The effect and safety of dexmedetomidine added to ropivacaine in brachial plexus block

Abstract

Background:Dexmedetomidine has been used as an adjuvanty added to local anesthetics to prolong analgesia following peripheral nerve blockade. The aim of this meta-analysis was to investigate the effect and safety of dexmedetomidine added to ropivacaine in brachial plexus block (BPB).Methods:A search strategy was created to identify eligible randomized clinical trial (RCT) in PubMed, Embase, and The Cochrane Library (updated May, 2018). The methodologic quality for each included study was evaluated using the Cochrane Tool for Risk of Bias by 2 independent researchers.Results:Twelve RCTs were included in the meta-analysis (n = 671). As an adjuvant to ropivacaine, dexmedetomidine significantly reduced the onset time of sensory (mean difference [MD], −3.86 minutes, 95% CI −5.45 to −2.27 minutes; I2 = 85%) and motor (MD, −5.21 minutes; 95% CI −7.48 to −2.94 minutes; I2 = 94%). In addition, it increased the blockade duration of sensory (MD, 228.70 minutes; 95% CI 187.87–269.52 minutes; I2 = 93%) and motor (MD, 191.70 minutes; 95% CI 152.48–230.91 minutes; I2 = 92%). Moreover, the combination prolonged the duration of analgesia (MD, 303.04 minutes; 95% CI 228.84–377.24 minutes; I2 = 86%). There was no difference of the incidence of bradycardia (risk difference [RD], 0.01, 95% CI −0.02 to 0.05, I2 = 45%; P = .45) and hypotension (RD, 0.01, 95% CI −0.01 to 0.03, I2 = 0%; P = .57) between 2 groups.Conclusion:Dexmedetomidine added to ropivacaine in BPB has a better analgesia effect (shorter onset time and longer duration) compared to ropivacaine alone. At the same time, there was no difference in the incidence of bradycardia and hypotension.

Efficacy of adjuvant dexmedetomidine in supraclavicular brachial plexus block for intractable complex regional pain syndrome: A case report with a 3‐year follow‐up

“…Dexmedetomidine (DEX), a potent and selective α 2 adrenoceptor agonist, was recently shown to prolong analgesic duration when added to local anaesthetics in regional anaesthesia . This effect is related to the enhancement of hyperpolarization‐activation cation currents, which prevents the nerve from returning to resting membrane potential from a hyperpolarized state and subsequent firing .…”

“…DEX has greater affinity for the α 2 adrenergic receptor than clonidine and a greater inhibitory effect on neuronal action potential; thus, it has superior analgesic qualities as a BPB adjuvant . Several studies have demonstrated increased duration and improved quality of analgesia when DEX was added to local anaesthetics for various indications . A 30‐40 mL mixture of 0.5% ropivacaine and 1 µg/kg DEX injection has been investigated for regional anaesthesia with BPB, and the addition of DEX was found to prolong the duration of sensory and motor blockade, and reduce the time required for onset of action, but the effect was not associated with the DEX dose .…”

“…[8][9][10]12 A 30-40 mL mixture of 0.5% ropivacaine and 1 µg/kg DEX injection has been investigated for regional anaesthesia with BPB, and the addition of DEX was found to prolong the duration of sensory and motor blockade, and reduce the time required for onset of action, but the effect was not associated with the DEX dose. 10 In a study of chronic post-ischaemia pain models, intraperitoneal DEX produced an antiallodynic effect by inhibiting of microglial activation, which is reportedly involved in the release of nociceptive mediators and facilitation of the pain pathway. 18 Nama et al reported the use of intravenous DEX and ketamine for acute pain management in patients with CRPS; they injected ketamine first, followed by injection of a 10 mL mixture of 40 µg DEX and normal saline, which provided pain relief for 24 hours.…”

“…The potential adverse effects of DEX are haemodynamic changes, dyspnoea, Horner syndrome and sedation after BPB. 10,27 A continuous femoral nerve block administered for 48 hours, in rabbits, with a 1-2 µg/mL dose of DEX and 0.25% ropivacaine produced no neurotoxic lesions, but a 3 µg/mL dose of DEX showed demyelination of nerve fibres; thus, it is suspected that local DEX injection leads to a dose-related decrease in local blood supply to the nerves, resulting in ischaemic damage to the nerve fibres. 28 In conclusion, this case report suggests that long-term, repeated DEX inclusion in BPB may be suitable for alleviating refractory CRPS pain.…”

“…6 Dexmedetomidine (DEX), a potent and selective α 2 adrenoceptor agonist, was recently shown to prolong analgesic duration when added to local anaesthetics in regional anaesthesia. [8][9][10][11] This effect is related to the enhancement of hyperpolarization-activation cation currents, which prevents the nerve from returning to resting membrane potential from a hyperpolarized state and subsequent firing. 12 Ghobadifar et al 13 reported that intrathecal DEX may play an important role in mitigating neuropathic pain.However, there has been no report on the effect of long-term repeated usage of DEX in conjunction with local anaesthetics in BPB for CRPS.…”