British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Effect of posture during the induction of subarachnoid analgesia for caesarean section. Right v. left lateral.
Thirty-five women scheduled for elective Caesarean section were randomly assigned to have subarachnoid analgesia induced in either the right or left lateral position. They were then turned supine with a wedge under the right hip. No patient in the right-sided group required further analgesia. Five patients in the left-sided group required postural manipulation to encourage the spread of analgesia and two required supplementary analgesia (P less than 0.01).
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Comparative Study
Differential nerve blockade: esters v. amides and the influence of pKa.
The in vitro sensitivities to local anaesthetic blockade of A, B and C fibres in rabbit vagus nerves were examined using a series of structurally similar amide agents, which varied in lipid solubility and anaesthetic potency. The actions of these drugs were compared with one another, and with those of a series of amino-ester local anaesthetics studied previously. The results demonstrated that A fibres are the most, and C fibres the least, sensitive to blockade by local anaesthetic agents. ⋯ As the latter increased, so did the rate of A fibre blockade. Combining the results of the two studies suggests that an agent of low lipid solubility and high pKa might be used to produce differential C fibre blockade. Comparison of the results obtained with the two different classes of drug indicates that the ester structure may have an inherently more potent action than the amide.
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We have examined the effects of isoflurane (0.6-2.9% end-tidal) on the auditory evoked response (AER) in six patients before elective surgery. Isoflurane produced significant dose-related changes in the AER: reductions in amplitude and increases in latency of the cortical waves Pa and Nb, and increases in the latency of the brainstem waves III and V. When isoflurane was compared with halothane and enflurane using an MAC-based comparison, we found no differences in the effect of the three agents on the amplitude of the early cortical waves, although the latencies showed significant differences. The consistent dose-related effect on the amplitudes of the cortical waves implies that the AER could be a promising index of the depth of anaesthesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Continuous intercostal blockade after cardiac surgery.
The provision of analgesia using continuous bilateral intercostal blockade was compared with that provided by conventional i.v. narcotics for the first 48 h after cardiac surgery. The subjective quality of analgesia was significantly superior with the regional technique. However, pulmonary function tests, gas exchange, lung volume, and radiological and clinical evidence of pulmonary complications were not improved. The failure to reduce morbidity and the potential for complications such as pneumothorax, makes it difficult to recommend the regional analgesia technique in this situation.
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Alcuronium 0.2 mg kg-1 was given to six patients to investigate the simultaneous recovery of breathing and peripheral neuromuscular function. Anaesthesia was maintained with 66% nitrous oxide in oxygen supplemented with 0.5% halothane, and the patients were ventilated to normocarbia. Patients were disconnected from the ventilator after the reappearance of the tetanic response. ⋯ Spontaneous breathing returned at a mean time of 23.6 min after the injection of alcuronium. Sixty minutes after the administration of alcuronium, respiratory exchange was judged adequate, and at that time neuromuscular function was still markedly depressed with a tetanic height less than 25% of control. It was concluded that, because of the slow recovery of neuromuscular function, alcuronium should be reserved for the longer surgical procedure.