The Effects of Esmolol on Neuromuscular Action of Succinylcholine or Mivacurium / 대한마취과학회지

Background: Esmolol is rapid hydrolyzed by plasma esterase but may inhibit plasma cholinesterase activity based on its structure. This study was designed to evaluate the interactions between esmolol and succinylcholine or mivacurium which are metabolized by plasma cholinesterase and to determine the inhibitory effect of esmolol on human plasma cholinesterase. Methods: Neuromuscular effects of succinylcholine (1.0 mg/kg) and mivacurium (0.15 mg/kg) with or without esmolol (0.5 mg/kg or 1.0 mg/kg) were compared in 57 adult patients (ASA class I) during O2-N2O-isoflurane anesthesia. Neuromuscular block was monitored by recording the compound electromyogram of the hypothenar muscle resulting from supramaximal train of four stimuli applied to the ulnar nerve. Also plasma cholinesterase activity was measured before and 5, 10 minutes after injection of esmolol. Results: Time from injection to onset of over 95% block, clinical duration from injection to 25% recovery of control twitch, and recovery index defined as from 25% to 75% twitch recovery of succinylcholine or mivacurium were not altered by pretreatment of esmolol. Plasma cholinesterase activity was not decreased after injection of esmolol 0.5 mg/kg, but decreased by 5% after injection of 1.0 mg/kg (p<0.05). Conclusions: It is unlikely that neuromuscular blocking effects of succinylcholine and mivacurium are prolonged by administration of clinical doses of esmolol (0.5~1.0 mg/kg) due to inhibition of plasma cholinesterase activity in human.

The Neuromuscular Effects of Succinylcholine, Mivacurium and Vecuronium Corresponding to the Blood Flow Occlusion of Time in the Isolated Forearm / 대한마취과학회지

BACKGREOUND: The magnitude of neuromuscular blockade is related to plasma concentration of muscle relaxants. This study was designed to compare the maximal depression of twitch height by blood flow occlusion using a tourniquet at various time interval after intravenous administration of muscle relaxants. METHOD: We studied 127 healthy male adult patients who underwent elective surgery under the general anesthesia with propofol infusion and 50% nitrous oxide. The single supramaximal twitch stimulation applied to the ulnar nerve at the wrist at 1 Hz. The twitch response of adductor pollicis muscles were measured by a 2 kg Load Cell strain gauge with a thumb piece modification and recorded by a Gould TA 240 recorder. After occlusion of blood flow by the tourniquet in the upper arm, in which the neuromuscular monitoring was applied on the wrist, we administered the equipotent dose (ED95) of succinylcholine (S group), mivacurium (M group), and vecuronium (V group) intravenously on the contralateral arm respectively. We measured the maximal depression (%) of twitch height after the releasing tourniquet at 30, 60, 90, 120, 150, and 240 second intervals after the injection of each drug. RESULTS: The depression of twitch height was not found from 90 seconds of tourniquet time in the M group, and 120 seconds of tourniquet time in the S group. However, in the V group, the depression of twitch height was maintained to 240 seconds of tourniquet time. CONCLUSIONS: It is suggested that the plasma concentration of mivacurium declined faster than that of succinylcholine, and that of vecuronium decreased slowest among the groups after intravenous administration of equipotent dose (ED95).