RESUMEN
BACKGROUND: The aim of this prospective, randomized, double-blind study was to compare tracheal intubating conditions and the duration of apnoea following administration of 0.4, 0.6 and 1.0 mg/kg of succinylcholine during simulated rapid sequence induction of anaesthesia. METHODS: Anaesthesia was induced with fentanyl 2 µg/kg and propofol 2 mg/kg followed by application of cricoid pressure. Patients were randomly allocated to three groups according to the dose of succinylcholine administered (0.4, 0.6 or 1.0 mg/kg). Intubating conditions were assessed at 60 s after succinylcholine administration. Time to first diaphragmatic contraction (apnoea time) and time to resumption of regular spontaneous breathing were noted. RESULTS: Excellent intubating conditions were obtained in 52.4%, 95.7% and 100% of the patients after 0.4, 0.6 and 1.0 mg/kg succinylcholine, respectively; P<0.001. Acceptable intubating conditions (excellent and good grade combined) were obtained in 66.7%, 100% and 100% of the patients after 0.4, 0.6 and 1.0 mg/ kg succinylcholine, respectively; P<0.001. Apnoea time and resumption of regular spontaneous breathing were dose-dependent. Apnoea time was 3.8±1.1 min, 4.3±0.9 min and 8.2±3.4 min in groups 0.4, 0.6 and 1.0 mg/kg, respectively; P<0.001. Time to regular spontaneous breathing was 5.3±1.2 min, 5.5±1.1 min and 8.9±3.5 min in groups 0.4, 0.6 and 1.0 mg/kg, respectively; P<0.001. CONCLUSION: A dose of 0.6 mg/kg succinylcholine can be used for rapid sequence induction of anaesthesia as it provides acceptable intubating conditions with a shorter apnoea time compared with a dose of 1 mg/kg.