The Infusion Rate of Cisatracurium and Its Spontaneous Recovery for Cesarean Section under Enflurane Anesthesia / 대한마취과학회지

BACKGROUND: Cisatracurium, one of 10 isomers of atracurium, undergoes pH and temperature-dependent Hofmann elimination in plasma and tissues. Physiologic changes may affect the pharmacodynamics of neuromuscular bldegrees Cking agent during pregnancy. So, we compared the difference in the infusion rate and its spontaneous recovery of cisatracurium between full-term pregnant and nonpregnant women. METHODS: Muscle relaxation of full-term pregnant(group I, n=10) and nonpregnant(group II, n=10) women was maintained by continuous infusion of cisatracurium to keep 1st twitch response of train-of-four(TOF) at 5~10% of control. After discontinuation of infusion, recovery index was measured without reversals using the accelerograph. RESULTS: The infusion rate of cisatracurium in group I(1.25+/-0.16 mcg/kg/min) was not significantly different from that in group II(1.31+/-0.22) and recovery indices were not different between two groups(10.7+/-2.0 vs. 11.6+/-1.9 min). CONCLUSION: The infusion rate of cisatracurium in parturients to maintain surgical relaxation is not different from that in non-parturients. For Cesarean section, the usual infusion rate of cisatracurium is recommeneded to achieve the adequate surgical relaxation.

The Effects of Magnesium-Pretreatment on the Neuromuscular Blocking Actions of Cis-atracurium in the Cat / 대한마취과학회지

BACKGROUND: Cis-atracurium is more potent, and less likely to release histamine and has better autonomic and cardiovascular stability, compared to atracurium. It is eliminated mainly by Hofmann reaction and produces less amounts of laudanosine, the first metabolite which has the CNS stimulating property. However, drug interactions with several ions, such as magnesium that is popular in treating eclampsia have not yet to be known. METHODS: Using sciatic nerve-anterior tibialis preparation in the cat, we tried to find out whether cis-atracurium has the cumulation effect by administering four consecutive 100 microgram/kg of cis-atracurium. After confirming that the cis-atracurium had no cumulation effect, we proceeded the dose-response study to find out the ED50, ED95 and action duration of cis-atracurium in control group(II) and magnesium-pretreated group(III). After cumulative dose -response study, in the half of the group II and III, the infusion rate to maintain 90% twitch depression at least for 20 minutes was obtained, and afterwards, the recovery index was measured after the discontinuation of infusion. In the other half of the group II and III, while maintaining 90% twitch depression at least for 20 minutes through continuous infusion of cis-atracurium, we administered the 10 microgram/kg of neostigmine to measure the onset time, action duration and antagonism effect of the drug. RESULTS: The cis-atracurium did not have the cumulation effect and in group III, ED50 and ED95 were decreased significantly from 234+/-82 microgram/kg to 103+/-18 microgram/kg and from 399+/-123 microgram/kg to 173+/-28 microgram/kg, respectively, compared with group II. The action duration of cis-atracurium ED95 in group III(190+/-52 sec) was significantly longer than in group II(143+/-29 sec). The infusion rate of cis-atracurium to maintain 90% twitch depression was significantly higher in group II in the spontaneous recoveryand the neostigmine-induced antagonism(6.63+/-2.37 and 4.47+/-1.58 microgram/kg/min), respectively. CONCLUSION: The cis-atracurium do not have the cumulation effect. And, the magnesium potentiates the neuromuscular blocking actions of cis-atracurium. However, it has no effect on the antagonism action of neostigmine.

The Effects of Acid-Base Imbalance on the Cisatracurium-Induced Neuromuscular Blockade in the Cat / 대한마취과학회지

BACKGROUND: Cisatracurium is a nondepolarizing muscle relaxant. It less likely release histamine and has better cardiovascular stability. It presumably undergoes pH and temperature- dependent, nonenzymatic chemical process, Hofmann reaction. In vitro studies, Hofmann reaction was enhanced with increasing pH, but, in vivo the influence of acid-base imbalance is not well defined. METHODS: To evaluate the effects of acid-base imbalance on the neuromuscular blockade of cisatracurium in the cat, we induced acid-base imbalance and performed cumulative dose-response studies. RESULTS: ED50 of the cisatracurium was significantly reduced in all groups. Dose-response curves from all acid-base imbalance groups did not have significant differences in slopes. But, all showed shift-to-left when compared with control curve, showing decreased ED50. Duration of action was not affected. Recovery index was significantly changed in respiratory and metabolic alkalosis. CONCLUSIONS: It may be concluded that acid-base imbalance significantly augmented the potency of cisatracurium, but, changes of recovery index in this study may be resulted from systemic instability such as unstable hemodynamic state by the prolonged experiment.