Anaesthesia
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Venous pressures in the forearm veins during the simulated performance of intravenous regional analgesia were measured. Pressures obtained equalled or exceeded the recommended occluding pressure of the tourniquet. This finding is proposed as one of the possible reasons for the occasional observation that convulsions may occur during Bier's block despite the presence of an intact tourniquet system.
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Randomized Controlled Trial Comparative Study Clinical Trial
Bupivacaine and prilocaine in intravenous regional anaesthesia.
Six volunteers underwent intravenous regional anaesthesia of the non-dominant arm on four occasions using two equipotent doses of bupivacaine and prilocaine, administered in a randomised double-blind sequence. Equipotent doses produced similar degrees of motor and sensory blockade. Bupivacaine produced more rapid motor power loss and delayed motor recovery (p less than 0.01). ⋯ Increase of dose with both drugs gave more rapid and complete sensory and motor blockade and delayed recovery (p less than 0.05). This was, however, associated with more marked toxicity. It is suggested that in intravenous regional anaesthesia there are no clinical differences between the drugs in equipotent solutions, and that the lower concentrations are the appropriate ones for standard use.
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A technique of continuous sciatic nerve block is described. The method was used to relieve pain from ischaemic gangrene of the foot for 2 days before below-knee amputation and, combined with a continuous inguinal paravascular block, to provide regional anaesthesia both for the surgery and for the first 2 postoperative days.
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Measurements of the vapour concentrations delivered by the EMO and Oxford Miniature Vaporizers (OMV) were made with both continuous (plenum mode) and intermittent (drawover mode) air flows. Leakage of ether, halothane and trichloroethylene vapours through the corrugated elephant tubing was also measured. Both vaporizers performed most consistently with the intermittent flows for which they were designed. ⋯ Minimal amounts of ether were lost through the tubing but halothane losses were appreciable, while losses of trichloroethylene were enough to reduce the concentrations available to the patient. The EMO is not suitable for plenum use with carrier gas flows below about 10 litres/min. The OMV is a useful plenum vaporizer although the outputs are generally lower than indicated at higher flows.