Donating Blood and Skydiving
TY
about donating blood not being a good idea for skydivers. Since I
normally donate blood at least a couple times a year this really
concerns me. I had never given it much thought before as I always
thought you were fine after a day or two, but I guess that although the
volume is replaced the oxygen carrying capacity is not. According to 1
post, "After giving blood, the volume is rapidly replaced, but the
oxygen carrying capacity is not. Giving a pint of blood may reduce the
oxygen carrying
capacity by over 10%. This will not matter to you at ground level but
may
make a big difference to how well your skydive goes at altitude. Most
blood
donors restore their blood to near to predonation levels within a few
weeks
but a minority may take several weeks (the slowest being small framed
people
with diets low in iron, particularly women with heavy periods)."
Has anyone heard this before? If it's true I'm surprised they don't
mention it when you donate or at the DZ especially in one of those
paragraphs in the waiver that each have to be individually initialed.
Does anyone else donate blood still and if so, do you wait a certain
amount of time before skydiving again?
Thanks,
TY
ocon...@slr.orl.lmco.com
I used to donate every 8 weeks practically to the day. But
I always donated before or on Wednesday. My personal perception
was that the effects were gone in 3 days. I noticed it more
in the running I did back then than in the skydiving.
Folks react differently to blood donation. I knew a small
group of folks like myself at one time at the company I worked.
Some had to do the whole "drink juice, eat a cookie" etc after
donating. I didn't ever notice anything unless I tried
to jog in the next 2 days (about 6 miles). By the third day
the effects were unnoticable to me.
The magnitude of the effects are going to be fairly personal.
It will have alot to do with what kind of shape you are in,
and what kind of diet you have. If you haven't noticed
anything to date, you're probably not at much risk. Your
diet that day probably affects you more.
Kevin O'Connell
Sent via Deja.com
http://www.deja.com/
kallend
If you're really concerned, see if you can borrow a pulse oxymeter
(quite a few pilots have them). Take an observation ride to altitude and
see how your blood oxygen levels behave after donation. Better advice
still - consult an aviation medical specialist.
In article <3A76CF7E...@net1plus.com>,
TY <ddoh...@net1plus.com> wrote:
--
jsk
145265
dances with clouds
My veins are soooooo small that I am not a candidate. Usually I
have to be poked by a anesthesiologist using a *really* small
needle, and even then I often have to get it in the wrist, center of the
arm below the elbow, foot, etc. etc.
Obviously I don't have a clue about the effects personally, but I
*would* surmise that it's a definite no-no if you combine it with
smoking...
Dances
--
Mark_Harju
morning, and people passing out in formation in the afternoon. I felt a
little fuzzy myself, and that was when I was young and very fit (19
years old), and that was only mile-hi altitude. I'd sure wait a day or
so after donating.
--
Opinions expressed are not
necessarily those of the
Boeing Company. Please
remove "NO-SPAM" to
reply. Thanks!
Jennifer Richter
get me the first time. Sometimes they have to have a second person get the
needle in.
JIMJUMPER
A lot depends on your weight. It is obviously harder on someone that weighs 120
pounds vice someone like me that weighs 190. I also do a bit of running and
again, I am usually back up to speed in a couple days. Also if you smoke it
will aggravate the effects at altitude.
TY
> When I was stationed at Lowry AFB in Denver, we had donations in the
> morning, and people passing out in formation in the afternoon. I felt a
> little fuzzy myself, and that was when I was young and very fit (19
> years old), and that was only mile-hi altitude. I'd sure wait a day or
> so after donating.
Well I'd definitely wait a day or two. I have no problem with that as it
makes sense, but these posts on the UK were saying you had to wait at least 6
weeks and even going so far as to say skydivers should never donate. It just
seemed extreme to me and I had never heard anything like this before so wanted
to find out more.
Thanks,
TY
TY
> Ah, to be able to donate blood!
>
> My veins are soooooo small that I am not a candidate. Usually I
> have to be poked by a anesthesiologist using a *really* small
> needle, and even then I often have to get it in the wrist, center of the
> arm below the elbow, foot, etc. etc.
I have really tiny veins, too, and usually end up with bruises all over my
arm from botched attempts and sometimes they can't get enough. When I got
bit by a cat last year and got a raging infection, I had to go in the
hospital for IV antibiotics. It took them over 4 hours and 5 different
people trying before they got an IV line running. I'd rather never give
again but I have O negative blood, which is the universal donor and they are
always short and looking for some, so I like to try anyway.
> Obviously I don't have a clue about the effects personally, but I
> *would* surmise that it's a definite no-no if you combine it with
> smoking...
I don't smoke. Never have. I did have one nurse insist I was lying to her
though as she said I couldn't have such crappy little veins if I didn't.
(Bitch!)
If I find out any more about this I'll post it.
TY
freefl...@my-deja.com
kallend <jkal...@my-deja.com> wrote:
>
>
> If you're really concerned, see if you can borrow a pulse oxymeter
> (quite a few pilots have them). Take an observation ride to altitude
and
> see how your blood oxygen levels behave after donation. Better advice
> still - consult an aviation medical specialist.
>
that your blood(Hb) is saturated with blood. Thus with a reduced
concentration of Hb (ie post donating) the Sa02 will not be affected at
ground level. Changes at Altitude are variable but taking Obs ride would
be interesting but take an O2 cylinder with you;)
The best way to tell about what your blood Hb is doing is to get a CBC
done. On the uk.rec discussion people were pulling all sorts of "facts"
out of their memory. Some right some wrong. So here we go with some
facts as I understand them.
Post donation:
The volume of your blood is returned to normal within 24hrs, but not the
constituant parts of the blood, ie Hb. This is what is required to
transport O2. The $64,000 is how long does this take to return to
normal, or when can I jump. There is no exact answer to this. It depends
on a multitude of things. For example: The bigger you are, the fitter
you are, the quicker you will recover. Chaps recover quicker than Girls.
