RESUMEN
Objective To observe and compare the effect of different concentration of ropivacaine on elderly patient with bra-chial plexus block under ultrasound-guided ,to assess its effectiveness and security ,so as to determine the optimum dosage of anes-thetic for elderly patients with brachial plexus block .Methods 120 patients undergoing elective surgery of forearm or hand in this hospital from February 2013 to December 2014 were selected as the observation group in this study .These patients were randomly divided into four groups on average ,narcosis was conducted in each group with ultrasound-guided :group A with 30 mL of 0 .250%ropivacaine ,group B with 30 mL of 0 .375% ropivacaine ,group C with 30 mL of 0 .500% ropivacaine ,group D with 30 mL of 0 .750% ropivacaine .The onset time of sensory block ,motor block level ,duration of analgesia and adverse reactions were observed and recorded .Results With the increase of concentration of ropivacaine ,the onset time of narcotize became shorter(P0 .05) .There was no complications occurred in four groups after narcosis .Conclusion Concentration of ropivacaine more than 0 .375% can achieve perfect clinical effect on elderly patients with brachial plexus block under guidance of ultrasound .