as I recall, unless
> you are an infant whereby you can get Retrolental Fibroplasia (RLF) and go
> blind like Stevie Wonder. Afterall, many patients at the hospital get
> pure 100% oxygen. Also, some patients on ventilators get 100% oxygen,
> which is important because they don't get any outside air entrainment.
> Oxygen doesn't cause alveolar collapse.
>
> Just my respiratory two cents.
>
> Glenn
>

I'm not sure if this applies, as I've not been following the thread too
closely, but I thought that a conventional "air" mix becomes quite lethal
at very high pressure...something about the oxygen concentrations and
pressure - net result is severe damage to the lungs. Thats why they
routinely use a mix with helium for extreme depth excursions. (Please
correct if I'm wrong, I'll try to remember where I read that..)

~Tim
Message no. 8
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Re: Underwater breathing
Date: Sun, 1 Dec 1996 13:13:13 +1100
On Sat, 30 Nov 1996, Glenn Robertson wrote:

> > > Just a thought use a internal air tank (cyber) then fill the lungs with
liquid
> > > and then go diving, then use the air in the tank to reinflate your lungs???
> > > (flame away I am not quite consious and what I just said might be a
loada...)
> > > >Shaman
> > > Tim (ntoo)
> > >
> > I thought about this. However, let's envisage this from a physiological
> > point of view. The alveolar of the lungs (where gas exchange takes place
> > between air and blood) expand against resistance and surface tension. It
> > uses surfactant to reduce this and also (most importantly) allow small
> > alveoli to reinflate before bloating up the larger ones. Removal of
> > surfactant with liquids has a devastating effect. So, in order to
> > include this idea, we have to incorporate a surfactant excreting
> > cyberware as well.
>
> Ahh, but there already is real liquid mediums to aid breathing. Liquid
> Perfluorocarbon Ventilation. Check it out. Being a liquid, the lungs
> are still inflated, they don't have to collapse. It was primarily used
> in premature infants, but recently it has undergone study for application
> for adults as well. Just thought I'd let you know, since I just read
> about it again last night at work --- I am a registered respiratory
> therapist and it was hanging in our break room. :)

Yeah, we were talking about it on NERPS a while back. I believe the US
military is already using it. NB: Movie called "Abyss"
>
>
> >
> > The other problem is the gas mixture. From memory (and name) the O2 gas
> > tank is pure O2.
> No, it doesn't have to be. You can put any mix you want in there. At
> the hospital we have varying mixes. Mostly pure oxygen tanks, granted,
> but we have two different heliox varieties, various mixes of regular air
> and anesthetic, and for machinery even tanks with oxygen, carbon dioxide,
> and nitrogen. So, you can put any gas mix you like in a tank.

My point was that the tank in SR was O2.
>
>
> > This has serious ramifications if we were to reinflate
> > with just O2. Hence, a better "air" mixture is needed. If reinflating
at
> > sea level, then an air mixture can be used. If in an underwater city or
> > something, then the pressure would require another mixture, to compensate
> > for the partial pressure of O2. So a helium/oxygen mix could be used.
>
> There is nothing wrong with using pure oxygen in tanks as I recall, unless
> you are an infant whereby you can get Retrolental Fibroplasia (RLF) and go
> blind like Stevie Wonder. Afterall, many patients at the hospital get
> pure 100% oxygen. Also, some patients on ventilators get 100% oxygen,
> which is important because they don't get any outside air entrainment.
> Oxygen doesn't cause alveolar collapse.

I believe from my physiology and clinical lectures there are. We humans
can handle up to a PO2 of 300mmHg. Any higher, such as under a couple of
atmospheres underwater, would give us severe O2 poisoning. Don't forget
that 10m of water is equal to 1atm pressure.

I know about the 100%O2 at hospital. But these are used in special
conditions where the ventilation/perfusion ratio of the alveoli are
extraordinarily out of whack. You must remember that 100%O2 would repress
the peripheral chemoreceptors. Also, the brain cannot take any large
amount of O2 for any period of time without suffering permanent damage. I
think you are not distinguishing between temporary therapeutic and long
term here. Shadowrunners do not suffer from CAL! :)

Shaman

>
> Just my respiratory two cents.
>
> Glenn
>
Message no. 9
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Re: Underwater breathing
Date: Sun, 1 Dec 1996 13:18:43 +1100
SNIP!
>
> I'm not sure if this applies, as I've not been following the thread too
> closely, but I thought that a conventional "air" mix becomes quite lethal
> at very high pressure...something about the oxygen concentrations and
> pressure - net result is severe damage to the lungs. Thats why they
> routinely use a mix with helium for extreme depth excursions. (Please
> correct if I'm wrong, I'll try to remember where I read that..)
>
> ~Tim
>
Yeah. You see, the partial pressure for O2 has to remain at a high amount
in order for us to take O2 from the air and into our red blood cells in
haemoglobin. We use helium because it is unreactive and does not dissolve
nor change in volume too significantly compared to nitrogen (air is about
80% nitrogen). Hence, helium is a good "carrier" gas for O2 delivery.

I'm cutting this explanation short as I don't want to become to
medicalized here.

