blood donation/dive tables
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Bonafide
Guest
Hi there, Dont worried it takes a couples hour for your body to compensate the 475 ml taken. Just don't donate right after diving coz of the "N" Nitrogen left in your blood. Otherwise, donate and DIVE...
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The place where I donate asks that you refrain from diving for 12 hours after giving blood. That's only prudent, I think.
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This is a forum dedicated for diving medicine. It advises posters regarding their health, medical well-being & even their lives, admittedly rather serious matters. As such, it is expected that those responding to questions will answer only when they have something accurate & useful to offer. Just like you'd want your doctor to do; just like you'd like your medical questions answered.
While our board is pretty loose in many forums, as a Medical Moderator of the Diving Medicine area I do not find such looseness appropriate here. Your response contains several statements that I would like to address:
1. "Dont worried it takes a couples hour for your body to compensate the 475 ml taken."
Actually, it takes about 24 hours to replenish the lost fluid. This is not to mention lost red cells and depletion of iron stores.
If you'd like a proper understanding of this, I'd suggest reading the following by Scubadoc---->
http://www.scuba-doc.com/blddon.html
2. "Just don't donate right after diving coz of the "N" Nitrogen left in your blood. Otherwise, donate and DIVE..."
Given a healthy individual, by the time one gets from diving to the completion of the donation process any clinically significant excess nitrogen in the blood will be long gone. This is not to mention that the unit donated will be mixed in with all of the blood existing in the donee.
Best regards.
DocVikingo
While our board is pretty loose in many forums, as a Medical Moderator of the Diving Medicine area I do not find such looseness appropriate here. Your response contains several statements that I would like to address:
1. "Dont worried it takes a couples hour for your body to compensate the 475 ml taken."
Actually, it takes about 24 hours to replenish the lost fluid. This is not to mention lost red cells and depletion of iron stores.
If you'd like a proper understanding of this, I'd suggest reading the following by Scubadoc---->
http://www.scuba-doc.com/blddon.html
2. "Just don't donate right after diving coz of the "N" Nitrogen left in your blood. Otherwise, donate and DIVE..."
Given a healthy individual, by the time one gets from diving to the completion of the donation process any clinically significant excess nitrogen in the blood will be long gone. This is not to mention that the unit donated will be mixed in with all of the blood existing in the donee.
Best regards.
DocVikingo
Wreckie
Guest
1. "Dont worried it takes a couples hour for your body to compensate the 475 ml taken."
Actually, it takes about 24 hours to replenish the lost fluid. This is not to mention lost red cells and depletion of iron stores.
>> To be fair doc he said compensate not replenish or replace, could he have been refering to the shock response (raised heart rate/breathing rate, restriction of blood flow), which is even more rapid than an hour? Once the symptoms you are awair of have gone you could correctly say that your body has 'compensated' for the lost fluid.
On a slight twist of the thread: While in the water (longish dives) the body removes fluid (hence the 'i need the loo' look on your buddy's face half an hour into the dive).
I have seen references to a kind of submersion shock after long periods in the water where the body removes so much fluid that once gravity takes over on the rescue boat/helicopter the casualty collapses.
In theory could giving blood (lower volume) then spending long periods in the water (body removes more fluid) followed by a walk up a ladder or beach result in collapse, cumulative effect.
Sound feasable Doc?
Mike
Actually, it takes about 24 hours to replenish the lost fluid. This is not to mention lost red cells and depletion of iron stores.
>> To be fair doc he said compensate not replenish or replace, could he have been refering to the shock response (raised heart rate/breathing rate, restriction of blood flow), which is even more rapid than an hour? Once the symptoms you are awair of have gone you could correctly say that your body has 'compensated' for the lost fluid.
On a slight twist of the thread: While in the water (longish dives) the body removes fluid (hence the 'i need the loo' look on your buddy's face half an hour into the dive).
I have seen references to a kind of submersion shock after long periods in the water where the body removes so much fluid that once gravity takes over on the rescue boat/helicopter the casualty collapses.
In theory could giving blood (lower volume) then spending long periods in the water (body removes more fluid) followed by a walk up a ladder or beach result in collapse, cumulative effect.
Sound feasable Doc?
