Needle bevel orientation does not affect the cranial spread of injectate in a lumbosacral epidural in canine cadavers.

OBJECTIVE

To investigate the cranial and circumferential spread of iohexol (240 mg/mL) diluted 1:3 with saline injected at the lumbosacral junction in canine cadavers using 0.1- and 0.2-mL/kg volumes administered with a cranial- or caudal-facing Tuohy bevel direction.

METHODS

Lumbosacral epidurals were performed with a cranial- or caudal-facing needle bevel. The median vertebrae reached and the estimated percentage of the spinal cord surrounded with injectate were assessed via CT after administering two 0.1-mL/kg aliquots of injectate. Contrast medium was diluted to achieve physical properties closer to local anesthetics.

RESULTS

5 cadavers in each group were assessed in August of 2024. The median vertebrae reached with a 0.1-mL/kg volume using a cranial bevel and 100%, ≥ 50%, and ≥ 1% circumferential epidural coverage contrast medium were 1, 7, and 10 bodies compared to a caudal bevel direction of 1, 7, and 9 bodies. For 0.2-mL/kg total volume using a cranial bevel and having 100%, ≥ 50%, and ≥ 1% circumferential epidural coverage, there were 2, 9, and 14 bodies compared to a caudal bevel direction being 2, 11, and 15 bodies.

CONCLUSIONS

The findings in this cadaveric study suggest that needle bevel direction does not affect the cranial epidural spread of injectate performed at the lumbosacral space.

CLINICAL RELEVANCE: While no benefit to performing a lumbosacral epidural with a caudally facing bevel in limiting cranial spread was found, further studies in live patients are required to adjust clinical recommendations.