British journal of anaesthesia
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The pharmacodynamics and pharmacokinetics of the two most recent aminosteroid neuromuscular blocking drugs to become available, rapacuronium bromide (Org 9487) and rocuronium bromide are reviewed. Two new classes of drug with neuromuscular blocking properties, the bis-tetrahydroisoquinolinium chlorofumarates and the tropinyl diester derivatives are introduced. Comparisons between these drugs and mivacurium and cisatracurium are made. ⋯ Ninety per cent recovery of the first twitch of the train-of-four occurs after 5-7 min using one ED80. A recovery index of less than 2 min has been reported in rats. All the tropinyl diesters appear to produce vagal block.
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Multicenter Study Clinical Trial
Transtracheal high frequency jet ventilation for endoscopic airway surgery: a multicentre study.
Serious complications during high frequency jet ventilation (HFJV) are rare and have been documented in animals and in case reports or short series of patients with a difficult airway. We report complications of transtracheal HFFJV in a prospective multicentre study of 643 patients having laryngoscopy or laryngeal laser surgery. A transtracheal catheter could not be inserted in two patients (0.3%). ⋯ Arterial desaturation of oxygen was more frequent during laser surgery and in overweight patients. Transtracheal ventilation from a ventilator with an automatic cut-off device is a reliable method for experienced users. Control of airway pressure does not prevent a low frequency of pneumothorax.
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A case of epidural analgesia in a parturient with neurofibromatosis (von Recklinghausen's disease) complicated by dural puncture and epidural haematoma is described and the management of the case is discussed. The case emphasizes the need for antenatal assessment of parturients with neurofibromatosis in order that the necessary investigations can be arranged and informed consent for analgesia and anaesthesia can be obtained.
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Comparative Study
Preoxygenation: a comparison of three different breathing systems.
An end-tidal expiratory oxygen concentration (FE'O2) greater than 0.90 is considered to be adequate for preoxygenation. This is generally achieved using a face mask, but this can be unsatisfactory in some patients. We compared preoxygenation in 30 healthy volunteers using a face mask, the NasOral system, which is a novel preoxygenation device, and a mouthpiece with a nose-clip. ⋯ The volunteers gave more positive ratings to the face mask and mouthpiece than to the modified NasOral system (P<0.001 and P<0.01). We conclude that the use of a mouthpiece can improve preoxygenation in some patients. The results obtained with the modified NasOral system do not justify its introduction into clinical practice.
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Patients with myasthenia gravis show sensitivity to non-depolarizing neuromuscular blocking drugs, but little is known about differences in this sensitivity between types of myasthenia. In 10 patients with ocular myasthenia gravis and 10 with generalized myasthenia gravis, twitch tension was monitored in the adductor pollicis muscle by supramaximal train-of-four stimulation of the ulnar nerve during anaesthesia with sevoflurane 2.5% and nitrous oxide 60%. After baseline measurement, an initial dose of vecuronium 10 microg kg(-1) was given. ⋯ Onset of block after the first dose of vecuronium was significantly slower in ocular than in generalized myasthenic patients (mean 300 vs 200 s; P<0.05). Doses required to attain a block of 90% or more were significantly higher in ocular than in generalized patients (median 20 vs 10 microg kg(-1); P<0.05). Clinicians should consider the type of disease according to the Osserman classification when using non-depolarizing neuromuscular. blocking drugs in patients with myasthenia gravis.