Effect of Priming with Atracurium or Pancuronium on the Onset Time of Pancuronium in Patients Undergoing General Anesthesia for Elective Surgery: A Randomised Controlled Trial

BACKGROUND: Suxamethonium, a rapid-acting muscle relaxant, has been conventionally preferred during rapid sequence induction (RSI). The priming principle, which uses non-depolarising muscle relaxants, is an alternative in situations where it is contraindicated. Unfortunately, its efficacy has not been sufficiently documented in Nigerian patients. AIMS: The study aimed to use atracurium and pacuronium to evaluate the efficacy of the priming principle. MATERIALS AND METHODS: In this randomised controlled trial, ninety adults undergoing elective surgery under general anaesthesia were randomly allocated into three equal groups. Group A (Atracurium), Group P (Pancuronium) and Group C (control) received 0.05 mg/kg atracurium, 0.01 mg/kg pancuronium and 1 ml saline, respectively, as the priming agent. Three minutes after, anaesthesia was induced with 2 mg/kg propofol and then the intubating dose of pancuronium administered. The onset time of neuromuscular block, intubating condition and occurrence of muscle weakness during the priming interval were noted. Data were analysed using the Statistical Package for the Social Sciences version 25, and a P < 0.05 was considered statistically significant. RESULTS: The mean onset time in Groups A, P and C was 215.7 ± 59.9 s, 237.1 ± 76.5 s and 265.8 ± 72.0 s, respectively, P = 0.024. Post hoc analysis showed that the onset time was only significant between Groups A and C (P = 0.02). The intubating condition was comparable in all groups (P = 0.25). The incidence of muscle weakness during the priming interval was 6.67% in the priming groups. CONCLUSION: In adults, priming with atracurium but not pancuronium shortens the onset time of pancuronium. However, during RSI, where a fast onset is crucial, the shortened onset time with priming is not clinically relevant.