title: Coiling of lumbar epidural catheters.
abstract: BACKGROUND
  The difficulties in threading an epidural catheter to vertebral levels remote to the puncture level have been well documented. This study was undertaken to determine the length that a single orifice epidural catheter can be threaded into the lumbar space without coiling (coiling length), and whether this is affected by the direction of the epidural needle bevel.
  
  
  METHODS
  Forty-five young male patients scheduled for surgery under epidural analgesia were enrolled. The epidural space was identified using a midline approach at the L(2-3) or L(3-4) interspace with the loss of resistance to air technique. A 19-G single-orifice epidural catheter (Flextip Plus, Arrow International, Inc, Reading, PA, USA) was inserted through a Tuohy needle oriented either cephalad (n=20) or caudad (n=25). During insertion, the path and the position of the catheter tip was determined by fluoroscopy using iohexol dye.
  
  
  RESULTS
  The median coiling length was 2.8 cm, ranging from 1.0 to 8.0 cm. Only 13% of epidural catheters could be threaded 4 cm beyond the tip of the needle without coiling. No significant difference was found in coiling length between the cephalad group (2.9 cm) and the caudad group (2.5 cm).
  
  
  CONCLUSIONS
  This study demonstrates that coiling length is independent of whether the bevel of the Tuohy needle is directed cephalad or caudad. We recommend that an optimal insertion depth of an end-hole single orifice catheter is 3 cm.
authors.affiliation: Department of Anesthesiology and Clinical Research Institute, Seoul National University Hospital, Korea. limyjin@snu.ac.kr
authors.forename: Y J
authors.initials: YJ
authors.lastname: Lim
authors.forename: J H
authors.initials: JH
authors.lastname: Bahk
authors.forename: W S
authors.initials: WS
authors.lastname: Ahn
authors.forename: S C
authors.initials: SC
authors.lastname: Lee
mesh_terms: D000328:Adult; D000767:Anesthesia, Epidural / Q000295:instrumentation* / Q000379:methods*; D002404:Catheterization / Q000379:methods*; D004824:Epidural Space / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D009339:Needles; D011859:Radiography