Posterior Tibial Nerve Sensory Blockade Duration Prolonged by Adding Dexmedetomidine to Ropivacaine
FRCPC,Université Laval, Département d'anesthésie 2705, boul Laurier, local 2206 Québec, Qc, Canada G1V 4G2. . Anesthesia and analgesia
(Impact Factor: 3.47).
07/2012; 115(4):958-62. DOI: 10.1213/ANE.0b013e318265bab7
Dexmedetomidine, an α(2)-receptor agonist, prolongs analgesia when used in neuraxial and IV blocks. We evaluated the effect of dexmedetomidine added to ropivacaine for tibial nerve block on the duration of the sensory blockade.
For this prospective, randomized, controlled, double-blind, crossover trial, 14 healthy volunteers were allocated to 2 groups. All volunteers received an ultrasound-guided tibial nerve block 4 to 5 cm proximally to the medial malleolus. In group R, 10 mL of 0.5% ropivacaine was injected for the block; in group RD, 10 mL of a solution containing 0.5% ropivacaine with 1 μg/kg of dexmedetomidine was administered. After the injection, monitoring of vital signs, evaluation of onset and resolution of sensory block, and level of sedation (Observer's Assessment of Alertness/Sedation scale) were performed. Three weeks later, the same procedure was repeated, but the study subjects were allocated to the other group in a crossover fashion. The primary end point was the duration of sensory blockade. The time and carryover effects were also evaluated. Secondary outcomes were the onset time and the presence of adverse effects such as hypotension, bradycardia, hypoxia, and sedation.
Sensory blocks lasted longer in group RD than in group R (21.5 vs 16.2 hours; mean pairwise difference 5.3 hours [95% confidence interval: 3.9-6.7 hours]; P < 0.0001). Onset times were similar between groups. The mean systolic and diastolic blood pressure levels were stable throughout the study period in group R. In group RD, a noticeable decrease in systolic and diastolic blood pressure was observed between 60 and 480 minutes (P < 0.05); 2 volunteers experienced a 30% decrease in systolic blood pressure when compared with the baseline value as compared with none in group R. Heart rate was similar between groups except at 60 minutes (P < 0.01).
Dexmedetomidine added to ropivacaine for tibial nerve block prolongs the duration of sensory blockade with similar onset time. However, patients should be monitored for potential adverse effects such as hypotension, bradycardia, and sedation.
Available from: PubMed Central
- "Gaumann et al. , using 150 µg clonidine as an adjuvant to 1% lidocaine in brachial plexus block, reported a sedative effect lasting 60 minutes starting 30 minutes after administration. Rancourt et al.  and Swami et al.  also reported a sedative effect after administering dexmedetomidine perineurally. The analgesic effect of dexmedetomidine and the mechanism for sedation are not yet completely understood and are thought to arise from various factors. "
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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.
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.
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.
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
- "Brummett et al. have reported that perineural administration of high-dose dexmedetomidine in combination with bupivacaine enhanced LA blockade in rats without inducing neurotoxicity. 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. On the other hand, Ozalp et al. have compared dexmedetomidine -ropivacaine mixture to ropivacaine alone in patient controlled interscalene analgesia and they reported similar pain scores in both groups without any advantageous effect of dexemedetomidine. "
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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.
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).
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
- "It has been reported to improve the quality of intrathecal and epidural anesthesia. Its use in peripheral nerve blocks has recently been described. However, the reports of its use in supraclavicular brachial plexus block are limited. "
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ABSTRACT: We compared the effects of adding dexmedetomidine to a 30 ml solution of 0.325% bupivacaine in supraclavicular brachial plexus block. Onset and duration of sensory and motor block along with the duration of analgesia were the primary endpoints.
Fifty patients posted for upper limb surgeries were enrolled for a prospective, randomized, double-blind, placebo-controlled trial. Patients were divided into two groups, the control group S and the study group SD. In group S (n = 25), 30 ml of 0.325% bupivacaine + 1 ml normal saline; and in group SD (n = 25), 30 ml of 0.325% bupivacaine + 1 ml (100 μg) dexmedetomidine were given for supraclavicular brachial plexus block using the peripheral nerve stimulator. Onset and duration of sensory and motor blocks were assessed along with the duration of analgesia, sedation, and adverse effects, if any. Hemodynamic parameters, like heart rate (HR), systolic arterial blood pressure (SBP), and diastolic arterial blood pressure (DBP) were also monitored.
Demographic data and surgical characteristics were comparable in both the groups. The onset times for sensory and motor blocks were significantly shorter in SD than S group (P < 0.001), while the duration of blocks was significantly longer (P < 0.001) in SD group. Except for the initial recordings (at 0, 5, 10, and 15 min), heart rate levels in group SD were significantly lower (P < 0.001). SBP and DBP levels in SD group at 15, 30, 45, 60, 90 and 120 min were significantly lower than in S group (P < 0.001). In fact, when the percentage changes in HR/SBP/DBP were compared from 0-5/0-10/0-15/0-30/0-45/0-60/0-90/0-120 min in SD with S group, they came out to be highly significant (P < 0.001) in group SD. The duration of analgesia (DOA) was significantly longer in SD group than S group (P < 0.001). Except that, bradycardia was observed in one patient in the group SD, no other adverse effects were observed in either of the groups.
Dexmedetomidine added as an adjuvant to bupivacaine for supraclavicular brachial plexus block significantly shortens the onset time and prolongs the duration of sensory and motor blocks and duration of analgesia. Patients in group SD were adequately sedated (modified Ramsay Sedation Score, RSS = 2/6 or 3/6) with no adverse effects except bradycardia in one patient of group SD.
Journal of Anaesthesiology Clinical Pharmacology 03/2014; 30(1):36-40. DOI:10.4103/0970-9185.125701
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