Rocuronium administration in children during isoflurane anesthesia: Neuromuscular effects

Background. The time-course of the effect of rocuronium during isoflurane a nesthesia in children has rarely been evaluated. Forty-five children, aged 2-14 years, ASA 1, undergoing elective surgery and receiving isoflurane ane sthesia, were studied. Methods. Patients randomly received a dose of 400, 600, or 800 mu g/kg of r ocuronium. The first response to the control height (T1:T0) was fitted to t ime in order to obtain times to onset of action (TOA) including time to 90 (B-90) and 99.9% (B-100) of relaxation and to spontaneous recovery of 10 (T -10), 25 (T-25), 50 (T-50), 75 (T-75), and 90% (T-90) of neuromuscular func tion (NMF). Each time was compared among groups. Linear regression analysis between the TOA or the times to spontaneous recovery of NMF (TSRNMF) and a ge or weight were also performed. Results. The TOA were similar among the three groups while TSRNF in childre n receiving 600 or 800 mu g/kg were longer (p <0.05) than children receivin g 400 mu g/kg. The T-10 and T-25 were related to age (p = 0.05), whereas T- 10, T-50, T-75, and T-90 were related to weight (p <0.01). These relationsh ips were stronger in males than females. Conclusions. Maximal relaxation was reached in all children receiving 600 o r 800 mu g/kg of rocuronium. The TSRNMF were mainly related to the weight o f the children, and gender affected each relationship. Widely variable resp onses were observed with all three doses. (C) 1999 IMSS. Published by Elsev ier Science Inc.