Wednesday 14 March 2007

Giving blood

Hello — yes, it's been a while. I promised myself I'd blog about this a month ago, so now I really will.

I've been going to donate blood for a few years now; it's a small price to pay for the knowledge that you are helping to provide an essential service — and you get free tea and biscuits!

Around the start of January (or possibly before Christmas; can't recall exactly) I got a letter from the National Blood Service about the possibility of giving platelets. These are the cells in your blood responsible for clotting. Platelet donations are needed for patients who have leukaemia and other cancers (as a result of their treatment) or those who have suffered serious blood loss sustained after injuries or major surgery.

The process of giving platelets is a bit more involved than for whole blood: they want you to go every month or so (technically you can donate once every two weeks); you have to go to a dedicated donor suite, and you're potentially there for nearly two hours.

The letter told me that, after some preliminary tests, they thought that I might be a suitable platelet donor candidate, and invited me to an open day where they would show me round the donor suite (in the John Radcliffe hospital) and take some further samples for analysis. I didn't really have any reason not to go; since I'm already giving blood it seemed like a small step to go and have some more tests to see if I could be even more beneficial to the blood service.

The open day was interesting and welcoming; much tea, and many biscuits and sandwiches were consumed, and my samples were taken. We also spoke to a few current donors about their experiences, and got a tour of the labs, where we got to find out more about how the donations are processed.

It turned out that my blood was suitable (in fact the phrase they used was "we like you!") and an appointment was duly made. A couple of weeks later, I turned up, filled in the usual tick-box questionnaire about blood safety, and listened while they told me a few more things about the process. They also asked me some specific questions about any drugs I might have taken recently (aspirin based drugs are a big no-no).

Platelets are extracted from you by a process known as apheresis, whereby the blood is passed through a centrifuge. After the required components (platelets in this case) are removed, the whole blood is then passed back through the needle into your vein. This is a little unnerving at first, but the parts of the machine that your blood passes through are part of a disposable kit which they fit to it, so your blood doesn't touch anything which isn't sterile. I found it difficult to picture this so didn't really realise how it worked until I saw them dismantle it after my first session: it's essentially a band of plastic, with leads at the centre, which is fitted to a spinning disk — obviously some sort of rotating joint is used at the axis. There are various channels within the band which contain your whole blood and the product.

These kits cost £100, apparently, and are fitted before you arrive. For this reason, they are understandably insistent that you give them plenty of notice if for some reason you can't make it!

After the initial mild nervousness, I found the process itself quite relaxing. The needle is a bit more scary looking than the whole blood donation needle (it has three lines going to it) but once it's in you can mostly forget about it. My blood flow rate when donating has tended to be quite low in general so I ended up having to make fists quite a lot.

The first time I donated, the (very friendly) nurse who did most of the work wanted to take a triple donation (i.e. the bag would be heat-sealed/split into three equal doses) but another nurse said that for the first donation they would take a double donation (they want people to give at least a double each time). At least I knew that at that point my platelet count seemed nice and high.

So, the relaxation. So far, I've been donating after work (leaving a bit early to fit in with the blood service schedules) and reclining on a couch and having as much tea and biscuits as you can manage brought to you, and reading a book, after a day at work, is just as good as it sounds! You get a nice LCD display of the progress of the donation (which takes between an hour and an hour and a half, depending on your count, and how much they're taking) including how many platelets have been collected, and how much longer you have to go.

Of course, it isn't wholly relaxing. Yesterday (the second time I've been) I ended up with a funny vibration feeling through my circulatory system, which I'd been warned about. It's caused, I was told, by the needle being close to a valve in my vein. For those who don't remember from GCSE biology, veins have one-way valves periodically throughout, to ensure that the blood flow remains towards the heart. Presumably the vibration was caused by the returned blood (flowing in the opposite direction to that in your vein) hitting the valve at some speed.

Other odd sensations include a sort of "fizzing" feeling caused by the anti-coagulant they add to your blood so that the donation doesn't clot, some of which remains in the returned blood. Even if you don't experience these effects, you're bound to feel a slight tingling near the site of the needle when the blood is returned (the "rinseback", as they call it). The cycle of extracting your blood and then replacing it happens about once a minute (you can hear the machine change tone, and it's displayed on the panel). The vibrating effect only lasted until a few minutes after I stopped donating, in any case, so it wasn't problematic.

Sadly, when I went yesterday, my platelet count had gone down so they weren't able to take a triple donation from me. However I did get my tacky "bronze award" pin (you get two, or maybe three ordinary donation "points" for an apheresis donation), and gave a respectable double dose. They said that the platelet count is related to stress levels — clearly I'd got complacent after feeling nervous at the first session, and was too relaxed about the affair the second time round!

So that's my story about donating. I'm posting it in case anyone feels moved to investigate it themselves as a result. You can read more about the process on the National Blood Service website. Do get in touch if you want to ask me anything about it.

Posted by Dominic at 23:08
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