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ABSTRACTOBJECTIVE: Dexmedetomidine is an a-2 adrenergic agonist having wide range of effects including sedation in mammalian brain, and has analgesic as well as sympatholytic properties. This study aimed to compare the effects of dexmedetomidine and propofol infusion on sedation characteristics in patients undergoing combined sciatic nerve and femoral nerve block via anterior approach for lower limb orthopedic procedure.METHODS: Forty patients, who were between 18 and 65 years old, this study was made at anesthesiology clinic of Bagcilar training and research hospital in 08 September 2011 to 07 June 2012, and underwent surgical procedure due to fractures lateral and medial malleol, were included. Sciatic nerve and femoral nerve block were conducted with an anterior approach on all patients included in the study, with an ultrasonography. The patients were randomly divided into dexmedetomidine [Group D (n = 20); 0.5 µg kg-1 h-1] and propofol [Group P (n = 20); 3 mg kg-1 h-1] infusion groups.RESULTS: The vital findings and intra-operative Ramsay sedation scale values were similar in both groups. Time taken for sedation to start and time required for sedation to become over of Group D were significantly higher than those of Group P (p < 0.001 for each).CONCLUSIONS: Substitution of dexmedetomidine instead of propofol prolongs the times to start of sedation, the times to end of sedation and duration of sedation.

Abstract The present study was designed to test the hypothesis that high dose dexmedetomidine would increase the duration of antinociception to a thermal stimulus in a rat model of sciatic nerve blockade without causing nerve damage. The rats were anesthetized with isoflurane. After electromyography (EMG) recordings, right sciatic nerves were explored and perineural injections were delivered: Group D (n = 7), 40 µg µg kg-1 dexmedetomidine administration, Group II (n = 6), (0.2 mL) saline administration, Group III (n = 2), only surgically exploration of the right sciatic nevre. Time to paw withdrawal latency (PAW) to a thermal stimulus for both paws and an assessment of motor function were measured every 30 min after the nerve block until a return to baseline. The compound muscle action potential (CMAP) of right and left sciatic nerves were recorded 10 times per each nerve once more after perineural injections at 14 day. After EMG recordings, right and the part of left sciatic nerve were excised at a length of at minimum 15 mm for histopathological examination. Comparison of right/left CMAP amplitude ratios before and 14 days after the procedure showed a statistically significant difference (p = 0.000). There were no differences in perineural inflammation between the Group D, Group S, and Group E at 14 days.