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

Abstract

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.

Differences in sensitivity to rocuronium among orbicularis oris muscles innervated by normal or damaged facial nerves and gastrocnemius muscle innervated by somatic nerve in rats

“…Stable MTAs were measured for at least 30 minutes before the tissues were exposed to rocuronium (Organon, Oss, The Netherlands). Both baseline MTA and MTAs under rocuronium concentrations of 2.5, 5, 7.5, and 10 μg/mL, respectively, were recorded 15, 16. Muscle strips were incubated at each rocuronium concentration for at least 15 minutes.…”

Influência dos Hipnóticos no bloqueio neuromuscular produzido pelo cisatracúrio: emprego da aceleromiografia

“…Factors related to neuromuscular block monitoring also interfere with the blockade time 1,22 . Experimental studies have shown that the onset of action of NDNMB is inversely proportional to the times for muscle response stabilization and stimulus frequency, as both periods are shorter and greater during stabilization and stimulus frequency is applied to achieve the response prior to NMB administration 1,23,24 .…”