| Lidocaine and Verapamil Enhances Neuromuscular Block Induced by Rocuronium. |
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Sung Yell Kim, Hee Chul Jin, Jeong Seok Lee, Jin Hyuk Park, Su Hyun Cho, Soon Im Kim |
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| Abstract |
BACKGROUND
Lidocaine or verapamil are used as an antiarrhythmic agent or agent blunting the cardiovascular changes induced by intubation or extubation during anesthesia. After recovery from general anesthesia with muscle relaxants, most patients remained in a residual paralytic state, hence it might develop easily recurarization by factors that affect neuromuscular transmission. Lidocaine and verapamil are well known as agents to potentiate the neuromuscular block. We investigated the effects of lidocaine or verapamil on neuromuscular transmission in vitro.
METHODS
Square wave, 0.2 ms duration at a frequency of 0.1 Hz supramaximal or train of four stimuli was applied and the twitch height response was recorded mechanomyographically on rat phrenic nerve hemidiaphragm preparations. Dose responses of rocuronium, lidocaine, verapamil, rocuronium pretreated with lidocaine or verapamil, lidocaine pretreated with rocuronium, and verapamil pretreated with rocuronium were observed by cumulative method, and effective doses (Lag dose, ED50 and ED95) between a pretreated and nonpretreated agent were compared statistically. TOF ratios were observed at 80, 70, 40 and 30% of the control twitch height value during the observation of dose responses.
RESULTS
Lag dose, ED50 and ED95 of rocuronium were reduced significantly after pretreatment of lidocaine, verapamil or their mixture, and the dose response of lidocaine, verapamil or their mixture were also reduced significantly by rocuronium pretreatment. TOF ratios at the point of each twitch height decreased significantly after pretreatment.
CONCLUSIONS
Lidocaine or verapamil itself did not affect the neuromuscular transmission but might have potentiated the neuromuscular blocking effect induced by rocuronium.
However, in excessive doses, these agents produced neuromuscular blockade. Consequently, in the residual neuromuscular block induced by rocuronium, lidocaine or verapamil may enhance recurarization. |
| Key Words:
Neuromuscular transmission: lidocaine; rocuronium; verapamil |
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