comparative study among different adjuvants to a mixture of lidocaine and bupivacaine for axillary brachial plexus block

The aim of this work is to compare the effect of adding each of sodium bicarbonate (alkalinization), fentanyl, neostigmine and verapamil to a mixture of local anesthetics (bupivacaine 0.5% and lidocaine 1.5%) on the quality of axillary brachial plexus anesthesia that produced by single injection technique for the upper limb surgery in adults to find out the best potentiating adjuvant with the least side effects.