Die Wirkung des Alters auf Anschlagszeit und Erholung nach Atracurium,Rocuronium und Vecuronium

Elderly patients may show an age-related decline in physiologic functions, which may be responsible for the prolonged duration of some neuromuscular blocking agents. Previous studies have yielded conflicting results as to the effects of these drugs in the elderly. Methods. After obtaining informed consent and approval of the Ethics Committee, we compared onset and recovery times of single IV doses of atracurium, rocuronium, and vecuronium given to 108 patients divided into three groups according to age (18–50, 51–64, ≥65 years). Following oxazepam premedication and fentanyl and thiopentone induction, patients were randomly allocated to receive atracurium, rocuronium or vecuronium (0.5, 0.6, or 0.1?mg/kg, respectively) in ≤0.8?vol.% enflurane (end-tidal)-nitrous oxide anaesthesia. Muscular relaxation was assessed by electromyographic (EMG) recording of the adductor pollicis muscle after supramaximal single-twitch stimulation of the ulnar nerve every 10?s. Onset time and recovery to 25%, 75% and 90% of twitch control values (DUR25, 75, 90) were recorded. Creatinine clearance predicted from serum creatinine (C_cr) was correlated with recovery from neuromuscular block. Results. Onset time was not different among groups or relaxants. The results showed a prolonged duration of action for atracurium (DUR75, DUR90), rocuronium (DUR25, DUR75), and vecuronium (DUR25) in the elderly. A number of patients did not reach DUR75 or DUR90. There was a significant relationship between age and failure to return to control values during recovery from neuromuscular block, especially after atracurium and rocuronium. C_cr showed a negative correlation with age for all relaxants, but a negative significant correlation between C_cr and recovery was found only for rocuronium. Conclusions. This study suggests that onset time for atracurium, rocuronium and vecuronium is not age-dependent. Recovery was prolonged in the elderly for all three relaxants. This effect appears to be secondary to changes in body composition and function accompanying the aging process. Neither atracurium nor vecuronium depends significantly on the kidney for elimination, but the negative correlation between C_cr and rocuronium suggests an appreciable role for the kidney in the elimination of this relaxant. The long recovery times observed in this study could also be related to enflurane anaesthesia. We suggest that failure of EMG responses to return to baseline values during recovery from neuromuscular block may be related to age, especially for atracurium and rocuronium.     

Die Wechselwirkung von Rocuronium und Rauchen Der Einfluß des Rauchens auf die neuromuskuläre Übertragung nach Rocuronium

Recent studies have shown different results concerning the effects of smoking on neuromuscular blocking agents. Some reports indicate that smokers need higher doses of vecuronium, but are more sensitive to atracurium. The aim of this study was to evaluate the effects of smoking on onset and recovery time after a single 0.6 mg/kg intubating dose of rocuronium an analog of vecuronium. Methods: Following institutional approval and informed consent, 20 smokers (>10 cigarettes/day) and 20 nonsmokers were included in the study. Following oxazepam premedication and induction with fentanyl and thiopental, single-twitch stimulation of the ulnar nerve was performed every 10 s. Following stabilisation of control responses, patients received rocuronium 0.6 mg/kg for intubation. Anaesthesia was maintained with enflurane ≤0.8 vol.% (end-tidal) and 65% nitrous oxide in oxygen. Onset time and recovery to 25% and 75% of the twitch control values were recorded. Results: Onset and recovery times were not different between smokers and nonsmokers. Conclusions: The results of the present study suggest that chronic nicotine exposure does not change onset time or duration of rocuronium neuromuscular blockade. A previous study found a greater need for vecuronium in smokers and discussed stimulation of the neuromuscular junction and enhanced biotransformation due to the enzyme-inducing properties of nicotine. The differences in our results could be partly due to a longer period of refraining from smoking in our patients, leading to very low nicotine blood concentrations without the proposed receptor-stimulating effect. Another cause for different behaviour of the two analogs could be different elimination pathways. Recent investigations suggest that rocuronium may not be eliminated principally by the liver. Therefore, enhanced nicotine-induced biotransformation, as suggested for vecuronium, would not occur with rocuronium.     

