Progress in diagnosis and treatment of congenital myasthenic syndromes / 中华实用儿科临床杂志

Characterized by impaired neuromuscular transmission, congenital myasthenic syndromes (CMS) are a group of genetic disorders.The main manifestations include fatigue and weakness of skeletal muscle, with most onset in infant or early childhood.The common cause of death is respiratory failure, with high disability rate.With the improvement of gene sequencing technology and the in-depth study on the structure and function of pathogenic proteins, the pathogenesis of the disease has been deeply understood in the past 20 years.Early diagnosis and treatment can significantly improve the symptoms in patients.In this manuscript, the etiology, clinical characteristics, diagnosis and treatment of CMS are reviewed.

The Coexistence of Myasthenia Gravis and Myotonic Dystrophy Type 2 in a Single Patient

BACKGROUND: Myasthenia gravis (MG) and myotonic dystrophy type 2 (DM2) are rare disorders individually, and their coexistence in the same patient is very rare. We present a patient in which these two diseases coexisted. CASE REPORT: The patient complained of diplopia, fluctuating limb weakness, and difficulties in swallowing and speaking. A neurological examination revealed diplopia, facial, weakness of the neck and proximal limb muscles, dysphagia, dysphonia, and myotonia. The patient's mother had DM2 and her maternal grandfather had cataracts. MG was confirmed in our patient by positive results for neostigmine and a repetitive nerve stimulation test, and elevated serum anti-acetylcholine-receptor antibodies, while DM2 was confirmed by electromyography and genetic testing. The patient improved remarkably after treatment with anticholinesterases, corticosteroids, and azathioprine. CONCLUSIONS: This is the second reported case of the coexistence of DM2 and MG in the same patient. Since the symptoms of these two diseases overlap it is very important to keep in mind the possibility of their coexistence, so that MG is not overlooked in patients with a family history of myotonic dystrophy.

Effects of Ondansetron on the Neuromuscular Block of Vecuronium, Rocuronium or Atracurium in a Rat Phrenic Nerve-Hemidiaphragm Preparation / 대한마취과학회지

BACKGROUND: Ondansetron, a 5-HT3 receptor antagonist, is widely used for the prevention of postoperative nausea and vomiting. However, the interaction of ondansetron with non-depolarizing muscle relaxants have not been reported until now. Therefore we studied the effects of ondansetron on the neuromuscular block of vecuronium, rocuronium or atracurium in vitro. METHODS: A square wave 0.1 Hz supramaximal stimuli was applied to the phrenic nerve-hemidiaphragm preparation of a rat, and the twitch height response was recorded mechanomyographically. We measured cumulative concentration response curves of vecuronium, rocuronium or atracurium alone and after pretreating with ondansetron (1microgram/ml). We also measured the effects of ondansetron. The EC50's and EC90's of these muscle relaxants alone and after pretreatment with ondansetron were calculated using an inhibitory sigmoid Emax model. RESULTS: Ondansetron depressed the twitch height in a dose-dependent manner, and its potency was lower than the muscle relaxants. The EC50 and EC90 of ondansetron were 14.7microgram/ml and 33.4microgram/ml, respectively. Pretreated ondansetron (1microgram/ml) significantly reduced the EC50's and EC90's of vecuronium, rocuronium and atracurium (P<0.05). CONCLUSIONS: Ondansetron itself may have neuromuscular blocking properties, and it significantly enhances the neuromuscular blocks induced by vecuronium, rocuronium or atracurium.

Neuromuscular Blocking Properties of beta-Bungarotoxin, Hexamethonium and Verapamil in the Rat Phrenic Nerve-Hemidiaphragm Preparation / 대한마취과학회지

