It has been estimated that more than 60% of all paediatric surgery is performed on a day case basis. The benefits of this type of surgery in children include reduced costs, avoidance of the stress of hospitalization and less disruption to family life. The growth of day surgery in children has been facilitated by the development of non-depolarizing neuromuscular blocking agents characterized by short and intermediate duration of action and fewer side-effects. The more rapid onset and shorter duration of action of non-depolarizing neuromuscular blocking agents in children should facilitate the use of these agents in place of succinylcholine for day case procedures.

Mitochondrial myopathies are rare complex multisystem disorders, which can present several potential anaesthetic problems. A 49-year-old man with mitochondrial myopathy was anaesthetized successfully for cataract extraction using propofol and alfentanil infusions. Vecuronium sensitivity was apparent, with a prolonged duration of action, despite dosage reduction

The aim of this study was to elucidate the influence of four neuromuscular blocking substances on coronary vascular tone using the model of isolated porcine coronary artery segments. We studied the effects of four muscle relaxants, atracurium, pancuronium, rocuronium, and vecuronium (0.1, 1, and 10 μg mL−1 each), on the contractile response to three vasoconstrictors: acetylcholine, histamine, and serotonin. None of the neuromuscular blocking agents under investigation exerted a significant influence on the vasoconstricting effects of these mediators except for pancuronium, which dose-dependently attenuated acetylcholine-mediated contractions (−10.8% attenuation for 10 μg mL−1 pancuronium, P < 0.05). There was no difference between vessels with intact endothelium and denuded preparations. It is concluded that high-dose pancuronium exerts an antimuscarinic effect in vascular smooth muscle. The other neuromuscular agents studied do not alter vascular reactivity of isolated porcine coronary arteries.

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 μg kg−1, dehydrobenzperidol 5 mg, fentanyl 5 μg 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 μg 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 T−1 and clinical duration of action were recorded. Then, maintenance doses of vecuronium 0.03 mg kg−1were 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.

Masseter muscle rigidity after suxamethonium, usually occurring in children induced with halothane,is associated with malignant hyperthermia. A case is reported in which masseter muscle rigidity occurred in an adult following vecuronium. From the limited data available, this and two similar reported cases, it appears that non-depolarizing muscle relaxants can, very rarely, cause masseter muscle rigidity in adults. This masseter muscle rigidity may complicate airway management, but is unlikely to progress to generalized rigidity and malignant hyperthermia.

Recovery of neuromuscular blockade after vecuronium 0.2 mg kg−1 was measured by post-tetanic burst count (PTBC) and train-of-four (TOF) in 120 adult patients anaesthetized by one of four techniques: neuroleptanaesthesia or one minimum alveolar concentration of isoflurane, enflurane, or sevoflurane. Onset of recovery was taken when there was reflex movement in response to carinal stimulation. The time course of recovery measured by burst count was similar for all four types of anaesthesia. Recovery of each of the twitches of the TOF was significantly shorter under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia [times to return of T1 were 41.4±5.4, 51.5±10.6, 52.2±10.0, or 55.3±11.2 min (mean±SD). P<0.05]. The burst count at the onset of reflex movement was less under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia (16.3±4.8, 26.7±6.7, 27.7±6.8, 28.0±8.4, P<0.05). The ratio of first twitch to control twitch at the onset of reflex movement was the same for all four types of anaesthesia.

This study was undertaken to investigate the neuromuscular blocking profile and cardiovascular effects of Org 9487, a new aminosteroidal, non-depolarizing, neuromuscular blocking agent structurally related to vecuronium, in anaesthetized animals and in isolated muscle preparations. In in vitro functional assays of neuromuscular blocking activity, Org 9487 was between eight and 15 times less potent than vecuronium. In cats and monkeys the potency of Org 9487 was approximately one-seventh and one-twentieth, respectively, that of vecuronium. In both species, Org 9487 induced rapidly developing (onset times between 1.5 min and 1.9 min) neuromuscular paralysis, which was shorter-lasting than that of vecuronium and similar in time course to suxamethonium. The vagal: neuromuscular blocking dose ratio for Org 9487 was 3 and ganglion block was seen only at approximately 20 times the neuromuscular blocking dose. There was no evidence in the rat that Org 9487, administered at doses up to 3mg kg−1, inhibited noradrenaline re uptake. In anaesthetized dogs, Org 9487 (3 × 90% blocking dose) induced only relatively small and transient haemodynamic effects. The administration of clinically relevant doses of neostigmine or pyridostigmine shortened the time–course profile of Org 9487, even when administered during profound neuromuscular block. In animals, Org 9487 is a low potency, nondepolarizing neuromuscular blocking agent with a time course profile similar to that of suxamethonium. Although Org 9487 is less selective than vecuronium for the neuromuscular junction, it is unlikely to produce prohibitive cardiovascular side effects in man.