Residual paralysis induced by either vecuronium or rocuronium after reversal with pyridostigmine

We investigated postoperative residual curarization after administration of either vecuronium or rocuronium with reversal by pyridostigmine in 602 consecutive patients without perioperative neuromuscular monitoring. On arrival in the recovery room, neuromuscular function was assessed both by acceleromyography in a train-of-four (TOF) pattern and also clinically by the ability to sustain a head-lift for >5 s and the tongue-depressor test. Postoperative residual curarization was defined as a TOF ratio <0.7. One fifth of 602 patients (vecuronium, 24.7%; rocuronium, 14.7%) had a TOF <0.7 in the recovery room. There were no significant differences in the TOF ratios between 10 mg and 20 mg of pyridostigmine. The patients with residual block had several associated factors: the absence of perioperative neuromuscular monitoring, the use of pyridostigmine, which is less potent than neostigmine, a larger dose of vecuronium, shorter time from the last neuromuscular blocker to TOF monitoring, or peripheral cooling. We conclude that significant residual neuromuscular block after vecuronium or rocuronium was not eliminated even with reversal by a large dose of pyridostigmine. IMPLICATIONS: Without monitoring, the significant residual neuromuscular block after vecuronium or rocuronium is not eliminated even by reversal with a large dose of pyridostigmine and can still be a problem in the recovery room.     

Postoperative residual block after intermediate-acting neuromuscular blocking drugs

The frequency and duration of postoperative residual neuromuscular block on arrival of 150 patients in the recovery ward following the use of vecuronium (n = 50), atracurium (n = 50) and rocuronium (n = 50) were recorded. Residual block was defined as a train-of-four ratio of <0.8. An additional group of 10 patients received no neuromuscular blocking drugs during anaesthesia. The incidence of postoperative residual neuromuscular block was 64%, 52% and 39% after the use of vecuronium, atracurium and rocuronium, respectively. Similar numbers of patients were not able to maintain a sustained head or leg lift for 5 s on arrival in the recovery ward. The mean [range] times to attaining a train-of-four ratio of > or =0.8 after arrival in the recovery ward were 9.2 [1-61], 6.9 [1-24] and 14.7 [1.5-83] min for vecuronium, atracurium and rocuronium, respectively. None of the 10 patients who did not receive neuromuscular blocking drugs had train-of-four ratios <0.8 on arrival in the recovery ward. It is concluded that a large proportion of patients arrive in the recovery ward with a train-of-four ratio <0.8, even with the use of intermediate-acting neuromuscular blocking drugs. Although the residual block is relatively short lasting, it may occasionally be prolonged, requiring close observation and monitoring of such patients in the recovery ward.     

Adenosine potentiation of neuromuscular blocking agents in guinea-pigs

We have investigated the effects of adenosine i.v. on neuromuscular block induced by rocuronium, vecuronium and pipecuronium in an in vivo guinea-pig sciatic nerve-tibialis anterior preparation. The ED50 of each neuromuscular blocker was determined from cumulative log dose- response regression lines (n = 14). In separate experiments, adenosine 0.1 mg kg-1 min-1 or the same volume of 0.9% NaCl was given i.v. via a constant infusion and the ED50 of each neuromuscular blocking agent was then administered (n = 24). Adenosine 0.1 mg kg-1 min-1 increased significantly maximal block induced by the ED50 of these neuromuscular blockers (55-72%, 49-73% and 60-96%, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). Time to maximal block after rocuronium was significantly prolonged by adenosine (1.4-2.1 min; P < 0.05) and time to maximal block after vecuronium and pipecuronium was unchanged by adenosine. Time to maximal recovery of twitch tension after administration of the ED50 of all neuromuscular blocking agents was prolonged significantly by adenosine (4.5-10.7 min, 8.2-15.8 min and 47.0-128.7 min, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). We conclude that continuous infusion of adenosine 0.1 mg kg-1 min-1 potentiated the effects of neuromuscular blocking agents in this in vivo guinea-pig preparation.      

Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED₅₀ doses (mean ± SD) being 149 ± 36 μg˙kg^?1 in infants, 205 ± 52 μg˙kg^?1 in children and 169 ± 47 μg˙kg^?1 in adults (P<0.05 between infants and children) and the ED₉₅ doses being 251 ± 73 μg˙kg^?1, 409 ± 71 μg˙kg^?1 and 350 ± 77 μg˙kg^?1, respectively (P<0.05 between all groups). The emg recovery following an average 94.5 ± 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED₉₅ dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.     

