Straight advancement of epidural catheter--comparative assessments by method and site of epidural needle puncture and angle of puncture.

The catheter straight advancement rate for introduction into the epidural space was investigated using a radiopaque catheter. One hundred patients were divided into two groups and underwent thoracic or lumbar epidural punctures, with one of two different puncture methods: the median approach or paramedian approach. Two different angles of epidural puncture needle insertion, 50-60 degrees and 90 degrees to skin surface plane, were used. A catheter was inserted into the epidural space about 5 cm cephalad and the course of the inserted catheter was ascertained by radiography. The results have shown that punctures performed at an insertion angle of 50-60 degrees yielded higher catheter straight advancement rates than those performed at an angle of 90 degrees in both thoracic and lumbar epidural punctures.