Time course of potentiation of cisatrarium by desflurane versus isoflurane

Objective: To investigate the time course of potentiation of cisatrarium produced by 1MAC of sevoflurane or isoflurane.Methods: Thirty ASA I～Ⅱ patients aged 18～60 years undergoing elective operation under general anesthesia were studied.Patients should have no neuromuscular,liver or kidney disease,and didn't receive any drug which might affect neuromuscular transmission.Anesthesia was induced with midazolam 0.1～0.2 mg·kg-1,fentanyl 4 μg·kg-1 and etomidate 0.3 mg·kg-1.Tracheal intubation was facilitated with cisatrarium 0.3 mg·kg-1 iv.The degree of neuromuscular block was monitored by using train-of-four(TOF) stimulation ulnar nerve.For maintenance of anesthesia,the patients were randomly assigned to receive either propofol+fentanyl(control group) or1 MAC of sevoflurane+propofol+fentanyl(sevoflurane group) or 1MAC of isoflurane+propofol+fentanyl(isoflurane group).Cisatrarium was continuously infused during operation to maintain T1at 5% of the control and the infusion rate was recorded every 15 min.Results: There were no significant differences among the three groups with respect to sex,age,body weight and duration of anesthesia.In Sevo and Iso groups the infusion rate of cisatrarium was reduced in an exponential manner and maximal potentiation occurred at 90 min of isoflurane or sevoflurane inhalation.The maximal reduction in infusion rate was 39.7% in Sevo group and 37.8%in Iso group.There was no significant difference between the two groups.Conclusion: Sevoflurane and isoflurane can potentiate the muscle relaxation produced by cisatrarium in a similar degree and the potentiation is time dependent.