七氟烷对罗库溴铵、维库溴铵及阿曲库铵临床药效的影响

目的 以丙泊酚为对照,观察1.3 MAC的七氟烷对罗库溴铵、维库溴铵及阿曲库铵临床药效的影响.方法 选择60例择期腹部手术的病人随机分为6组,每组10人.七氟烷罗库溴铵组(sR组)、七氟烷维库溴铵组(SV组)及七氟烷阿曲库铵组(SA组)分别吸入1.3 MAC的七氟烷及静注芬太尼维持麻醉,丙泊酚罗库溴铵组(CR组)、丙泊酚维库溴铵组(CV组)及丙泊酚阿曲库铵组(CA组)以丙泊酚6 mg·kg-1·h-1～8 mg·kg～·h-1及芬太尼维持麻醉.监测起效时间、最大抑制程度、作用时间、维持速率、恢复时间、恢复指数.结果 七氟烷组与相应的对照组在最大抑制程度、恢复指数方面的无统计学差异,起效时间、作用时间、维持速率、恢复时间有统计学差异.结论 七氟烷能明显延长罗库溴铵、维库溴铵以及阿曲库铵的作用时间和恢复时间并减少其起效时间、维持剂量,但对最大抑制程度和恢复指数则无明显影响.     

Effects of vecuronium and rocuronium in antagonistic laryngeal muscles and the anterior tibial muscle in the cat

BACKGROUND: Adequate vocal cord paralysis and full recovery of laryngeal muscle function are important when muscle relaxants are used perioperatively. This study was designed to compare the effects of vecuronium and rocuronium at the vocal cord abductor and adductor muscles and the anterior tibial muscle in cats. METHODS: Twelve adult cats were studied under pentobarbitone-N2O/O2-anesthesia. After supramaximal electrical stimulation of the peroneal nerve and the recurrent laryngeal nerve (0.1 Hz and intermittent train-of-four) evoked electromyographic responses were obtained from the anterior tibial muscle, the posterior cricoarytenoid muscle (vocal cord abductor) and two vocal cord adductor muscles, the lateral cricoarytenoid and the vocal muscle. Six cats received bolus doses of increasing size of vecuronium (ED90 22.5 microg x kg(-1)) and six cats rocuronium (ED90 90 microg x kg(-1)). RESULTS: Equipotent doses of vecuronium and rocuronium caused a similar degree of paralysis in all muscles (vecuronium ED90: 70% blockade at the posterior cricoarytenoid, 83% at the lateral cricoarytenoid, 84% at the vocal muscle and 90% at the anterior tibial muscle; rocuronium ED90: 71% at the posterior cricoarytenoid, 67% at the lateral cricoarytenoid, 78% at the vocal muscle and 90% at the anterior tibial muscle; vecuronium 2 x ED90: 93% blockade at the posterior cricoarytenoid, 95% at the lateral cricoarytenoid, 97% at the vocal muscle and 99% at the anterior tibial muscle; rocuronium 2 x ED90: 89% blockade at the posterior and lateral cricoarytenoid, 93% at the vocal muscle and 100% at the anterior tibial muscle). Onset time was significantly shorter at the posterior cricoarytenoid muscle (290 s) compared to the lateral cricoarytenoid muscle (400 s) after vecuronium ED90 and to the vocal muscle (150 s versus 210 s) after rocuronium ED90. Compared to the anterior tibial muscle (interval 25-75%: 6.5 min after vecuronium 2 x ED90 and 3.3 min after rocuronium 2 x ED90 and to the posterior cricoarytenoid muscle (interval 25-75%: 7 min after vecuronium 2 x ED90 and 4.3 min after rocuronium 2 x ED90), recovery of laryngeal adductor muscle function was markedly delayed with both neuromuscular blocking drugs (interval 25-75% at the lateral cricoarytenoid and vocal muscle: 14 min and 15.8 min after vecuronium 2 x ED90 and 10.3 min and 11.6 min after rocuronium 2 x ED90 respectively). CONCLUSION: In cats, the time course of neuromuscular blockade after vecuronium and rocuronium differs in antagonistic laryngeal muscles. The protective laryngeal function of glottis closure recovers later than vocal cord abduction after both vecuronium and rocuronium.     