BACKGROUND: beta-Bungarotoxin irreversibly changes the presynaptic membrane, hexamethonium acts on the presynaptic nicotinic receptor, and verapamil blocks the ion channels on the presynaptic membrane. The effect of these drugs on twitch height and train of four (TOF) ratio were investigated, as well as the reversal effects of neostigmine, pyridostigmine or 4-aminopyridine (4-AP) on the partial neuromuscular blockade induced by these drugs. METHODS: Square wave, 0.1 Hz supramaximal stimuli or 2 Hz, 0.2 ms train of four stimuli, was applied to the phrenic nerve-hemidiaphragm preparation of the rat, and the twitch height response was recorded mechanomyographically. The cumulative concentration effects and TOF ratios at each point of twitch depression after beta-bungarotoxin, hexamethonium or verapamil were measured. TOF ratios were observed at 75, 50 and 25% of the control twitch height value during observation of the concentration effect. The EC50 and EC95 of beta-bungarotoxin, hexamethonium or verapamil were calculated using an inhibitory sigmoid Emax model. The reversal effect of some doses of neostigmine, pyridostigmine or 4-aminopyridine to the partial neuromuscular block produced by EC50 of beta- bungarotoxin, hexamethonium or verapamil was determined. RESULTS: The EC50 and EC95 of beta-bungarotoxin, hexamethonium and verapamil were 0.0695 and 0.1160 microgram/ml, 1267.0 and 2033.5 microgram/ml and 29.45 and 37.99 microgram/ml respectively. TOF fade was marked with hexamethonium or verapamil but small with beta-bungarotoxin. Neostigmine or pyridostigmine did not reverse the partial neuromuscular block induced by beta-bungarotoxin, hexamethonium or verapamil. However, 4-AP produced a dose-dependent recovery of the twitch response (P < 0.05). CONCLUSIONS: beta-Bungarotoxin, hexamethonium and verapamil produced different degree of TOF fade, and this may be due to different sites of action of these drugs. 4-AP reversed effectively the partialneuromuscular block induced by beta-bungarotoxin, hexamethonium and verapamil, whereas, neostigmine and pyridostigmine did not.

Evaluation of Presynaptic Action of Depolarizing Neuromuscular Blocking Agents with Single Twitch Response in Vitro / 대한마취과학회지

BACKGROUND: This study was performed to evaluate the presynaptic effects of depolarizing neuromuscular blocking drugs by using slow and fast frequencies of indirect stimulation on partial twitch depression in vitro. METHODS: A rat phrenic nerve hemidiaphragm was dissected and was mounted in an organ bath containing an oxygenated Krebs solution. The phrenic nerve was stimulated supramaximally and the twitch response (0.1 Hz) was stabilized for at least 30 minutes. T200/T1 ratio (twitch height of the 200th stimuli divided by that of the first stimuli) at frequencies of 0.2, 0.5, 1.0, and 2.0 Hz using a drug concentration which provided approximately 20% twitch depression at 0.1 Hz was calculated. To compare T200/T1 ratios with TOF ratios, a 2.0 Hz TOF response was measured immediately after the 200th stimuli at either frequency of stimulation. RESULTS: T200/T1 ratios produced by succinylcholine (SCC) and decamethonium (C10) were located between alpha-bungarotoxin (ABX) and hexamethonium (C6), however, significant differences among the four drugs were found at 2.0 Hz. The propensity for a decrease in T200/T1 ratios at 2.0 Hz might differ from this study: C6 > C10 > SCC > ABX. T200/T1 ratios at 2.0 Hz were not different from TOF ratios. CONCLUSIONS: It is concluded that small doses of C10 have a greater presynaptic activity than that of SCC, when the observed effects in this study were compared with the result of ABX acting predominantly at postsynaptic receptors and C6 acting predominantly at presynaptic receptors.

Studies of Interaction between Hexamethonium and Lidocaine, alpha-Bungarotoxin or Decamethonium in Vitro / 대한마취과학회지

