Pharmacodynamics of high-dose vecuronium in children during balanced anesthesia.

To compare the speed of onset, intubating conditions, duration of action, and recovery from neuromuscular blockade with vecuronium to those with succinylcholine, 40 ASA physical status 1 or 2 children (ages 2-9 yr) were studied during N2O-O2-opioid anesthesia. Each child was randomly assigned to receive a bolus dose of one of the following muscle relaxants: succinylcholine 2.0 mg/kg (n = 10), vecuronium 0.1 mg/kg (n = 10), vecuronium 0.2 mg/kg (n = 10), or vecuronium 0.4 mg/kg (n = 10). The evoked electromyogram of the abductor digiti minimi to train-of-four stimulation was monitored. We found that with succinylcholine, the time to 95% twitch depression (speed of onset, mean +/- SD), 24 +/- 7 s, was significantly less than that with each dose of vecuronium: 0.1 mg/kg, 83 +/- 21 s; 0.2 mg/kg, 58 +/- 17 s; and 0.4 mg/kg, 39 +/- 11 s, respectively (P less than 0.05). The time to laryngoscopy and intubation did not differ significantly between succinylcholine (48 +/- 10 s) and vecuronium 0.4 mg/kg (57 +/- 13 s); however, both were significantly less than than with vecuronium 0.1 and 0.2 mg/kg (P less than 0.005). The intubating conditions were excellent in 100% of patients. The duration of action was least with succinylcholine (5.7 +/- 1.5 min) and increased with increasing doses of vecuronium: 0.1 mg/kg, 23.9 +/- 5.1 min; 0.2 mg/kg, 55.2 +/- 11.6 min; and 0.4 mg/kg, 74.6 +/- 9.9 min, respectively (P less than 0.001). The recovery index was most rapid with succinylcholine (1.6 +/- 0.4 min) and was slowest with vecuronium 0.4 mg/kg (22.6 +/- 2.1 min) (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapid tracheal intubation with vecuronium: the priming principle

Following the administration of a single 0.1 mg/kg dose of vecuronium bromide, satisfactory conditions for tracheal intubation developed in 156 +/- 12 s (mean +/- SEM), and the clinical duration of the initial dose was 36 +/- 2 min. When the initial dose of vecuronium was administered in two increments, a 0.015 mg/kg "priming" dose, followed 6 min later by a 0.050 mg/kg "intubating" dose, intubation time decreased to 61 +/- 3 s and clinical duration to 21 +/- 1 min. The priming dose that had no unpleasant effect on premedicated, awake patients could be administered 3-4 min before, and the intubating dose 2 to 3 min after induction of anesthesia. With the described technique, comparable intubating conditions could be obtained just as rapidly with vecuronium as with succinylcholine chloride, without subjecting the patients to the side effects of and the complications occasionally encountered with succinylcholine. An added advantage of the use of a priming dose is that it will reveal undiagnosed, pathologic, or idiopathic increase of sensitivity to nondepolarizing muscle relaxants.     

Onset and duration of neuromuscular blockade following high-dose vecuronium administration

To determine the onset time and duration of high doses of vecuronium, 40 ASA Physical Status 1 and 2 patients were randomly assigned to receive either 100, 200, 300, or 400 micrograms/kg of vecuronium bromide for muscle relaxation during elective general surgery. Neuromuscular blockade was continuously quantitated by recording the electromyographic response to stimulation of the ulnar nerve train-of-four. The rate of onset of neuromuscular blockade, endotracheal intubating conditions, duration of neuromuscular blockade, and hemodynamic effects of vecuronium at each dose were evaluated and compared. The time from vecuronium administration to complete abolition of twitch tension (T1 = 0%) decreased from 208 +/- 41 to 106 +/- 35 s as the vecuronium dose was increased from 100 to 400 micrograms/kg (P less than 0.01). Corresponding times to endotracheal intubation (T1 less than 20%) also decreased from 183 +/- 24 to 96 +/- 31 s with increasing doses (P less than 0.01). Recovery time (T1 = 25%) increased from 37 +/- 13 to 138 +/- 24 min with increasing doses (P less than 0.01). No significant hemodynamic differences between the four groups were observed. Endotracheal intubating conditions were good or excellent in all patients. High doses of vecuronium may, therefore, be a useful alternative to succinylcholine when a rapid onset of neuromuscular blockade is required.     