Rocuronium administration may cause tachycardia and an increase in cardiac index. Pancuronium, another steroidal non-depolarizing muscle relaxant, augments release of, and blocks re-uptake of catecholamines at adrenergic nerve endings. This study compared the haemodynamic effects of, and changes in catecholamine concentrations following administration of vecuronium (0.12 mg kg−1) or rocuronium (0.9 mg kg−1) to elderly patients. Thirty patients, 65 years or older, not receiving β-blockers, were studied. During thiopentone, fentanyl, nitrous oxide anaesthesia, either rocuronium (0.9 mg kg−1) or vecuronium (0.12 mg kg−1) was administered, according to random allocation. In all 30 patients, blood pressure and heart rate were measured before induction of anaesthesia, immediately and 1 min after induction, 1 and 2 min after muscle relaxant administration, and immediately, 1 and 2 min after tracheal intubation. In the latter 20 patients, samples for plasma catecholamine estimation were obtained prior to, and 1 min after muscle relaxant administration and 1 min after tracheal intubation. Blood pressure and heart rate were similar in the two groups throughout the study. Plasma noradrenaline concentrations were similar in the vecuronium and rocuronium groups prior to muscle relaxant administration (589(SD240) and 444(SD213) pg mL−1, respectively), 1 min after muscle relaxant administration (602(SD220) and 520(SD392) pg mL−1, respectively) and 1 min after tracheal intubation (597(SD351) and 440(SD181) pg mL, respectively). There was no significant change in either plasma noradrenaline or adrenaline concentrations in either group following muscle relaxant administration or tracheal intubation. The use of rocuronium (0.9 mg kg−1) in elderly patients does not result in a clinically significant change in heart rate, blood pressure or plasma catecholamine concentration.

Anaesthetic agents for day-case surgery ideally should have a short duration of action. This study was designed to compare the efficacy and safety of mivacurium and vecuronium for healthy adults undergoing dental day-case surgery. Thirty fit healthy adult patients (ASA I or II) randomly received either mivacurium 0.15 mg kg−1 (n = 15) or vecuronium 0.1 mg kg−1 (n = 15). Anaesthesia included propofol, fentanyl, nitrous oxide and isoflurane. Maximum depression of T1 was greater in the vecuronium group (99.8%) than in the mivacurium group (98.3%). There was no difference between grade of intubation at 2 min between the two groups, although patients receiving vecuronium had a more profound block at the time of intubation than those who received mivacurium (89.2% vs. 78.9%). Recovery to 10% T1 was faster in the mivacurium group (11.2 min vs. 33.1 min). All patients in the vecuronium group received neostigmine at the termination of surgery. The neostigmine evoked recovery index in the vecuronium group (4.39 min) was less than the spontaneous recovery index in the mivacurium group (6.78 min). One patient in the mivacurium group had a low plasma cholinesterase concentration (0.43 ku L−1); recovery times however, fell within the 95% confidence intervals (CI) for the group. There was no correlation between cholinesterase levels and recovery time. Mivacurium may be the more appropriate agent for dental day-case surgery because it has a shorter duration of action and does not generally require antagonism with an anticholinesterase.

The sensitivity of train-of-four (TOF) or double burst stimulation3,3 (BBS3,3) was examined to detect fade by visual inspection, at varying stimulating currents, using the thumb of the investigated arm maintained abducted by the use of a rubber band. One-hundred adult patients were allocated randomly to (1) train-of-four-rubber band (TOF-RB), (2) train-of-four-control (TOF-control), (3) double burst stimulation-rubber band (DBS-RB), or (4) double burst stimulation-control (DBS-control) group. Each group contained 25 patients. The thumb of the investigated arm was kept abducted using a rubber band in the TOF-RB band and DBS-RB group and was free in the TOF-control and DBS-control. TOF stimuli were delivered in the TOF-RB and TOF-control groups, and DBS3,3 in the TOF-RB and TOF-control at 50, 30 and 20 mA. The probability of visual detection of TOF fade was the same in the TOF-RB and TOF-control groups. In contrast, when measured TOF ratio was 0.51–0.80, at the stimulating current of 50 or 30 mA, the likelihood of visual detection of fade in the DBS-RB group was significantly higher than in the DBS-control group (P < 0.05). With a TOF ratio of 0.61–0.70, in the DBS-RB group the probability of visual detection of fade at 50 or 30 mA was significantly higher than at 20mA (P < 0.05). This study suggests that when using a rubber band, fade in response to the DBS3,3 is detected by visual inspection more readily at a stimulating current of 50 or 30mA than without the rubber band.

The most suitable time for tracheal intubation, following vecuronium 0.1 mg kg−1, was estimated in 120 patients. The trachea was intubated at cessation of the visually observed response of the orbicularis oculi muscle to facial nerve stimulation (group 1; n = 30), or of the manually detected response of the adductor pollicis to ulnar nerve stimulation (group 2; n = 30), or after waiting 3 min (group 3; n = 30), or 4 min (group 4; n = 30). There were no significant differences in intubation scores between the four groups of patients. Loss of response to train-of-four stimulation occurred significantly sooner in group 1 (orbicularis oculi) than in group 2 (adductor pollicis) P = 0.021). However, intubating conditions were poor in four patients (14%) in group 1, compared with none in group 2 and one in groups 3 and 4, respectively. Thus, contrary to expectations, the cessation of the response of the orbicularis oculi muscle did not guarantee good or even satisfactory intubating conditions. The results suggest that in fit adult patients it is as good to wait 3 min after injection of vecuronium 0.1 mg kg−1 before tracheal intubation, as to use a nerve stimulator.