Also depends on what height you are going to, height of DZ above
sealevel, a number of things. Because they variability and the risks
involved no-one will officially say "you can jump x days after donating"
so they say don't donate. BUT.
I think that 10-14 days should cover most normal people easily, as being
able to jump you need to be semi fit. But if you feel bad on the 14th
day obviously don't jump, wait a little longer, also if you get to 'tude
and feel shit, go down with the plane. another thing to consider is
plasmaphoresis. leave 2 days post plasmaphoresis then you should be fine
to jump.
Obviously if you aren't normal shape and size(esp small women) you might
want to leave it longer, or not donate at all.
Hope this helps,
Paul
Brien K. Meehan
never
> get me the first time. Sometimes they have to have a second person get the
> needle in.
What good would getting the needle in a second person do? Isn't it YOUR
blood that they're trying to get?
ljs...@hotmail.com
with this, here's the scoop: using one needle, they take out whole
blood, separate it into plasma (the liquid part of blood) and cells.
They keep the plasma and give the cells back to you. Since it's the
red cells that have hemoglobin (the part that carries oxygen), you're
oxygen carring capacity isn't reduced. Problem solved.
Deg
entitled "Recommended Minimum Student Performance Standards" it says:
Before all skydives:
[Student] Has not participated in scuba diving (environment at higher
than atmospheric pressure) or donated blood recently.
We all know about scuba diving, but this was the first I'd heard about
donating blood. I was also a bit suprised I hadn't been aware of it
sooner. Seems like a sensible precaution.
Darin
crwmike
body
tissues during light to moderate work loads. In addition, the body's
compensatory
mechanisms are abundantly capable of dealing with a 500cc blood volume
loss (assuming you weigh
more than 50 kg).
Hypoxia is a state of oxygen deficiency in the body which is sufficient
to cause an impairment of function. Hypoxia is caused by 1)the
reduction in partial pressure of oxygen, 2)inadequate oxygen
transport, or 3)the inability of the tissues to use oxygen. Blood
donation
has nothing to do with 1 and 3 and only affects the second one at severe
work loads
(e.g. running six miles).
As for people getting light headed and passing out after donating blood,
I suspect
there are emotional factors at play. I've seen several people pass out
before they donate.
Most people would have no problem skydiving several hours after donating
blood. There is
no physiological reason why virtually any reasonably healthy person
would be limited a week later.
Kallend's suggestion of using a pulse oxymeter as a measure of the
effect of blood donation is amusing.
People who lament they have the 'small vein gene', are almost always
people who have spent their lives
avoiding virtually any cardiovascular activity and/or have major layers
of fat over them (making it difficult to see a vein). In my experience
they have usually been women and are also identified (after age 35) by
that sagging, swaying bag of loose skin hanging from the triceps area.
Blue Skies and oxygen rich red blood,
Michael
D-6139
TY
> People who lament they have the 'small vein gene', are almost always
> people who have spent their lives
> avoiding virtually any cardiovascular activity and/or have major layers
> of fat over them (making it difficult to see a vein). In my experience
> they have usually been women and are also identified (after age 35) by
> that sagging, swaying bag of loose skin hanging from the triceps area.
Oh, bullshit! I have always been very active. I'm involved in a lot of
outdoor activities and sports and always taken aerobic or cardioboxing
classes, too. I do not have major layers of fat nor do I have swaying bags of
loose skin hanging from my triceps and I am over 35. I doubt the other women
that mentioned small veins on here are as you described either. Also, I draw
blood from dogs and cats every day and in my experience the fat ones have the
easiest veins to find. They have nice plump ones. Another factor is how well
hydrated a person (or pet) is. Plus, I have found that a skilled nurse can get
a vein without much trouble. The problem is finding someone with good skills.
TY
crwmike
TY wrote:
>
> Oh, bullshit! I have always been very active. I'm involved in a lot of
> outdoor activities and sports and always taken aerobic or cardioboxing
> classes, too. I do not have major layers of fat nor do I have swaying bags of
> loose skin hanging from my triceps and I am over 35.
MEOOOWWWW!
In the absence of severe peripheral vascular disease and eating
disorders, any mild to moderate regular exercise of the arms will
produce abundant veins just begging for a needle. There are occasional
exceptions.
> I doubt the other women
> that mentioned small veins on here are as you described either.
Other than the fact that you are just pissed, do you have any data to
back up this conclusion?
> Also, I draw
> blood from dogs and cats every day and in my experience the fat ones have the
> easiest veins to find. They have nice plump ones. Another factor is how well
> hydrated a person (or pet) is. Plus, I have found that a skilled nurse can get
> a vein without much trouble. The problem is finding someone with good skills.
I bow to your experience ...in discussing venipuncture on cats and
dogs. Fat people have nice plump veins
also (you build up muscle or fat, the body must provide a vascular
system to feed them)...it's just difficult to see or palpate them. Out
of curiosity, what is your height and weight?
Michael
dances with clouds
>People who lament they have the 'small vein gene', are almost
>always people who have spent their lives
>avoiding virtually any cardiovascular activity and/or have major
>layers of fat over them (making it difficult to see a vein). In my
>experience they have usually been women and are also identified
>(after age 35) by that sagging, swaying bag of loose skin hanging
>from the triceps area.
HEY!!! I RESEMBLE THAT REMARK!!!! My sagging, swaying bags
of loose skin hanging from my triceps area have saved me a
FORTUNE on camera suits! But even when I was a young girl,
before I grew to be a giant sky-cow, I STILL had little bitty veins!
And so did my mum. And my sisters.
So there.
"NANNY NANNY POO POO!!!"
DWC
0:-P
Ron Luke
best go with Dr. John Carter's advice. He is an experienced skydiver and
medical doctor, in fact the British Parachute Association Medical Adviser.