BACKGROUND: Interactions of neuromuscular blocking agents are antagonistic in a combination of depolarizing and nondepolarizing agents, additive in a combination of relative two compounds or synergistic in a combination of different two nondepolarizing agents. However, the interactions of neuromuscular blocking agents with a different site of action from each other have not been studied clearly. This study was designed to examine the interaction between hexamethonium and lidocaine, alpha-bungarotoxin or decamethonium with markedly different pre and postsynaptic sites of action. METHODS: Square wave, 0.1 Hz supramaximal stimuli or 2 Hz, 0.2 ms train of four (TOF) stimuli, was applied to the rat phrenic nerve-hemidiaphragm preparation, and the twitch height response was recorded mechanomyographically. The cumulative concentration effect and TOF ratio at each point of twitch depression after hexamethonium, lidocaine, alpha-bungarotoxin or decamethonium given were measured. The EC50 and EC95 of hexamethonium, lidocaine, alpha-bungarotoxin and decamethonium were calculated using an inhibitory sigmoid Emax model. In the experiment of each combination of two drugs, three points of the isobole for hexamethonium-lidocaine, hexamethonium-alpha-bungarotoxin and hexamethonium-decamethonium were established using ratios of 1 : 3, 1 : 1 and 3 : 1 of their EC50. Points on the line of theoretical additivity and 95% confidence intervals were calculated according to Tallarida et al. TOF ratios were observed at 75, 50 and 25% of the control twitch height value during each combination ratio of their EC50. RESULTS: Significant deviations of points on the isobole from the line of additivity to the left were found at all EC50 ratios of hexamethonium-lidocaine (P < 0.05 respectively), that to the right was found at all EC50 ratios of a hexamethonium-alpha-bungarotoxin and hexamethonium-decamethonium (P < 0.05 respectively). The magnitude of TOF fade depended upon the mixed ratios for their EC50. CONCLUSIONS: The interaction was found to be synergistic in the combination of hexamethonium- lidocaine, and antagonistic in the combination of hexamethonium-alpha-bungarotoxin and hexamethonium- decamethonium.

Effects of Lidocaine, Verapamil and Their Mixture on Neuromuscular Blockade / 대한마취과학회지

BACKGROUND: Lidocaine, verapamil or a lidocaine-verapamil mixture was effectively applied for blunting extubation during recovery from anesthesia. However, these drugs can enhance neuromuscular blockade and cardiovascular depression. We investigated the neuromuscular and the cardiovascular effect of lidocaine, verapamil or a lidocaine-verapamil mixture before extubation in the recovery from anesthesia. METHODS: We studied ninety nine healthy adult patients (ASA class I or II), excluding the patients with cardiovascular diseases and with factors affecting neuromuscular function. Induction of anesthesia was performed with thiopental sodium 5 mg/kg and fentanyl 0.1 mg, and maintained with O2-N2O (50%)-enflurane (2%). Supramaximal single twitch stimuli (0.1 Hz) were applied to the ulnar nerve and the twitch response of the adductor pollicis was recorded by the Gould TA 240 recorder via a 2 kg Load Cell Strain Gauge modification. After stabilization of the twitch response, mivacurium (0.16 mg/kg) or vecuronium (0.1 mg/kg) was administered intravenously and endotracheal intubation was performed. Twitch heights were spontaneously recovered without a reversal agent from the neuromuscular blockade as a spontaneous group. Pyridostigmine 10 mg and glycopyrrolate 0.2 mg were administered intravenously around the time of 10% recovery of baseline twitch height as a reversal recovery group. At the time of 100% recovery of twitch height, train of four (TOF) stimuli was applied and then lidocaine, verapamil or a lidocaine-verapamil mixture was administered intravenously in both groups. Maximum depression of twitch height and the TOF ratio at this point, recovery index (RI) measured, and mean arterial pressure and pulse rates were measured before and at 2, 5, 10, 20 and 30 min. after the lidocaine-verapamil mixture administration. RESULTS: Twitch heights were depressed slightly after lidocaine, verapamil or a lidocaine-verapamil mixture administration; however, there were no significant differences to compare with the control. TOFratios were unchanged after lidocaine, verapamil or lidocaine-verapamil administration compared at the 100% twitch height recovery. RI indices were not significant between groups in reversal recovery or in spontaneous recovery. Mean arterial pressure was reduced significantly until 20 min after a lidocaine-verapamil mixture administration, pulse rates were increased at 2 min only after a lidocaine- verapamil mixture administration. CONCLUSIONS: Twitch height and TOF ratios were not affected by clinical doses of lidocaine, verapamil or a lidocaine-verapamil mixture. However, mean arterial pressure and pulse rates were changed significantly by a lidocaine-verapamil mixture.

