Anaesthesia
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The accuracy of the Dinamap 845 automatic blood pressure recorder was assessed by comparing its own indirect determinations of blood pressure with direct intra-arterial recordings. It was found that in the majority of cases it was capable of producing reliable trend information during anaesthesia. The instrument may not be able to interpret pressure signals from a patient with a severe dysrhythmia. It is probably an unsuitable monitor for use with very rapidly acting drugs such as sodium nitroprusside.
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In investigating the possible causes of an observed complication of intravenous regional anaesthesia, cubital fossa venous pressures were measured distal to an inflated tourniquet as standard 40 ml volumes of normal saline were injected. The maximal pressures obtainable were limited by tourniquet pressure since the veins compressed under the tourniquet acted as 'Starling' spillover resistors. ⋯ The rates of rise and maximum values of venous pressures tended to be increased by increased injection rates, and by failure to exsanguinate the arm, but the choice of injection site was paramount. Compared with more distal injections, cubital fossa venous injections are more likely to lead to leakage under the tourniquet and should never be used for intravenous regional anaesthesia.
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A case of glottic valvular obstruction following extubation is reported. The cause was bilateral dislocation of arytenoids due to coughing on the tracheal tube, which resolved automatically following a further bout of coughing.
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IgE levels were measured in 105 patients after immediate (101) and delayed (4) anaphylactoid reactions to anaesthetic drugs. It was not possible on the basis of allergic history and IgE levels in patients to determine the drugs to which the patients were likely to react. A history of allergy, atopy with or without elevated IgE levels, does not aid the selection of anaesthetic drugs for initial or repeat anaesthesia.
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In patients given epidural analgesia who had singleton vertex vaginal deliveries the normal delivery rate was 57%, compared to 80% in all this group. The increase in instrumental delivery rate could partly be accounted for by parity (primigravidae are over-represented in the epidural group), by obstetric and medical indications for epidurals, and by the need for sitting top-ups to relieve perineal pain. There remained a small population of patients in whom epidurals may have contributed to the need for instrumental delivery.