Comparative clinical studies of vecuronium, atracurium and pancuronium

The new relaxants vecuronium (Norcuron) and atracurium (Tracrium) have been compared with pancuronium (Pavulon) with respect to onset and duration of action and intubating conditions under clinical situations. A variant of the balanced anaesthesia technique with flunitrazepam, fentanyl and N2O/O2 was used. The following doses were considered equipotent (mg/kg body weight): vecuronium 0.07/0.10; atracurium 0.35/0.50; pancuronium 0.08/0.115. The degree of neuromuscular block was assessed in a semiquantitative manner, using the train of four. No difference between the three relaxants in onset of action was found. After the high doses, however, full paralysis developed 60 s earlier. The same is true of intubating conditions. Good or very good intubating conditions were obtained in the majority of cases 3 minutes after injection of the drug. Following the higher dose, good intubating conditions are achieved approximatively 1/2-1 min sooner. Both new relaxants allow for relatively rapid intubation without the inconvenience of a long duration of action. After a low initial dose the following time for recovery to 25% was noted (means +/- S.D., min): vecuronium 20.3 +/- 7.0; atracurium 28.0 +/- 3.1; pancuronium 53.3 +/- 14.8. The early recovery phase (from 5% to 25% recovery) was 6.1 +/- 2.4 after vecuronium, 8.3 +/- 1.7 after atracurium, 17.2 +/- 10.8 after pancuronium. There is a good correlation between our semiquantitative results, using the train of four, and quantitative recordings of muscle contractions reported in the literature. Both drugs show no cumulative effect after five repeated administrations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapid sequence induction using vecuronium

The purpose of this study was to determine the ideal priming and total dose of vecuronium when used as the relaxant during rapid sequence induction of anesthesia and tracheal intubation. Seventy patients were studied. Various priming and total dose schedules using vecuronium were compared with succinylcholine, 1.5 mg/kg. The mean onset times, intubating conditions, and mean duration times were compared. A priming dose of 10 micrograms/kg produced good intubation conditions with both 70 micrograms/kg and 150 micrograms/kg (total doses), but the mean onset times remained significantly longer than succinylcholine 1.5 mg/kg (P less than 0.05). A priming dose of 15 micrograms/kg of vecuronium with 100 micrograms/kg total dose, on the other hand, not only produced excellent intubating conditions but also resulted in a mean onset time not significantly different from succinylcholine, 1.5 mg/kg. This latter dose schedule of vecuronium is recommended for rapid sequence induction when succinylcholine is contraindicated. Vecuronium is preferable to pancuronium for rapid sequence induction because of its lack of cardiovascular side effects and short duration.     