Neuromuscular Blocking Properties of alpha-Bungarotoxin, Decamethonium and Lidocaine in the Rat Phrenic Nerve-Hemidiaphragm Preparation / 대한마취과학회지

BACKGROUND: alpha-Bungarotoxin, decamethonium or lidocaine has a neuromuscular blocking effect. The aim of this study was to evaluate the pharmacodynamic properties of these drugs at the neuromuscular junction and the reversal effects of antagonists in vitro. METHODS: The effects of evoked twitch tension response have been studied on the isolated phrenic nerve hemidiaphragm preparation of the rat, using a single twitch (0.1 Hz) and the train of four (TOF; 2 Hz for 2 s) stimulation. The cumulative concentration effect and TOF ratio at each point of twitch depression after alpha-bungarotoxin, decamethonium or lidocaine were measured mechanomyographically. The EC50 and EC95 of alpha-bungarotoxin, decamethonium or lidocaine were calculated using an inhibitory sigmoid Emax model. The reversal effects of various doses of neostigmine, pyridostigmine or 4-aminopyridine (4-AP) to the partial neuromuscula r block produced by EC50 of alpha-bungarotoxin, decamethonium or lidocaine were determined. RESULTS: The EC50 and EC95 of alpha-bungarotoxin, decamethonium or lidocaine were 0.179 and 0.320 microgram/ml, 17.07 and 26.84 microgram/ml or 76.80 and 105.70 microgram/ml. TOF fade was produced by alpha-bungarotoxin or decamethonium but not by lidocaine. Neostigmine or pyridostigmine did not reverse the partial neuromuscular block induced by alpha-bungarotoxin, decamethonium or lidocaine. However, 4-AP produced a dose-dependent recovery of the twitch response (P < 0.05). CONCLUSIONS: alpha-Bungarotoxin, decamethonium or lidocaine produced different degree of TOF fade, and it means that this may be due to different site of action of these drugs. 4-AP reversed effectively the partial neuromuscular block induced by alpha-bungarotoxin, decamethonium or lidocaine, whereas neostigmine or pyridostigmine did not.

Lidocaine and Verapamil Enhances Neuromuscular Block Induced by Rocuronium / 대한마취과학회지

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.

Clinical Significance of Axonal Stimulation Single Fiber Electromyography in Patients with Myasthenia Gravis

BACKGROUND: The axonal stimulation single fiber electromyography (S-SFEMG) is a relatively new electrophysio-logical technique and has several advantages over conventional voluntarily activated single fiber electromyography (V-SFEMG). This study was performed in patients with myasthenia gravis (MG) in order to analyze their neuromuscular transmission defects and thus to verify the usefulness of the S-SFEMG technique. METHODS: In 44 patients with MG, S-SFEMG was performed on the extensor digitorum communis muscle. The repetitive nerve stimulation test (RNST) on orbicularis oculi, trapezius, flexor carpi ulnaris, and abductor digiti quinti muscles was also performed at the same time. The results of the RNS and S-SFEMG were then analysed in detail. RESULTS: The S-SFEMG was found abnormal in 84.1%, while RNST was found abnormal in 75.0% of the patients tested. The normal S-SFEMG result was observed exclusively among 7 ocular type MG patients. The mean of the mean consecutive difference (MCD) value, % of fibers with blocking and % of fibers with abnormal jitter, was more increased in patients with generalized type MG than those with ocular type MG. This difference was statistically significant (P<0.01) in all 3 variables. CONCLUSIONS The S-SFEMG is a highly sensitive and useful diagnostic tool in MG. Although it demands more strict technical consideration than V-SFEMG, it is less time-consuming and applicable to uncooperative patients including children. Our study shows S-SFEMG to be especially useful in patients with ocular type MG whose RNST results do not show definite decremen-tal responses.