Neostigmine injected 5 minutes after low-dose rocuronium accelerates the recovery of neuromuscular function

Study ObjectiveTo determine whether neostigmine 5 minutes after 0.4 mg/kg rocuronium accelerates reversal.DesignProspective, randomized, comparative open-label study.SettingOperating room.Patients60 ASA physical status I and II patients, aged 18 to 65 years.InterventionsPatients received 0.4 mg/kg rocuronium during nitrous oxide (N₂O)-propofol-opioid anesthesia. Reversal of neuromuscular blockade was achieved with neostigmine, either at 0.03 mg/kg or 0.05 mg/kg intravenously (IV), together with glycopyrrolate administered 5 minutes after relaxant and compared with spontaneous recovery. Onset, depth, and duration of neuromuscular block, as well as recovery of train-of-four (TOF) to 0.8 and 0.9 were evaluated.Main ResultsTimes to achieve TOF ratios of 0.8 and 0.9 were significantly shorter when 0.03 mg/kg or 0.05 mg/kg neostigmine was administered 5 minutes after administration of rocuronium (20.2 ± 5 min and 22.6 ± 5.9 min or 17.8 ± 4.8 min and 19.4 ± 5.1 min, respectively) compared with controls (36.2 ± 8.5 min and 39.0 ± 8.7 min; P < 0.01). Duration to spontaneous T1 25% recovery after rocuronium was 15.5 ± 6.5 min versus 9.3 ± 2.3 min and 7.7 ± 1.6 min in the treatment groups (P < 0.01). Recovery index (T1 from 25% to 75%) was significantly shorter after neostigmine (7.1 ± 2.4 min and 5.7 ± 4.0 min) versus controls (13.3 ± 8.3 min; P < 0.01). Speed of reversal did not differ significantly between IV neostigmine doses of 0.03 mg/kg or 0.05 mg/kg.ConclusionNeostigmine accelerates recovery when administered 5 minutes after injection of IV rocuronium 0.4 mg/kg.     

Atracurium and vecuronium interaction with gentamicin and tobramycin

Drug interactions between the aminoglycosides (tobramycin and gentamicin) and atracurium and vecuronium were studied prospectively in 44 patients. Twenty-two patients had therapeutic serum levels of tobramycin or gentamicin and 22 served as controls. Onset time, clinical duration, and time to spontaneous recovery of T4/T1 ratio of 0.70 after atracurium or vecuronium injection were measured. No statistically significant differences were found in onset time, but clinical duration and time to recovery were significantly longer in patients receiving tobramycin or gentamicin and paralyzed with vecuronium than for controls (P less than 0.01 for clinical duration and P less than 0.0005 for recovery). The neuromuscular block produced by atracurium was not significantly influenced by the presence of therapeutic serum levels of tobramycin or gentamicin. We conclude that for patients treated with these antibiotics, atracurium may present some advantages over vecuronium when a prolonged block is not desired.     

Acceleromyographic monitoring of neuromuscular block over the orbicularis oris muscle in anesthetized patients receiving vecuronium

Study ObjectiveTo evaluate the level of neuromuscular block acceleromyographically over the orbicularis oris muscle.DesignProspective, randomized, controlled study.SettingOperating room of a university-affiliated hospital.Patients36 adult, ASA physical status I and II women scheduled for mastectomy with air-oxygen-isoflurane-fentanyl anesthesia.InterventionsPatients were randomized to two groups. In the orbicularis oris group (n=18), the facial nerve was stimulated and movement of the orbicularis oris muscle was measured acceleromyographically. In the control group (n=18), adduction of the thumb was quantified mechanically.MeasurementsOnset and recovery of neuromuscular block caused by vecuronium 0.1 mg/kg were compared between the groups.Main ResultsTime to onset of neuromuscular block in the orbicularis oris group was significantly shorter than in the control group (176 ± 52 vs. 220 ± 34 sec, mean ± SD; P = 0.004). Times to return of the first, second, third, or fourth (T1, T2, T3, or T4) response of train-of four (TOF), and recovery of T1/control were comparable between the groups. Train-of-four ratio (T4/T1) in the orbicularis oris group was significantly higher than in the control group 50 to 120 minutes after vecuronium administration (P < 0.05).ConclusionDepth of neuromuscular block can be assessed acceleromyographically over the orbicularis oris muscle. Onset of neuromuscular block is quicker and recovery of TOF ratio is faster over the orbicularis oris muscle than at the thumb in patients receiving vecuronium.     

