British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Haemodynamic effects of vecuronium, pancuronium and atracurium in patients with coronary artery disease.
Thirty patients with ischaemic heart disease scheduled for coronary artery bypass grafting were randomly allocated to three equal groups. Following morphine, hyoscine and pentobarbitone premedication, anaesthesia was induced with diazepam 0.3 mg kg-1. Five minutes later neuromuscular blockade was induced with pancuronium 0.1 mg kg-1, vecuronium 0.1 mg-1 or atracurium 0.5 mg kg-1, followed after 6 min by fentanyl 25 micrograms kg-1. ⋯ Systemic vascular resistance decreased significantly from 1515 dyn s cm-5 to 1200 dyn s cm-5 following atracurium. Cardiac index was increased transiently in the atracurium group, but a more sustained increase was observed following pancuronium. Nine patients in the atracurium group showed skin flushing and one developed skin weals.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of gravity on the spread of extradural anaesthesia for caesarean section.
The effect of gravity on the spread of extradural anaesthesia was evaluated in a series of parturients undergoing elective Caesarean section. Following placement of an extradural catheter, 25 patients were placed 30-40 degrees head-up for 20 min during the administration of the local anaesthetic drug; 25 additional patients remained supine during injection. ⋯ There were no differences in the rate of onset of sacral blockade or in the extent of neural blockade between the two groups. The semi-upright position was not necessary to ensure adequate sacral anaesthesia for Caesarean section.
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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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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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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.