A fuzzy clustering approach to understanding religious and socioeconomic determinants of public perceptions of environmental regulation in the United States.

Interscalene brachial plexus block (ISB) targeting cervical nerve roots C5 to C7 is frequently performed to provide safe and effective postoperative analgesia for shoulder surgery, which commonly involves moderate to severe postoperative pain []. Continuous peripheral nerve block catheters offer the advantage of prolonged analgesia; however, improper execution of this technically demanding technique, combined with inadequate postoperative care team preparation, can lead to catheter dislodgement and suboptimal analgesia. As an alternative, single-shot ISB provides a simpler approach that delivers effective analgesia for a limited duration. To extend the duration of postoperative analgesia, long-acting local anesthetics are often combined with adjuvants. Dexamethasone, a corticosteroid, has consistently been shown in systematic reviews to significantly prolong the duration of analgesia (DOA) when combined with local anesthetics [,]. It exerts analgesic effects by inhibiting phospholipase A2 and stimulating the glucocorticoid system, producing systemic anti-inflammatory effects. It is also thought to prolong the DOA by acting on nociceptive C fibers and inhibiting potassium channel function, thereby preventing nerve cell depolarization and the transmission of pain signals to the brain []. Perineural administration produces longer-lasting effects than the systemic route [–]. A systematic review identified 4 mg as a ceiling dose for perineural dexamethasone, extending analgesia by an average of 8 hours when combined with long-acting local anesthetics []. Despite these benefits, dexamethasone is generally avoided in patients with poorly controlled diabetes because of its hyperglycemic effects. Alpha-2 adrenergic agonists such as clonidine and dexmedetomidine have also been shown to prolong the effects of brachial plexus block [–]. Of these, dexmedetomidine is more effective than clonidine in enhancing the analgesic effects of local anesthetics owing to its stimulation of hyperpolarization-activated cyclic nucleotide-gated channels, which prevents pain signal transmission, and its vasoconstriction of neural blood vessels [–]. Dexmedetomidine is increasingly used to enhance brachial plexus nerve block analgesia, with efficacy dependent on the route of administration; both intravenous (IV) and perineural routes significantly enhance pain relief [,].