Influence of the priming technique on pharmacodynamics and intubating conditions of cisatracurium

Study Objectives: To determine the effects of the priming technique on the intubating conditions and pharmacodynamics of different doses of cisatracurium. Design: Open-label, randomized study. Setting: Operating room of a university-affiliated hospital. Patients: 60 ASA physical status I, II, and III female patients. Interventions: Patients were randomly assigned to one of four groups. Patients from Groups 1, 2, and 3 received 0.01 mg/kg cisatracurium as a priming dose, and patients from Group 4 received placebo. Four minutes later, patients from Groups 1, 2, 3, and 4 received the following intubating doses of cisatracurium: 0.09 mg/kg, 0.14 mg/kg, 0.19 mg/kg, and 0.2 mg/kg, respectively. Anesthesia was induced with thiopental sodium, sufentanil, droperidol, and nitrous oxide (N2O; 6 L/min) in oxygen (O2; 4 L/min) and maintained with isoflurane up to 0.7%, N2O in O2, and sufentanil. Mechanomyography assessed the neuromuscular function of the adductor pollicis with train-of-four supramaximal impulses. The trachea was intubated when the amplitude of the first twitch decreased to 10% to 15% of control. Measurements and Main Results: There were no significant differences among the groups regarding the demographic data, the value of the first twitch at 60 seconds, the time to 90% block, and the onset time. Clinical duration of cisatracurium was significantly different between Group 3 and Groups 1 and 2, whereas Group 4 differed significantly from Group 1. Intubating conditions did not differ significantly among the groups. Conclusion: When primed, cisatracurium 0.09 mg/kg and 0.14 mg/kg produced an onset time comparable with that of 0.2 mg/kg and allowed an earlier spontaneous recovery (p < 0.05). In this study, there was no benefit in priming cisatracurium 0.19 mg/kg