Prolongation Of Action Of Lignocaine By Addition Of Dextran 40 In Brachial Plexus Block. A Randomised Controlled Trial

摘要

Adjuncts to local anesthetics for peripheral plexus blockade have been proposed to enhance the quality and duration of anesthesia and postoperative analgesia. The effect of lignocaine can be prolonged by adding adrenaline, by alkalinization of solution, by adding opioids like fentanyl and also by addition of alpha2 adrenergic agonist. Lignocaine has been found to be a drug with very short latency period. Dextrans are complex, branched polysaccharides consisting of chains of individual glucose units, and are synthesised from sucrose by the action of certain lactic-acid bacteria. It is hypothesised that dextrans may form water-soluble complexes with LAs that remain at the site of injection longer than the unbound drug, dextran also alters the pH of the injected LA solution, and this alkalinisation may contribute to the prolongation of action8. The present study is designed to asses the prolongation of action of lignocaine by addition of dextran 40 in brachial plexus block. Introduction Brachial plexus block may be more advantageous for routine as well as emergency surgery in upper limb. Brachial plexus comprises cervical roots of C5,6,7,8 and T1 nerves. These supply the entire motor and almost the entire sensory nerve supply of the upper limb. Brachial plexus block can be performed with any local anaesthetic drug like bupivacaine, lignocaine etc. But most commonly used 15-20ml of 1-2% lignocaine with or without adrenaline in the nerve trunk forming brachial plexus either by supraclavicular or axillary approach. It provides good analgesia with good surgical condition for approximate one hour duration. In our study we used dextran 40 with lignocaine to assess the efficacy, safety and duration of brachial plexus block. Lignocaine is a tertiary amide, a derivative of the acetanilide synthetic nitrogenous compound. This drug is used for spinal anaesthesia, epidural anaesthesia, and peripheral nerve block, as well as topical and infiltrative anaesthesia. It is excreted through kidney. The maximum safest dose of lignocaine is 5mg/kg body wt. without adrenaline and 7mg/kg body wt. with adrenaline. The middle trunk of the brachial plexus (C7) represented by the palmer distribution of the median nerve was found to be slow to develop analgesia1. In supraclavicular brachial plexus blockade lignocaine 1% with adrenaline2, found a mean total latency of 14.07 ± 3.76 minutes in major nerve blocks.The addition of dextran as an adjunct to LAs was first studied in 1960 in an attempt to prolong the duration of action of the sensory blockade. Since that time there have been conflicting results from numerous other studies, with some demonstrating a prolongation of analgesia3,4 while others have been unable to show any conclusive benefit5,6. The mechanism of action is unclear, but it is hypothesised that dextrans may form water-soluble complexes with LAs that remain at the site of injection longer than the unbound drug, due to an increase in viscosity with reduced diffusion of the complex7. Alternatively, the addition of dextran alters the pH of the injected LA solution, and this alkalinisation may contribute to the prolongation of action8. Dextrans have been shown to decrease the systemic absorption of lidocaine, offering benefits in decreasing the incidence of toxicity. The present study is designed to asses the prolongation of action of lignocaine by addition of dextran 40 in brachial plexus block. AIMS OF STUDY To see the efficacy and safety of brachial plexus block after injecting lignocaine with dextran 401. Onset and duration of analgesia produced by lignocaine with Dextran 40 in brachial plexus block2. Degree of sensory and motor block achieved3. Incidence of side effect and complication4. Failure rates MATERIAL AND METHODS This study was conducted after the approval of the institutional ethical committee. It was carried out on 60 patients of either sex, ASA grade I-II between 15–65 years undergoing upper limb surgery and the supraclavicular b