The prominent advice that I remember is that if you wish to skydive, do not
donate. He did go into it a bit more, if you want to check it out:
http://x59.deja.com/getdoc.xp?AN=718056032.1&CONTEXT=980906105.171704368&hit
num=5
I think that the relative proportion of skydivers to general population in
the UK are likely to apply just as well in the US; they won't miss your
contribution.
freezinnutzoff,
Ron
"TY" <ddoh...@net1plus.com> wrote in message
news:3A76FBB7...@net1plus.com...
D16842
>> People who lament they have the 'small vein gene', are almost always
>> people who have spent their lives
>> avoiding virtually any cardiovascular activity and/or have major layers
>> of fat over them (making it difficult to see a vein). In my experience
>> they have usually been women and are also identified (after age 35) by
>> that sagging, swaying bag of loose skin hanging from the triceps area.
>
Wow Mike! That troll is worthy of one of Goatboy's best! Keep the count as it
goes! As for the other issue of your recent absence, it has been my experience
that married men are far more aware of the potential of an ALF female, and have
correspondingly better hiding skills. :)
Tom B
D16842
>Hi TY,
>best go with Dr. John Carter's advice. He is an experienced skydiver and
>medical doctor, in fact the British Parachute Association Medical Adviser.
>The prominent advice that I remember is that if you wish to skydive, do not
>donate. He did go into it a bit more, if you want to check it out:
>http://x59.deja.com/getdoc.xp?AN=718056032.1&CONTEXT=980906105.171704368&hit
>num=5
Not having my old military documentation around here to quote, lets move this
argument to a common sense approach. Next time you are orbiting the DZ on a
hold of some kind at 15K or so, look around the plane. You will see some people
start to show hypoxia symptoms reasonably quickly. Talking in general, always a
dangerous undertaking, women are more quickly/seriously impaired than men.
Smokers are more quickly impacted than non. I recally reading that the
"average" smoker is already in the hole more than 10% just from residual CO
levels in the blood, then add lung damage to that if it applies as well.
Overall health and physical conditioning count as well. Reduced hemoglobin has
to play a role, even if small.
Now combine the factors that apply to you and you have to accept the premise of
a general risk increase. Read up on hypoxia (someone had a great post months
ago that I wished I had saved) and consider how it applies to you.
Not wanting to miss any opportunity to bring up CYPRES, some here on the NG
beleive you can just gut it out and stay alert if you want to badly enough.
While that argument has some merit too, just remember one of the first
limitations of hypoxia is a severe lack of judgement of one's level of
impairment, followed by a reduction in physical abilities.
I have to believe Ron and Doc Carter have a solid position in this argument.
The degree is different with each person.
Tom B
Ron Luke
"D16842" <d16...@aol.com> wrote in message
news:20010130220954...@ng-fk1.aol.com...
I heard a common sense argument from an extremely experienced skydiver (who
also happens to smoke like there's no tomorrow), that heavy smokers tend to
suffer less from hypoxia (I guess, provided they've left off the smokes
prior to jumping), because their bodies are used to coping with low oxygen
availability.
>
> Now combine the factors that apply to you and you have to accept the
premise of
> a general risk increase. Read up on hypoxia (someone had a great post
months
> ago that I wished I had saved) and consider how it applies to you.
>
> Not wanting to miss any opportunity to bring up CYPRES, some here on the
NG
> beleive you can just gut it out and stay alert if you want to badly
enough.
> While that argument has some merit too, just remember one of the first
> limitations of hypoxia is a severe lack of judgement of one's level of
> impairment, followed by a reduction in physical abilities.
>
> I have to believe Ron and Doc Carter have a solid position in this
argument.
> The degree is different with each person.
Nothing to do with me, I'm not a medical doctor. I just pointed out that
Doc Carter has some valid opinions, worth taking on board.
>
> Tom B
ljs...@hotmail.com
> a vein without much trouble. The problem is finding someone with
good skills.
You're half-way right. A skilled nurse can get blood out of just about
anything, but there has to be a vein there to hit. I'm a nurse, and a
pretty good phlebotomist, but people with shitty veins are why art
lines were invented.
I talked to one of our attendings last night at work, and her comment
was that anyone in decent shape wouldn't miss a pint of blood from the
5 liters that we have flowing through us, and that giving blood
shouldn't make your crit drop significantly at all.
kallend
crwmike <crw...@Bellsouth.net> wrote:
>
>
> Kallend's suggestion of using a pulse oxymeter as a measure of the
> effect of blood donation is amusing.
>
Well, you're the expert. I'm curious as to why a situation where the
metabolic demand for O2 remains but the transport system is compromised
would not result in a measurable change in saturation levels. This would
be expected behavior in a chemical system. Has the experiment actually
been done or are you just opining?
--
jsk
145265
crwmike
issued by a stale bureaucracy. He sums it up best when he says:
"It is extremely unlikely that either the BPA or the BTS will attempt
to write a formal protocol to regulate how to be both a blood donor and
a skydiver. It would involve each organization in regulation and legal
liability in areas where they have limited knowledge, little to gain and
a lot to lose if something went wrong."
There is no medical justification for such a conclusions. Working from
an admitted position of ignorance, they support a ban to cover their
asses. It is this mentality that will eventually provide the impetus to
mandate an 'approved' AAD for all skydivers.
D16842 wrote:
kallend
freefl...@my-deja.com wrote:
> In article <956nbf$648$1...@nnrp1.deja.com>,
> kallend <jkal...@my-deja.com> wrote:
> >
> >
> > If you're really concerned, see if you can borrow a pulse oxymeter
> > (quite a few pilots have them). Take an observation ride to altitude
> and
> > see how your blood oxygen levels behave after donation. Better
advice
> > still - consult an aviation medical specialist.
