Bevel direction of epidural needles reliably predicts direction of catheter placement and contrast spread in human cadavers: results of a pilot study.

STUDY OBJECTIVE

To confirm the relationship between bevel orientation, catheter direction, and radiopaque contrast spread in the lumbar region.

DESIGN

Pilot cadaver study.

SETTING

Anatomy laboratory of a university hospital.

MEASUREMENTS

Cadavers were randomized to two groups of 4 cadavers each. In Group 1, needle bevel direction at epidural entry was cephalad; in Group 2, it was caudad. After placement of each epidural catheter in L4-L5 interspace, 2 mL of radiopaque contrast was injected and a lumbar posterior-anterior radiograph was obtained. Catheter direction and direction of radiopaque contrast spread were collected.

MAIN RESULTS

Due to the inability to access the epidural space secondary to surgical changes in the lumbar spine, one cadaver in the cephalad group was excluded. In 7 of 7 (100%) cadavers, the catheter tip direction according to the radiograph corresponded directly with bevel direction.

CONCLUSIONS

A strong relationship exists between bevel orientation and catheter direction; however, catheter position does not reliably predict the direction in which the injected fluid spreads in all cadavers.