The effects of nimodipine on vecuronium-induced neuromuscular blockade

Nimodipine, a calcium channel blocking drug, is used in the treatment of cerebral arterial spasm after subarachnoid haemorrhage due to bleeding from an intracranial aneurysm. The purpose of this study was to evaluate the effects of nimodipine on neuromuscular blockade after vecuronium had been given to facilitate tracheal intubation and maintenance of muscle paralysis in patients undergoing clipping of intracranial aneurysm. Twenty patients were divided into two groups: a control group (n = 10) who received no calcium channel blocking drug, and a nimodipine group (n = 10) consisting of patients treated with nimodipine at clinically used doses of 0.03 mg kg(-1) h(-1) pre- and perioperatively. Anaesthesia was induced with atropine 10 microg kg(-1), dehydrobenzperidol 5 mg, fentanyl 5 microg kg(-1), thiopental 5 mg kg(-1) and maintained with a mixture of N2O and isoflurane (0.5-1% inspired concentration) in O2, and additional doses of fentanyl 2.5 microg kg(-1). Neuromuscular responses were monitored by acceleromyograpy. The first twitch of the train-of-four response (T1) was considered as twitch height. After a stabilization period, an intubating dose of vecuronium 0.1 mg kg(-1) was administered. The onset of action, the time of first appearance of T1 and clinical duration of action were recorded. Then, maintenance doses of vecuronium 0.03 mg kg(-1) were administered twice more when T1 had recovered to 25% of control twitch height. The study ended when the recordings of the 3rd 25% T1 recovery had been obtained. There were no statistical differences in the onset time (120+/-44 s in the control group, 141+/-33 s in the nimodipine group), in the first appearance time of T1 (28+/-6 min in the control group, 30+/-8 min in the nimodipine group), and in the times for 25% recovery in T1 (41+/-11, 32+/-2, 40+/-13 min in the control group, respectively, and 44+/-16, 36+/-15, 38+/-15 min in nimodipine group, respectively) between the groups studied. The time between the injection of the intubating dose of vecuronium and the third recovery of T1-25% of control was not significantly different between the control group (113+/-34 min) and the nimodipine group (117+/-42 min). This study indicates that nimodipine does not have any significant effect on the time course of action of vecuronium including the onset time and its clinical duration of action after the initial and the two maintenance doses in these patients.     

Priming with vecuronium and atracurium--a comparison

Vecuronium (V) and atracurium (A) were compared in a randomised study in premedicated patients undergoing laparoscopy for gynecological pathology. Both groups contained ten patients. Anesthesia was induced with fentanyl (0.1 mg) and thiopentone (1 mg/kg initially and subsequently 4 mg/kg). A priming dose of vecuronium (20 micrograms/kg) or atracurium (100 micrograms/kg) was given one minute before the intubating dose (60 micrograms/kg for vecuronium and 300 micrograms/kg for atracurium). Ninety seconds thereafter intubation was performed. Maintenance of anesthesia consisted of isoflurane at an inspiratory concentration of 1% in a mixture of O2/N2O (50%/50%) with small supplements of fentanyl. Neuromuscular block was monitored with the Datex Relaxograph. Results show that neither drug offers major clinical advantages over the other: there is no difference in speed of onset (V:T190sec 14.6 +/- 4.3%; A:T190sec 23.5 +/- 6.5%; Mean +/- SEM) and duration of neuromuscular block (V:T150sec 34.2 +/- 3.5 min; A:T150sec 41.3 +/- 2.8 min; Mean +/- SEM) and intubation conditions are almost identical.     

Neuromuscular blockade following high-dose vecuronium administration

To determine the onset time, duration of action and recovery time of high-dose vecuronium, 70 patients were assigned to receive either 100, 150, 200 or 300 micrograms.kg-1 of vecuronium for muscle relaxation during elective surgery. Neuromuscular blockade was continuously quantitated by recording the EMG response to stimulation of the ulnar nerve. The onset time from the time of vecuronium administration to maximum blockade decreased from 4.6 +/- 1.1 to 2.4 +/- 0.5 min when the vecuronium doses increased from 100 to 300 micrograms.kg-1. Significant differences were observed in the onset time between the 100 micrograms.kg-1 dose and the other dose groups. Endotracheal intubating conditions were excellent in all patients except 3 in the 100 micrograms.kg-1 dose group. The duration of action from the time of injection to 25% recovery increased from 32 +/- 9 to 138 +/- 48 min in a dose dependent manner. The duration of action after increment doses of 40 or 50 micrograms.kg-1 up to 25% recovery of T1 did not vary significantly within the same dose group. With an initial dose of 150 micrograms.kg-1 and subsequent increment doses of 50 micrograms.kg-1 or less, the duration of action remained constant. The recovery time from 25 to 75% recovery was within 11 minutes when antagonists were administered. High-dose vecuronium may, therefore, be a useful alternative to SCC, when a rapid onset is required and to pancuronium, when a rapid recovery from neuromuscular blockade is requested.     

