RT Journal Article SR Electronic T1 Safety of epidural gravity flow technique JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP rapm-2020-102105 DO 10.1136/rapm-2020-102105 A1 Lenin Babu Elakkumanan YR 2020 UL http://rapm.bmj.com/content/early/2020/11/24/rapm-2020-102105.abstract AB