Influence of stimulus frequency on blockade induced by pancuronium and rocuronium: study on rats phrenic nerve-diaphragm preparation

Influência da freqüência de estímulos no bloqueio neuromuscular produzido pelo pancurônio e rocurônio: estudo em preparação nervo frênico-diafragma de ratos

Angélica de Fátima de Assunção Braga Derli Conceição Munoz Franklin Sarmento da Silva Braga Daniele Ribeiro de Araujo Glória Maria Braga Potério Mario Mantovani About the authors

PURPOSE: To evaluate the influence of two stimulation frequencies on the installation of neuromuscular blockade produced by pancuronium and rocuronium on the rat diaphragm. METHODS: Diaphragms were submitted to an indirect frequency stimulation of 0.1 and 1Hz (Groups I and II, respectively). Subgroups were formed (n=5) according to the neuromuscular blocker employed (pancuronium-2µg/ml and rocuronium-4µg/ml). The twitch height depression was evaluated at 5, 15 and 30 minutes after adding the neuromuscular blocker. RESULTS: The decrease in twitch height was greater (p<0.01) with a frequency of 1Hz at all time periods studied both in preparations that are blocked with pancuronium and in those that are blocked with rocuronium. CONCLUSION: The frequency of stimulation interferes significantly with the installation of neuromuscular blockade produced by pancuronium and rocuronium, since the reduction in amplitude of the rat diaphragm response was greater for 1Hz frequencies, at all periods studied.

Neuromuscular nondepolarizing agents; Neuromuscular Blocking Agents; Phrenic Nerve; Diaphragm; Electric Stimulation; Rats


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