Pharmacodynamic interactions between cisatracurium and rocuronium

Objectives To evaluate the interaction between cisatracurium and rocuronium when administered the maintenance doses of cisatracurium after rocuronium in total intravenous anesthesia.Methods Forty-eight patients scheduled for ENT (ears, nose, throat) surgery undergoing total intravenous anesthesia anesthesia with propofol by TCI and fentanyl were randomized to receive the following.interventions Group ⅠA=rocuronium 0.6mg/kg followed by cisatracurium 0.025 mg/kg when T1 recovered to 25%; Group ⅠB =rocuronium 0.6 mg/kg followed by cisatracurium 0.025 mg/kg when T1 recovered to 75%; Group ⅡA =cisatracurium 0.1mg/kg followed by cisatracurium 0.025 mg/kg when T1 recovered to 25%; Group ⅡB =cisatracurium 0.1mg/kg followed by cisatracurium 0.025 mg/kg when T1 recovered to 75%.The bispectral index was kept between 40 and 50 during maintenance of anesthesia.Thumb adductorius contractile response was monitored with TOF stimulation.Results Compared with group Ⅱ A (5.3% ), the minimum value of T1 in group Ⅰ A (0.6% ) was significantly lower; compared with group ⅡB(12.6%), the minimum value of T1 in group ⅠB(2.9%) was significantly lower too (P0.05).The time of 25% T1 recovering of the control value (T25) was prolonged by 39% in group ⅠA(22.8min) compared with ⅡA(16.4min),and 40% in group ⅠB(16.2min)compared with ⅡB(11.6min)(P0.05).The time of 95% T1 recovering of the control value (T95) was prolonged by 22% in group ⅠA(37.7min)compared with IIA(30.9min),and 18% in group ⅠB(30.5min)compared with ⅡB(25.9min)(P0.05).There was no difference between group ⅠA(9.7min)and ⅡA (9.7min),group IB(10.4min)and ⅡB(10.2min)in the recovery parameters(P0.05).Conclusions When administered the maintenance doses of cisatracurium after rocuronium, the maximum block degree is enhanced and the clinical duration is prolonged.But the recovery index is similar in all groups.