Perineural Dexmedetomidine as an Adjuvant Reduces the Median Effective Concentration of Lidocaine for Obturator Nerve Blocking: A Double-Blinded Randomized Controlled Trial

Safety and efficacy of dexmedetomidine in combination with local anesthetics for orthopedic nerve blocks: a systematic review and meta-analysis

INTRODUCTION

Peripheral nerve block, a common technique for managing postoperative pain and providing intraoperative analgesia, often includes adjuncts like dexmedetomidine (DEX) to enhance the effectiveness of local anesthetics. DEX, known for its α2-adrenoceptor agonist properties, extends sensory blockade and improves postoperative analgesia while offering sedative benefits. The objective of this study is to rigorously assess the effectiveness and safety of perineural DEX injection in orthopedic nerve block procedures, focusing on orthopedic surgeries to minimize heterogeneity and provide clearer insights for clinical practice.

EVIDENCE ACQUISITION

This meta-analysis, registered on PROSPERO, involved a comprehensive literature search across multiple databases, focusing on RCTs comparing DEX with local anesthetics for peripheral nerve blocks in orthopedic surgery patients. The eligibility criteria included adult participants and various nerve block methods in orthopedic surgeries. Studies were rigorously appraised for methodological quality using Cochrane Handbook guidelines. GRADE profiler 3.6 was used for evidence grading.

EVIDENCE SYNTHESIS

Among 1391 documents, 21 studies were included, focusing on DEX with local anesthetics in orthopedic nerve blocks. Findings showed significant improvements in analgesia duration, sensory and motor block duration, and reduced postoperative opioid consumption, with an increased risk of bradycardia. Quality assessments indicated moderate bias risk.

CONCLUSIONS

DEX with local anesthetics significantly enhances nerve block effectiveness, extending analgesia and block durations while reducing opioid need. However, it requires careful monitoring due to increased bradycardia risk. These findings highlight the need for cautious use in clinical practice, considering both potential benefits and adverse effects.

Perineural Dexmedetomidine Reduces the Median Effective Concentration of Ropivacaine for Adductor Canal Block

BACKGROUND Multimodal analgesic regimens are well known as the best option for total knee arthroplasty. They include the adductor canal block, combined with local infiltration analgesia and a block of the interspace between the popliteal artery and the capsule of the posterior knee. However, these analgesic techniques all require a large amount of local anesthetics. In this study, we explored whether the quantity of local anesthetics could be decreased by using dexmedetomidine for the adductor canal block. MATERIAL AND METHODS Fifty-four patients scheduled for unilateral, primary total knee arthroplasty were allocated into 2 groups: the ropivacaine group (group R) and the dexmedetomidine group (group RD). Ropivacaine 0.5% was chosen as the initial concentration, and the concentration was decreased or increased according to the response of the previous participant. Based on Dixon's up-and-down method, the median effective concentration was calculated. RESULTS The quadriceps strength was similar between the 2 groups, both at 30 min after adductor canal block and during recovery from general anesthesia in the Postanesthesia Care Unit. None of the patients in this study exhibited bradycardia or hypotension. The median effective concentration of ropivacaine for adductor canal block was 0.29% (95% confidence interval [CI], 0.28-0.31%) in group RD, which was lower than that in group R (0.38% [95% CI, 0.36-0.41%]). CONCLUSIONS This study found perineural dexmedetomidine 1 μg/kg could reduce the median effective concentration of ropivacaine for the adductor canal block.

Pharmacologic Properties of Novel Local Anesthetic Agents in Anesthesia Practice

Therapeutic duration of traditional local anesthetics when used in peripheral nerve blocks is normally limited. This article describes novel approaches to extend the duration of peripheral nerve blocks currently available or in development. Three newer approaches on extending the duration of peripheral nerve blocks include site-1 sodium channel blockers, novel local anesthetics delivery systems, and novel adjuvants of local anesthetics. Compared with plain amide-based and ester-based local anesthetics, alternative approaches show significant promise in decreasing postoperative pain, rescue opioid requirement, hospital length-of-stay, and overall health care cost, without compromising the established safety profile of traditional local anesthetics.