Effects of different concentrations of dexmedetomidine on neuromuscular block induced by rocuronium

Objective To investigate effects of different concentrations of dexmedetomidine on onset time and clinical time-effect of rocuronium in the processes of the total intravenous anesthesia.Methods Sixty patients with elective anesthesia breast modified radical mastectomy,aged 26 to 55 years,were randomly divided into four groups of 15 patients.Group A (control group):uniform within 10 min before induction of anesthesia saline infusion (NS ; 0.25 ml/kg) ; group B:dexmedetomidine given initial dose 0.3 μg/kg uniform within 10 min before induction of anesthesia infusion finished,anesthesia period 0.3 μg/(g · h) continuous infusion until the end of surgery; group C:dexmedetomidine given initial dose 0.6 μg/kg uniform within 10 min before anesthesia infusion finished,during anesthesia with continuous infusion 0.6 μg/'(kg · h) until the end of surgery ; and group D:dexmedetomidine given initial dose 1 μg/kg uniform within 10 min before anesthesia infusion finished,during anesthesia to 1 μg/(kg · h) continuous infusion to the end of surgery.Patients after the burglary were under multi-monitor vital signs monitoring blood pressure (BP),heart rate (HR),oxygen saturation (SPO2),electrocardiogram (ECG),and after intubation monitoring end-tidal carbon dioxide (EtCO2),recording time T0 and T25.Results No significant difference was found at the T0 time in each group.However,the T25 time (48 ± 6) min in group C and (51 ±6) min in group D was significant longer than that (40 ±6)min in group A (P ＜0.05).The mean artery pressure(MAP) of group C and D [(88.76 ± 7.06)mmHg,(87.89 ± 6.95)mmHg] were significantly lower than group A after dexmedetomidine infusion 5 min later(P ＜ 0.05); The HR of groups B and C [(60.80 ± 7.11)bpm,(63.31 ± 5.78)bpm] were significantly lower than group A before induction (P ＜ 0.05).The HR of group D was significantly lower than group A before induction and after infusion 5 and 30 min later[(66.40 ± 9.49) bpm,(60.52 ± 7.45) bpm,(61.32 ± 7.11) bpm,P ＜ 0.05].Conclusions Under the status of total intravenous anesthesia,different concentrations of dexmedetomidine did not affect the onset time of rocuronium,but dexmedetomidine given up to a certain concentration could enhance the clinical time-effect of rocuronium. Key words: Dexmedetomidine/administration & dosage ;  Dexmedetomidine/pharmacology;  Muscle relaxation/drug effects ;  Androstanols/pharmacology;  Neuromuscular blockade