Anaesthesia
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Despite advances in clinical practice, local anaesthetic systemic toxicity continues to occur with the therapeutic use of local anaesthesia. Patterns of presentation have evolved over recent years due in part to the increasing use of ultrasound which has been demonstrated to reduce risk. Onset of toxicity is increasingly delayed, a greater proportion of clinical reports are secondary to fascial plane blocks, and cases are increasing where non-anaesthetist providers are involved. ⋯ Advances in the changing clinical landscape with novel applications and settings for the use of local anaesthesia are also described. Finally, we signpost future directions to potentially improve the management of local anaesthetic systemic toxicity. The utility of local anaesthetics remains unquestionable in clinical practice, and thus maximising the safe and appropriate use of these drugs should translate to improvements in patient care.
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Ultrasound-guided fascial plane blocks of the chest wall are increasingly popular alternatives to established techniques such as thoracic epidural or paravertebral blockade, as they are simple to perform and have an appealing safety profile. Many different techniques have been described, which can be broadly categorised into anteromedial, anterolateral and posterior chest wall blocks. Understanding the relevant clinical anatomy is critical not only for block performance, but also to match block techniques appropriately with surgical procedures. ⋯ The current evidence for their clinical applications indicates that certain chest wall techniques provide significant benefit in breast and thoracic surgery, similar to that provided by thoracic paravertebral blockade. Their role in trauma and cardiac surgery is evolving and holds great potential. Further avenues of research into these versatile techniques include: optimal local anaesthetic dosing strategies; high-quality randomised controlled trials focusing on patient-centred outcomes beyond acute pain; and comparative studies to determine which of the myriad blocks currently on offer should be core competencies in anaesthetic practice.
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Moderate-to-severe postoperative pain persists for longer than the duration of single-shot peripheral nerve blocks and hence continues to be a problem even with the routine use of regional anaesthesia techniques. The administration of local anaesthetic adjuncts, defined as the concomitant intravenous or perineural injection of one or more pharmacological agents, is an attractive and technically simple strategy to potentially extend the benefits of peripheral nerve blockade beyond the conventional maximum of 8-14 hours. Historical local anaesthetic adjuncts include perineural adrenaline that has been demonstrated to increase the mean duration of analgesia by as little as just over 1 hour. ⋯ Neither perineural dexmedetomidine nor dexamethasone fulfils all the criteria of the ideal local anaesthetic adjunct. Dexmedetomidine is limited by side-effects such as bradycardia, hypotension and sedation, and dexamethasone slightly increases glycaemia. In view of the concerns related to localised nerve and muscle injury and the lack of consistent evidence for the superiority of the perineural vs. systemic route of administration, we recommend the off-label use of systemic dexamethasone as a local anaesthetic adjunct in a dose of 0.1-0.2 mg.kg-1 for all patients undergoing surgery associated with significant postoperative pain.
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Regional anaesthesia in children has evolved rapidly in the last decade. Although it previously consisted of primarily neuraxial techniques, the practice now incorporates advanced peripheral nerve blocks, which were only recently described in adults. These novel blocks provide new avenues for providing opioid-sparing analgesia while minimising invasiveness, and perhaps risk, associated with older techniques. ⋯ In addition, the estimated frequency of serious adverse events demonstrates that regional blocks in children under general anaesthesia are no less safe than in awake adults. In infants, the techniques of direct thoracic epidural placement or caudal placement with cephalad threading each have distinct advantages and disadvantages. As the data cannot support the safety of one technique over the other, the site of epidural insertion remains largely a matter of anaesthetist discretion.
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This narrative review discusses recent evidence surrounding the use of regional anaesthesia in the obstetric setting, including intrapartum techniques for labour and operative vaginal delivery, and caesarean delivery. Pudendal nerve blockade, ideally administered by an obstetrician, should be considered for operative vaginal delivery if neuraxial analgesia is contraindicated. Regional techniques are increasingly utilised in clinical practice for caesarean delivery to minimise opioid consumption, reduce pain, improve postpartum recovery and facilitate earlier discharge as part of enhanced recovery protocols. ⋯ Transversus abdominis plane blockade, wound catheter insertion and single shot wound infiltration are all effective techniques for reducing postoperative opioid consumption, with transversus abdominis plane blockade favoured, followed by wound catheters and then wound infiltration. Ilio-inguinal and iliohypogastric, erector spinae plane and rectus sheath blockade all require further studies to determine their efficacy for caesarean delivery in the presence or absence of long-acting neuraxial opioids. Future studies are needed to: compare approaches for individual techniques; determine which combinations of techniques and dosing regimens result in optimal analgesic and recovery outcomes following delivery; and elucidate the populations that benefit most from regional anaesthesia in the obstetric setting.