Quantitative comparison of atropine and tricyclamol with standard blocking agents of neuromascular transmission in cats under dial-urethane anesthesia

A quantitative comparison of atropine sulfate and tricyclamol chloride with tubocurarine chloride with tubocurarine chloride and succinylcholine chloride on neuromuscular block reveals the following salient observations: 1. Atropine and tricyclamol produce neuromuscular blockade comparable with that caused by tubocurarine and succinylcholine2. With regard to potency by dose, tubocurarine is 55 times more potent than tricyclamol and 277 times more potent than atropine; while succinylcholine is 250 times more potent than tricyclamol and 1250 times more potent than atropine3. Atropine causes the longest duration of neuromuscular block, outlasting that which is produced by tubocurarine4. Tricyclamol gives a transient blockade which closely resembles the one elicited by succinylcholine. (Summary)

Comparison between the Electric and Magnetic Stimulations for a Repetitive Nerve Stimulation Test

The low rate repetitive nerve stimulation test(RST) using the electric stimulation has been known the best procedure among the electroliagnostic evaluations for the neuromuscular transmission. However, the electric stimulation often causes a considerable discomfort and pain during the procedure. On the contrary, the magnetic stimulation is much easier and less painful in activating to activate the deep seated nerves. The purpose of this study was to compare the effect of repetitive magnetic and electric stimulation for the induction of compound muscle action potentials(CMAP) of abductor digiti quinti and deltoid muscles in 25 healthy subjects. The results were showed there were no significant differences in the amplitudes of CMAP of axillary and ulnar nerves between the magnetic and electric stimulations. And there were no significant differences in the decremental ratio of CMAP between the magnetic and electric stimulations. The magnetic stimulations were less painful for the subjects than electric stimulations in both proximal and distal muscles. In conclusion, the magnetic stimulation proved to be a useful method for repetitive nerve stimulations in the diagnosis of neuromuscular disease.

The Effect of Frequency of Stimulation on Partial Twitch Depression in a Rat Phrenic Nerve Hemidiaphragm Preparation / 대한마취과학회지

Background: This study was designed to determine whether presynaptic receptor blockade could be differentiated from postsynaptic receptor blockade by examining the effect of increasing frequencies of indirect stimulation on partial twitch depression in vitro rat phrenic nerve hemidiaphragm preparations. Methods: After isolating rat phrenic nerve hemidiaphragm preparation, T200/T1 ratio (twitch height of the 200th stimuli divided by that of the 1st stimuli) at frequencies of 0.2, 0.5, 1.0, and 2.0 Hz using a drug concentration which provided approximately 20% twitch depression at 0.1 Hz was calculated. To compare T200/T1 ratios with TOF ratios, 2.0 Hz TOF response was measured immediately after 200th stimuli at either frequency of stimulation. Results: Hexamethonium caused a marked decrease in T200/T1 ratio at 0.5~2.0 Hz of stimulation, whereas alpha-bungarotoxin caused no change in T200/T1 ratios at up to 2.0 Hz of stimulation. The T200/T1 ratios produced by d-tubocurarine, vecuronium, mivacurium, and rocuronium located intermediate between alpha-bungarotoxin and hexamethonium, however significant differences among four drugs were found at 2.0 Hz. The propensity for decrease in T200/T1 ratios at 2.0 Hz might differ from this study: hexamethonium >d-tubocurarine >rocuronium >mivacurium = vecuronium >alpha-bungarotoxin. T200/T1 ratios at 2.0 Hz were not different from TOF ratios. Conclusions: When the observed effects in this study were provided with result of alpha-bungarotoxin acting predominantly at postsynaptic receptors and hexamethonium acting predominantly at presynaptic receptors, the effects of nondepolarizing muscle relaxants at each binding site could be differentiated by examining the T200/T1 ratios at 2.0 Hz.

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.

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).

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.

The Effect of Neostigmine on the Train-of-four Ratio during the Recovery from Vecuronium- or Atracurium-induced Neuromuscular Blockade / 대한마취과학회지

