Perineural Administration of Dexmedetomidine in Combination with Bupivacaine Enhances Sensory and Motor Blockade in Sciatic Nerve Block without Inducing Neurotoxicity in Rat

Department of Anesthesiology, Division of Pain Medicine, The University of Michigan Health System, 7433 Medical Sciences Building 1, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109-5615, USA.
Anesthesiology (Impact Factor: 5.88). 10/2008; 109(3):502-11. DOI: 10.1097/ALN.0b013e318182c26b
Source: PubMed


The current study was designed to test the hypothesis that high-dose dexmedetomidine added to local anesthetic would increase the duration of sensory and motor blockade in a rat model of sciatic nerve blockade without causing nerve damage.
Thirty-one adult Sprague-Dawley rats received bilateral sciatic nerve blocks with either 0.2 ml bupivacaine, 0.5%, and 0.5% bupivacaine plus 0.005% dexmedetomidine in the contralateral extremity, or 0.2 ml dexmedetomidine, 0.005%, and normal saline in the contralateral extremity. Sensory and motor function were assessed by a blinded investigator every 30 min until the return of normal sensory and motor function. Sciatic nerves were harvested at either 24 h or 14 days after injection and analyzed for perineural inflammation and nerve damage.
High-dose dexmedetomidine added to bupivacaine significantly enhanced the duration of sensory and motor blockade. Dexmedetomidine alone did not cause significant motor or sensory block. All of the nerves analyzed had normal axons and myelin at 24 h and 14 days. Bupivacaine plus dexmedetomidine showed less perineural inflammation at 24 h than the bupivacaine group when compared with the saline control.
The finding that high-dose dexmedetomidine can safely improve the duration of bupivacaine-induced antinociception after sciatic nerve blockade in rats is an essential first step encouraging future studies in humans. The dose of dexmedetomidine used in this study may exceed the sedative safety threshold in humans and could cause prolonged motor blockade; therefore, future work with clinically relevant doses is necessary.

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    • "A study by Brumett et al (9) showed that dexmedetomidine enhances duration of bupivacaine anaesthesia and analgesia of sciatic nerve block in rats without any damage to nerve. Histopathological evaluation of the nerve axon and myelin were normal in both groups were normal at 24 hours and 14 days. "
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    ABSTRACT: Background Apha-2 agonists are combined with local anesthetics to extend the duration of regional anesthesia. We evaluated the effect of combining dexmedetomidine with levobupivacine with respect to duration of motor and sensory block and duration of analgesia. Methods Sixty patients scheduled for elective forearm and hand surgery were divided into two equal groups in a randomized double blind fashion. The patients received brachial plexus block via supraclavicular route with the help of nerve stimulator. In group L (n=30) 35cc of levobupivacaine with 1ml of isotonic saline and in group LD (n=30) 35cc of levobupivacine with 1 ml of (100 microgram) of dexmedetomidine was given. Duration of motor and sensory block and time to first rescue analgesia were recorded. Data analysis was done by SPSS version 16.0 [SPSS Inc ILLINOIS, USA, 2008]. Categorical variables were analyzed using Pearson”s Chi-square test. Normally distributed numerical variables were analyzed using unpaired “t” test. Skewed numerical variables within the group were analyzed using Man-Whitney “U” test. All tests were two tailed. Statistical significance was defined as P<0.05. Results Sensory and motor block durations were longer in group LD as compared to L (P<0.01). Duration of analgesia was significantly longer in group LD as compared to group L (p<0.05). Conclusion Dexmedetomidine added to levobupivacaine in supraclavicular brachial plexus block prolongs the duration of block and the duration of postoperative analgesia.
    Ethiopian journal of health sciences 07/2014; 24(3):203-8. DOI:10.4314/ejhs.v24i3.3
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    • "Many studies have reported that dexmedetomidine extends the duration of nerve block when administered perineurally together with local anesthetics [4,5]. Brummett et al. [4] reported that dexmedetomidine administered with bupivacaine in sciatic nerve block of a mouse resulted in extended sensory nerve block and motor nerve block without nerve toxicity. Esmaoglu et al. [5] reported that the addition of dexmedetomidine to axillary brachial plexus block resulted in a shorter onset time of the nerve block, an extended duration, and a longer postoperative painless period. "
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    ABSTRACT: Background Dexmedetomidine 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. Results In 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. Conclusions Perineural 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.
    Korean journal of anesthesiology 04/2014; 66(4):283-9. DOI:10.4097/kjae.2014.66.4.283
    • "The duration of LA was longer, VAS was lower and the need for rescue morphine doses was less when dexmedetomidine was added to bupivacaine. Brummett et al. have reported that perineural administration of high-dose dexmedetomidine in combination with bupivacaine enhanced LA blockade in rats without inducing neurotoxicity.[19] Many studies have found that the addition of dexmedetomidine to LA in central neuraxial blocks and in peripheral nerve blockades in human was a safe and effective way to potentiate the LA effect and reduce the required analgesics.[141516171820212223] "
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    ABSTRACT: Background: Dexmedetomidine is an alpha 2 adrenergic agonist, prolongs analgesia when used in neuraxial and peripheral nerve blocks. We studied the effect of addition of dexmedetomidine to bupivacaine to perform transversus abdominis plane (TAP) block. Materials and Methods: A total of 50 patients scheduled for abdominal hysterectomy were divided into two equal groups in a randomized double-blinded way. Group B patients (n = 25) received TAP block with 20 ml of 0.25% bupivacaine and 2 ml of normal saline while Group BD (n = 25) received 0.5 mcg/kg (2 ml) of dexmedetomidine and 20 ml of 0.25% bupivacaine bilaterally. Time for first analgesic administration, totally used doses of morphine, pain scores, hemodynamic data and side-effects were recorded. Results: Demographic and operative characteristics were comparable between the two groups. The time for the first analgesic dose was longer in Group BD than Group B (470 vs. 280 min, P < 0.001) and the total doses of used morphine were less among Group BD patients in comparison to those in Group B (19 vs. 29 mg/24 h, P < 0.001). Visual analog scores were significantly lower in Group BD in the first 8 h post-operatively when compared with Group B, both at rest and on coughing (P < 0.001). In Group BD, lower heart rate was noticed 60 min from the induction time and continued for the first 4 h post-operatively (P < 0.001). Conclusions: The addition of dexmedetomidine to bupivacaine in TAP block achieves better local anesthesia and provides better pain control post-operatively without any major side-effects.
    04/2014; 8(2):161-6. DOI:10.4103/1658-354X.130683
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