Effects of Aminophylline on the Dose-Response Curve of Vecuronium on Rat Hemidiaphragm Preparation / 대한마취과학회지

BACKGROUND: Aminophylline is an inhibitor of phosphodiesterase; it increase the cAMP and, in turn, the level of acetylcholine at the neuromuscular junction. In doing so, it has an antifatigue action. It antagonizes nondepolarizing neuromuscular blockade in animals, and has been anecdotally noted to do so in humans, as well. We investigated the interaction of aminophylline and vecuronium on the dose response curve in vitro. METHODS: Institutional approval was obtained. Thirty seven male Spague Dawley rats (150~200 g) were divided into four groups (control, aminophylline 2.5, 5.0 and 7.5 microgram/ml). The animal were anesthetized with 40 mg/kg phentobarbital. The left hemidiaphragm with phrenic nerve was dissected and mounted within 5 minutes in bath containing 100 ml Krebs solution at 32oC. The phrenic nerve was stimulated at supramaximal intensity by a Grass S88 stimulator through an SIU5 isolation unit. The twitch height was measured by precalibrated Grass FT03 force displacement transducer and recorded. After stabilization of twitch response, vecuronium was added to the solution to obtained an initial concentration 1.0 microgram/ml with aminophylline 0, 2.5, 5.0, or 7.5 microgram/ml. When a stable 3~5 twitch was obtained after first dose, additional vecuronium was added to the Krebs solution in increments of 0.5 microgram/ml to achieve a more than 90% neuromuscular block. The data were analyzed by repeated measures of ANOVA and kappa2 test. RESULTS: There was a significant increase in the effective dose of vecuronium needed to depress the twitch response in aminophylline 5.0 and 7.5 microgram/ml added groups compared with control group and aminophylline 2.5 microgram/ml group. CONCLUSIONS: We conclude that aminophylline shows decreased sensitivity to vecuronium in the phrenic nerve diaphragm preparation of rats.

The Effect of Oral Clonidine on the Duration of Vecuronium / 대한마취과학회지

BACKGROUND: As of alpha2-agonist, clonidine reduces generalized sympathetic outflow in nervous system and also reduces acetylcholine release at cholinergic terminals presynaptically. So clonidine premedication is possibly able to decrease muscle contraction and prolong the duration of neuromuscular blockers. Therefore, the aim of our current study is to investigate the effect of oral clonidine on the duration of vecuronium. METHODS: Forty patients (ASA I or II) sheduled for elective low abdominal or extrimities operation were randomly divided into 2 groups. Clonidine group (n=20) received 5 microgram/kg oral clonidine at 90 min before operation. Control group (n=20) received nothing. Neuromuscular transmission was measured with relaxograph. After injection of vecuronium 0.1 mg/kg, we measured onset time (the time from injection of vecuronium to decrease to the 25% of baseline value, duration 1 (the time interval between injection and recovery of the first twitch to 25% of the baseline value), and duration 2 (the time interval between second injection of 0.02 mg/kg vecuronium and recovery of the first twitch to 25% of the baseline value). RESULTS: There were no statistical differences between control and clonidine group in onset time (2.6 +/- 0.6 min vs 2.7 +/- 0.5 min), duration 1 (37.5 +/- 8.9 min vs 40.3 +/- 8.6 min) and duration 2 (22.0 +/- 6.8 min vs 24.4 +/- 6.1 min). CONCLUSIONS: Five microgram/kg of oral clonidine premedication did not prolong the duration of vecuronium.

Vecuronium Administration for Endotracheal Intubation: The Priming Method vs. Intravenous Infusion Method / 대한마취과학회지

BACKGROUND: Priming significantly shortened the onset of neuromuscular blockade(NMB), but also results in a high incidence of side effects. This study was designed to determine the effect of infusion priming method on the side effects, intubation condition, and onset of NMB compared with divided priming method. METHOD: The effects of different priming method of vecuronium on onset time and endotracheal intubation condition were investigated. 40 patients were studied in two parts. In control part, 20 patients were allocated into two groups(n=10 in each group) receving 10, 20 g/kg vecuronium as a priming dose, followed by a intubating dose(0.1 mg/kg-priming dose) 3 min later; the other part, 20 patients were allocated into two groups(n=10 in each group) receving 0.2 mg/kg/hr vecuronium continuous intravenous infusion, followed by a intubating dose(0.1 mg/kg-total infusion dose) 3, 5 min later. Onset time is calculated by single twitch stimulation test from injection of the intubating dose to maximum depression of the single twitch. Intubatin condition was appreciated based on vocal cord reflex, coughing, and jaw relaxation and scored. RESULTS: The times to fade out on the single twitch of the intravenous infusion priming group were shorter than control priming group. There was no difference between control priming group and infusion priming group to evaluate the intubation conditions. Side effects in the continuous infusion group were lesser than control priming group. CONCLUSION: This results suggest that the use of continuous infusion method is one of the promising methods to shorten the neuromuscular blockade and to provide more comfort to the patients.

The Effects of Furosemide on the Recovery from Neuromuscular Blockade Induced by Vecuronium / 대한마취과학회지

BACKGROUND: The interactions between furosemide and muscle relaxants is controversial. In this study, the effects of furosemide on the recovery from neuromuscular blockade induced by vecuronium were investigated in thirty ASA class 1 or 2 adult patients undergoning elective orthopedic surgery under the general aneshtesia with O2-N2O-enflurane. METHODS: Furosemide was administered intravenously at 20% spontaneous recovery of first twitch height of TOF(T1) under the neuromuscular monitoring using Relaxograph?(Datex Co. Finland) as follows: placebo in control group, 5mg in group 1 and 20mg in group 2. Recovery index(RI) defined as the time from 25% to 75% recovery of T1, urinary output during this period and serum K+ levels at 10% and 75% recovery of T1 were measured. RESULTS: RI was shortened significantly in group 1 (11.2+/-3.4 min.) and group 2 (14.9+/-2.7 min.) compared with control group (19.3+/-4.0 min.)(P<0.05). The urinary output was significantly greater in the groups received furosemide than that in the control group(P<0.05), but serum K+ levels were not significantly changed after administration of furosemide. CONCLUSIONS: Furosemide facilitates recovery of neuromuscular blockade induced by vecuronium.

Clinical Evaluation of the Two Times Priming and Pancuronium as a Priming of Vecuronium for Endotracheal Intubation / 대한마취과학회지

The individual onset of action of pancuronium and vecuronium has been examined with a priming dose of same or the other agent or two times priming. Measurement of changes in the Tl% of TOF ratio of the adductor pollicis muscle were performed by Accelograph (Biometer). Sixty adult patients were administered Vecuronium(V) 0.015mg/kg (group 1), V 0.005mg/kg 3 minutes after 0.01mg/ kg(group 2), Pancuronium(P) 0. 015 mg/kg(group 3,4) as a priming agents. After 5 minutes, the intubating dose of V 0.085mg/kg (group 1,2,3), P 0.085 mg/kg (group 4) were administered with the induction agent, thiopental sodium 5 mg/kg. All sixty patients underwent orotracheal intubation at 60 seconds after the injection of intubating dose. Intubation condition, reduction of Tl% at 60 seconds, the onset time of maximal blockade (Tl 0%) were evaluated. There was no difficulty in intubation. Fifty-two (86%) patients were distributed in exellent and satisfactory grade of largest in group 2. While group 3 showed more rapid than group 4, group 2 showed the most rapid onset time significantly. These results indicate that the twicely divided dose of vecuronium for priming agent may be adequate and vecuronium after priming with pancuronium is more rapid than priming with same agent.