Mike
sharpenu
Contributor
The bathroom effect is caused by stimulation of baroreceptors while diving, which (to make a long story short)cause the kidneys to lower blood volume. There is also (I think) a fluid shift caused by the salt water.
miketsp
Contributor
DocVikingo:
Doc,
I'd like to explore this particular topic a little.
I remember one trip where getting back to the boat after the second of 2 dives at 30m+, one of the divers gashed himself badly on the leg and needed a tourniquet, which was applied (after a big argument among the various qualified contenders as to who was the most qualified to apply it).
Anyway the boat blasted back at full throttle and within the hour the victim was delivered to a clinic that asked for 3 blood donors. The whole group accompanying the patient was still with significant residual N2.
As it turned out the clinic used blood from its own stock which had already been fully tested and the blood request was for replacement purposes but this thread now made me curious.
If it was necessary to give a significant sized transfusion (3pints+) directly, under these circumstances are there any extra precautions to be taken or risks involved?
Less than 1 hour after 2 deep dives & due to emergency deco time was cut to minimum safe.
Mike
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Interesting inquiry.
Based on my admittedly limited knowledge, I'd say that such a transfusion posed very minimal risk from a blood gases perspective. In any event, any risk appears much smaller than that posed by blood loss in the range reported here.
A transfusion of 3 pints will be mixed in with the donee's remaining pints. The amount of blood in the body is largely dependent upon body weight and you can figure on about 2 pints for every 25 lbs. You do not provide any indication of the weight of the diver, but I think it would be safe to say that he had a post-trauma circulating blood volume of at least 10 pints and well could have had more. This would provide quite a dilution factor for any excess nitrogen being introduced into the blood stream.
Also, I would assume that the injured diver was placed on 02 while on the boat or at the very least upon arrival at the clinic. This situation would provide considerable impetus in the elimination of excess blood nitrogen regardless of how it was introduced.
If I am mistaken, I hope that some of the more diving medicine savvy physicians on the board will correct me.
Best regards.
DocVikingo
Based on my admittedly limited knowledge, I'd say that such a transfusion posed very minimal risk from a blood gases perspective. In any event, any risk appears much smaller than that posed by blood loss in the range reported here.
A transfusion of 3 pints will be mixed in with the donee's remaining pints. The amount of blood in the body is largely dependent upon body weight and you can figure on about 2 pints for every 25 lbs. You do not provide any indication of the weight of the diver, but I think it would be safe to say that he had a post-trauma circulating blood volume of at least 10 pints and well could have had more. This would provide quite a dilution factor for any excess nitrogen being introduced into the blood stream.
Also, I would assume that the injured diver was placed on 02 while on the boat or at the very least upon arrival at the clinic. This situation would provide considerable impetus in the elimination of excess blood nitrogen regardless of how it was introduced.
If I am mistaken, I hope that some of the more diving medicine savvy physicians on the board will correct me.
Best regards.
DocVikingo
Saturation
Medical Moderator
DocVikingo and others post interesting questions.
A great bulk of inert gas stores are from other tissues that 'spill' into the blood.
Luckily, blood is one of 'fast' tissues to offgas and in theory, the act of donation [flowing into plastic tubes, shaking, collection containers, and blood bank prepartion including centrifugation] tribonucleates blood to see bubbles and coincidentally help de-nitrogenated them ... it would be in excess of shaking serum in a fresh venopuncture.
Any decompression completed by divers, including the surface activity, further offgasses blood.
So in toto, there are few problems with inert gas stores when donating blood from divers in an emergency.
A great bulk of inert gas stores are from other tissues that 'spill' into the blood.
Luckily, blood is one of 'fast' tissues to offgas and in theory, the act of donation [flowing into plastic tubes, shaking, collection containers, and blood bank prepartion including centrifugation] tribonucleates blood to see bubbles and coincidentally help de-nitrogenated them ... it would be in excess of shaking serum in a fresh venopuncture.
Any decompression completed by divers, including the surface activity, further offgasses blood.
So in toto, there are few problems with inert gas stores when donating blood from divers in an emergency.
DallasNewbie
Contributor
When I called DAN with this question I was told that in a healthy person that the bigger concern is not the loss of red blood cells, but dehydration. According to them your body is usually able to compensate for the slightly reduced red blood count, but replacing the fluid makes you more suceptible to the dehydration that diving causes.
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