BACKGROUND: Sevoflurane inhalation induction is widely used in pediatric anesthesia, but the minimum alveolar concentration for endotracheal intubation (MACEI) when combined with neuromuscular blockade in neonates has been largely unexplored. This study assessed the MACEI of sevoflurane combined with cisatracurium in neonates.

MATERIAL AND METHODS: Anesthesia induction was commenced by inhaling 4% sevoflurane with 2 l/min of 100% oxygen via mask. Neonates were administered cisatracurium 0.2 mg/kg followed by adjustment of inspired sevoflurane to target end-tidal concentration based on intubation condition of the preceding subject. When the steady-state end-tidal sevoflurane concentration target was maintained for at least 15 min, endotracheal intubation by direct laryngoscope was performed. The intubation condition was considered failed if either heart rate (HR) after intubation increased by 20% or mean arterial blood pressure (MAP) by 30% or more than that before intubation. Otherwise, the intubation condition was regarded as successful. Dixon’s up-and-down method was used with 0.2% as the step size to determine the target end-tidal sevoflurane concentration.

RESULTS: The MACEI of sevoflurane combined with cisatracurium in neonates was 2.76±0.24%. Using probit analysis, the 50% effective end-tidal sevoflurane concentration (ED50) for successful condition of endotracheal intubation was 2.61% (95%CI 2.07–2.88%) and the 95% effective end-tidal sevoflurane concentration (ED95) was 3.28% (95%CI 2.95–7.19%). Hypotension and bradycardia occurred in 2 neonates during induction.

CONCLUSIONS: Sevoflurane combined with cisatracurium is feasible and effective for intubation in neonates, and the MACEI of sevoflurane in this subpopulation is 2.76±0.24%. However, cardiovascular adverse effects should be taken into consideration.

Keywords: Anesthetics, Atracurium, Infant, Newborn, Intubation, Dose-Response Relationship, Drug, Heart Rate, Intubation, Intratracheal, Pulmonary Alveoli