RT Journal Article SR Electronic T1 Ultrasound guidance for peripheral nerve blocks: an observational trend study of national data JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP rapm-2019-101113 DO 10.1136/rapm-2019-101113 A1 Stephen C Haskins A1 Megan Fiasconaro A1 Lauren Wilson A1 Jashvant Poeran A1 Jiabin Liu A1 Stavros Memtsoudis YR 2020 UL http://rapm.bmj.com/content/early/2020/02/12/rapm-2019-101113.abstract AB