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

https://doi.org/10.1016/j.jclinane.2014.04.004Get rights and content

Abstract

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.

Introduction

In lower extremity surgery, direction of catheter insertion influences the efficacy of epidural anesthesia [1]. Bevel direction in the epidural space correlates with the directional spread of the injectate [2]. When a catheter is placed with the bevel of the needle facing in the cephalad direction in the mid-thoracic and low-thoracic spine, injected contrast spreads preferentially in the cephalad direction [3]. However, there are limited data assessing the direction of flow of the injectate when a catheter is threaded in the caudad direction. In this cadaver study, radiopaque contrast was used to confirm the relationship between bevel orientation, catheter direction, and radiopaque contrast spread in the lumbar region.

Section snippets

Materials and methods

After University of Medicine and Dentistry of New Jersey Institutional Review Board approval, 8 human cadavers were obtained from the anatomy laboratory. The cadavers were randomly divided into two groups of 4 cadavers. In Group 1, needle bevel direction at epidural entry was cephalad, while in Group 2 it was caudad. After each cadaver was placed prone, the L4-L5 interspace was identified using the posterior superior iliac crests as landmarks. We used anatomic landmarks because the study was

Results

Due to our 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. In Group 1, the radiopaque contrast flowed primarily in the cephalad direction in all three cadavers. In Group 2, radiopaque contrast flowed primarily in the caudad direction in three cadavers and equally caudad and cephalad

Discussion

For patients undergoing total hip replacement, neuraxial anesthesia (spinal and/or epidural) results in better outcomes than general anesthesia [4]. According to Capdevila et al, regional techniques also improved early rehabilitation after major knee surgery by effectively controlling postoperative pain during continuous passive motion, hastening convalescence. [5]. In addition, for patients who are elderly and/or have multiple comorbidities, regional anesthesia may be preferred over general

References (13)

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☆

Supported by departmental funding only.

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