Comparison of dexmedetomidine and epinephrine as an adjuvant to 1% mepivacaine in brachial plexus block

Abstract

BackgroundDexmedetomidine extends the duration of nerve block when administered perineurally together with local anesthetics by central and/or peripheral action. In this study, we compared the duration of nerve block between dexmedetomidine and epinephrine as an adjuvant to 1% mepivacaine in infraclavicular brachial plexus block.Methods Thirty patients, scheduled for upper limb surgery were assigned randomly to 3 groups of 10 patients each. We performed brachial plexus block using a nerve stimulator. In the control group (group C), patients received 40 ml of 1% mepivacaine. In group E, patients received 40 ml of 1% mepivacaine containing 200 µg of epinephrine as an adjuvant. In group D, patients received 40 ml of 1% mepivacaine containing 1 µg/kg of dexmedetomidine as an adjuvant. Sensory block duration, motor block duration, time to sense pain, and onset time were assessed. We also monitored blood pressure, heart rate, oxygen saturation and bispectral index.ResultsIn group D and group E, sensory block duration, motor block duration and time to sense first pain were prolonged significantly compared to group C. However, there was no significant difference between group D and group E.ConclusionsPerineural 1 µg/kg of dexmedetomidine similarly prolonged nerve block duration compared to 200 µg of epinephrine, but slowed heart rate. Thus, dexmedetomidine is expected to be a good alternative as an adjuvant to local anesthesia in patients who are cautioned against epinephrine.

Investigating the Efficacy of Dexmedetomidine as an Adjuvant to Local Anesthesia in Brachial Plexus Block

“…In regard to the type of brachial plexus block used, a total of 10 studies utilized a supraclavicular block, 4,15,18,19,[22][23][24][25]27,30 3 used an axillary block, 20,26,29 3 used an interscalene block, 14,17,21 and 2 used an infraclavicular block. 16,28 Dexmedetomidine was used as an adjuvant to several different local anesthetics, which included levobupivacaine, 17,18,20,25,28 ropivacaine, 14,19,21,23,24,27,29,30 bupivacaine, 4,15,16,22 and mepivacaine. 28 Across the studies, the dose of dexmedetomidine ranged from 0.5 μg/kg to a total of 150 μg.…”

“…16,28 Dexmedetomidine was used as an adjuvant to several different local anesthetics, which included levobupivacaine, 17,18,20,25,28 ropivacaine, 14,19,21,23,24,27,29,30 bupivacaine, 4,15,16,22 and mepivacaine. 28 Across the studies, the dose of dexmedetomidine ranged from 0.5 μg/kg to a total of 150 μg. Local anesthetic dosages also varied across the studies.…”

“…The addition of dexmedetomidine significantly prolonged duration of sensory blockade irrespective of the dosage (≤50 μg [22][23][24]29 or >50 μg 4,15,16,18-20,25-28 ), location of block (eg, supraclavicular, 4,15,18,19,[22][23][24][25]27 infraclavicular, 16,28 or axillary 20,26,29 ), or the local anesthetic given (eg, ropivacaine, 19,23,24,27,29 bupivacaine, 4,15,16,22 levobupivacaine, 18,20,25,26 or mepivacaine 28 ).…”

Dexmedetomidine Dose Dependently Enhances the Local Anesthetic Action of Lidocaine in Inferior Alveolar Nerve Block

“…This finding is in accordance with previous reports in which DEX used with local anesthesia had sedative effects. 26 Dexmedetomidine leads to sedation via inhibition of the locus coeruleus, which inhibits ventrolateral preoptic nucleus firing and mimics non-rapid eye movement sleep. 27 Patients are thus easily arousable, which generates falsely high scores on the sedation scale.…”

“…A previous study on addition of DEX to local anesthetics evaluated a much larger dose of 4.8-to 18.1-fold the dose required to achieve the concentration of 2.5 to 7.5 ppm used in this study. 26 In terms of DEX concentration, according to internal data of the manufacturer (Maruishi Pharmaceutical), application of an undiluted DEX solution and twice the concentration of the undiluted DEX solution to local tissue does not lead to a tissue reaction, whereas application of 10 times the concentration of the undiluted DEX solution causes slight irritation of the tissue. The amount of DEX in the 2.5 ppm DEX solution used in this study was equivalent to 0.125-fold of the undiluted solution, and that in the 7.5 ppm solution was 0.375-fold the amount in the undiluted solution.…”