Why not use larger guage needles?

[red22]

I know that for IV use people use like 28-31 guage needles which are thread-like needles that are so light-weight they bend, however when I had my blood drawn recently, the guy used a needle that looked like it was the guage of a spore syringe. You know, it was like a tiny "pipe." And completely stiff. Not flexible.

 

[Jabberwocky]

because it hurts and is gonna be harder to get it in the vein lol

 

[prospectator]

how funny you should ask,,i havent "shot up" in years, and back then it probably hurt a little the first few times so anything larger meant more pain, then when it wouldnt hurt the skin had become tougher and there was a better chance of missing the vein,,,youd never want a big hole in your arm and have missed so you have to try again,,,then once you hit the vein and pull it out theres a good change plenty of blood may come out for a few seconds,,trying to avoid others noticing that spot wouldnt be very easy,,,having said all that,it doesnt sound like its something you have done,,if so ask plenty of questions before you start doing it,,,i had seen enough about it before i chose to do it therefore i was responsible for its effects.

 

[sekio]

Because they'll trash your veins with repeated use, much moreso than the fine needles. Think of driving a bus through a shopping mall vs firing a 50 cal bullet, one leaves a lot bigger hole.

 

[Owl Eyed]

Take a meat cleaver, and now take a piece of paper.

Cut yourself with both. Which leaves a bigger cut?

 

[Scorched Earth]

Sustainability and also the tiny gauges aid in the filtration somewhat.

If you can't have a decent filter then better to limit the chunks to 133 microns with a 31 gauge needle than like 413 microns with a 22G. Cotton provides a little filtration but I would be surprised if it really filtered at a level of 50 microns optimally like they say or really got much meaningful stuff out the needle wouldn't have prevented from passing. Seems like machine pressed steel has a better chance of providing a small passage for filtration than a piece of wet cotton I am pressing on with a flimsy needle. I think the original purpose of the cotton was to pad the needle from getting dulled in the spoon.

Also they say they use the big gauges for blood because the smaller ones damage the red blood cells by smashing them as they are drawn through. Seems to me if a capillary is big enough to allow a blood cell to pas through without bruising and sticking it should be big enough to allow anything to pass that was not filtered out by the needle. Any phlebotimists around with any info on that? It is just bruising from crowding that makes the smaller gauges unsuited to blood work?