Disclaimer, I haven’t read any of the replies here so if anyone has mentioned this already then disregard.
The key to good topicalization is hitting the artery on the first attempt. Once you start probing around things start to get uncomfortable.
I typically make a good skin wheel and then drive the local needle right under the skin about a cm cephalad making a larger wheel of local superficial to the artery. Then I will sometimes go medial or lateral to the artery and deep so that the local might spread around and under the artery. I never give so much that I can’t feel the artery. I’m not talking about the pulse, I’m talking about the artery. You just be able to feel the artery. Except those of you routinely using the US. You probably don’t k know what I talking about and I can’t help.
But the key to painless A line placement is to hit the artery first pass without redirecting.
Oops, it looks like pgg already said this. I just disagree with the US part.
I learned to do blocks, central lines, and arterial lines before ultrasound became ubiquitous and I got good at them. I can feel the artery in some patients but by no means all (some thick or edematous wrists just can't be felt).
Years later I did a fellowship where the standard accepted approach for awake a-lines was to stick by feel, and if you had trouble after a couple attempts, to grab the ultrasound.
These days I just go for ultrasound on the first attempt. There's no reason not to. If it's a heart, the machine is right there next to the table gel'd up and waiting for the central line. Even if it's not primed already, it doesn't take long to turn on.
I watch experienced people go for landmark/feel attempts and most of the time they get it, but sometimes they don't and I just wonder why.
As
@nimbus pointed out, sometimes you'll see a nasty, calcified, plaque-encrusted artery and you won't bother sticking it at all, because you'll know to go more proximal.
Few things look as slick as a wire-less arterial stick, one pass, flash, spin 180, advance, thread, done ... but while I respect and admire style, I'd rather make my landmark 90% first pass success rate 99% with ultrasound. If it was my wrist, I'd wonder why the hell the person needling my arm wouldn't bother to use the device that nearly guaranteed a quick single attempt success.