BACKGROUND: The train-of-four(TOF) fade known as expression of prejuntional receptor binding was useful for evaluating the residual neuromuscular blockade(NMB). The present study was undertaken to investigate the effect of the neostigmine(Neo) on TOF ratio during the recovery from vecuronium(V) or atracurium(A) induced NMB under the general anesthesia. METHODS: Forty healthy adult patients were randomly divided into 4 groups as follows; spontaneous recovery from V-induced NMB(V-C group) or A-induced NMB(A-C group), reversed recovery with Neo at 20% recovery of control first twitch height(T) from V-induced NMB(V-R group) or A-induced NMB(A-R group). TOF ratio at 25 and 75% recovery of T and recovery index(RI) defined as time from 25 to 75% recovery of T were measured. RESULTS: TOF ratios at 25 and 75% recovery of T were 3.7 & 35.8%(V-C group), 8.4 & 46.9%(A-C group), 3.7 & 48.7%(V-R group) and 15.2 & 55.6%(A-R group) respectively(P>0.05). RI were 19.2 min(V-C group), 19.5 min(A-C group), 3.5 min(V-R group), and 5.6 min(A-R group) respectively (P<0.05). CONCLUSIONS: RI were significantly shortened in reversed recovery groups with Neo than spontaneous recovery groups (P<0.05). However TOF ratio at 75% recovery of T1 were not significantly different between spontaneous recovery and reversed recovery groups.

Onset and Duration of Succinylcholine and Vecuronium Neuromuscular Blockade at Laryngeal Adductor and Adductor Pollicis Muscles / 대한마취과학회지

Adequate relaxation of the laryngeal adductor muscle is required to obtain good tracheal intubating condition. But we couldnt check rountinely laryngeal adductor muscle response, so we quantify the effects of succinylcholine and vecuronium at the laryngeal adductor muscles and the adductor pollicis. Twenty adult patients of ASA physical status 1-2 were studied during propofol-fentanyl anesthesia. The trachea was intubated without the use of muscle relaxants and the tube cuff placed between the vocal cords. Succinylcholine 1.5 mg/kg or vecuronium 0.1 mg/kg was given as a single bolus by random allocation. Muscular activity was evoked with supramaximal stimuli in a train-of-four sequence every 12 sec to the ulnar nerve and the anterior branch of the recurrent laryngeal nerve at the notch of the thyroid cartilage and forehead. Neuromuscular transmission was monitored at wrist by mechano-myography and laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Pressure inside the cuff was measured with an air-filled transducer. TOF responses of both sites were continuously recorded on strip chart. Lag time and onset time were no statistically significant differences at the laryngeal adductor and adductor pollicis after succinylcholine or vecuronium bolus injection. Clinical durations were significantly shorter at the laryngeal adductor than at the adductor pollicis after succinylcholine and vecuronium injection. In one patient, onset of neuromuscular blocking effect with vecuronium was 125 sec slower at the laryngeal adductor than at the adductor pollicis. We recommand that if vecuronium is selected for gentle and smooth tracheal intubation, intubation will be delayed sufficient time after adductor pollicis relaxation.

The Effect of Regional Hypothermia of Neuromuscular Transmission / 대한마취과학회지

To determine the influence of hypothermia on the neuromuscular transmission, 25 patients were studied during O2-N2O(50%)-enflurane(1-2%) anesthesia without any muscle relaxants. Ventilation was controlled to maintain normocapnia and neuromuscular transmission was monitored by delivering train-of-four(TOF) stimuli to the ulnar nerve at wrist(Accelograph, Biometer) while the circulation to the ipsilateral forearm was occluded by tourniquet for 20 minutes. Regional hypothermia was induced to the isolated arm by intravenous injecton of 20ml normal saline cooled by 10degrees C and by surface cooling with ice pack in 15 patients (hypothermia group). To compare the neuromuscular transmission in hypothermia with 10 patients in normothermia whose temperature were maintained at normothermia by intravenous injection of 20ml normal saline of 36degrees C(normothermia group), TOF response was measured following temperature gone down. The results obtained were as follows. First twitch height of TOF response(T1) was not changed, significantly in normothermia group for 20 minutes. In hypothermia group, T1 was decreased insignificantly until the temperature fell to 32degrees C, but it began to decrease significantly from below 31degrees C as compared to normothermia group, e. g., 82.4+/-31.2/o(p<0.05), 73.1+/-29.6%(p<0.0l), 53.2+/-14.4%(p<0.01), 38.7+/-18.7% (p<0.01), and 35.9+/-16.3%(p<0.01) at 31, 30, 29, 28 and 27C respectively. T4 ratio was not affected in both normothermia and hypothermia groups. In 5 eases of 15 hypothermia patients, we observed transient increase of T, under the moderate hypothermia(35~32degrees C) before markedly diminution of T, under the profound hypothermia(< or =31degrees C)