> >
> Nice idea, but Pulse Ox only measures Percent SaO2. ie the percentage
> that your blood(Hb) is saturated with blood. Thus with a reduced
> concentration of Hb (ie post donating) the Sa02 will not be affected
at
> ground level. Changes at Altitude are variable but taking Obs ride
would
> be interesting but take an O2 cylinder with you;)
>
Would you expect an observable effect?
When Kevin Uliassi made his attempt to fly an unpressurized balloon
around the world last year (http://j.renee.iit.edu) he spent several
weeks beforehand sleeping every night in an altitude chamber. He
increased his blood count by something like 25% (I can get the exact
number from him if anyone is interested). He wore a pulse-ox during the
flight, and maintained essentially normal saturation to 18,000ft. He did
not need to wear oxygen mask until 24,000ft, and when his oxygen system
failed (regulator blew) at 32,000ft he was able to manage a controlled
descent to 24,000ft without passing out. Although he didn't make it
round the world, it was the longest duration solo flight ever made
(over 10 days), and the longest ever unpressurized flight above
24,000ft.
The web site has photos of him working outside the gondola at 22,000ft
without a mask.
Anyway, bottom line - INCREASING his hemo resulted in increased O2
saturation levels at high altitude. Why would you not expect the inverse
to happen with reduced hemo?
--
jsk
145265
David TK Hayes
donate platelets every 2 weeks, have been for years,
TK
"TY" <ddoh...@net1plus.com> wrote in message
news:3A76CF7E...@net1plus.com...
crwmike
compromised. Convenient for debate but lacking in science.
I assume you are referring to a drop in hemoglobin (since the volume
loss is pretty much immediately taken care of by a virtual army of
compensatory mechanisms and baroreceptors ...and completely replaced in
roughly a day). How much of a drop have you measured after donating
blood (assuming you are basing your 'compromised' theory on actual
data).
Free oxygen, the plant kingdom's unique gift to this planet, is a highly
reactive, dangerous substance capable of laying waste the
delicate molecules that form the basis of life. How peculiar that we, as
aerobes, have traded the security of a languid existence in a reducing
milieu for the high-stakes, fast-lane life of free-flowing ATP, the dear
currency that gives us the strength, speed, and mental facility to
profoundly alter our world. Aerobic respiration, for all the complexity
of the chemical reactions of intermediary
metabolism, simply boils down to the body's need to find something to do
with the spare electron left over from the destruction of
the glucose molecule. This orphaned lepton, bereft of binding energy by
its repeated violation at the hands of the cytochrome
gantlet, finds no comfort in the carbon dioxide rubble of its former
hexose home. Should it not find the succor of oxygen, it would
escape to a feral existence of unsavory chemical reactions, where it
would find itself in the company of the opprobrious Free
Radicals, miscreants whose only purpose is the steric vandalism of the
macromolecular cathedrals of life.
It has been said that all damage to the body from any pathologic state
in the end is caused by hypoxia at some level. If this is true, the
story of pathology is the story of hypoxia. Preventing or correcting
hypoxia is then the ultimate goal of all medical specialties.
Pulmonologists and cardiologists deal with hypoxia at the gross
mechanical level, but hematologists do so at the finer cellular and
molecular levels. The physicochemical properties of hemoglobin and
biochemical housekeeping in the erythrocyte are both in their purview,
but what hematologists contend with at the grossest level is anemia.
So, what does the body do to compensate for the approximate 500ml volume
loss and very slight hemoglobin loss resulting from donating blood?
Well, it does several things, quickly and automatically:
1.Decreased hemoglobin oxygen affinity
Increased oxygen extraction of anemic blood by the tissues produces
increased concentration of deoxyhemoglobin in the rbc,
which stimulates the production of 2,3-diphosphoglycerate (2,3-DPG).
2,3-DPG shifts the hemoglobin-oxygen dissociation
curve to the right, thus allowing the tissues to more easily strip
the hemoglobin of its precious electron-accepting cargo.
2.Redistribution of blood flow
In anemia selective vasoconstriction of blood vessels subserving
certain nonvital areas allows more blood to flow into critical
areas. The main donor sites who sacrifice their aerobic lifestyle
are the skin and kidneys. Shunting of blood away from
cutaneous sites is the mechanism behind the clinical finding of
pallor, a cardinal sign of anemia. Although the kidney can
hardly be thought of as a nonvital area, it receives (in the normal
state) much more blood flow than is needed to meet its
metabolic requirements. Although (by definition) total body red cell
mass is decreased in anemia, in the chronically anemic
patient the total blood volume paradoxically is increased, due to
increased plasma volume. It is as if the body were trying to
make up in blood quantity what it lacks in quality.
3.Increased cardiac output
The heart can respond to tissue hypoxia by increased cardiac output.
The increased output is matched by decreased peripheral
vascular resistance and decreased blood viscosity (thinner blood
flows more freely than thick blood), so that cardiac output
can rise without an increase in blood pressure. Generally, anemia
must be fairly severe (hemoglobin < 7 g/dL) before cardiac
output rises.
Here's a project for you. Wear your pulseoxymeter and check the reading
before giving blood (FYI: normal for a otherwise healthy non-smoker is
>98% and >95% for a otherwise healthy smoker). Now check it after giving blood (hell, wear it while you are giving blood). You won't see any changes. If you are in a hurry and don't want to wait for the blood donation center to open, you could just sever a vein and bleed out 500 ml.
One reason is that shining a light through the end of your finger is a
pretty crude way of approximating oxygen saturation. It takes some
pretty 'crude' changes, however, to make *any* difference in normal body
function.
I'll leave the opining to the ALF's of the world.
Michael
D-6139
kallend
crwmike <crw...@Bellsouth.net> wrote:
> Your premise contains the conclusion that the transport system is
> compromised. Convenient for debate but lacking in science.
