Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Anaesthesia

Rationale and background: Peri-neural administration of alpha-2 adrenoceptor agonists includingdexmedetomidine extends the duration of local anesthetic-induced peripheral nerve blocks in the experimental and the clinical settings. Thisstudy was designed to explore and compare the possible effects of different dose levels of peri-neural dexmedetomidine on the clinical and side effect profiles of bupivacaine-induced femoral nerve block in patients undergoing arthroscopic knee surgery under general anesthesia. Patients and methods: This randomized, controlled double blinded study included 60 adult patients undergoing arthroscopic knee surgery. Ultrasound-guided femoral nerve block was initiated 30 min before induction of general anesthesia. Femoral nerve block was achieved with the use of 25 ml of bupivacaine 0.5% in all patients. Bupivacaine was combined with 1 ml normal saline (control group, n=15), 25, 50 or 75 og (1 ml) peri-neural dexmedetomidine groups (n= 15, each). All patients received a standard general anesthetic after ensuring successful femoral nerve block. The onset and duration of sensory and motor blocks, the time to first request to postoperative rescue analgesic, Richmond Agitation-Sedation Score, perioperative hemodynamic data, resting and dynamic visual analogue pain scores, were reported at predetermined time assessment points. Total postoperative rescue intravenous morphine consumption was recorded over 24 hours

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