Time Course of a Single, 0.6 mg/kg Dose of Rocuronium Neuromuscular Block During Sevoflurane or Propofol Anesthesia in Infants—A Prospective, Randomized Trial

<b>Background:</b> There is little data available in infants on the extent to which inhalational anesthetics prolong the effects of neuromuscular blocking agents compared with intravenous agents. Here, we assessed the differences between the neuromuscular blocking effects (duration and recovery time) of a single dose of rocuronium during propofol vs. sevoflurane anesthesia. <b>Methods:</b> The prospective study enrolled 20 infants (4-12 months of age) scheduled for craniosynostosis surgery, randomly assigned to receive general anesthesia maintenance with sevoflurane or propofol. All patients received 0.6 mg/kg rocuronium as a single bolus dose to facilitate tracheal intubation and surgery. Primary study endpoint was the clinical duration of rocuronium, from administration until spontaneous recovery to a train-of-four ratio (TOFR) > 0.90. Secondary endpoints were times for reappearance of the first, second, third, and fourth twitches of the TOF (T1, T2, T3 and T4, respectively) in the two patient groups. <b>Results:</b> There were no differences in the infants' age (sevoflurane maintenance: 5.8 ± 2.4 months; propofol maintenance: 6.7 ± 3.1 months, <i>p</i> = 0.47) or weight (sevoflurane: 7722 ± 1644 g; propofol: 7433 ± 1782 g, <i>p</i> = 0.71). Rocuronium onset time was 101.0 ± 55.0 s in the sevoflurane group and 83.4 ± 47.9 s in the propofol group (<i>p</i> = 0.46). Total duration of anesthesia was comparable in the sevoflurane (122.0 ± 23.8 min) and propofol (107.7 ± 25.2 min, <i>p</i> = 0.18) groups. Rocuronium recovery to TOFR > 0.9 required 136 min (CI: 123.7-149.5 min) in the sevoflurane group and 61.5 min (CI: 58.0-101.0 min) in the propofol group (<i>p</i> < 0.001). <b>Conclusions:</b> In infants, sevoflurane maintenance enhances the neuromuscular blocking effect of a single, 0.6 mg/kg BW dose of rocuronium as compared to propofol maintenance. After discontinuation of sevoflurane, additional time is necessary to reach the acceptable TOFR >0.9 needed before tracheal extubation. The present study further underscores the importance of objective (quantitative) neuromuscular monitoring in infants to guide intraoperative management and prevent residual neuromuscular block.