Needles » Mark

NEEDLES » MARK

January

The committee of gods don’t say anything — but on Friday I am scheduled back at my normal Menlo Park clinic. I hope Nancy doesn’t think I ghosted her. I can’t call her and never got her email address, so I guess I will have to visit her in Sacramento soon. I am thinking this is the beginning of a beautiful friendship, even if there were initially intended (but unperformed) ulterior motives.

History

Inserting dialysis needles into your arm — is painful for most patients. The needles commonly used for hemodialysis are ‘15gauge ’, which means 15 of them will fit into an inch diameter tube, or each is about one-fifteenth of an inch in their outer diameter. For metric people that is a bit less than 2mm. I have heard of patients that use 14-gauge needles, which are more than 2mm. This is big enough that it is quite difficult not to flinch, and I regularly fail in spite of the lack of actual injury. I commonly chat or play music to distract myself.

A matured fistula used for hemodialysis is normally about 6mm, so a bit larger than a major vein (the ‘great saphenous vein’ returning blood to your heart from each leg is 2-4mm) and a bit smaller than a major artery (the ‘femoral artery’ providing blood to your arm is about 10mm in a 50-year-old). Returning to the needles, that means a 14-15 gauge needle is taking up about a third of the ‘tube’ of the fistula. Presumably the other two-thirds are to make sure your arm does not fall off due to gangrene.

In my case, I have a bit-better-than-normal sized fistula (8mm) and given gangrene is not an issue, I could use quite a bit bigger of a needle. But this would be a bit too conspicuous since needles are physical objects and would need to be in inventory (“do you have any 8mm / 2-gauge needles available?”), or would have to be carried. And in either case, someone needs to put them into your arm. Not a good way to keep a vampire under cover.

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Instead, I use normal needles and the machine lies about its flow rate. The 15-gauge needles in my arm are used by the dialysis machine to pump huge amounts of blood through my body at a much higher pressure (flow rate) than normal. This is equivalent to having larger needles and enables me to support dialysis for a dozen people during the four hour session.

Removing dialysis needles — from your arm is less painful but more problematic. The problems arise from having two 2mm holes in your body, that have been there for as much as four hours. Your body does have a desire/ability to close these holes. But at the same time, your blood stream has a desire to take advantage of them: they are like two holes in a dike and are the ‘easy way out’ for the blood.

For a fistula, the dialysis needles are taken out in reverse order: the downstream needle (closer to returning to your heart) is taken out first and covered with _a lot_ of gauze and then pressurebandaged to your arm (or leg) to plug the hole. This combined with either hand-pressure or a mechanical (plastic) pressure system will enable the body to close the hole without the blood streaming through it getting in the way. The second needle is done the same way, but (for me at least, post-dialysis when my blood has been replenished), this one has a lot more pressure on it and is more likely not to close properly if anything is amiss.

An unclosed 2mm hole sprays blood into and then through the gauze very quickly. Then down your arm. Onto the chair, floor, neighboring patient, helpful RNs, and so on. The solution is simple though: be like the little Dutch boy and stick your finger into the dike… until a technically savvy nurse with a lot more gauze can come and help. As mentioned above, this has happened to me multiple times, and by just using the ‘Dutch method’, I have managed to live through all of them.

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