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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- "For example, caudal dexmedetomidine achieves significant postoperative pain relief and less incidence of emergence agitation  . Dexmedetomidine is combined with bupivacaine, levobupivacaine and ropivacaine for brachial plexus block (supraclavicular, infraclavicular , axillary)  and tibial nerve block  to enhance local anesthetics' functions. Moreover, intra-articular dexmedetomidine improves the quality of postoperative analgesia . "
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; 561. DOI:10.1016/j.neulet.2013.12.039 · 2.06 Impact Factor
- International anesthesiology clinics 01/2013; 51(2):81-96. DOI:10.1097/AIA.0b013e31828d58c7
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ABSTRACT: A variety of drugs such as opioids, alpha 2 adrenergic agonists, NMDA receptor antagonists, midazolam, adenosine and neostigmine have been used as adjuvants to local anaesthetics for improving quality and prolonging the effects of peripheral nerve blocks. In this article, literature has been reviewed to find the various drugs that have been used as additives to local anaesthetics while performing nerve blocks and the advantages gained in terms of prolongation of anaesthetic or analgesic effects.01/2013; 4(1). DOI:10.1016/j.tacc.2014.05.003