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viperdoc(at)mindspring.co
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 Posted: Wed Jan 18, 2006 4:21 pm Post subject: More Decompression Sickening sickness. |
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Bian wrote, it is the rate of ascent that influences the incidence of Decompression Sickness (DCS).
Although true to an extent I have to disagree. Certainly a rapid decompression at or above FL 250 has an increased risk of developing DCS. It is the gradual lose of cabin pressure over time that has an increased incidence also. As are repeated exposures to altitude to name a few.
The predisposing factors to the developement of DCS are as follows from taken directly from the textbook Fundementals of Aerospace Medicine , pp 137-140.
"Altitude Attained
No reliable evidence exists for the occurence of DCS with altitude exposures of less the 5486 m unless there was a recent (within 24 hours) previous exposure to compressed gas breathing (eg., scuba diving). With increasing altitude, the incidence of decompression sickness increases, as does the ratio of severe to mild cases. Exposures to altitudes of 7925 to 14,478 m for times from approximately 30 minutes to 3 hours will result in a 1.5% incidence of decompression sickness. The severity of the cases will increase with increasing altitude.
In a review of 145 cases of altitude-induced decompression sickness necessitating treatment, Davis and colleagues reported that 13% of the cases occurred with altitude exposres of 7620 m or below and 79% occurred with exposures of 9144 m or greater.
Duration of Exposure
At all altitudes above 5486 m, the longer the duration of exposure, the greater the incidence of decompression sickness.
Temperature
No correlation exists between the frequency of decompression sicness thd the ambient tempperature in the range of 21.1 to 24.3 deg.C. At an ambient temperature of -23.3 deg C, however, the incidence of decompression sickness is twice that at 21.1 deg.C, with a larger ratio of serious cases to mild cases.
Previous Exposure to Altitude
A second exposure to an altitude greater han 5486 m following an exposure to such an altitude in the preceeding 3 hours will greatly increase the chance of DCS occurring, even if the first exposure was asymptomatic. A recurrence of symptoms is almost certain if the first exposure is symptomatic.
A 2-hour exposure to an altitude of 7622 m followed in 18 hours by a rapid decompression from 2439 m to 6707 m will result in detectable Doppler bubble signals over the pulmonary artery. In addition, the incidence of DCS following the rapid decompression will be twice that following the intial altitude exposure.
Repeated daily exposure to altitude have been reported as increasing susceptibility. Interestingly the incidence of DCS in inside observers undergoing two to three altitude exposures per week accompanying students in altitude chamber training was three times greater than the incidence in students.
Flying Following Diving
If an individual breathes a gas at pressures greater than sea level before altitude exposure, his susceptibility to DCS will significantly increase. Altitude DCS has occured at altitudes as low as 1372 m several hours following scuba diving. Any exposure to compressed gas breathing occurring within 24 hours of altitude exposure will increase the chance of altitude DCS.
AGE
A striking increase in the incidence of DCS occures with increasing age. This increase occures with an increase incidence between the 19 to 25 year old and 40 to45 year old age groups. The mechanism is not understood but may result from changes in circulation due to aging.
SEX
A great deal of conroversy exist regarding the posible differences in susceptibility to DCS between men and women. The scientific resolution of this question has been hampered by emotionl and political factors and unfortunately no valid studies have been done.
Exercise
The association between physical exertion and DCS has been well established. The effect of exercise on the incidence of decompression sickness is equivalent to increasing the exposure altitude from 915 m to 1524 m.
Injury
No convincing evidence exist to associate previous injury with DCS. Based on theoretical considerations, however, is is now thought that an acute injury to a joint has increased susceptibilty to the "bends" because of perfusional changes associated with the injury and/or healing mechanisms.
Body Build
For a long time, a basic tenet of diving and aerospace medicine has been that obesity increases the susceptiblity to DCS. Although it seems prudent to continue to accept this principle because of other known adverse effects of obesity, no scientific validation exists.
Other Factors
No definitive results have come from investigations of possible correlations between DCS and such factors as physical fitness, hypoxia , diet, and fluid intake."
And those are the predisposing factors to DCS as textually stated to date. If you are planning on flying your unpressurized spam can at altitudes > Fl 180 and you are fat, between the ages of 19 to 25 or 40 to 45, its cold as hell outside, you have had a previous flight to FL 180 or greater in the past 3 hours, have exercised heavily, been scuba diving in the past 24 hours, injured a joint receintly, and been at altitude for 30 min or longer...You are risk for DCS. Guess some days Shit just happens. Like I tell my personal injury lawyer friends (used quite loosely), "Life is Hazardous to your health"! But if you are in that catagory above an ugly too, you are just SOL. Make your reservation at Pensacola or Brooks now for personal recompression chamber ride.
Draw your own conclusions.
