Anaesthesia
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Having used the Boyle's bottle vaporizer apparatus out of necessity in a developing country, the concentration of agent that had been administered was investigated retrospectively. Three anaesthetic agents, halothane, isoflurane and enflurane, were measured at different temperatures, using a Boyle's anaesthetic machine and a Boyle's bottle in circuit with a Magill breathing system connected to a Rascal II Agent Monitor. Bubbling a fresh gas flow of 5 l.min-1 through the anaesthetic liquids generated concentrations in excess of 12%. ⋯ The Boyle's bottle vaporizer may be used with modern anaesthetic agents such as halothane, isoflurane and enflurane. However, the limitations of and variations between vaporizers should be borne in mind. An agent monitor employed at the patient end of the circuit would be an important safety feature.
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Randomized Controlled Trial Clinical Trial
Effect of transcutaneous electrical nerve stimulation on onset of axillary plexus block.
We examined the effect of high frequency transcutaneous electrical nerve stimulation on the onset of brachial plexus block. Three groups of patients scheduled for surgery of the hand had a local anaesthetic block performed with 40 ml mepivacaine 1.5% using the axillary approach. ⋯ There were no differences in the onset of block between the groups. Thus, the frequency-dependent action of local anaesthetics could not be demonstrated.
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Comparative Study Clinical Trial Controlled Clinical Trial
The effect of introducing fibreoptic bronchoscopes on gas flow in laryngeal masks and tracheal tubes.
The laryngeal mask airway, reinforced laryngeal mask airway and tracheal tube were studied to determine (1) flow resistance during simulated inspiration and (2) the maximum size of fibreoptic scope which can be passed down the lumen at clinically useful ventilatory settings. In addition, the flow resistance imposed by the mask aperature bars was quantified. ⋯ Removal of the mask aperture bars resulted in a mean decrease in flow resistance of 3.6%. Our data have shown that the laryngeal mask airway can accommodate a larger fibrescope than either the reinforced laryngeal mask airway or tracheal tube at clinically useful ventilatory settings and that the current recommendations for maximum size of fibrescope should be revised.
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Randomized Controlled Trial Comparative Study Clinical Trial
Neuromuscular and cardiovascular advantages of combinations of mivacurium and rocuronium over either drug alone.
We investigated isobolic mixtures of mivacurium and rocuronium to determine if the combination offered any advantages over either drug alone. We used five dose regimens to achieve ED95 x 2: [(1.5 x ED95 mivacurium) + (0.5 x ED95 rocuronium); (1 x ED95 mivacurium) + (1 x ED95 rocuronium); (0.5 x ED95 mivacurium) + (1.5 x ED95 rocuronium); (2 x ED95 mivacurium); (2 x ED95 rocuronium)]. We studied onset time, duration of block, recovery of block, arterial blood pressure and heart rate. ⋯ Onset time was shortest in the rocuronium alone group and was significantly faster in all the rocuronium treated groups compared to mivacurium alone (p < 0.001). Arterial blood pressure and heart rate decreased transiently in the mivacurium alone group but not in the other groups. These results demonstrate increased cardiovascular stability and more rapid onset of block with combinations of mivacurium and rocuronium without significant prolongation of the block.