> I assume you are referring to a drop in hemoglobin (since the volume
> loss is pretty much immediately taken care of by a virtual army of
> compensatory mechanisms and baroreceptors ...and completely replaced
in
> roughly a day). How much of a drop have you measured after donating
> blood (assuming you are basing your 'compromised' theory on actual
> data).
>
Enlightening article snipped. I'm not debating, I'm trying to learn
something by asking questions.
The premise of the original question was the effect at altitude, not the
effect at sea level. I'd like to know if blood donation effects oxygen
saturation at altitude, where the O2 partial pressure is lower. It is
naive to say that the transport mechanism is not compromised when the
hemoglobin content in the blood is reduced. The fact that compensatory
mechanisms as you describe are established indicates that the body is
responding to a reduced oxygen transport efficiency.
Tibetans, Nepalese, Bhutanese and others who live at very high altitudes
have increased hemoglobin in the blood. Since this raises their risk of
heart attack and stroke, why does it happen unless there is some benefit
that outweighs this risk? Mountaineers can achieve the same result by
spending several weeks at altitude.
I know for a fact that long distance balloonist Kevin Uliassi maintained
"normal" O2 saturation levels (as measured by pulse-oximeter) to about
18,000ft after he spent a month acclimatizing to altitude, and he also
had a significant rise in his red blood cell count. Are you suggesting
that these are unrelated?
shr...@my-deja.com
Nerd alert! Another long technical post (yawn)
In article <9595k1$9mg$1...@nnrp1.deja.com>,
kallend <jkal...@my-deja.com> wrote:
> Well, you're the expert. I'm curious as to why a situation where the
> metabolic demand for O2 remains but the transport system is
compromised
> would not result in a measurable change in saturation levels.
Mike's right:
The value on a pulse oximeter reflects the percent of hemoglobin in the
blood that is carrying oxygen (hemoglobin is the stuff in red blood
cells that allows them to carry oxygen). A pulse oximeter is basically
a spectrophotometer. Since the hemoglobin molecule undergoes a
structural change when it takes on oxygen, oxygenated hemoglobin has a
different absorption spectrum than deoxygenated hemoglobin. The device
can determine the relative percentages of oxy- and deoxyhemoglobin by
measuring at two different wavelengths.
Because it only tells you the percent of hemoglobin that's carrying
oxygen (or that is "saturated"), a pulse oximeter doesn't tell you
anything about the concentration of hemoglobin. A red blood cell is
really just a little bag of hemoglobin, so for the purposes of this
argument, hematocrit (or red blood cell concentration) is equivalent to
hemoglobin concentration.
Oxygen carrying capacity is the dependent on hemoglobin saturation and
the amount of hemoglobin in the blood (of course there are other
variables, but this is roughly true in a healthy person). Since blood
donation depletes the total amount of hemoglobin in your blood without
changing the ability of each hemoglobin molecule to carry oxygen, it
will change oxygen carrying capacity (of the blood as a whole) _without_
changing the percentage of hemoglobin that's carrying oxygen. Thus, it
won't change the number you read on a pulse oximeter.
As for data or experimentation to back this up, it's seen in patients
with anemia and in trauma, where over-dependence on pulse oximetry are
recognized pitfalls.
You may also be right:
A reasonably healthy person can compensate for this change in carrying
capacity pretty easily, primarily by increasing their heart rate. The
potential problem is when you put further stress on the system. Flying
at 13,000 feet decreases the partial pressure of oxygen in your lungs
and potentially decreases your oxygen saturation. This _would_ change
the readout on a pulse ox.
I've never carried a pulse oximeter to altitude, so I'm not sure how
high you'd have to climb to actually see a difference on the device. If
I remember correctly, 10,000 feet is where the hemoglobin saturation
curve starts to fall off, but that may or may not be true for a given
individual. There are numerous compensatory mechanisms within
hemoglobin that will affect this. And then there's the question of just
how accurate a pulse ox is, and where the drop becomes significant
enough to register.
As to whether the data that a pulse oximeter would give you is useful in
this situation...if you're in reasonable shape you will probably still
be able to compensate for a small change in oxygen saturation even after
donating blood. What altitude you start to have trouble at is going to
be a pretty individual thing, depending on how big you are (losing a
unit of blood lowers a big person's hemoglobin concentration less), your
degree of cardiovascular conditioning (affects your ability to
compensate), how well hydrated you are (also effects your ability to
compensate), whether you were anemic to start with, and numerous other
factors that are specific to the individual.
Also keep in mind that if you read a difference on the pulse ox at
12,000 feet, that will probably be true whether you just donated blood
or not. Blood donation only affects how much hemoglobin you have, not
how effective it is at carrying oxygen.
So John, you are right that a pulse ox would register some change at
altitude, but I think that Mike is differing with you on the question of
whether that would be affected by blood donation, and just how
meaningful that change is in any case. A better measure is probably
common sense and how you feel.
Your question about people who spend a lot of time acclimating addresses
a different issue. Acclimating to altitude involves a lot of
compensatory mechanisms that are separate from hemoglobin concentration.
Yes, your blood count (and thus hemoglobin concentration) increases.
But hemoglobin undergoes changes on a molecular level in response to
long-term oxygen deprivation. Those changes _do_ affect its affinity
for oxygen and can cause the changes you cite in the balloonist. But
oxygen affinity is a separate issue from the blood donation and altitude
question, which is a short-term issue.
A caveat (for those of you who actually read this far): you should
probably wait 24 hours or so for your blood volume to equilibrate before
you jump, anyway. Just like you probably shouldn't try and run 6 miles
a few hours after you donate.
Amy
kallend
shr...@my-deja.com wrote:
>
Thanks, Amy, that was informative.
Nerd alert continued:
I'm a physicist/engineer, not a physiologist. I have a question that
may seem stupid but it's still bothering me.