Doc
Roger "Doc" Kemp
viperdoc(at)mindspring.com (viperdoc(at)mindspring.com)
Aint no sound like a Radial
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brian
Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA
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| Posted: Wed Jan 18, 2006 5:39 pm Post subject: More Decompression Sickening sickness. |
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Roger Kemp wrote:
| Quote: | Bian wrote, it is the rate of ascent that influences the incidence of
Decompression Sickness (DCS).
Although true to an extent I have to disagree.
|
Uh, it certainly has an effect when ascending from diving. Why would it
be different when flying?
| Quote: | Certainly a rapid
decompression at or above FL 250 has an increased risk of developing
DCS. It is the gradual lose of cabin pressure over time that has an
increased incidence also. As are repeated exposures to altitude to name
a few.
|
I don't have the stats so I can't argue with you other than to say that
the primary problem is dissolved N2. With time at a lower ambient
pressure and partial pressure of N2 the body will reach a new
equilibrium and decompression sickness becomes far less likely.
But you are going to have to test with subjects that live at a higher
altitude most of the time. In the US you can find people living near
8000' much of the time. They could be a statistically valid sample. You
can also find people regularly living above 12,000' in the Andes. I
wonder if we could get a grant for this.
| Quote: | The predisposing factors to the developement of DCS are as follows from
taken directly from the textbook _Fundementals of Aerospace Medicine_ ,
pp 137-140.
_"_*Altitude Attained*
No reliable evidence exists for the occurence of DCS with altitude
exposures of less the 5486 m unless there was a recent (within 24 hours)
previous exposure to compressed gas breathing (eg., scuba diving). With
increasing altitude, the incidence of decompression sickness increases,
as does the ratio of severe to mild cases. Exposures to altitudes of
7925 to 14,478 m for times from approximately 30 minutes to 3 hours will
result in a 1.5% incidence of decompression sickness. The severity of
the cases will increase with increasing altitude.
|
OK, 5486M is actually 18000 feet. At least we know what units they were
using when they did the initial studies. 7925M is 26,000'. 14,478M is
47,500'. That is above the limit for pressure breathing O2. They sure as
heck aren't talking about sustained time up there.
So they are talking about ambient pressure altitude of 26,000' and
above. I don't think this qualifies as much of a threat to any of us in
our CJs and Yak-52s, even nuts like me who like to fly high and suck on O2.
| Quote: | In a review of 145 cases of altitude-induced decompression sickness
necessitating treatment, Davis and colleagues reported that 13% of the
cases occurred with altitude exposres of 7620 m or below and 79%
occurred with exposures of 9144 m or greater.
|
You know, probably the greatest exposure to this low-pressure
environment comes form hypobaric chamber rides. I would bet that they
get a lot of info from there.
| Quote: | Repeated daily exposure to altitude have been reported as increasing
susceptibility. Interestingly the incidence of DCS in inside observers
undergoing two to three altitude exposures per week accompanying
students in altitude chamber training was three times greater than the
incidence in students.
|
Ah, I see they beat me to it.
| Quote: | *Flying Following Diving*
If an individual breathes a gas at pressures greater than sea level
before altitude exposure, his susceptibility to DCS will significantly
increase. Altitude DCS has occured at altitudes as low as 1372 m several
hours following scuba diving. Any exposure to compressed gas breathing
occurring within 24 hours of altitude exposure will increase the chance
of altitude DCS.
|
Yeah. This is why I don't take divers flying until the next day.
| Quote: | *AGE*
A striking increase in the incidence of DCS occures with increasing age.
This increase occures with an increase incidence between the 19 to 25
year old and 40 to45 year old age groups. The mechanism is not
understood but may result from changes in circulation due to aging.
|
Shoot.
| Quote: | *SEX*
A great deal of conroversy exist regarding the posible differences in
susceptibility to DCS between men and women. The scientific resolution
of this question has been hampered by emotionl and political factors and
unfortunately no valid studies have been done.
|
I volunteer! I will go have repeated sex with women in the hypobaric
chamber to see if it increases my or their susceptibility to DCS! Yes! I
am prepared to make this supreme sacrifice in the name of science!
This is a way for RPA to provide a service to our fellow airmen (and
women)! How many of you will volunteer with me to collect the necessary
data?
| Quote: | *Exercise*
The association between physical exertion and DCS has been well
established. The effect of exercise on the incidence of decompression
sickness is equivalent to increasing the exposure altitude from 915 m to
1524 m.
*Injury*
No convincing evidence exist to associate previous injury with DCS.
Based on theoretical considerations, however, is is now thought that an
acute injury to a joint has increased susceptibilty to the "bends"
because of perfusional changes associated with the injury and/or healing
mechanisms.
*Body Build*
For a long time, a basic tenet of diving and aerospace medicine has been
that obesity increases the susceptiblity to DCS. Although it seems
prudent to continue to accept this principle because of other known
adverse effects of obesity, no scientific validation exists.
