Influences Of Inhalant Anesthetics On Neuromuscular Blockade Produced By Cisatracurium In The Elderly Patients

Objective:To compare the effects of sevoflurane and isoflurane on the neuromuscular blockade produced by cisatracurium after infusion in the elderly patients. Methods:Sixty ASAⅠ-Ⅱpatients aged 60-80 years undergoing general anesthesia were monitored using train-of-four (TOF) stimulation by recording the force of contraction of adductor pollicis muscle with a muscle relaxation monitor (TOF Watch SX). Anesthesia was induced with propofol by TCI (target plasma concentration 4-5ug/ml) and intravenous injection (Ⅳ) fentanyl 3～4μg·kg-1. All patients were administered by Cis 0.1mg-kg-1 as a bolus to facilitate endotracheal intubation, followed by continuous intravenous infusion adjusted manually to maintain T1, the first twitch in the TOF, at 10% of control. The patients were randomly divided into 3 groups(n= 20 each), in sevoflurane (Sev) group and (isoflurane) Iso group maintain anesthesia by sevoflurane (1MAC) and isoflurane (1MAC) respectively during operation. Control (Con) group maintained anesthesia with propofol by TCI (target plasma concentration 2-3μg/ml). Cisatracurium was continuous intravenous infusion adjusted manually to maintain T1 at 10% of control. The following variables were recorded:the onset time (time from injection of Cisatracurium to maximal paralysis of twitch), the infusion rate, the recovery index(time for T1 from 25%to 75%/T25-75) and TOFr0.9(time for T1 to return to 0.9). Results:There were no significant differences among the three groups on the onset time(P>0.05). The infusion rate of cisatracurium in Sev group and Iso group were reduced greater than Control group (P<0.05).The infusion rate of cisatracurium in Sev group was reduce greater and faster than Iso group (P<0.05). There were no significant differences in the recovery index and TOFr0.9 among Sev,Iso and Con group (P>0.05). Conclusion:In the elderly patients, When end-tidal concentration was maintained at 1MAC, the synergism of sevoflurane on neuromuscular blockade produced by cisatracurium get to the maximal effect at 75min, and can reduce the infusion rate about 48%. But isoflurane get to the maximal effect at 105min, and can reduce the infusion rate about 39%. While keep the same TOF value, sevoflurane and isoflurane are no effect on the RI and TOFr0.9 of cisatracurium.