IV and Perineural Dexmedetomidine Similarly Prolong the Duration of Analgesia after Interscalene Brachial Plexus Block

Abstract

Background Perineural and IV dexmedetomidine have each been suggested to prolong the duration of analgesia when administered in conjunction with peripheral nerve blocks. In the first randomized, triple-masked, placebo-controlled trial to date, the authors aimed to define and compare the efficacy of perineural and IV dexmedetomidine in prolonging the analgesic duration of single-injection interscalene brachial plexus block (ISB) for outpatient shoulder surgery. Methods Ninety-nine patients were randomized to receive ISB using 15 ml ropivacaine, 0.5%, with 0.5 μg/kg dexmedetomidine administered perineurally (DexP group), intravenously (DexIV group), or none (control group). The authors sequentially tested the joint hypothesis that dexmedetomidine prolongs the duration of analgesia and reduces the 24-h cumulative postoperative morphine consumption. Motor blockade, pain severity, hemodynamic variations, opioid-related side effects, postoperative neurologic symptoms, and patient satisfaction were also evaluated. Results Ninety-nine patients were analyzed. The duration of analgesia was 10.9 h (10.0 to 11.8 h) and 9.8 h (9.0 to 10.6 h) for the DexP and DexIV groups, respectively, compared with 6.7 h (5.6 to 7.8) for the control group (P < 0.001). Dexmedetomidine also reduced the 24-h cumulative morphine consumption to 63.9 mg (58.8 to 69.0 mg) and 66.2 mg (60.6 to 71.8 mg) for the DexP and DexIV groups, respectively, compared with 81.9 mg (75.0 to 88.9 mg) for the control group (P < 0.001). DexIV was noninferior to DexP for these outcomes. Both dexmedetomidine routes reduced the pain and opioid consumption up to 8 h postoperatively and did not prolong the duration of motor blockade. Conclusion Both perineural and IV dexmedetomidine can effectively prolong the ISB analgesic duration and reduce the opioid consumption without prolonging motor blockade.

Systemic dexmedetomidine is not as efficient as perineural dexmedetomidine in prolonging an ulnar nerve block

“…A clinical trial investigated the perineural and intravenous addition of dexmedetomidine 0.5 µg/kg vs placebo to an interscalene nerve block using 15 mL ropivacaine 3. They reported that both perineural and systemic dexmedetomidine prolonged the duration of the nerve block significantly, which is in support of our results.…”

“…In healthy volunteers, a dramatic effect was observed when dexmedetomidine was administered perineurally, but also a lesser result when administered intravenously 2. In patients, systemic and perineural dexmedetomidine prolonged the duration of interscalene nerve blocks similarly 3. These trials, however, used a suboptimal dose of dexmedetomidine4 and lacked control of systemic effects: the extended block duration observed in the perineural groups may have been caused by absorption and re-distribution of the perineural dexmedetomidine triggering systemic effects and not by a perineural mechanism 2 3…”

Effect of Dexmedetomidine Infusion During Orthopedic Surgery on Postoperative Analgesic Consumption in Opium Addict Patients; A Randomized Clinical Trial

“…The efficacy of IV Dex in prolonging the analgesic duration of brachial plexus block for shoulder surgery was assessed in a randomized clinical trial and it was found that Dex reduced the pain and opioid consumption up to 8 hours postoperatively and did not prolong the duration of the motor blockade (22).…”

Coadyuvantes farmacológicos con efecto ahorrador de opioides en el periodo perioperatorio

“…Es de destacar que hay algunos estudios de que la dexmedetomidina i.v. puede ser tan efectiva como la perineural para prolongar la analgesia y reducir el consumo de opioides en el período postoperatorio temprano (73).…”