RESUMEN
BACKGROUND: Combined rocuronium and cisatracurium have synergistic effects. We investigated whether reduced doses are effective during coadministration, by monitoring neuromuscular relaxation during surgery. METHODS: This randomized, controlled clinical trial was registered at http://clinicaltrials.gov (registration number NCT02495038). The participants were 81 patients scheduled for elective mastoidectomy and tympanoplasty. Participants were assigned to groups, including the intubating dose group (Group I, nâ=â27; combined ED95 rocuronium and ED95 cisatracurium), the small reduction group (Group S, nâ=â27; dose reduced by 10% of each ED95), or the large reduction group (Group L, nâ=â27; dose reduced by 20% of each ED95). Drugs were administered to patients and a timer was started using TOF-Watch monitoring. TOF (train-of-four) was monitored at the ulnar nerve, at a setting of 2âHz/12âs. We recorded the time to TOF ratioâ=â0 (onset), time to first TOF ratio >â25% (duration 25%), and TOF 25-75% (recovery index) under total intravenous anesthesia. One-way analysis of variance was used for statistical analyses (αâ=â0.05, ßâ=â0.2). RESULTS: There were no significant demographic differences between groups. Group L had a longer duration to onset (meanâ±âstandard deviation, 399.3â±â147.8âseconds) and shorter duration 25% (39.4â±â6.8âminutes) compared to Group I (212.8â±â56.0âs and 51.3â±â8.47âminutes, respectively) and Group S (230.7â±â60.6âs and 47.9â±â10.7âminutes, respectively). There were no other significant differences between groups. CONCLUSION: Our findings contribute to determining clinically effective combinations of rocuronium and cisatracurium, as well as to predicting the pharmacokinetic characteristics of the synergistic effects. We suggest that reducing doses of both drugs by approximately 10% of their respective ED95 values is sufficient to maintain neuromuscular relaxation during minor surgery.