British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Intradermal study of a new local anaesthetic agent aptocaine.
In a double-blind trial in 28 human volunteers, a new local anaesthetic agent, aptocaine, was compared intradermally at 1, 2 and 3% concentrations with lignocaine 2% and bupivacaine 0.5%. In a second trial in 27 subjects, 1% aptocaine was compared with mepivacaine and prilocaine, both 1, 2 and 3%. In terms of activity as determined by area of anaesthesia, and of duration of action, aptocaine was similar to mepivacaine and more active and long-lasting than lignocaine and prilocaine. ⋯ Duration of action was unaffected by concentration. Aptocaine had marked vasoconstrictor activity, which was maximal at 1%. These local anaesthetic properties suggest that aptocaine merits clinical trials, especially in dentistry.
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Porcine malignant hyperthermia was studied in seven Pietrain pigs under standardized experimental conditions. In five animals malignant hyperthermia was triggered with suxamethonium and halothane, but in two pigs suxamethonium alone was used. Characteristic metabolic and physiological changes were found and these are discussed with regard to a possible mechanism to explain the malignant nature of the syndrome.
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Comparative Study
Effect of lithium and rubidium on the sleeping time caused by various intravenous anaesthetics in the mouse.
The effects of acute and long-term lithium (LiCl) and rubidium chloride (RbCl) treatments on the sleeping time caused by intravenous thipentone, methohexitone, ketamine, propanidid. Althesin and diazepam were studied in white mice. ⋯ Both LiCl and RbCl, given acutely, enhanced the sleeping time caused by diazepam. The rectal temperatures were lower in the LiCl-treated mice than in the control and RbCl-treated mice.
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Pulmonary gas distribution, functional residual capacity (FRC), closing capacity (CC), arterial oxygen tension (PaO2) and alveolar-arterial oxygen tension gradient (PAO2-PAO2) were measured in seven subjects before and after the induction of extradural analgesia for routine surgery. It was found that pulmonary gas distribution was within normal limits throughout the study, although there were two patients in whom airway closure occurred consistently within the tidal volume. ⋯ CC and FRC were substantially unchanged by the induction of extradural analgesia. Changes in (PAO2-PaO2) and PaO2 were usually not large, and are apparently related to factors other than changes in lung geometry.