RT Journal Article SR Electronic T1 Erratum JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 189 OP 189 DO 10.1136/rapm-00115550-200803000-00018 VO 33 IS 2 YR 2008 UL http://rapm.bmj.com/content/33/2/189.abstract AB