I assume (ha ha) that the rate of oxygen transport into unit quantity of
hemoglobin is a diffusion controlled process and depends on the
difference in oxygen activity (chemical sense of the word) between the
air in the lungs and the O2 in the blood. The O2 activity in the air is
the O2 partial pressure, and in the blood will be the concentration or
saturation multipled by some activity coefficient that depends on the
chemical free energy of the reaction between hemoglobin and oxygen. If
this is the case, then O2 transport into the blood would be affected
both by the O2 partial pressure, and the O2 saturation level in the
blood. The same argument would apply to CO2 removal rate.
At the consumption end, O2 transport out of the blood will basically be
controlled by the organ's metabolic demand.
I'm guessing that getting O2 from the air into the blood is the rate
determining step here, and that once it's in the blood getting it to the
organs is easier.
If the number of hemoglobin molecules is now reduced, you and Mike say
that the shortfall in O2 delivery rate to the organs can be made up by
moving the remaining molecules around faster (increase in heart rate).
From what you and Mike said, it appears that this is all that's needed
at low altitude. OK - that's in line with any mass-transfer process.
Fewer trains running faster can deliver the same amount of freight.
But at high altitude there is going to be a point when this can no
longer compensate. The O2 demand from the organs will now cause the
blood saturation to drop. If O2 saturation drops then the driving force
for diffusing O2 across the lung membranes will increase, partially
compensating fro the drop in partial pressure. This may or may not be a
significant effect. Since there are fewer hemoglobin molecules present
after donating blood, I would expect this to occur at a lower altitude
than if the hemoglobin content were "normal" (whatever that means)
because the cardio vascular system was already stressed in the blood
donor. Hence I would expect a Pulse Ox measurement to show a decline in
saturation at a lower altitude than normal in someone who had just
donated blood.
What is the fallacy in this line of reasoning? Serious question, I'm
not trying to have an argument.
>
--
jsk
145265
D16842
>Anyway, bottom line - INCREASING his hemo resulted in increased O2
>saturation levels at high altitude. Why would you not expect the inverse
>to happen with reduced hemo?
Look at it from a slightly different perspective. If increased hemo didn't
help, artifically raising it it would not be banned in sporting competitions.
From a functional arobic point of view, more is good. How about less? If the
hemo level goes to zero, that is bad. The effects have to vary between the two.
The degree will almost certainly be a function of many variables, including
general health, age, fitness, etc.
I go back to my argument of the other day. People will be differently affected,
but an average older female smoker with low fitness is going to be at one end,
and a young male non-smoking marathon athlete is likely to be at the other. How
big is the effect? I don't know, but some people feel sluggish and or pass out
after giving blood, and there is no reason to believe skydivers are immune.
Simply saying that it is not a factor is a pretty narrow point of view.
Tom B
crwmike
performance now compromised?
I intend no disrespect, Tom, but such a strong opinion in the face of no
significant
knowledge on the subject is ...well, not very impressive.
Red Blood Cells,
Michael
D16842
>
>I intend no disrespect, Tom, but such a strong opinion in the face of no
>significant
>knowledge on the subject is ...well, not very impressive.
I am not trying to be disrepectful either Mike. Read my statement again, and
then please tell me where I expressed a "strong opinion". To save you a trip to
Deja, here it is again:
> How
>> big is the effect? I don't know, but some people feel sluggish and or pass
>out
>> after giving blood, and there is no reason to believe skydivers are immune.
>
Gee Mike, are you saying that when I ask a question, and suggest that no real
evidence has yet been presented to prove it either way.... That is a strong
opinion? Opinion of what?
The standard in science, including medicine, is to reject a hypothesis unless
it can be absolutely proven to be true. Doing anything less is unimpressive,
and against the base rules of reaearch
As for no significant knowledge, human factors and performance measurement were
a major part of my education and early carreer years. I also went through the
Navy's flight physiology program several times (The OIC there was a fellow
skydiver, and her facility was the only air conditioned space available to me).
I do remember the general nature of the issue. Not the medical mechanism per
say, but the range of results. My statements are factual. Blood doping with red
cells does increase performance to a degree. Zero hemoglobin is indeed a bad
thing. People are differently affected in the range between. I made no claims
at all on the degree of any impairment. Strong opinion?
Tom B
UPP
"dances with clouds" <dances_wi...@my-deja.com> wrote in message
news:957slo$9up$1...@nnrp1.deja.com...
<snip>
> before I grew to be a giant sky-cow, > DWC
> 沂^^^^^^
> 0:-P
BWaahahahahahaaa... never heard that one, you crack me up!
-mika-
UPP
"TY" <ddoh...@net1plus.com> wrote in message
news:3A76CF7E...@net1plus.com...
> I was just reading the UK rec.skydiving and saw a bunch of posts talking
> about donating blood not being a good idea for skydivers. Since I
> normally donate blood at least a couple times a year this really
> concerns me. I had never given it much thought before as I always
> thought you were fine after a day or two, but I guess that although the
> volume is replaced the oxygen carrying capacity is not. According to 1
> post, "After giving blood, the volume is rapidly replaced, but the
> oxygen carrying capacity is not. Giving a pint of blood may reduce the
> oxygen carrying
> capacity by over 10%. This will not matter to you at ground level but
> may
> make a big difference to how well your skydive goes at altitude. Most
<snip>
> Thanks,
> TY
>
Duh! Expose more skin to the airstream, you will absorb more O2 molecules...
really a no-brainer! :-P
-mika-
crwmike
D16842 wrote:
>
> crwmike wrote:
> >
> >I intend no disrespect, Tom, but such a strong opinion in the face of no
> >significant
> >knowledge on the subject is ...well, not very impressive.
