Effect of intravenous infusion of rocuronium on emergence from propofol anesthesia in rats

Abstract

Background: Central nervous system effects of neuromuscular blocking agents have been indicated in some case reports. We investigated whether intravenous (IV) infusion of rocuronium affects emergence from propofol anesthesia in rats.Methods: We used Sprague Dawley rats. Propofol infusion was initiated with a bolus of 15 mg/kg and continued at a rate of 40 mg/kg/h. For the rocuronium group (n = 18), rocuronium was administered as an initial IV bolus of 5 mg/kg followed by continuous infusion at a rate of 250, 500, or 1000 μg/kg/min along with propofol infusion. Infusion was continued for 60 min, and sugammadex (32 mg/kg) was injected at the end of infusion. In a separate group of rats (n = 12), normal saline was administered along with propofol infusion. After continuous infusion for 60 min, normal saline or sugammadex (32 mg/kg) was injected. The time to emergence from propofol anesthesia was evaluated. To ascertain possible factors affecting emergence, the neuromuscular blocking, circulatory, and respiratory properties of IV rocuronium infusion at 1000 μg/kg/min were assessed (n = 18).Results: The time to emergence from propofol anesthesia was 239 ± 94 s after simultaneous infusion of normal saline without rocuronium and was 346 ± 78, 518 ± 134, and 638 ± 219 s after IV infusion of rocuronium at 250, 500, and 1000 μg/kg/min, respectively. The simultaneous IV infusion of rocuronium dose-dependently increased the time to emergence (ρ = 0.624; p = 0.006). Sugammadex alone did not delay emergence (280 ± 60 s; p = 0.39). Neuromuscular blockade induced by rocuronium at 1000 μg/kg/min was completely antagonized at 99 ± 21 s by sugammadex (32 mg/kg). Mean arterial pressure, heart rate, partial pressures of oxygen and carbon dioxide, and pH were not affected by rocuronium infusion.Conclusions: Our results show that IV infusion of rocuronium delays the emergence from propofol anesthesia in rats, despite the complete recovery from neuromuscular blockade by sugammadex. The use of neuromuscular blocking agents in neonates or patients with cerebrovascular diseases, whose blood-brain barrier might be immature or disrupted, should be carefully considered.