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.     

Pretreatment with d-tubocurarine, vecuronium, and pancuronium attenuates succinylcholine-induced increases in plasma norepinephrine concentrations in humans.

We studied in patients the effect of d-tubocurarine, which has sympathetic ganglion blocking action, on succinylcholine-induced increases in plasma levels of catecholamines, and compared it with the effects of vecuronium and pancuronium, which have little sympathetic ganglion blocking action. Thirty-two patients were divided into five groups: seven were given 3 mL saline; seven received 1 mg/kg succinylcholine; and six, seven, and five patients were given 0.08 mg/kg d-tubocurarine, 0.01 mg/kg vecuronium, and 0.01 mg/kg pancuronium, respectively, all of which were injected 5 min before 1 mg/kg succinylcholine. Succinylcholine alone significantly increased plasma norepinephrine concentrations, systolic blood pressure, and heart rate from 187 +/- 39 pg/mL (mean +/- SEM), 93 +/- 2 mm Hg, and 77 +/- 4 beats/min to 429 +/- 61 pg/mL, 120 +/- 7 mm Hg, and 102 +/- 6 beats/min, respectively, with onset of fasciculations. Pretreatment with d-tubocurarine, vecuronium, and pancuronium significantly and equally attenuated both the fasciculations and the cardiovascular responses to succinylcholine. These results suggest that the sympathetic ganglion blocking action of neuromuscular relaxants when given before succinylcholine is not an important factor in attenuation of succinylcholine-induced increases in plasma levels of catecholamines.     

Clinical use of vecuronium (ORG NC 45) in balanced anesthesia. Comparison with pancuronium

In 2 groups of 25 patients 0.1 mg/kg vecuronium (Org NC 45) or pancuronium, according to a randomised basis, was injected during balanced anesthesia (thiopental, fentanyl, dehydrobenzperidol and N2O). Intubation conditions 120 seconds after injection were satisfactory. After intubation, a heart rate increase was present with pancuronium (p less than 0.01), but not with vecuronium (difference: p less than 0.05); heartrate decreased 15 and 30 minutes after injection of vecuronium (p less than 0.01). The clinical duration of action of vecuronium was 32.7 +/- 2.4 min (Mean +/- SEM) and of pancuronium 73.5 +/- 4.8 min (p less than 0.01). Successive maintenance doses of 0.025 mg/kg of vecuronium had a duration of action of 23.1 +/- 1.7, 26.8 +/- 2.1, 27.6 +/- 4.0 and 24.0 +/- 2.8 min (diff. NS), showing no cumulative activity. The duration of action of identical doses of pancuronium were 56.9 +/- 3.1, 52.1 +/- 7.2 and 61.3 +/- 17.6 min (diff. NS), values nearly +/- 220% above those of vecuronium (p less than 0.01). Reversion of neuromuscular blockade after vecuronium with small amounts of neostigmine was clinically adequate.     

Rapid onset of the action of vecuronium by administration of a precurarizing dose

The administration of vecuronium in divided doses with respect to onset of action and intubating conditions was investigated. This study was conducted in 3 parts. In part 1 the maximal precurarizing dose of 0.015 mg/kg vecuronium was found. In the second part we showed that the optimal time interval between divided doses was 3 min. In the third part we made a comparative investigation between the effect of 0.015 + 0.085 mg/kg body wt. at a 3 min interval and that of a single dose of 0.1 mg/kg body wt. vecuronium. --Neuromuscular function was assessed in semiquantitative manner, using the train of four (TOF) stimulation of ulnar nerve. Administration of vecuronium in divided doses, compared with a single dose of 0.1 mg/kg body wt., resulted in a more than 1 min earlier onset time of 1.5-2.5 min and facilitated early intubation. As soon as twitch tension had completely disappeared uniform by excellent intubating conditions were available in all cases. The administration of vecuronium in divided doses enabled better intubating conditions than the same single dose of vecuronium.     

