Effects of Different Dosage of Dexmedetomidine on Propofol Cp50 under General Anesthesia with Propofol TCI

Objective To study the effect of different dosage of dexmedetomidine on propofol Cp50 under general anesthesia with propofol TCI.Methods Seventy four ASA I~II patients aged 18~65yr with body weight index 18~30 kg.m-2 undergoing the selective limb surgery.The patients were randomly divided into 4 groups:propofol group(P group,n =21):threated with propofol alone;Alpharemifentanil group(R group,n =18):propofol plus remifentanil target plasma concentration of 2.0 ng/mL;dexmedetomidine group:propofol plus dexmedetomidine 0.5 μg/kg(D1,n =16)and 1 μg/kg(D2,n =16).Laryngeal mask to be insert until propofol plasma concentration and effect-site concentration is equilibrium.According to the patient′s body movement in response to increase or to decrease 0.5 μg/mL of propofol Cp.Cp50 of propofol in each group was calculated using ‘up and down’method.Results No differences were found in the demographic data among the four groups.Cp 50 of propofol was 4.86±0.40 μg/mL,2.42±0.33 μg/mL,3.94±0.63 μg/mL and 2.44±0.27 μg/mL in P,R,D1 and D2 group,respectively;it was significantly deceased in R,D1 and D2 groups as compared with P group(P 0.05).Cp50 in D2 group was lower that in D1 group(P 0.05).Conclusion Our study shown that dexmedetomidine able to reduce propofol Cp50 during successfully inserted the laryngeal mask under general anesthesia,the effect of dexmedetomidine 1.0 μg/kg to be quite with remifentanil 2.0 ng/mL.