h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Which broadly follows the same procedures and conditions, with one or two specific additions:

1. Apheresis is done only at the regional National Blood Service centres, so you need to be able to get there.

2. You give more frequently, so a more understanding employer helps.

3. The sessions are longer, with donors hooked up to the apheresis machines, because of this and the frequency, you need big and robust veins: some whole-blood donors may be advised that this process is not for them, others may drop out because of a reaction to the anti-coagulant used: although this is not a serious problem.

On the up side, you get to sit in a comfy chair/couch rather than being laid out flat on your back, so you can read, drink your tea & biccies and chat to the nurses during your donation.

Apheresis is also known as Plasma & Platelets donation, because that is essentially what you're doing. The machine you're plugged into withdraws about the same amount of blood as a standard donation, and then centrifuges it to separate the components. A small amount of anticoagulant is dripped in to stop things clotting and gumming up the works. Once separated, the red cells are returned to you, and the plasma and platelets routed to collection bags. The cycle is repeated until a unit of each has been collected, at which point you're unplugged and plastered up as normal. Most, if not all, donors have a local anaesthetic before the main needle goes in; you can do without this, but I wouldn't.

The machines are designed so that all the parts in actual contact with blood (centrifuge bowl, piping etc) are used once and once only: there is no danger of contamination. One of the more fascinating parts of the process is watching the nurses stripping the machine down and fitting the new sterile kit for the next donor.

Astute observers will have spotted that two units of blood products are taken. As these are replaced more quickly than red cells, apheresis can be done up to fortnightly if the demand is there: those so inclined can rack up some big numbers fairly quickly on their donation record.

Sounds like there's a whole other entry right there!

They wouldn't let me donate platelets cos I'm not fat enough!

Possibly, although since I'm typing one-handed at the moment (see journal), it'll take a while if it's coming from me

As I said, you've ably covered the procedures and conditions for whole blood, apheresis is broadly the same with a few tweaks and stuff about the machines....

What are the odds on a Ferrari clean sweep this year?

Ferrari'll probably do it. Who hates Schumacher as much as I do?

The separation into constituent parts.. I've heard about packed cells being used in surgery. Are these extracted when a regular donation is taken? It makes sense to take them then rather than returning them to you during a completely different session.

Red cells would have to come from a whole blood donation; the processing would be done at one of the National Blood centres where the donations are taken to once collected.

With apheresis, plasma and platelets are separated from the returned red cells at the time of donation, further processing and separation takes place afterwards.

Thanks for clearing that up. This just goes to show that a little medical knowledge can be a dangerous thing. A medical background and a history of hopsital contact can leave one with all sorts of strange ideas. Just wish I could donate blood, I've wanted to ever since I was a kid but can't yet.