Neuromuscular and cardiovascular effects of high-dose vecuronium

The effects of bolus administration of large doses of vecuronium on the onset and duration of neuromuscular blockade and histamine release were studied during fentanyl-nitrous oxide anesthesia. Forty adults were randomly assigned to receive a bolus injection of either 0.1, 0.2, 0.3, or 0.4 mg/kg of vecuronium. The evoked electromyogram of thumb adduction to train-of-four stimulation was monitored. The time of onset and clinical duration (mean +/- SEM) after each dose were as follows: 0.1 mg/kg, 164 +/- 27 s and 42 +/- 5 min; 0.2 mg/kg, 120 +/- 17 s and 68 +/- 8 min; 0.3 mg/kg, 88 +/- 17 s and 111 +/- 19 min; 0.4 mg/kg, 78 +/- 19 s and 115 +/- 19 min. Both time of onset and duration after doses of 0.3 or 0.4 mg/kg were significantly different from values after the lower doses. No dose-related changes in blood pressure, heart rate, or histamine release were observed. The authors conclude that large bolus doses of vecuronium can be safely used to speed the onset of blockade, but with a significantly prolonged duration of action.     

Cisatracurium versus vecuronium: a comparative, double blind, randomized, multicenter study in adult patients under propofol/fentanyl/N2O anesthesia

AIM: The aim of this study was to compare the time course characteristics of cisatracurium (C) and vecuronium (V) induced neuromuscular block (NMB) following multiple doses, allowing spontaneous complete recovery (SCRT) and evaluating the influence of age. METHODS: Following institutional approval and signed informed consent, 177 adult ASA 1-2 patients were included in a randomized, double-blind, multicenter study under N20/02/fentanyl/propofol anesthesia. Muscle relaxation was induced with 0.15 mg/kg C or 0.l mg/kg V and was maintained with 0.03 mg/kg of C or 0.02 mg/kg of V injected at T1 25% recovery. Intubating conditions were assessed at 2 min after the initial dose. Time course of NMB was monitored using accelerography (Tofguard) of the adductor pollicis with train-of-four (TOF). Data were analyzed with parametric (Anova) and non parametric statistics (c2, Kruskal Wallis). RESULTS: Both drugs offered good/excellent intubating conditions: duration of action of NMB (mean values +/- SD, minutes) were: dur25 first dose: V 38.20+/-13.2 vs C 51.5+/-11.3 (P<0.02 ); dur25 following repeated boluses (average): V 23.2+/- 8.6 vs C 28.2+/-9.5, ns; dur25 last dose: V 25.1+/-11.5 vs C 31.5+/-11.4, ns: SCRT following last dose: V 50.2+/-23.2 vs C 46.4+/-17.5, ns: t125% to t4/T1 0.80:V 27.1+/-18.7 vs C 18.8+/-10.2, ns. Stratifying for age >or< 65 no differences were noted in the intervals studied following C, while all were longer following V. The duration of block of C was longer than V; the SCRT after the final dose of C was shorter than V albeit not significant. There was a clinically significant increase in duration of block and recovery time in elderly patients for V but not for C. CONCLUSIONS: C and V allow predictable NMB duration and spontaneous recovery even if administered in multiple repeated doses; but in elderly patients duration of block and recovery time is longer following V.     

