Does Addition of Midazolam to Bupivacaine Prolong the Analgesic Characteristics of Brachial Plexus Block

To evaluate the effect of adding midazolam to bupivacaine to prolong the analgesia characteristics of brachial plexus block. After preanaesthetic assessment all the patients were premedicated with diazepam 0.1mg/kg orally one hour before the surgery. Patients were randomly divided into group1 & 2. Group -1 patients received supraclavicular brachial plexus block with 30ml of 0.5% bupivacaine & group -2 patients received a mixture of 30ml of 0.5% bupivacaine & midazolam 50μg/kg body weight. On arrival in the operating room, standard base line vital signs readings were recorded. Intra –operatively HR, BP, oxygen saturation & sedation, time of establishment of sensory & motor block were recorded in all patients. Post-operatively HR, BP, sensory & motor block, pain score & sedation score, time of requirement of rescue analgesia were assessed at 0,30min,2hr,6hrs,12 hrs & 24 hrs in all patients. Demographic variables were comparable. There was no significant difference in monitoring of intraoperative & post-operative Vital signs (HR, SBP, DBP, MAP & oxygen saturation). Post–operative sedation score, pain score, requirement of rescue analgesia, sensory & motor block were significantly less in group-2 (p –value-<0.05). Conclusion-addition of midazolam to bupivacaine in brachial plexus block produces early onset of sensory and motor block, increased sedation score intraoperatively & prolongs postoperative analgesia. KEYWORDSBRACHIALPLEXUS, SENSORY BLOCK, MOTOR BLOCK, SEDATION SCORE, PAIN SCORE, RESCUE ANALGESIA *Corresponding author DR SULOCHANA DASH Asst. Prof. , anaesthesiology at MGMC and RI, puducherry Int J Pharm Bio Sci 2014 July ; 5 (3) : (B) 491 498 This article can be downloaded from www.ijpbs.net B 492 INTRODUCTION Brachial plexus block is a useful alternative to general anaesthesia for upper limb surgeries. It provides ideal operating condition; complete relaxation of muscles of upper extremities, intra-operative haemodynamics are not altered significantly, sympathetic block of blood vessels which lessens post-operative vasospasms, pain and postoperative period free from nausea, vomiting, cerebral depression . A large number of local anaesthetics have been used for brachial plexus block. Bupivacaine is one of the most frequently used local anaesthetics for brachial plexus block by virtue of its long duration of action. Studies have shown that the duration of analgesia produced by bupivacaine when injected into brachial plexus sheath varies from 3 hrs to 15 hrs. Several studies have been done to find a suitable adjunct to local anaesthetics to improve and prolong the analgesia produced by local anaesthetics. Opioids, Clonidine, neostigmine, hyaluronidase, bicarbonate, etc have been tried as adjuncts. The results have been inconclusive. Hence, the search for the suitable agents to be used along with local anaesthetics to potentiate their action is still going on. Midazolam (preservative free), a water-soluble benzodiazepine, when administered centroneuraxially has been shown to produce segmental anti-nociception and the midazolam induced analgesia has been found to enhance the effects of local anaesthetics given in combination epidurally or intrathecally without any adverse effects. Midazolam produces this additive effect on local anaesthetics by its action on the benzodiazepine GABAA receptor complexes present in the spinal cord. GABAA receptors have been demonstrated in peripheral nerves and it has been shown that the activation of peripheral GABAA receptors decreases the transmission of nociceptive signals and this results in local analgesic effect. However, the effect of adding midazolam to local anaesthetic solution on analgesia characteristics in peripheral nerve blocks has not been sufficiently studied. This study aims to evaluate the effect of midazolam on analgesia characteristics produced by bupivacaine 0.5% in brachial plexus block .