[Effects of pri ming different low-dose rocurium on pharmacodynamics of mivacurium]

To explore the effects of pri ming rocuronium on neuromuscular blockade produced by mivacurium.

Ethical approval was granted by the medical ethics committee of our hospital with a reference number of C-2013-018-01. A total of 120 ASA physical status I and II patients undergoing selective otorhinolaryngologic surgery under general anesthesia signed the form of informed consent. And they were randomly divided by a random number table into 4 groups. After a standardized imidazole-propofol-fentanyl induction, they received a saline placebo injection (GroupI) and a pri ming dose of rocuronium 0.06 mg/kg (GroupII) , rocuronium 0.075 mg/kg (Group III) and rocuronium 0.1 mg/kg (Group IV). An intubating dose of mivacurium 0.15 mg/kg was offered 3 minutes later. Anesthesia was maintained with propofol and remifentanyl continuous infusion. Neuromuscular block was monitored with train of four (TOF) stimulation. The onset time, reappearance of T1 (DUR TOFc 1), times of T1 25% and 75% recovery, recovery index and times of TOF25%, 75% and 90% recovery were recorded.

The onset time of mivacurium was significantly shorter and the times of T1 25% and 75% recovery were significantly longer in groups of II, III and IV than those in groupI. No significant difference existed in recovery index among 4 groups. The onset time of mivacurium became progressively shorter with the growing pri ming dose of rocurium among three experiment groups. And it was not statistically significant.

Pri ming rocuronium decreases the onset and intubating times of mivacurium without effect on recovery index. No significant difference exists in drug effect among 3 experiment groups.