Local Anesthetic Peripheral Nerve Block Adjuvants for Prolongation of Analgesia: A Systematic Qualitative Review

Abstract

BackgroundThe use of peripheral nerve blocks for anesthesia and postoperative analgesia has increased significantly in recent years. Adjuvants are frequently added to local anesthetics to prolong analgesia following peripheral nerve blockade. Numerous randomized controlled trials and meta-analyses have examined the pros and cons of the use of various individual adjuvants.ObjectivesTo systematically review adjuvant-related randomized controlled trials and meta-analyses and provide clinical recommendations for the use of adjuvants in peripheral nerve blocks.MethodsRandomized controlled trials and meta-analyses that were published between 1990 and 2014 were included in the initial bibliographic search, which was conducted using Medline/PubMed, Cochrane Central Register of Controlled Trials, and EMBASE. Only studies that were published in English and listed block analgesic duration as an outcome were included. Trials that had already been published in the identified meta-analyses and included adjuvants not in widespread use and published without an Investigational New Drug application or equivalent status were excluded.ResultsSixty one novel clinical trials and meta-analyses were identified and included in this review. The clinical trials reported analgesic duration data for the following adjuvants: buprenorphine (6), morphine (6), fentanyl (10), epinephrine (3), clonidine (7), dexmedetomidine (7), dexamethasone (7), tramadol (8), and magnesium (4). Studies of perineural buprenorphine, clonidine, dexamethasone, dexmedetomidine, and magnesium most consistently demonstrated prolongation of peripheral nerve blocks.ConclusionsBuprenorphine, clonidine, dexamethasone, magnesium, and dexmedetomidine are promising agents for use in prolongation of local anesthetic peripheral nerve blocks, and further studies of safety and efficacy are merited. However, caution is recommended with use of any perineural adjuvant, as none have Food and Drug Administration approval, and concerns for side effects and potential toxicity persist.

Effects of Adjuvant in Potentiating the Analgesic Effect of Fascia Iliaca Compartment Block

“…Recently, nerve blocks for postoperative analgesia has increased significantly, with using of adjuvants plus local anesthetics which extends the analgesia time [1] . A wide variety of agents have been tested as adjuvant to nerve blocks, which are commonly performed for regional anesthesia, for example opioids (acting in peripheral kappa receptors) [2] , midazolam( via acting on peripheral GABA receptors) [3] naloxone [4] dexmede-tomidine (has synergistic effect in nerve block and it has a high binding affinity to nerve fiber α2-adrenoreceptors) [5,6] clonidine (binding affinity to nerve fiber α2-adrenoreceptors) [7] , epinephrine (induced vasoconstriction with decrease absorption of local anesthetic) [8] , Ketamine (via acting as noncompetitive antagonist of the N-methyl-D aspartate receptor (NMDAR) [9] and recently dexamethasone (may be through its proinflammatory effect) [10] .…”

Duration of post-operative analgesia with Fascia iliaca compartment block (ficb) using Bupivacaine with Dexmedetomidine and Bupivacaine with Dexamethasone in patients with proximal fracture femur

“…In such cases Fascia iliaca compartment block (FICB) can be used for the purpose of positioning and postoperative analgesia. Many adjuvants like epinephrine, clonidine, Opioids, ketamine, dexamethasone and dexmedetomidine were combined with local anaesthetics to prolong the post-operative analgesia 6 . Dexamethasone has been shown to be effective in few clinical studies.…”

Effect of dexmedetomidine as adjuvant in supraclavicular block for upper limb orthopedic surgeries

“…Adjuvants which are commonly used are opioids, steroids, sodium bicarbonate, Hyaluronidase, α2 agonists, neostigmine, magnesium and adrenalin. 6,7 Dexmedetomidine is highly specific α2 adrenoreceptor agonist and has sympatholytic, sedative, hypnotic, Anxiolytic, analgesic, anti-shivering properties and promotes cardio-respiratory stability as well as neuroprotecion. [6][7][8][9] Different local anesthetic agents are used in brachial plexus block individually or in mixture.…”

“…6,7 Dexmedetomidine is highly specific α2 adrenoreceptor agonist and has sympatholytic, sedative, hypnotic, Anxiolytic, analgesic, anti-shivering properties and promotes cardio-respiratory stability as well as neuroprotecion. [6][7][8][9] Different local anesthetic agents are used in brachial plexus block individually or in mixture. Combination of local Anaesthetic agents, like lignocaine and bupivacaine-provides early onset of action, longer duration of block and reduced incidence of local anaesthesia toxicity.…”