studying the effects of adding dexmedetomidine to bupivacaine on supraclavicular nerve block in upper limb orthopedic surgery among chronic opium abusers compared with non users.

This study aims to evaluate the effect of adding perineural Dexmethetomidine to Bupivacaine on the duration of supraclavicular nerve block in chronic opium abusers compared with non abusers. Inclusion criteria: ASA class I and II; male; current smokers; aged between 18-60; scheduled for elective upper limb orthopedic surgery under supraclavicular nerve block. Exclusion criteria: Patients with any contraindications to supraclavicular nerve block; addiction to any substance other than opium and cigarettes; known history of cardiac, respiratory, or psychological diseases; block failure of any nerve distributions (i.e. if the patient feel pain in those regions) 84 patients will be randomly assigned into 4 groups, 21 in each group: groups A and B without a history of opium abuse ,and groups C and D with a history of opium abuse which all of their members were scheduled for elective upper limb orthopedic surgery, and then these groups fall into two categories: to block, the first category (including groups A & C) receives only 30 ml bupivacaine and the second one (including groups B & D) receives the 30 ml bupivacaine in combination with an additional 20 μg Dexmedetomidine. An ultrasound-guided technique will be applied to perform upper extremity brachial plexus blockade. The onset and duration of sensory and motor blocks will be recorded and compared between the four groups. Primary outcome variables: sensory block onset; sensory block duration; motor block onset; motor block duration

Tehran University of Medical Science