Comparison of duration of action of cisatracurium and rocuronium during hypothermic cardiopulmonary bypass: A prospective randomized double-blind trial in cardiac surgery

Context and Aims: Intermediate-acting, nondepolarizing neuromuscular blocking drugs (NMBDs), such as cisatracurium and rocuronium, are commonly used in cardiac surgery. Pharmacokinetics of NMBD alters with hypothermia. This study aims to examine the dosing interval of maintenance doses of rocuronium and cisatracurium required during moderate hypothermic (28°C–32°C) cardiopulmonary bypass (CPB). Subjects and Methods: In this prospective randomized controlled trial, patients were allocated into two groups of 30 patients each. Standard induction was performed with Group A receiving 0.1 mg/kg cisatracurium. Group B received 0.6 mg/kg rocuronium to facilitate intubation. Group A and Group B received intermittent bolus doses of 0.02 mg/kg of cisatracurium and 0.12 mg/kg of rocuronium, respectively, whenever one twitch response appeared to maintain zero twitch TOF. Results: Intergroup analyses revealed the increase in duration of action (DOA) of rocuronium was statistically significant than cisatracurium during CPB ( P = 0.001) and post-CPB ( P = 0.001). Intragroup analyses revealed that the difference in DOA of rocuronium and cisatracurium was significantly prolonged during CPB ( P = 0.001 and P = 0.001, respectively) and post-CPB ( P = 0.001 and P = 0.04, respectively) compared to the pre-CPB period. Cisatracurium was administered significantly more number of times as compared to rocuronium on CPB, while the number of times of drug administration was comparable pre-and post-CPB. Conclusions: There is significant prolonged DOA of both cisatracurium and rocuronium on moderate hypothermic CPB as evidenced by neuromuscular monitoring guided dosing during CPB. Conservative dosing of NMBD during CPB might help in fast-tracking patients postoperatively.