Anaesthesia
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In this article, we will discuss the pathophysiology of peripheral nerve injury in anaesthetic practice, including factors which increase the susceptibility of nerves to damage. We will describe a practical and evidence-based approach to the management of suspected peripheral nerve injury and will go on to discuss major nerve injury patterns relating to intra-operative positioning and to peripheral nerve blockade. We will review the evidence surrounding particular strategies to reduce the incidence of peripheral nerve injury during nerve blockade, including nerve localisation methods, timing of blocks, needle techniques and design, injection pressure-monitoring and local anaesthetic and adjunct choice.
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'Obstetric anaesthesia is a litigious area of medical practice - patient expectations are high, and many of the interventions undertaken by anaesthetists are performed urgently or emergently, frequently out of hours. The complications that occur during obstetric practice are not unique to this area of anaesthesia, but some of the physiological and anatomical changes that take place during pregnancy can affect the frequency with which these happen. In this narrative review, we hope to cover a few of the more common complications in obstetric anaesthesia, as well as some of the more severe, yet less frequently occurring problems.
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It is commonly assumed that loss of responsiveness and recovery of responsiveness occur at similar concentrations of propofol. However, the 'conscious' and 'anaesthetised' conditions produced by general anaesthetics may behave as two bistable states. We hypothesised that loss of responsiveness and recovery of responsiveness occur at different propofol concentrations. ⋯ Propofol plasma concentration and the corresponding bispectral index values measured at minute 7 and minute 14 of the long step performed at loss of responsiveness were 2.6 (1.2-4.7) vs. 2.6 (1.3-4.3) at recovery of responsiveness, (p = 0.96) and 61.2 (49.0-77.0) vs. 58.4 (45.0-74.0), (p = 0.058), respectively. Loss of responsiveness and recovery of responsiveness appear to occur at different propofol concentrations. However, it is possible that, if equilibration was not achieved between plasma and effect-sites at the end of each 7-min step, the higher concentrations found at loss of responsiveness compared with those observed during recovery of responsiveness could be explained by a possible bias in estimations of the effect-site concentrations of propofol by the Schnider model, rather than neural inertia.
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Peripheral nerve blocks are popular as a mode of anaesthesia for limb surgery and their beneficial effects are well documented in elective surgery. However, concerns have been raised about potential rebound pain outweighing the benefits in acute ankle fracture surgery. Furthermore, pain scores and morphine consumption do not provide a full picture, as pain is subjective. ⋯ They had misunderstandings regarding the blocks' effect on sensation, resulting in fear of feeling pain during surgery and of permanent nerve damage after surgery. However, patients valued the mental alertness, ability to ambulate and efficient pain relief provided by the blocks. We recommend that patients be given thorough and repeated information as we feel this is crucial in preventing undesirable responses from patients, and is likely to increase the overall clinical usefulness of nerve blocks in acute limb surgery.
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Intra-operative acute hypersensitivity reactions require a decision to be made regarding whether to proceed with or abandon the planned surgical procedure once the patient has stabilised. Using retrospective case controls, we examined all cases (223) of proven acute hypersensitivity reactions from 2005 to 2014 in Western Australia, in which the syndrome was recognised by the treating clinician before or during surgery, to determine whether recovery outcomes were adversely affected by proceeding with the planned procedure. Surgery proceeded in 104 patients (47%) and was abandoned in 119 (53%). ⋯ Our results suggest that, once initial resuscitation has been achieved and if resuscitative efforts can be re-instituted if required, continuing with planned surgery in grade 1, 2 and 3 immediate hypersensitivity was not associated with poorer outcomes. After grade 3 reactions, there was a significant incidence of complications attributable to acute hypersensitivity regardless of whether surgery proceeded or was abandoned. Surgery was frequently abandoned in grade 4 immediate hypersensitivity and was associated with a high rate of complications.