Well, since few people are answering your question, I'll try. I believe there can be benefit to an art line during a code, but not for every patient, and ONLY if you are not the physician running the code. For anyone that has run a code on a patient that already has an arterial line, you know that it makes decision making less burdensome, and I'm all for cognitive offloading.
Anyway, here's my approach.
I almost never use ultrasound if I'm placing it with active compressions, it is just too difficult to maintain a static view, not to mention find your needle tip. At most, if it's already at bedside I will take a quick peek before donning sterile gloves to identify the general location of the vessels. If I can't get access blind then I will abandon the procedure until ROSC is achieved.
Open both a femoral arterial line kit (NOT the integrated seldinger arrow kit, but the kit that has an 18gauge hollow bore needle and you have to thread the wire separately), and a central line kit. Chances are you will miss and then you can just put in the correct line.
I try to abduct the leg slightly, widely chlorhex (takes 10 seconds), find the crease and be confident about the location of the inguinal ligament before stabbing. Attempt to palpate a pulse with my non-dominant hand, and if I feel it, enter about 2cm caudad at a 45 degree angle and slightly medially to where I palpate. If I can't palpate a pulse, I enter typically more medially than my brain wants me to, as I find most people tend to miss because they are going too lateral. I don't go at a steep angle, I find this leads to a higher chance the wire doesn't thread. It also doesn't make sense to go steep and "flatten out" in a code situation, because it's just too likely you'll get outside the lumen when you attempt this with the entire patient bouncing. After I get flash, I swap hands and hold the needle stable (my nondominant hand is firmly on the crease prior to this to try to limit the "bouncing" from compressions and so I can immediately swap hands. The other key is having your wire immediately next to your dominant hand so you can enter as fast as possible, as well as having the wire "pre-loaded". What I mean is I extend the wire about 6cm out from the spool before I do anything so that once I get flash I can push it through the needle in a single motion with my arm, rather than awkwardly putting it up to the needle hub and scrolling it in with my thumb, inevitably losing my needle position in the lumen in the meantime. I also enter with the J tip pointing up (so the tip of the curl faces towards the ceiling), because it will enter the vessel more smoothly this way.
If I get flash and think it's venous, perfect, now you have a marker... I thread the CENTRAL LINE wire and remove the needle and just leave the wire flopping there (well, not quite flopping, I allow about 10cm to be out of the skin), and then stick about 1cm lateral to this floating wire with my art line needle, and you tend to quite easily find the artery at this point, thread the ART LINE wire, now you have two wires sticking out of the patient, make a couple nicks and you throw both lines in.
One other thing I thought of, if I get flash and can't thread and I think it's because there's too much movement so I'm not able to be steady enough, I will get through the skin with my dominant hand, but then switch to my nondominant, with my wrist resting firmly on the crease I'll try to find the vessel with this hand while hovering the wire at the hub with my dominant hand, so I can enter within a second or two of obtaining a flash.
Hope this is helpful if you choose to do a code art line. One last thing, it makes everything safer if you have an assistant gloved up to hand you the scalpel and take your sharps, as I agree that this is a risky procedure, and should only be undertaken if you're confident in your team to help you stay safe and if you are meticulous with handling sharps.
