A systematic review and meta-regression analysis of mivacurium for tracheal intubation.

We systematically reviewed factors associated with intubation conditions in randomised controlled trials of mivacurium, using random-effects meta-regression analysis. We included 29 studies of 1050 healthy participants. Four factors explained 72.9% of the variation in the probability of excellent intubation conditions: mivacurium dose, 24.4%; opioid use, 29.9%; time to intubation and age together, 18.6%. The odds ratio (95% CI) for excellent intubation was 3.14 (1.65-5.73) for doubling the mivacurium dose, 5.99 (2.14-15.18) for adding opioids to the intubation sequence, and 6.55 (6.01-7.74) for increasing the delay between mivacurium injection and airway insertion from 1 to 2 min in subjects aged 25 years and 2.17 (2.01-2.69) for subjects aged 70 years, p < 0.001 for all. We conclude that good conditions for tracheal intubation are more likely by delaying laryngoscopy after injecting a higher dose of mivacurium with an opioid, particularly in older people.

Comparison of mechanomyography and acceleromyography for the assessment of rocuronium induced neuromuscular block in myotonic dystrophy type 1.

We measured acceleromyography and mechanomyography simultaneously with monitoring of rocuronium-induced neuromuscular block in four patients with myotonic dystrophy type 1. Furthermore, we compared neuromuscular block measures from these patients with those from normal controls from previous studies. In myotonic dystrophy type 1 patients, the dose-response curve obtained with acceleromyography was steeper and right-shifted compared with that obtained using mechanomyography. However, the effective doses to produce 95% neuromuscular block determined with both acceleromyography and mechanomyography were similar to each other and to values found in normal patients. In the three myotonic dystrophy type 1 patients with mild to moderate disease, times to recovery from block were similar to those observed in normal controls. In both patients and normal controls, neuromuscular block recovered faster with acceleromyography. However, in one patient with severe muscle wasting, recovery of neuromuscular block was prolonged. We conclude that mechanomyography and acceleromyography cannot be used interchangeably to monitor neuromuscular block in myotonic dystrophy type 1 patients.

Effect of isoflurane and sevoflurane on the magnitude and time course of neuromuscular block produced by vecuronium, pancuronium and atracurium.

We have compared the ability of equipotent concentrations of isoflurane and sevoflurane to enhance the effect of non-depolarizing neuromuscular blocking drugs. Ninety ASA I and II patients of both sexes, aged 18-50 yr, were stratified into three blocker groups (Vec, Pan and Atr), to undergo neuromuscular block with vecuronium (n = 30), pancuronium (n = 30) or atracurium (n = 30), respectively. Within each group, patients were allocated randomly to one of three anaesthetic subgroups to undergo maintenance of anaesthesia with: (1) alfentanil-nitrous oxide-oxygen (n = 10); (2) alfentanil-nitrous oxide-oxygen-isoflurane (n = 10); or (3) alfentanil-nitrous oxide-oxygen-sevoflurane (n = 10) anaesthesia. During maintenance of anaesthesia, end-tidal concentrations of isoflurane, sevoflurane and nitrous oxide were 0.95, 1.70 and 70%, respectively. Both the evoked integrated electromyogram and mechanomyogram of the adductor pollicis brevis muscle were measured simultaneously. In the Vec and Pan groups, a total dose of 40 micrograms kg-1 of vecuronium or pancuronium, respectively, was given, and in the Atr group a total dose of atracurium 100 micrograms kg-1. Each blocker was given in four equal doses and administered cumulatively. We showed that 0.95% isoflurane and 1.70% sevoflurane (corresponding to 0.8 MAC of each inhalation anaesthetic, omitting the MAC contribution of nitrous oxide) augmented and prolonged the neuromuscular block produced by vecuronium, pancuronium and atracurium to a similar degree.

Response to suxamethonium during propofol-fentanyl-N2O/O2 anaesthesia in a patient with active myasthenia gravis receiving long-term anticholinesterase therapy.

We describe the effect of repeated suxamethonium doses during propofol-fentanyl-N2O/O2 anaesthesia in a 29-year-old woman with active myasthenia gravis receiving chronic pyridostigmine therapy. Despite adequate pre-operative pseudocholinesterase activity, suxamethonium resistance occurred. Neither bradycardia nor residual neuromuscular block were seen after repeated doses of suxamethonium.

Factors affecting magnitude and time course of neuromuscular block produced by suxamethonium.

This study was designed to identify factors that significantly alter the magnitude and duration of suxamethonium-induced neuromuscular block in patients with an apparently normal genotype for pseudocholinesterase. One hundred and fifty-six adults (ages 18-65 yr) were allocated to 13 subgroups. Patients in each subgroup received suxamethonium 50-2000 micrograms kg-1. The mechanographic response of the adductor pollicis brevis muscle to ulnar nerve stimulation was recorded. The ED50 was found to be 167 micrograms kg-1, ED90 was 316 micrograms kg-1 and ED95 was 392 micrograms kg-1. The duration of action (delta t) was in agreement with earlier published results. The magnitude of block was dose-related and decreased with increasing onset time (ton) and pseudocholinesterase activity (PChA). Neither age nor gender affected the degree of suxamethonium-induced block. Delta t was dose-related, decreased with increasing PChA, and was shorter for women. Age and ton had no effect on delta t.

Rapid determination of succinylcholine in human plasma by high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method with fluorometric detection has been developed for the determination of succinylcholine in human plasma. Succinylcholine shows fluorescence at 282 nm with an excitation at 257 nm. The assay is sensitive, reproducible and linear for concentrations ranging from 100 ng/ml to 100 micrograms/ml of succinylcholine. In a pilot study the plasma concentration-time curve showed a triphasic elimination, with half-lives of 0.4, 1.2 and 8 min, respectively. In a clinical setting, drugs commonly administered during anaesthesia did not interfere with the assay. This method provides a simple and time-saving alternative to existing methods.