Brachial plexus blocks: infusions and other mechanisms to provide prolonged analgesia.

PURPOSE OF REVIEW: Regional anesthesia has numerous benefits for upper extremity surgery such as improved analgesia, opioid sparing and reduced side effects. However, many of these advantages are lost after block regression. Recently, several strategies such as continuous ambulatory local anesthetic infusions and adjuvants that may potentiate analgesia after a brachial plexus block have been described and investigated. This review will highlight and place in context this recent work. RECENT
FINDINGS: Current investigations have demonstrated that brachial plexus analgesia can be extended by combining existing solutions and technology. This has been most evident in the use of ambulatory continuous peripheral nerve blocks such as the interscalene, infraclavicular and axillary approaches. Accomplishing this safely in an outpatient setting requires the use of basic infusion pumps, patient education and a mechanism for follow-up after discharge. This strategy has prolonged pain relief and facilitated major operations on an outpatient basis. An alternative to this strategy is to combine adjuvants such as opioids, clonidine, ketamine and neostigmine to potentiate the effects of local anesthetics. These additives have had mixed results. The most promising solutions are the alpha-2-adrenergic agonists but further investigation is necessary to confirm their efficacy and quantify their appropriate dose and side effects.
SUMMARY: The advances and techniques recently described demonstrate that prolonging analgesia after brachial plexus blocks is possible. This may be accomplished via several different approaches and mechanisms resulting in improved patient analgesia and side effects.