Cumulation and reversal with prolonged infusions of atracurium and vecuronium

A randomized, double-blind study was undertaken to compare the tendencies for cumulation, and reversal characteristics of atracurium (ATR) and vecuronium (VEC) when administered by continuous infusion for long surgical procedures under balanced anaesthesia. Eligible subjects were between 50 and 75 yr of age and were free of neuromuscular disease. Patients in the ATR group (n = 25) received a loading dose of atracurium 0.25 mg.kg-1, followed by an infusion initially set at 5.0 micrograms.kg-1.min-1. In the VEC group (n = 25) patients received a loading dose of vecuronium 0.05 mg.kg-1, followed by an infusion at 1.0 microgram.kg-1.min-1. During surgery, the infusions of both ATR and VEC were titrated in increments or decrements of 12.5% to maintain first twitch (T1) suppression of 90-95%. Neuromuscular block was measured by recording the integrated evoked electromyographic response (EMG) of the first dorsal interosseous muscle in response to supramaximal TOF stimuli on the ulnar nerve. The durations of infusion were similar for the two groups (164 +/- 42 and 183 +/- 67 min for ATR and VEC, respectively). The infusion rates of ATR (mean +/- SD) remained between 4.0 +/- 0.7 and 5.0 +/- 1.0 microgram.kg-1.min-1 throughout the study period. In contrast, a progressive decrease (P less than 0.05) in the infusion rate of VEC, from 1.0 to 0.47 +/- 0.13 micrograms.kg-1.min-1, was observed during the study period. The number of adjustments required to maintain 90-95% T1 suppression decreased between the second and fourth hours of administration, but were similar at corresponding times when comparing the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evolution of vecuronium requirements for stable mechanical effect: comparison with or without previous succinylcholine administration

To evaluate possible interactions between residual succinylcholine and vecuronium, the amount of vecuronium required to maintain the twitch height (TH) at 10% of its initial value was measured over a 90-min period by the on-demand infusion method in two series of 15 adult patients (ASA class I-II). One group, the vecuronium treatment (V) group, received 70 micrograms X kg-1 of vecuronium and the on-demand infusion. The second group, the succinylcholine-vecuronium treatment group (SV), was given 30 micrograms X kg-1 of vecuronium and on-demand infusion 5 min after the complete recovery of TH after administration of 1 mg X kg-1 of succinylcholine. During the first 10 min, the amount of vecuronium required to maintain TH at 10% of its control was significantly greater in the group given V than in the group given SV, 15122 +/- 856 (mean +/- SEM) vs 9851 +/- 486 micrograms X m-2 X hr-1 (P less than 0.001). Thereafter, the amount of vecuronium required to maintain TH at 10% of control was similar: 2808 +/- 275 and 3068 +/- 206 micrograms X m-2 X hr-1. When the infusion of vecuronium was stopped after 90 min, the time required for spontaneous recovery from 25 to 75% of control TH levels was similar: 20.1 +/- 3.3 min in the group given V and 18.9 +/- 2.5 min in the group given SV (not significant). We conclude that after a vecuronium on-demand infusion of long duration (lasting more than 90 min), previous succinylcholine administration does not interfere with late vecuronium requirements and the spontaneous rate of recovery of TH.     

Evaluation of the degree of muscle blockade: a comparative study using electromyography of the muscular relaxation induced by pancuronium, atracurium and vecuronium

To compare the muscle relaxing effect of pancuronium, atracurium and vecuronium, 99 patients operated on under neuroleptanesthesia were divided in three groups depending on whether they had received, during induction, pancuronium 0.1 mg/kg, atracurium 0.5 mg/kg, or vecuronium 0.1 mg/kg. One-fourth of the initial dose was repeated if necessary. The electromyographic study of the muscle relaxing effect was carried out with stimulation of the cubital nerve with courses of supramaximal square wave electric stimuli in 'trains of four'. The time to maximal blockade (TMB), the time of clinical effectiveness (TCE), the total duration time (TDT), the time of duration of the maintenance dose (DM 25) and the recovery index (RI) were measured. TMB was 4.3 +/- 1 min for pancuronium, 3.5 +/- 0.8 min for atracurium, and 3.3 +/- 0.98 min for vecuronium. The differences between pancuronium and the other drugs were statistically significant, but they were not so between the latter two. TCE was 67.9 +/- 13.5 min for pancuronium, significantly longer than with vecuronium and atracurium (28.2 +/- 5.7 and 31.5 +/- 4.7, respectively). TDT was 126.2 +/- 19.9 min for pancuronium, 61.2 +/- 11.5 min for atracurium and 55.5 +/- 16.7 for vecuronium. The mean duration of the repeated dose was 52.7 +/- 8.4 min for pancuronium, 19.9 +/- 5 min for vecuronium and 10.9 +/- 5 min for atracurium. RI, which was similar for atracurium and vecuronium (12.7 +/- 1.7 min and 12.8 +/- 3.3 min), was longer for pancuronium (27.7 +/- 4.3 min).     

