[Priming versus bolus: a comparative study with different cisatracurium doses.].

BACKGROUND AND OBJECTIVES: The priming technique is an alternative to shorten nondepolarizing neuromuscular blockers onset time. This study aimed at evaluating maximum neuromuscular block onset, tracheal intubation conditions and cardiocirculatory changes determined by different cisatracurium single or fractional doses. METHODS: Participated in this study 80 patients physical status ASA I and II, who were distributed into two groups according to cisatracurium doses: Group I (0.1 mg.kg-1) and Group II (0.2 mg.kg-1). Subgroups were constituted according to the curarization technique employed: subgroups P1 and P2 (priming-dose) - 0.02 mg.kg-1 or 0.04 mg.kg-1cisatracurium, respectively, followed one minute later, by 0.08 mg.kg-1 or 0.16 mg.kg-1 of the same neuromuscular blocker, respectively; subgroups U1 and U2 - total bolus injection of 0.1 mg.kg-1 or 0.2 mg.kg-1 cisatracurium, respectively. Anesthesia was induced with etomidate, preceded by alfentanil. Train of Four (TOF) stimulation was applied at 12-second intervals to monitor neuromuscular function. Maximum neuromuscular blockade onset time, tracheal intubation conditions and changes in hemodynamic parameters (arterial mean blood pressure and heart rate) were evaluated. RESULTS: Mean times for maximum neuromuscular block onset were: Group I (3.90 +/- 0.60 min and 3.88 +/- 0.74 min, for subgroups P1 and U1, respectively) and Group II (1.40 +/- 0.40 min and 2 +/- 0.30 min, for subgroups P2 and U2, respectively) with no significant differences. Comparison between subgroups P1 and P2 and between subgroups U1 and U2, has shown statistically significant differences. Tracheal intubation conditions were acceptable in all patients and there were no cardiovascular changes. CONCLUSIONS: Fractional cisatracurium doses have not shortened maximum neuromuscular block onset as compared to bolus injections. They have however produced acceptable tracheal intubation conditions without cardiovascular changes.