Prolonging Peripheral Nerve Blocks in Adults: A Narrative Review of Adjunct Medications for Single-Injection Techniques.
Dexamethasone prolongs single-injection peripheral nerve block analgesia by about 6-8 hours
Prolonging Peripheral Nerve Blocks in Adults: A Narrative Review of Adjunct Medications for Single-Injection Techniques.
Single-injection peripheral nerve blocks (peripheral nerve blocks) are a cornerstone of multimodal perioperative analgesia.
To review the effectiveness and safety of pharmacologic adjuncts used to prolong adult single-injection peripheral nerve blocks and to provide practical, clinically oriented recommendations for their use.
I conducted a focused narrative review of randomized controlled trials, observational studies, and systematic reviews or meta-analyses evaluating adjunct medications administered with single-injection peripheral nerve blocks in adults.
Buprenorphine, administered perineurally, often extends analgesia to 24-48 hours but increases postoperative nausea.
Clonidine yields smaller gains in a block's duration with similar hemodynamic and sedative concerns to dexmedetomidine.
Magnesium sulfate and midazolam produce modest and more variable benefits.
LIMITATIONS: This is a narrative rather than a systematic review; heterogeneity among studies in block type, local anesthetic formulation, dosing, and outcome definitions precludes pooled quantitative estimates.
Dexamethasone and buprenorphine have the strongest and most consistent evidence for clinically meaningful prolongation of single-injection peripheral nerve blocks in adults and may be considered first-line adjuncts in appropriate patients.
Dexmedetomidine, clonidine, magnesium, midazolam, and ketamine may be useful in some situations when their specific benefit-risk profiles are acceptable.
Conventional opioids offer little advantage as perineural adjuncts and are not recommended for routine use.