Rapid induction sequence with vecuronium: should we intubate after 60 or 90 seconds?

The purpose of the study was to determine intubating conditions after administration of either succinylcholine or vecuronium in a rapid induction sequence. Patients received either succinylcholine 1.5 mg.kg-1 (Groups I and II) after d-tubocurarine 0.05 mg.kg-1 four minutes earlier, or vecuronium (Groups III and IV) in an initial dose of 0.01 mg.kg-1 followed four minutes later by 0.1 mg.kg-1. In Groups I and III an apnoeic delay of one minute was allowed before intubation whereas in Groups II and IV the delay was 90 sec. There was no significant difference in intubating conditions between Groups I and IV. Intubating conditions in Group III (vecuronium-delay of one minute) were statistically worse than in any of the three other groups. A delay of 90 sec after succinylcholine improved intubating conditions in male patients. Considering that intubating conditions obtained after 90 sec in patients given a priming sequence with vecuronium (Group IV) were not different from those obtained 60 sec after succinylcholine (Group I), the authors conclude that vecuronium is an acceptable alternative for rapid tracheal intubation. In the doses used in this study, intubating conditions 60 sec after vecuronium were unacceptable for rapid induction of anaesthesia.     

Accelerated onset of non-depolarizing neuromuscular blocking drugs: pancuronium, atracurium and vecuronium. A comparison with succinylcholine

The time of onset and degree of neuromuscular blockade (NMB) in 80 anaesthetized patients, following either a single bolus injection of pancuronium 0.95 mg kg-1, atracurium 0.53 mg kg-1 or vecuronium 0.07 mg kg-1, or divided doses of pancuronium 0.15 mg kg-1, atracurium 0.07 mg kg-1 or vecuronium 0.01 mg kg-1 administered 3 min or 5 min before the second dose of pancuronium 0.08 mg kg-1, atracurium 0.46 mg kg-1 or vecuronium 0.06 mg kg-1, were determined and compared to the same parameters measured following succinylcholine administration (1 mg kg-1). The time to maximum NMB (100%) following the administration of succinylcholine was 58.1 +/- 5.3 s, whereas the time to maximum NMB (100%) following a single bolus injection of either pancuronium, atracurium or vecuronium was 130.6 +/- 22.2, 93.0 +/- 6.4, 127.5 +/- 13.0 s, respectively. These values for time to maximum NMB are significantly longer than the time required for succinylcholine to achieve maximal blockade. The time to attain maximum NMB following divided doses of pancuronium, atracurium or vecuronium separated by 3 min decreased significantly to 77.9 +/- 4.3, 77.5 +/- 7.6, 89.0 +/- 8.6 s, respectively. However, when the two doses of drug were separated by 5 min, only small, non-significant further decreases occurred in the time required to achieve maximum blockade. Although the time to maximum NMB following divided doses of pancuronium, atracurium or vecuronium is significantly longer than that for succinylcholine, divided dosing significantly decreases the time required to reach maximal NMB.     

Response to vecuronium in a patient with facioscapulohumeral muscular dystrophy

Increased sensitivity to vecuronium has been noted in patients with Duchenne muscular dystrophy. We report the response to vecuronium in a patient with facioscapulohumeral muscular dystrophy (FSHD), an autosomal dominant disorder with an incidence of 10-20 cases per million. In this patient, sensitivity to an initial dose of vecuronium (0.02 + 0.08 mg kg-1) was normal, but recovery was faster and the effect of incremental doses of vecuronium (0.02 mg kg-1) was less than expected. Onset time and 25% recovery of T1/T0 after the intubating dose of vecuronium were 240 s and 22 min, respectively. Recovery index (spontaneous recovery of T1/T0 from 25% to 75%) was 9 min.