>
> I am not trying to be disrepectful either Mike. Read my statement again, and
> then please tell me where I expressed a "strong opinion". To save you a trip to
> Deja, here it is again:
>
> > How
> >> big is the effect? I don't know, but some people feel sluggish and or pass
> >out
> >> after giving blood, and there is no reason to believe skydivers are immune.
Some people feel sluggish and pass out over lunch.
> >
>
> Gee Mike, are you saying that when I ask a question, and suggest that no real
> evidence has yet been presented to prove it either way.... That is a strong
> opinion? Opinion of what?
You did not ask a question, you repeated the same opinion you had
earlier.
>
> The standard in science, including medicine, is to reject a hypothesis unless
> it can be absolutely proven to be true. Doing anything less is unimpressive,
> and against the base rules of reaearch
Your hypothesis is that donating blood can adversly affect skydiving
performance/safety. The null
hypothesis is that there is no effect.
For the 'cypres/ya never know' crowd, don't donate blood (or wait six
weeks) For the rest of us,
wait a day to cover all bets, then go live your life in a manner of your
choosing. Following your
hypothesis, (ya never know!) all pre-menopausal women should wait six
weeks after their periods before skydiving :)
Ray Giese
When I donated, I asked the nurse if there would be any ill effects due to higher
altitude, and how long before I could skydive again. The general concensus among a
bunch of nurses was that 3 days was enough recovery time, since that is the rule
for pilots. After 3 days, you may still be marginally affected, but I bet a
hangover has worse effects than a blood donation 3 days ago.
Ray
kallend
If the O2 saturation level is just a matter of chemical equilibrium
between the hemoglobin and the atmospheric oxygen, then Mike is right.
Trouble is, a system in chemical equilibrium can't do any work, and a
human body in chemical equilibrium would be dead. Once you factor in
metabolism, kinetics have to be accounted for. None of Mike's
statements have addressed the effects of altitude on the kinetics of
blood chemistry.
D16842
>Your hypothesis is that donating blood can adversly affect skydiving
>performance/safety. The null
>hypothesis is that there is no effect.
No Mike, that is not my hypothesis, and never was. The only thing I have a
strong opinion is that there are lots of factors involved (age, sex, fitness,
smoker, size,...) and if you happen to be a person where they all stack up
against you that it might be an issue. I would personally have no trouble
jumping the day I gave blood, but I am a non smoking 45 year old male, of
normal fitness.
But I will ask you this in all seriousness. How do they define the safe limit
for minimum weight for giving blood? I have to assume it has something to do
with the ratio of blood removed to total volume, but if taking a pint has no
effect, then why is there a limit at all?
Tom B
Paul Martin
will not say you can do anything that will leave them liable.
Paul
On Wed, 31 Jan 2001 09:34:21 -0500, crwmike <crw...@Bellsouth.net>
wrote:
Paul Martin
wrote:
---snip---
>
>I heard a common sense argument from an extremely experienced skydiver (who
>also happens to smoke like there's no tomorrow), that heavy smokers tend to
>suffer less from hypoxia (I guess, provided they've left off the smokes
>prior to jumping), because their bodies are used to coping with low oxygen
>availability.
>
CO binds to Hb in a 200:1 ratio ie. you need 200 times more oxygen to
get the CO to dissociate from the Hb. This is why the Rx for CO
poisoning is to use a diving pressure chamber with high pressure O2 to
get the CO to dissociate.
The fact that they smoke will lead to them having less of a
pysiological reserve when it comes to hypoxia. The thing that makes
extreemly experienced skydivers able to cope with hypoxia better, if
it is true, is that they are fit, and the constant hypoxia due to
altitude will lead to and increased number of red cells in their
system. (I am assuming that most extreemly experienced skygods are
professional skydivers) Also they will be reasonably athletically fit.
Put simply, it is not the smoking, it is the being an extremely
experienced skydiver and if they didn't smoke, they would cope even
better. I think that the skydiver in question was just trying to
justify their smoking using pseudoscience.
Paul
Paul Martin
wrote:
---sniped science bit----(someones got a text book out the library;)
>Here's a project for you. Wear your pulseoxymeter and check the reading
>before giving blood (FYI: normal for a otherwise healthy non-smoker is
>98% and >95% for a otherwise healthy smoker). Now check it after giving blood (hell, wear it while you are giving blood).
>You won't see any changes. If you are in a hurry and don't want to wait for the blood donation center to open, you could just sever a vein and bleed out 500 ml.
>
>One reason is that shining a light through the end of your finger is a
>pretty crude way of approximating oxygen saturation. It takes some
>pretty 'crude' changes, however, to make *any* difference in normal body
>function.
If you have done any medicine, you will know that a person who has
just experienced a loss of blood (through whatever means) will not
have a drop of Hb level until the next day. There are two mechanisms
at work here.
1 immediatly post donation/blood loss people faint because of
hypovoleamia mixed with emotion and postural hypotention, stuff like
that.
2. a while later people feel groggy due to decreaded RBC's and
therefore O2 carrying capacity. This is the bit that skydivers should
be concerned about.
The reason why Hb drops the next day is that the RBCs are diluted, to
make up volume. Will this affect pulse Ox? not significantly. Why?
because there is enough of a reserve at ground level for this not to
be affected, but at 'tude. Well this is where the 'it depends' comes
in.
On the ground the Pulse Ox (PO) will not show any significant change,
this means that is is useless as a test for "can I skydive today" will
it change from a normal ride to altitude to a post donation ride to
'tude. Yes I think it will, but then you have paid for your slot on
the plane and wasted a jump ticket, and as we all know that judgement
is impaired when hypoxic so what is the likelyhood that you are going
to say "fuckit" and jump anyway?
In conclusion, some of the heros out there will donate and carry on
jumping only taking a break to get a frosty one down yer neck, others
will take a break for some days, visit the wife and kids, so they
remember what you look like, and then crack on. Others will not
donate. At the end of the day there is no right and wrong to this, it
is a very individual thing, IMHO the best thing is to decide how fit
etc you are and make your own mind up. Enough has been posted in this
thread to give you the information.