Muskelrelaxanzien Neue Substanzen und neuromuskuläres Monitoring

Introduction: Recent developments in both the quantitative evaluation of neuromuscular blockade and new muscle relaxants are reviewed. With respect to nerve stimulation, neuromuscular recording, and definition of parameters, the results of the 1994 Copenhagen International Consensus Conference are highlighted. Future clinical studies should adhere to these standards. Muscle relaxants: Rocuronium, cisatracurium, and mivacurium are new muscle relaxants that were released for clinical use in 1995/1996. Of these, rocuronium has the shortest time of onset, whereas its recovery characteristics closely resemble those of vecuronium. Rocuronium is five times less potent than vecuronium. Twice the ED₉₅ of rocuronium provides good or excellent intubating conditions within 60 to 90?s. Slight vagolytic effects were reported following injection of 0.6?mg/kg rocuronium, while histamine release was not observed. Cisatracurium is one of the ten steroisomers of atracurium. It is five times as potent as the chiral mixture while having a similar pharmacodynamic and -kinetic profile. Up to eight times the ED₉₅ did not cause significant histamine release or clinically relevant cardiovascular effects. Mivacurium is a short-acting nondepolarizing benzylisoquinoline muscle relaxant that undergoes rapid breakdown by plasma cholinesterase (PChE). Its duration of action is about one-half as long as that of equipotent doses of atracurium and vecuronium and three times as long as succinylcholine. Mivacurium has a moderate histamine-releasing potential. In patients with atypical or reduced PChE activity, the duration of action of mivacurium is prolonged.     

Early and late reversal of rocuronium and vecuronium with neostigmine in adults and children.

We investigated the influence of the timing of neostigmine administration on recovery from rocuronium or vecuronium neuromuscular blockade. Eighty adults and 80 children were randomized to receive 0.45 mg/kg rocuronium or 0.075 mg/kg vecuronium during propofol/fentanyl/N2O anesthesia. Neuromuscular blockade was monitored by train-of-four (TOF) stimulation and adductor pollicis electromyography. Further randomization was made to control (no neostigmine) or reversal with 0.07 mg/kg neostigmine/0.01 mg/kg glycopyrrolate given 5 min after relaxant, or first twitch (T1) recovery of 1%, 10%, or 25%. Another eight adults and eight children received 1.5 mg/kg succinylcholine. At each age, spontaneous recovery of T1 and TOF was similar after rocuronium and vecuronium administration but was more rapid in children (P < 0.05). Spontaneous recovery to TOF0.7 after rocuronium and vecuronium administration in adults was 45.7 +/- 11.5 min and 52.5 +/- 15.6 min; in children, it was 28.8 +/- 7.8 min and 34.6 +/- 9.0 min. Neostigmine accelerated recovery in all reversal groups (P < 0.05) by approximately 40%, but the times from relaxant administration to TOF0.7 were similar and independent of the timing of neostigmine administration. Recovery to T1 90% after succinylcholine was similar in adults (9.4 +/- 5.0 min) and children (8.4 +/- 1.1 min) and was shorter than recovery to TOF0.7 in any reversal group after rocuronium or vecuronium administration. Recovery from rocuronium and vecuronium blockade after neostigmine administration was more rapid in children than in adults. Return of neuromuscular function after reversal was not influenced by the timing of neostigmine administration. These results suggest that reversal of intense rocuronium or vecuronium neuromuscular blockade need not be delayed until return of appreciable neuromuscular function has been demonstrated. Implications: These results suggest that reversal of intense rocuronium or vecuronium neuromuscular blockade need not be delayed until return of appreciable neuromuscular function has been demonstrated. Although spontaneous and neostigmine-assisted recovery is more rapid in children than in adults, in neither is return of function as rapid as after succinylcholine administration.     

