Effects of Using the Posterior or Anterior Approaches to the Lumbar Plexus on the Minimum Effective Anesthetic Concentration (MEAC) of Mepivacaine Required to Block the Femoral Nerve: A Prospective, Randomized, Up-and-Down Study

Abstract

Using a posterior psoas compartment approach to the lumbar plexus does not increase the minimum effective anesthetic concentration of mepivacaine required to block the femoral nerve as compared with the anterior 3-in-1 approach, and provides better quality of intraoperative anesthesia due to the more reliable block of the lateral femoral cutaneous and obturator nerves.

Dose-Finding Methodology for Peripheral Nerve Blocks

“…[9][10][11] Despite the onslaught of new publications, the optimal methodology remains ambiguous. Whereas the Dixon-Mood up-and-down method remains most prevalent, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] recent trials have advocated using a Biased Coin Design variant. [27][28][29][30][31] Alternately, 3 studies published in 2013 used Bayesian analysis and the Continual Reassessment Method.…”

A randomised controlled comparison between stimulating and standard catheters for lumbar plexus block

“…The lumbar plexus block was performed by injecting mepivacaine 1.5% through the catheter. In the first patient of both groups the volume was 30 ml, corresponding to the ED 95 calculated using standard catheters . The volume of local anaesthetic was determined by the response of the previous patient in that group using the modified Dixon's up‐and‐down sequential allocation technique .…”

“…The primary outcome was the EV 50 of mepivacaine 1.5% to achieve complete sensory and motor block in all three branches of the lumbar plexus at 30 min using the up‐and‐down method with Choi's turning point estimator concept . Based on published data we anticipated a mean (SD) volume requirement of mepivacaine 1.5% of 30 (4) ml to obtain lumbar plexus block using a standard catheter . According to Dixon and Massey's method , sample size was calculated on the basis of a 2‐SD difference as significant.…”

“…Lumbar plexus block is a useful technique for hip and knee surgery . The posterior approach to the lumbar plexus provides anaesthesia of the femoral, obturator and lateral femoral cutaneous nerves, allowing reliable sensory and motor block of the anterior, medial and lateral portions of the hip and knee joints . Unfortunately, despite the potential benefits of lumbar plexus block, reports of major complications such as bleeding, total spinal and local anaesthetic systemic toxicity have discouraged more widespread adoption of this technique .…”

Reply to Drs. Abdallah and Brull

“…Lumbar plexus block provides a reliable obturator nerve block. 8 But unfortunately, the literature does not support the hypothesis that continuous lumbar plexus block offers any benefit compared with continuous femoral nerve block in postoperative analgesia after TKA, and further head-to-head comparisons are needed. Having patients totally free from pain after TKA might lead to the improvement of the outcome or shorten hospital length of stay.…”