Paul
kallend
on this thread no-one here has actual data from a pulse-ox measurement
at altitude immediately following blood donation, just a lot of
theorizing.
I didn't like the suggestion of seeing if you feel bad, since symptom 2
of hypoxia is generally that you feel good. (Maybe the idea is that if
you feel bad, you're OK to jump :-)
In article <fejl7tkiabnf98mgq...@4ax.com>,
Wendy Faulkner
kallend <jkal...@my-deja.com> wrote:
>Well, I suggested an observation ride to altitude. From what I've read
>on this thread no-one here has actual data from a pulse-ox measurement
>at altitude immediately following blood donation, just a lot of
>theorizing.
I can't say that I've done it after giving blood, but I have done it on
the ride to altitude. There were 4 of us testing ourselves - me, 130 lb
female, average condition, 145 lb male, good physical condition, 185 lb
male, excellent physical condition, and , uh, large older male, who was
also a smoker. On the ground the first 3 of us all registered 99%,
except the smoker, who was 97%. We all got progressively worse on the
ride to altitude, with the final results being - small male, 82%, 185 lb
male - 80% O2 saturation. I was at 74-75%, and the other was at 72%.
It did make me understand why I get so sleepy at altitude (but
interestingly enough - if I do a "hit" of an asthma inhaler before I go,
I don't feel any symptoms of hypoxia. That stuff works.)
W
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Wendy Faulkner I haven't lost my mind -
wendy.f...@ni.com Its backed up on tape somewhere.
http://www.eco.utexas.edu/~faulkner
TY
where I had read about somebody using one. I finally found it in the
October 1999 issue of "Skydiving". Since I'm a horrible typer and my son
isn't home, I'm just going to type a few parts that might be interesting to
some.
***********************************************************
Exerpts from "Handy Device Helps Skydivers Minimize Hypoxia"
At altitudes we skydivers frequent (13,000 for a few minutes) hypoxia's
symptoms aren't easily recognized. There are few outward signs, and the
jumpers themselves might feel euphoiric rather than drowsy or confused.
(euphoria is one of the symptoms and so is confusion.)
Hypoxia is like drinking alcohol. Drink a little and one's performance is
only slighty degraded. Drink a lot and you are incapacitated. Really
overdo it and you could die. It's all a matter of "dose".
some jumpers believe hypoxia plays a more debilitating role in our sport
than we realize, especially on demanding jumps. Perhaps competitors are
more likely to brainlock if they are hypoxic. Skydivers faced with a
difficult malfunction might be more likely to make a big mistake - like
pulling the wrong handle- if their brains are a bit fogged from oxygen
deprivation.
<snip a bunch of stuff about the military doing studied but not at skydiver
altitudes and info about pulse-ox devices>
Next few paragraphs were about testing some jumpers in FL. All had O2
saturation > 95% (most >97%) on the ground. They took a bunch of jumps to
14,000 ft (aircraft ride about 15 min). Right before jump run O2 levels
were in the high 80's, none above 90%.
"Two weeks later we loaned the little gizmo to Kate Cooper and Tony
Domenico; they were doing formation loads from 17,000 ft. The aircraft had
been fitted with crude but effective on-board oxygen system.
They found their O2 sat stayed at 90% or so when using supplemental O2, even
at 17,000 ft. But within a minute of going off O2, the oximeter showed how
saturation had dropped to 8-% or less.
The process quickly reversed itself if the jumper put his nose cannula back
on; it took less than a minute to return to a little above 90%.
On one load, Domenino volunteered to stay off supp. O2 until the aircraft
reached 15,000 ft. At that point his O2 was only at 72%. But donning a
cannula quickly brought it back up to above 90%.
What do the numbers mean? According to doctors familar with oximeters,
healthy people at sea level will measure 95% or higher. Those that measure
less need to be rechecked or checked for anemia, pulmonary disease and other
problems.
Aviators can safely tolerate concentrations down to 90% for long amounts of
time. They are not in tip top mentalor physical condition - night vision is
noticeably degraded, for instance - but most can do their jobs.
Values below 90% are considered unacceptable except for brief periods,mostly
because judgement is impaired at that concentration. O2 below 80% are
simply dangerous. Aviators are likely to be seriously confused and
incapable of performing simple tasks. Worse still, they often feel great.
Blood O2 concentrations are affected by more than just altitude. Time at
altitude is of course important, as is the person's physical condition and
level of physical activity.
Our little experiments weren't science by any means, but they impressed the
participants with how sensitive their body chemistry is to changes in the
altitude."
Then they go on to suggest some graduate student ought to document hypoxia
and it's effects on jumpers now that the technology is available and
affordable. nd that a study might convince some competitors to use
supplemental O2 in the aircraft and that tandem instructors might rethink
taking students to 13,000.
**************************************
After reading that I would have thought that there would not be much concern
on a normal run unless you were at altitude for a while like if you had to
make a second pass or circle waiting for traffic or looking for holes in the
cloud layer. But when I read Wendy's results I thought it was a little
scary. Can I ask what altitude you went to and how long it took you to get
to altitude?
TY
kallend
is not simply a function of the hemo/oxygen equilibrium, but also of the
efficiency of the entire system. Still wonder if blood donation does
the same.
In article <95g0a4$jht$1...@geraldo.cc.utexas.edu>,
--
kallend
TY <ddoh...@net1plus.com> wrote:
Thanks, TY. Lots snipped.
>
> What do the numbers mean? According to doctors familar with
oximeters,
> healthy people at sea level will measure 95% or higher. Those that
measure
> less need to be rechecked or checked for anemia, pulmonary disease and
other
> problems.
IIRC, CRWMike told us earlier that anemia (as induced by blood donation)
wouldn't have an effect!