Donating Blood and Diving - Q&A

[Gavin Smith]

Originally Posted by Juz

is your circulation recovered enough for effective off gassing?

Juz

Perhaps balanced as you can't on-gass as efficiciently either

[tiewrapdiver]

Would using a higher O2 mix offset the amount of red blood cells you've lost?

so dive after 24hrs of donating but dive on nitrox instead.

[AdmiralHanson]

Originally Posted by Juz

Personally I don't think 24 hours is enough, I was under the impression it took longer than that to replace the red cells. Although you might be physically strong again within 24hours for working or playing sport, is your circulation recovered enough for effective off gassing?

Juz

I ws under the understanding that it was around 4 days to get your red cells back, even at 'normal' rates.

All the drink fluids malarkey is merely to get your total blood volume back up, not as a direct replacement of the content of blood.

I usually time my donations in the week before I know I'm not in the water at the weekend. With donation timescales of every four months, there really only should be a 2 out of 3 donations that are a problem.

[dougal]

Originally Posted by Juz

Personally I don't think 24 hours is enough, I was under the impression it took longer than that to replace the red cells. Although you might be physically strong again within 24hours for working or playing sport, is your circulation recovered enough for effective off gassing?

Juz

By donating blood you're reducing your stock of red cells, white cells, platelets and plasma. If you're healthy enough to donate, the loss of platelets and white cells will make no difference so we can ignore them. The bulk of your donation is plasma, and this is what you're seeking to replace by drinking water etc in the 24 hours after donating blood. The red cells are not fully replaced for many days (in the order of 14-21 days IIRC) - however the red cells in a blood donation represent such a small proportion of your oxygen carrying capacity that the loss should have no noticeable effect.

The risk when diving, if there is one, is more likely to be as a consequence of being dehydrated than the lack of oxygen-carrying capacity. Dehydration acts to reduce total blood volume. I'm no physiologist but my understanding is that nitrogen is transported in the body by being dissolved directly - unlike oxygen which binds to the haemoglobin in the red cells. Lower blood volume means less nitrogen can be absorbed.

The NBS advice about not giving blood before operating a crane etc probably has more to do with being ultra-cautious. Risk = likelihood x consequences - small likelihood and big consequences (dropping something heavy into a crowded city street for example!) can give rise to a risk so the advice is just precautionary - it doesn't mean a crane operator is more likely to experience any adverse effect of giving blood.

A

[Hellvet]

I have posted this on the LDC site and emailed the National blood service but have only recieved a reply from the LDC so far. I know i enquired about this the last time i gave blood as i had been diving either 24 or 48h before, and all was well, the recommendation was only about diving within a certain period AFTER giving blood but i can't remember the exact details!
Anyhow - copy of posts below!

giving blood and diving
Posted: Tue Apr 19, 2005 7:27 pm
This came up at a previous donation session, but though i remember i was allowed to give blood, i can't remember what the answer was - have rung the national blood service - but need to ring between 9-5 to speak to a doctor about the answer...
How long should you avoid diving before and after giving blood? Does it affect off-gassing, or on-gassing? Does it affect the chances of DCI?


Posted: Wed Apr 20, 2005 12:21 pm
Dr J Eden
Resident Doctor
It would do in the immediate term, ie the same day or a day after, but the body can produce blood easily again, so you should be fine 3 days after.
Dr J

[Hairball]

As a youngster I used to go with my Dad, on an occasional Saturday morning, when he went to give blood at a local school. I used to enjoy my orange juice and biscuit while he had a quick kip!

So, when I was 18, I was going to follow my Dad's example. BUT, at 18 I was in a serious accident and ended up requiring major surgery and a number of blood transfusions.

Once I was able to I, somewhat belatedly, started to 'give blood'. But I felt I was now in debt and trying to catch-up, as opposed to just giving. This was not a competition with my Dad, I just felt that it was a great thing to do to save a life, following his example.

Last year, after 25 donations (would have been many more if their system had listened to me when I moved home, instead of trying to get me to donate where I used to live) I was told, with thousands of other regular donors, that they could no longer accept my blood due to the 'possible' exposure to BSE through transfusions after 1992.

Damn shame - I'm no saint - but this was a relatively easy way (I don't like needles at all - but it ain't for long) to REALLY help someone.

There's loads of blood still in me!

[Hairball]

Perhaps a little off-topic - but a genuine disappointment at being 'forced not to help!'

[Hellvet]

Originally Posted by Hairball

Perhaps a little off-topic - but a genuine disappointment at being 'forced not to help!'

I know how you feel. I have only managed to give blood a few times but the National Blood Service is overly restrictive AFAIC. They stopped me from giving blood for 1 year post (NHS) acupuncture, for 2y post 2 GA's (to remove impacted wisdom teeth), and for 6m post travel to a malarial country (ALL these restrictions have now changed!), and stopped me from donating bone marrow to someone with leukaemia because i had had a GA in the preceding 6m! I think they're also gonna stop me from giving blood now i have a PFO, but i have yet to get this confirmed!

Hey - ho - at least i tried!

[big kev]

The plasma you lose in blood donation is replaced by the body in about 24 hours. As others have said, keep well hydrated before and after donating and don't dive for a couple of days.

The red blood cells however take up to 3 months to renew. Until they do you are to all intents and purposes a little bit aneamic. This should pose no problem to recreational divers, but could be an issue for those using hypoxic mixes - no ones really sure so best not to chance it.

Kev.

[Ness]

In Oz, I donated blood probably 15 times, and always waited 24-48 before a rec dive and never donated in the week preceeding a planned deep/deco dive.
Then I switched to aspherisis donations where they just take plasma & platelets and put all your red cells back in, and I had no qualms in waiting just long enough not to injure the needle site (they use bigger needles and they're in your arm for 2-3 hours with aspherisis). Usually 24 hours.
Now when I eventually get home from my RTW trip, I won't be allowed to donate blood in Oz again. Disapointing, coz I really felt good about donating previously, but there was no way I was going to can my trip just so I could keep donating!