ULTRASOUND AS AN ADJUNCT TO EPIDURAL CATHETER PLACEMENT.

Accurate knowledge of the distance from the skin to the lumbar epidural space should facilitate the placement of an epidural catheter and decrease the incidence of dural puncture. We report an ultrasonic method for determining this depth with precision. Data were collected on 22 term obstetric patients who required placement of an epidural anesthetic for analgesia during labor or delivery. Prior to placement of the epidural catheter, ultrasound scans of lumbar spines L2 though L4 were obtained using a 3. 0 MHz real-time linear ultrasound transducer. The analysis shows that a formula, which takes into account the angle of entry, results in a high correlation between the ultrasonically measured perpendicular distance and that encountered during insertion of the Touhy needle.