*Other Factors*
No definitive results have come from investigations of possible
correlations between DCS and such factors as physical fitness, hypoxia ,
diet, and fluid intake."
And those are the predisposing factors to DCS as textually stated to
date. If you are planning on flying your unpressurized spam can at
altitudes > Fl 180 and you are fat, between the ages of 19 to 25 or 40
to 45, its cold as hell outside, you have had a previous flight to FL
180 or greater in the past 3 hours, have exercised heavily, been scuba
diving in the past 24 hours, injured a joint receintly, and been at
altitude for 30 min or longer...You are risk for DCS. Guess some days
Shit just happens.
|
That is a lot of shit dude!
| Quote: | Like I tell my personal injury lawyer friends (used
quite loosely), "Life is Hazardous to your health"! But if you are in
that catagory above an ugly too, you are just SOL.
|
I bet the ugly part makes it more difficult to get partners for testing
for increased incidence of DCS when having sex at altitude. This is
likely to result in a lower incidence of DCS in ugly men and women.
| Quote: | Make your reservation
at Pensacola or Brooks now for personal recompression chamber ride.
Draw your own conclusions.
|
It has been a long time since I have gotten a chamber ride. Do you know
if they have a chamber at Beale (given the U-2 wing there I bet they
have one) and, if so, whether they give civilians a ride?
--
Brian Lloyd 2243 Cattle Dr.
brian-yak at lloyd dot com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery
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_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery |
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viperdoc(at)mindspring.co
Guest
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| Posted: Wed Jan 18, 2006 7:01 pm Post subject: More Decompression Sickening sickness. |
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Brian wrote,
| Quote: | It has been a long time since I have gotten a chamber ride. Do you know
if they have a chamber at Beale (given the U-2 wing there I bet they
have one) and, if so, whether they give civilians a ride?
|
Brian,
My last chamber ride was at Tyndall, in Panama City, Fl.
The last I knew Beale still had a hyperbaric chamber for support.
They do fly civilians in the AF hypobaric chambers by appointment.
Tomorrow, I will check with Brooks to see where a chamber is close to you.
Doc
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vorchaser(at)hotmail.com
Guest
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| Posted: Thu Jan 19, 2006 8:46 am Post subject: More Decompression Sickening sickness. |
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Before I joined the AF, I wanted to get my High Altitude sign-off in a
P-Navajo. So, to get the physiological training, I went down to Peterson
AFB, paid 25 bucks and they let me go thru the entire course, just like I
have to do now every five years. I remember that they only ran the civilian
course once a quarter.
Smash
| Quote: | From: "Roger Kemp" <viperdoc(at)mindspring.com>
Reply-To: yak-list(at)matronics.com
To: yak-list(at)matronics.com
CC: viperdoc(at)mindspring.com
Subject: Re: More Decompression Sickening sickness.
Date: Wed, 18 Jan 2006 21:00:14 -0600
Brian wrote,
> It has been a long time since I have gotten a chamber ride. Do you know
> if they have a chamber at Beale (given the U-2 wing there I bet they
> have one) and, if so, whether they give civilians a ride?
Brian,
My last chamber ride was at Tyndall, in Panama City, Fl.
The last I knew Beale still had a hyperbaric chamber for support.
They do fly civilians in the AF hypobaric chambers by appointment.
Tomorrow, I will check with Brooks to see where a chamber is close to you.
Doc
|
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viperdoc(at)mindspring.co
Guest
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| Posted: Thu Jan 19, 2006 9:20 am Post subject: More Decompression Sickening sickness. |
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Smash,
Thanks. Have not had a chance to work on setting up the chamber rides yet.
To many "O' by the ways" today!
Doc
| Quote: | [Original Message]
From: Sarah Tobin <vorchaser(at)hotmail.com>
To: <yak-list(at)matronics.com>
Date: 1/19/2006 10:46:32 AM
Subject: Re: More Decompression Sickening sickness.
Before I joined the AF, I wanted to get my High Altitude sign-off in a
P-Navajo. So, to get the physiological training, I went down to Peterson
AFB, paid 25 bucks and they let me go thru the entire course, just like I
have to do now every five years. I remember that they only ran the
civilian
|
| Quote: | > > if they have a chamber at Beale (given the U-2 wing there I bet they
> > have one) and, if so, whether they give civilians a ride?
>
>Brian,
>My last chamber ride was at Tyndall, in Panama City, Fl.
>The last I knew Beale still had a hyperbaric chamber for support.
>They do fly civilians in the AF hypobaric chambers by appointment.
>Tomorrow, I will check with Brooks to see where a chamber is close to
you.
|
| Quote: | >Doc
>
>
>
>
>
>
>
>
>
>
>
>
>
>
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's
FREE!
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