Relationship between the bevel of the Tuohy needle and catheter direction in thoracic epidural anesthesia

Background and Objectives: Directing an epidural catheter cephalad or caudad is usually attempted by orienting the beveled edge of the epidural needle. However, there have been few studies about the relationship between the direction of the bevel of epidural needle and the resulting position of the catheter. We studied this relationship in thoracic epidural catheter placement. Catheter position was confirmed by using picture archiving communication systems (PACS). PACS is a workstation that stores radiologic images, which can be manipulated to visualize the catheters. Methods: One hundred six patients receiving thoracic epidural anesthesia were enrolled. The cephalad and caudad groups (each with 53 patients) received epidural anesthesia at the T6-7 interspace with either a cephalad- or caudal-directed Tuohy needle. The final position of all of the catheters was confirmed by PACS. Results: In the cephalad group, 63.5% of the catheters were confirmed to travel in a cephalad direction. In the caudad group, 22.0% of the catheters advanced in a caudad direction. Curling of the catheters occurred in 17.6%. PACS showed the catheter positions with satisfactory quality. Conclusions: The correlation between bevel direction and location of the thoracic epidural catheter was relatively low. Practices such as threading an epidural catheter by manipulation of the Tuohy needle for the control of pain at a distant site may not yield good results.