Shaman
Message no. 10
From: Josha The Weird <josha@*********.COM>
Subject: Re: Underwater breathing
Date: Sun, 1 Dec 1996 11:14:15 -0500
Tim Cooper wrote:
> On Sat, 30 Nov 1996, Glenn Robertson wrote:
> > > The other problem is the gas mixture. From memory (and name) the O2 gas
> > > tank is pure O2.
> > No, it doesn't have to be. You can put any mix you want in there. At
> > the hospital we have varying mixes. Mostly pure oxygen tanks, granted,
> > but we have two different heliox varieties, various mixes of regular air
> > and anesthetic, and for machinery even tanks with oxygen, carbon dioxide,
> > and nitrogen. So, you can put any gas mix you like in a tank.
> >
> >
> > > This has serious ramifications if we were to reinflate
> > > with just O2. Hence, a better "air" mixture is needed. If
reinflating at
> > > sea level, then an air mixture can be used. If in an underwater city or
> > > something, then the pressure would require another mixture, to compensate
> > > for the partial pressure of O2. So a helium/oxygen mix could be used.
> >
> > There is nothing wrong with using pure oxygen in tanks as I recall, unless
> > you are an infant whereby you can get Retrolental Fibroplasia (RLF) and go
> > blind like Stevie Wonder. Afterall, many patients at the hospital get
> > pure 100% oxygen. Also, some patients on ventilators get 100% oxygen,
> > which is important because they don't get any outside air entrainment.
> > Oxygen doesn't cause alveolar collapse.
> >
> > Just my respiratory two cents.
> >
> > Glenn
> >
>
> I'm not sure if this applies, as I've not been following the thread too
> closely, but I thought that a conventional "air" mix becomes quite lethal
> at very high pressure...something about the oxygen concentrations and
> pressure - net result is severe damage to the lungs. Thats why they
> routinely use a mix with helium for extreme depth excursions. (Please
> correct if I'm wrong, I'll try to remember where I read that..)
>
> ~Tim

Correct. They use a helium/ oxygen mixuture due to the pressure at great
depths. This means that if you don't want to sound like a Chipmunk,
you'd better sub- vocalize.
--
Josha The Weird,
Chairman And Fouder
The Earthdawn Thread Gathers Group
josha@*********.com
Message no. 11
From: Glenn Robertson <Glenn.Robertson@***.EDU>
Subject: Re: Underwater breathing
Date: Tue, 3 Dec 1996 10:22:06 -0700
> I'm not sure if this applies, as I've not been following the thread too
> closely, but I thought that a conventional "air" mix becomes quite lethal
> at very high pressure...something about the oxygen concentrations and
> pressure - net result is severe damage to the lungs. Thats why they
> routinely use a mix with helium for extreme depth excursions. (Please
> correct if I'm wrong, I'll try to remember where I read that..)

Hmm, I can't recall that. I do know that heliox (the mix) can be used to
aid in breathing for patients with severe stiff lungs. They can't move
air as effectively, so it can aid a little bit. This may be exactly
why heliox would be effective in DEEP water, as the pressure of the
surroundings is exerted inward on the thoracic cage, not enabling
deep breaths. Hence, the heliox would move easier into the lungs
for breathing. I suspect that is the reason. If so, the lethality isn't
caused by air under pressure. It is caused by you not being able to
effectively move the heavier gas in and out due to thoracic
constriction. Heliox is also used to enable severely obstructed
(pulmonary-wise) patients to breathe easier as it can get around the
obstructions easier, being lighter.

Hope that helps.

Glenn
Message no. 12
From: Calvin Hsieh <u2172778@*******.ACSU.UNSW.EDU.AU>
Subject: Re: Underwater breathing
Date: Wed, 4 Dec 1996 09:45:03 +1100
On Tue, 3 Dec 1996, Glenn Robertson wrote:

> > I'm not sure if this applies, as I've not been following the thread too
> > closely, but I thought that a conventional "air" mix becomes quite
lethal
> > at very high pressure...something about the oxygen concentrations and
> > pressure - net result is severe damage to the lungs. Thats why they
> > routinely use a mix with helium for extreme depth excursions. (Please
> > correct if I'm wrong, I'll try to remember where I read that..)
>
> Hmm, I can't recall that. I do know that heliox (the mix) can be used to
> aid in breathing for patients with severe stiff lungs. They can't move
> air as effectively, so it can aid a little bit. This may be exactly
> why heliox would be effective in DEEP water, as the pressure of the
> surroundings is exerted inward on the thoracic cage, not enabling
> deep breaths. Hence, the heliox would move easier into the lungs
> for breathing. I suspect that is the reason. If so, the lethality isn't
> caused by air under pressure. It is caused by you not being able to
> effectively move the heavier gas in and out due to thoracic
> constriction. Heliox is also used to enable severely obstructed
> (pulmonary-wise) patients to breathe easier as it can get around the
> obstructions easier, being lighter.

I'm not too sure this is the main reason all the time. You have to
remember that we breathe via a pressure difference gradient between the
ambient air and the pleural pressure. Hence, the density or the increased
pressure of the gas does not have such a significant effect. What it may
differ from is the pressure between the pleural capillaries and the
alveoli. If so, the increased pressure can possibly collapse the
capillaries, preventing proper perfusion of gas. But, I do not think this
is of too much importance, or that it is even true. I'll have to look it up.

Shaman

>
> Hope that helps.
>
> Glenn
>

Further Reading

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