Donating Blood

[Steve in Seattle]

The objective factors include the donor's hemoglobin (blood) level before donation, the hemoglobin level after donation, whether volume loss was replenished, the presence or absence of heart problems (known or unknown), the health of the lungs, and the overall conditioning of the donor -- which can also include such factors as recent illnesses, medications, etc.

As for the subjective factors, in my experience as a hematologist who has worked with high performance, national-class athletes in the past, I can tell you anecdotally that the more fit someone is, the more likely that person is to notice some decrease in his/her performance after blood donation. While one might initially think that the less fit people would notice this more, the opposite actually seems to be true.

The reason, I believe, is because sedentary people never push themselves enough to be able to detect small changes in their physical capacity. If their hemoglobin levels drop one or two points, they may not even notice. On the other hand, people who push themselves with exercise or athletic endeavors often complain that they have lost some of their capacity after donating blood. And why not? It is just the opposite of blood doping, if you think about it.

Nope, I have to disagree.

A 340 pound male, healthy enough to dive, but really obese by BMI standards will see less changes in heme levels from the same donation vs a skinny 170 pound man of the same height. Why? Because blood VOLUME and hemoglobin mass removed is proportionally less in the large man if both donate 1 pint. Blood volume is not directly proportional to total mass, but its close. Surgeons and anesthesiologists actually calculate this with various formula, but it's usually about 70 mL/kg for a healthy male (BV = 70/[BMI/22]^0.5).

68 mL/kg (5.1L total) for the 170pound guy (23.1 BMI),
and 48.5 ml/kg (7.3L total) for the obese man (46.1 BMI) assuming they're both 6 feet tall.

As you can imagine, a 1L loss of blood from a 5.1L body vs a 7.3L body makes a HUGE difference in volume, but after the plasma levels return (the next day), RBC and other blood solutes with longer-replacement times are much lower in the "healthier" man.

The other issue of course is that the liver regulates a lot of blood chemistry values, and the larger man would also have a larger liver making it more likely he could produce higher levels of EPO sooner.


BTW, the lost blood volume itself is NOT a problem... a large man who donates 900cc is able to donate that amount twice a week ad infinim. Plasma, the bulk of your blood volume is NOT the issue. Erythrocyte concentration however IS an issue.

Red Blood Cells (RBC) are responsible for O2 transport from the lungs to myoglobin in skeletal muscle. The loss of hemoglobin(which is packed into RBCs) is replaced by the body when stimulated by the liver... when it releases EPO hormone. This is why EPO doping is so dangerous... it stimulates RBC growth in the same blood volume... making the blood thicker and thicker making clots and heart attacks more likely.

The reason smaller men feel the effects of blood donation more than larger men is NOT because the larger men are unaware of what real exercise is... it's that a 1 pint donation DOES have more affect on the donors blood volumes (and after plasma replaces that missing volume, until all solutes are replaced) RBC/heme concentration levels and O2 delivery ability.


Reccomendations:
- If you donate plasma or platelets... no sweat, just give it a day to get your plasma levels back.
- If you donate whole blood? I'd suggest a week if you're skinny... maybe less if you're "larger"

Outside of extreme cases I doubt its a major concern... max O2 isn't exactly an issue with diving... but decreased blood volume could be (nitrogen loading may be the same right after whole blood donation, but the next day when plasma has been replaced and there are less solutes than normal I suspect nitrogen gas diffusion rates would increase?). I'd be interested in seeing someone post a chart for such a thing. Its likely dive charts have enough cushion in them to make this a moot point, but dive computers may narrow that margin for error somewhat.

 

[lowviz]

68 mL/kg (5.1L total) for the 170pound guy (23.1 BMI),
and 48.5 ml/kg (7.3L total) for the obese man (46.1 BMI) assuming they're both 6 feet tall.

As you can imagine, a 1L loss of blood from a 5.1L body vs a 7.3L body makes a HUGE difference in volume, but after the plasma levels return (the next day), RBC and other blood solutes with longer-replacement times are much lower in the "healthier" man.

Thanks for this input, it explains a lot also. -but it seems to me that this re-inforces wve's observation. Since sedentary doesn't necessarily mean overweight, a more active person is likely to see the difference sooner than a similar sedentary person and a smaller person is likely to see a bigger difference for the same donation than a larger person. I'm active and in the mid-to-high 180's most of the time so my guess is that I see both effects. Thanks for all the great input and 'Hi' to the new posters from another ex-lurker.