The agreement between adductor pollicis mechanomyogram and first dorsal interosseous electromyogram

The agreement between evoked adductor pollicis mechanomyogram and first dorsal interosseous evoked electromyogram (EMG) was evaluated during a pharmacodynamic study of rocuronium and vecuronium. In the first place the effective doses of rocuronium producing 50% and 90% block (ED₅₀ and ED₉₀, respectively) were established in 32 neurolept anaesthetized patients from the adductor pollicis mechanomyogram and the first dorsal interosseous EMG area and amplitude. Secondly, limits of agreement between the two methods were evaluated from the mean difference between methods 2 s.d. in 20 patients during onset of block following 2 × ED₉₀ of rocuronium and vecuronium, and during recovery from the last supplementary dose of 1/2 × ED₉₀. Limits of agreement show how much the EMG may be above or below the mechanomyogram. No differences were found between mechanomyographical and EMG based ED₅₀ (0.20 mg kg^-1) and ED₉₀ (0.30–0.32 mg kg^-1), respectively. The first EMG train–of–four (TOF) response overestimated block at 25% recovery and underestimated block at 75% and 90% recovery by only 3–7%. Limits of agreement suggested that the EMG may be 7–8% above or below the mechanomyogram during onset compared to 12–17% during recovery. The EMG TOF ratio lagged behind that of the mechanomyogram by 0.05 at TOF ratios below 0.50. No difference was found between methods at a TOF ratio of 0.75. Limits of agreement indicated that the EMG TOF ratio may be 0.12–0.15 above or below that of the mechanomyogram. Agreement between the amplitude and the area of the EMG were better than between the mechanomyogram and the EMG. Evaluation of the time courses of action showed that rocuronium had a faster onset of action than vecuronium (1.8 min compared to 2.8 min) while duration of action and reversal were similar. In conclusion, the first dorsal interosseous EMG amplitude and area can be used to assess rocuronium and vecuronium block.     

Different priming techniques,including mivacurium,accelerate the onset of rocuronium

Different priming sequences of equipotent doses of rocuronium and mivacurium on the onset of maximum neuromuscular block and intubating conditions were compared with those obtained after succinylcholine. During thiopentone-fentanylnitrous oxide anaesthesia, 70 patients were randomly assigned into seven groups. Group I received mivacurium 0.15 mg · kg^?1 as a single bolus dose. Group II received a priming dose of mivacurium 0.015 mg · kg^?1 followed three minutes later by mivacurium 0.135 mg · kg^?1. Group III received rocuronium 0.6 mg · kg^?1 as a single bolus dose, and Group IV received an initial dose of rocuronium 0.06 mg · kg^?1 followed by rocuronium 0.54 mg · kg^?1. Group V received a priming dose of mivacurium 0.015 mg · kg^?1 followed by rocuronium 0.54 mg · kg^?1. Group VI received an initial dose of rocuronium 0.06 mg · kg^?1 followed by mivacurium 0.135 mg · kg^?1. Group VII received succinykholine 1.0 mg · kg^?1. Groups I, III, and VII received a placebo injection before the administration of the neuromuscular blocking drug. Additional thiopentone 2 mg · kg^?1 iv was given 30 sec before intubation. Onset times (mean (95% confidence interval)) after priming a rocuronium block with either rocuronium (73 (57–90) sec) or mivacurium (58 (47–69) sec) were similar to those after succinykholine (54 (40–68) sec), and were shorter (P < 0.01) than that observed in other groups. Intubating conditions were not different between the groups. The duration of neuromuscular block was shortest with succinykholine. It is concluded that priming a rocuronium block with either mivacurium or rocuronium resulted in a neuromuscular block comparable to that of succinykholine in both the onset of action and intubating conditions.     

Neuromuscular blockade using vecuronium in dermatomyositis

The significant features of neuromuscular blockade with vecuronium in a patient with dermatomyositis are described: vecuronium 0.08 mg/kg resulted in 90%, 0.12 mg/kg in 100% neuromuscular blockade. In contrast to claims made in some previous publications, dermatomyositis did not produce increased sensitivity to vecuronium. Onset time and duration of action were also within normal limits in our patient. Time of spontaneous recovery until antagonism with neostigmine was markedly prolonged, but the dermatomyositis was only one of various possible explanations. Although there are potential hazards in the use of neostigmine in patients with dermatomyositis, antagonism of the neuromuscular block with 2 mg neostigmine was without problems in our patient. Our data support recent suggestions to reconsider the implications of dermatomyositis for anesthesia.     

