To compare the analgesic efficacy of perineural and intravenous Dexamethasone as an adjuvant to 0.5% Ropivacaine for ultrasound guided brachial plexus block for upper limb surgeries: A randomised, triple blind placebo controlled trial.

Supraclavicular brachial plexus block is considered to be one of the most effective approach for anesthesia for upper limb surgery. The brachial plexus is most compact at the level of the trunks formed by the C5–T1 nerve roots, so nerve block at this level has the greatest likelihood of blocking all of the branches of the brachial plexus.  The compactness of the brachial plexus in this location facilitates a rapid onset and complete block of the brachial plexus for procedures distal to the shoulder. Ultrasound guided supraclavicular brachial plexus block has improved the success rate of block with excellent localization as well as improved safety margin.The supraclavicular block is ideal for operations involving the arm and forearm.

Various local anesthetics like  Ropivacaine, Bupivacaine etc ,have been used with safety and efficacy in performing such blocks. Local anesthetics act on the voltage-gated sodium channels that conduct electrical impulses and mediate fast depolarization along nerves.  they target open channels and prevent ion flow. This act on potassium channels, but they block sodium channels more.They preferentially binds to the inactivated state of voltage gated sodium channels, but has also been found to bind potassium channels, G-protein coupled receptors, NMDA receptors, and calcium channels in vitro.

Adjuvants are those drugs which, when co-administered with local anesthetic agents, may improve the speed of onset and duration of analgesia and counteract disadvantageous effects of local anesthetics. By adding these adjuvants, the dose of local anesthetics can be reduced,thereby reducing its side effects like myocardial depression, hypotension, bradycardia, heart block, and ventricular arrhythmias. Various adjuvants has been introduced with these agents to prolong the duration of blockade in long surgeries. Some of the additives used with local anesthetics include alpha2 agonists, NSAIDS, opioids, and glucocorticoids. Addition of long acting glucocorticoids like Methylprednisolone with local anesthetics have been used to treat chronic pain. Latest to this series is Dexamethasone which not only prolongs the analgesia but also decreases the local inflammation by inhibiting action of phospholipase A2 at the site of surgery. Dexamethasone helps by attenuating the release of inflammatory mediators, reducing ectopic neuronal discharge and inhibiting potassium channel-mediated discharge of nociceptive C-fibres.Addition of steroid to local anesthetics effectively and significantly prolongs the duration of analgesia as well as producing earlier onset of action in adults. Based upon previous studies as an adjuvant to regional analgesia perineural Dexamethasone significantly shortened the onset of sensory and motor block, prolong duration of analgesia, prolong the time to first analgesic request with minimal side effects. Intravenous Dexamethasone during general anesthesia has proven beneficial in reducing pain, postoperative nausea and vomiting, decreasing airway complications in patients with bronchial hyperreactivity  because of worry of physiochemical impacts from perineural adjuvants Dexamethasone, few authors have suggested against its use as an adjuvant to local anesthetic or have proposed that alternative route of administration i.e. intravenous are preferable. Dexamethasone has been used in different doses ranging between 1 to 8 mg. but it has been found that 1, 2 and 4 mg dexamethasone when added to 0.5% Ropivacaine resulted in similar prolongation of motor blockade and analgesia.

The present study is undertaken with null hypothesis that perineural and i.v administration of Dexamethasone have no clinical difference in terms of block characteristics.