I'm a new grad who is also new to the SICU...I know this sounds lame but I'm having some probs figuring out the differences about central lines. What exactly is different about an A-line verses a CV-line? Why is the subclavian the preferred site? Why would a doc choose to put in one vs. the other? I feel cheesy that I don't get this yet..but I'd rather ASK! Thanks in advance!