Administration of magnesium sulphate before rocuronium: effects on speed of onset and duration of neuromuscular block

The speeds of onset of pancuronium, atracurium and vecuronium are increased by prior administration of magnesium sulphate. A prospective, randomized, double-blind, controlled, clinical study was performed to examine the effects of prior i.v. administration of magnesium sulphate 60 mg kg-1 on the neuromuscular blocking effects of rocuronium 0.6 mg kg-1 during isoflurane anaesthesia. Neuromuscular function was measured electromyographically (Relaxograph) in 30 patients who received either magnesium sulphate 60 mg kg-1 or normal saline, 1-min before rocuronium 0.6 mg kg-1. Mean onset times were similar in the two groups (magnesium sulphate 71 (SD 20) s; normal saline 75 (23) s), but times to initial, 10% and 25% recovery from neuromuscular block were significantly longer in the magnesium sulphate group (42.1 (16.3), 49.0 (12.4) and 56.5 (13.2) min, respectively) than in the saline group (25.1 (9.1), 33.0 (11.1) and 35.6 (13.2) min, respectively) (P < 0.05 in all three cases). Administration of magnesium sulphate was not associated with adverse haemodynamic effects. Prior administration of magnesium sulphate, under the study conditions described, prolonged rocuronium- induced neuromuscular block but did not increase speed of onset.      

Neuromuscular blocking agents and reversal agents

The neuromuscular junction consists of the motor nerve terminal, the synaptic cleft and post-synaptic nicotinic receptors on the motor end-plate of striated muscle. Neuromuscular blocking drugs are categorized into depolarizing and non-depolarizing agents. They are structurally related to acetylcholine (ACh), containing at least one positively charged quaternary ammonium radical that binds to the nicotinic receptor. Depolarizing agents (e.g. suxamethonium) act as agonists like ACh at the nicotinic receptor, but cause a more prolonged depolarization of the motor end-plate, thus rendering the ion channel insensitive to further action potentials. Non-depolarizing agents, in contrast, compete directly with ACh for nicotinic receptor binding sites and prevent neurotransmitter–receptor binding. These are either benzylisoquinoliniums (e.g. atracurium) or aminosteroids (e.g. rocuronium). Once recovery has commenced, neuromuscular block can be reversed with anticholinesterases (e.g. neostigmine). In contrast, the novel cyclodextrin sugammadex can be used to reverse any degree of neuromuscular block produced by rocuronium or vecuronium.     

Neuromuscular blocking agents and reversal agents

The neuromuscular junction consists of the motor nerve terminal, the synaptic cleft and post-synaptic nicotinic receptors on the motor end-plate of striated muscle. Neuromuscular blocking drugs are categorized into depolarizing and non-depolarizing agents. They are structurally related to acetylcholine (ACh), containing at least one positively charged quaternary ammonium radical that binds to the nicotinic receptor. Depolarizing agents (e.g. suxamethonium) act as agonists like ACh at the nicotinic receptor, but cause a more prolonged depolarization of the motor end-plate, thus rendering the ion channel insensitive to further action potentials. Non-depolarizing agents, in contrast, compete directly with ACh for nicotinic receptor binding sites and prevent neurotransmitter–receptor binding. These are either benzylisoquinoliniums (e.g. atracurium) or aminosteroids (e.g. rocuronium). Once recovery has commenced, neuromuscular block can be reversed with anticholinesterases (e.g. neostigmine). In contrast, the novel cyclodextrin sugammadex can be used to reverse any degree of neuromuscular block produced by rocuronium or vecuronium.     

Reversal of rocuronium‐induced profound neuromuscular block by sugammadex in Duchenne muscular dystrophy

A case is reported in which a child with Duchenne muscular dystrophy received a dose of sugammadex to reverse a rocuronium‐induced profound neuromuscular block. Sugammadex is the first selective relaxant binding agent and reverses rocuronium‐ and vecuronium‐induced neuromuscular block. A fast and efficient recovery from profound neuromuscular block was achieved, and no adverse events or other safety concerns were observed.