RT Journal Article SR Electronic T1 Dueling Guidelines JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 291 OP 291 DO 10.1097/AAP.0000000000000358 VO 41 IS 2 A1 Mark C. Norris YR 2016 UL http://rapm.bmj.com/content/41/2/291.1.abstract AB