Influence of stimulus frequency on blockade induced by pancuronium and rocuronium: study on rats phrenic nerve-diaphragm preparation.
OBJECTIVE
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 1 Hz (Groups I and II, respectively). Subgroups were formed (n=5) according to the neuromuscular blocker employed (pancuronium-2 microg/ml and rocuronium-4 microg/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 1 Hz at all time periods studied both in preparations that are blocked with pancuronium and in those that are blocked with rocuronium.


CONCLUSIONS
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 1 Hz frequencies, at all periods studied.
Braga
Angélica de Fátima de Assunção
Ade F
Department of Anesthesiology, Faculty of Medical Sciences, UNICAMP, São Paulo, Brazil. franklinbraga@terra.com.br
Munoz
Derli Conceição
DC
Braga
Franklin Sarmento da Silva
FS
Araujo
Daniele Ribeiro de
DR
Potério
Glória Maria Braga
GM
Mantovani
Mario
M
D000732:Androstanols; D000818:Animals; D003964:Diaphragm / Q000187:drug effects / Q000294:innervation; D004558:Electric Stimulation / Q000379:methods*; D008297:Male; D019148:Neuromuscular Blockade / Q000379:methods; D003473:Neuromuscular Nondepolarizing Agents; D010197:Pancuronium; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D000077123:Rocuronium
D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D010197:Pancuronium; D000077123:Rocuronium