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, 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’ in a 50-year-old is about 10mm). Returning to the needle, that means a 14-15 gauge needle is taking up about a third of the ‘tube’. 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 can 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?”) and someone needs to put them into my arm. Not a good way to keep a vampire under cover. 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 - 56 -
