Effects of intravenous lidocaine on the pharmacodynamics of rocuronium

Rocuronium is an intermediate nondepolarizing neuromuscular blocker (NMB) with faster onset and indicated in situations requiring rapid tracheal intubation. Intravenous lidocaine is often used to decrease hemodynamic responses to tracheal intubation. The association of NMB to local anesthetics results in potentiation of NMB effects. The purpose of this study was to evaluate the influence of lidocaine on rocuronium's pharmacodynamics determined by acceleromyography.

Forty-six ASA I-II patients, aged 18 to 65 years, were randomly distributed in two groups (CG: control and LG: lidocaine). Rocuronium was given to all patients for neuromuscular block. LG received lidocaine (1.5 mg.kg(-1)) 3 minutes before rocuronium. Neuromuscular function was evaluated by adductor pollicis muscle response to TOF. After NMB injection, times for first TOF response (T(1)) to reach 10 and 0% of baseline value and recover 25%, 75% and 95% of contraction height (Dur(25%), Dur(75%), Dur(95%)) were recorded. Recovery time of T(4)/T(1) = 0.8 and intervals Dur(75%)-Dur(25%) (IR(25-75)) and T(4)/T(1) = 0.8 - Dur(25%) were also recorded.

This study has not shown statistically significant differences between groups when T(1)= 10%, T(1) = 0, RI(25-75), T(4)/T(1) = 0.8 - Dur(25)% were compared. Times for Dur(25%), Dur(75%), Dur(95%) in LG were significantly higher as compared to CG.

Lidocaine associated to rocuronium has prolonged early blockade recovery stage without interfering with onset or late recovery stage.