Ultrasound has been a friend to central venous catheter placement for a long time. It's always there to make sure you are putting that line in the right place without causing problems. While this has been standard for internal jugular lines for years, it is only more recently that this has been proposed for subclavian lines. There is now ample literature supporting this latter practice, although as far as I know, it is not yet widely adopted. This article starts off with the assumption that ultrasound is being used for subclavian lines and now asks the question, which is the safer approach - above or below the clavicle?

https://www.ultrasoundgel.org/122
https://pubmed.ncbi.nlm.nih.gov/34231204/