RT Journal Article SR Electronic T1 Upper trunk block: ‘primum non nocere’ JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 155 OP 156 DO 10.1136/rapm-2019-101162 VO 45 IS 2 A1 José Cros Campoy A1 Oscar Domingo Bosch A1 Xavier Sala-Blanch YR 2020 UL http://rapm.bmj.com/content/45/2/155.2.abstract AB