Posterior Tibial Nerve Sensory Blockade Duration Prolonged by Adding Dexmedetomidine to Ropivacaine
ABSTRACT 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.
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ABSTRACT: Dexmedetomidine was initially approved for clinical use as a sedative. Its development in pain management has been limited. Dexmedetomidine has analgesic effects and analgesic-sparing properties, especially for patients with obstructed airways. Mixing dexmedetomidine with local anesthetics is a promising new avenue to enhance local anesthetics' effectiveness. Peripheral, spinal and supraspinal α2A-ARs are responsible for the analgesic function of dexmedetomidine. Animal studies have shown that antinociceptive synergism results from co-application of dexmedetomidine and opioids or local anesthetics. Dexmedetomidine has potential adverse effects such as hypotension and bradycardia. Therefore, dexmedetomidine is contraindicated for patients suffering from bradycardia or using β-adrenergic antagonists. Clinical trials of dexmedetomidine in chronic pain or hyperalgesia are lack.Neuroscience Letters 12/2013; DOI:10.1016/j.neulet.2013.12.039 · 2.06 Impact Factor
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ABSTRACT: The effect of perineural dexmedetomidine on the time to onset, quality and duration of motor block with ropivacaine has been equivocal and its interaction with general anaesthesia (GA) has not been reported. We assessed the influence of dexmedetomidine added to 0.5% ropivacaine on the characteristics of supraclavicular brachial plexus block and its interaction with GA. In a randomised, double blind study, 36 patients scheduled for orthopaedic surgery on the upper limb under supraclavicular block and GA were divided into either R group (35 ml of 0.5% ropivacaine with 0.5 ml of normal saline [n - 18]) or RD group (35 mL of 0.5% ropivacaine with 50 μg dexmedetomidine [n - 18]). The onset time and duration of motor and sensory blockade were noted. The requirement of general anaesthetics was recorded. Both the groups were comparable in demographic characteristics. The time of onset of sensory block was not significantly different. The proportion of patients who achieved complete motor blockade was more in the RD group. The onset of motor block was earlier in group RD than group R (P < 0.05). The durations of analgesia, sensory and motor blockade were significantly prolonged in group RD (P < 0.00). The requirement of entropy guided anaesthetic agents was not different in both groups. The addition of dexmedetomidine to 0.5% ropivacaine improved the time of onset, quality and duration of supraclavicular brachial plexus block but did not decrease the requirement of anaesthetic agents during GA.Indian journal of anaesthesia 02/2015; 59(2):89-95. DOI:10.4103/0019-5049.151369
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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