Anaesthesia
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Subdural placement of the tip of the Tuohy needle or epidural catheter may account for many unexpected complications of attempted epidural blockade, for example, 'unexplained' headache, false-negative aspiration test down needle or catheter, false-negative test dose, unilateral block, delayed total spinal and neurological sequelae, as well as profound block of delayed onset that is characteristic of subdural blockade. Cases are reported in support of this hypothesis.
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Life-threatening extensions of conduction block during obstetric epidural analgesia can be classified according to the risk to the mother. High blocks that occur in the presence of the anaesthetist should present a readily treatable problem. Reports of total spinal anaesthesia that occur with no anaesthetist in attendance call for a reappraisal of present practice. Changes in current anaesthetic practice, which might increase safety with epidural analgesia, are top-ups by midwives, but only when the anaesthetist is on the delivery suite; repeated assessment of the nature of the conduction block by an anaesthetist; and continuous infusions with anaesthetist-only top-ups.
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Two cases are presented which illustrate the essential features, diagnosis and management of malignant hyperthermia. Both cases occurred in association with isoflurane, and in patients who were exposed during previous anaesthetics to recognised trigger agents without apparent manifestation of the syndrome.
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Equipment deadspace can be a hazard in drug administration. The aim of this study was to measure the size of this problem. The deadspaces of a selection of cannulae, syringes and epidural catheters were measured by displacing the deadspace volume with water and measuring the weight gain. ⋯ The deadspace of an epidural catheter and filter is approximately 1 ml. All cannulae should be flushed after drug administration. Epidural catheters must be flushed with the same solution as the test dose before insertion.