 

[pittyyofool]

All I know is my experience with it. If I Wait a day I am fine. If I stop and give blood in the way to a dive, I am a little tired and get Narked easy. And if I follow that dive up with 1 Beer. I get quite tipsy before I finish it.

 

[sibermike7]

Maybe off topic, but it sounds like you have an awesome buddy! Responsibly accessed the situation and acted accordingly. Kudos!

 

[lowviz]

Maybe off topic, but it sounds like you have an awesome buddy! Responsibly accessed the situation and acted accordingly. Kudos!

Thanks! He took that as quite a compliment. And I agree with you, I'm lucky.

Stay safe.

 

[Walter]

I started donating blood in 1974 (35 gallons) and started diving in 1983. In 1988, I learned I should wait 48 hours after donating before diving. Prior to that, I often dived within 15 hours of donations. I've never had any problems of any sort related to donating blood and diving. I do now follow that 48 hour DAN recommendation.

 

[lowviz]

I started donating blood in 1974 (35 gallons)

wow.

In 1988, I learned I should wait 48 hours after donating before diving.

Had an issue or just learned about the recommendation?

 

[wve]

Walter, thanks for your donations! Many of my patients are alive because of unselfish people such as you.

Steve,

I'm not sure what I said that you disagree with, unless you are saying that whether or not a blood-donating diver perceives any decrease in his or her performance depends upon the donor's body size more than any other factor.

I think we agree that when divers donate blood, the two most important considerations are (a) the effect that the removal of red blood cells will have on the body's ability to maintain adequate oxygen delivery to the tissues, and (b) how the loss of blood volume may affect the body's ability to maintain adequate tissue perfusion.

We agree that blood and plasma volumes vary with body size. Therefore, we agree that the removal of the same amount from different-sized people could have a proportionally different effect on them.

The liver does not play as important a role in blood production as you describe. Removing a unit of blood from someone has virtually no effect on blood chemistry. Also, erythropoietin, the hormone responsible for stimulating red blood cell production, comes from the kidneys, not the liver.

All of these points, though, get chalked up to the objective factors that might affect one's performance status. These are things that can be measured one way or another.

But there are also subjective factors that are important in how a person (diver) feels. These cannot be measured except by the one who is experiencing the sensations. For example, let's suppose a diver says, "I donated blood 3 days ago, and I still don't feel like I have all my energy back." Well, who can argue with that? We cannot get in there and tell him that he's wrong.

My observation over the years has been that high-performance athletes report such sensations much more often than average. They sense changes that unfit individuals do not.

So, for example, a 150 lb marathoner who donates a unit of blood may notice decreased endurance on the next training run, while a 150 lb desk jockey would report that he feels just fine. The sedentary person simply does not push to the edge of the envelope, so he doesn't notice the change. Put another way, if your speed limit is 55 mph, you probably won't notice that your car's engine can no longer go 120 mph.

Hope that helps clarify my earlier remarks.

 

[sibermike7]

Walter, thanks for your donations! Many of my patients are alive because of unselfish people such as you.

My observation over the years has been that high-performance athletes report such sensations much more often than average. They sense changes that unfit individuals do not.

So, for example, a 150 lb marathoner who donates a unit of blood may notice decreased endurance on the next training run, while a 150 lb desk jockey would report that he feels just fine. The sedentary person simply does not push to the edge of the envelope, so he doesn't notice the change.

Hope that helps clarify my earlier remarks.

MAN! First you THANK Walter for his donation then you go on to tell him that he is an overweight desk jockey who needs to exercise!! Poor guy was just trying to help!

Sorry about that, couldn't refuse!

Seriously, THANK YOU WALTER!!

I also was an avid blood donor when I was in the Corps. They used to give us free haircuts at 29 Palms every time we donated and I donated like clockwork. Unfortunately, in 1994 I needed huge amounts of blood and plasma (300 units). I eventually learned that one of the donors was HIV+. So I have been banned from donating since. :depressed:

When I WAS donating, I never noticed any difference and we never varied our work out schedules to accommodate. Nobody ever told us to and so we never did! Hmmm.

 

[wve]

When I WAS donating, I never noticed any difference and we never varied our work out schedules to accommodate. Nobody ever told us to and so we never did!

Yeah, but that's when you were young and invulnerable -- and a Marine! Heck, you guys never feel anything, especially not a little ol' unit of blood.

And by the way, thank you for your service, too.