Advancing towards the next frontier in regional anaesthesia

Abstract

There will always be a frontier where there is an open mind and a willing hand.Charles F. Kettering Regional anaesthesia is the art and science of selectively relieving pain in a specific part of the body by the percutaneous administration of local anaesthetic drugs. We are currently in a golden age with regard to the practice of regional anaesthesia, and in this special supplement of Anaesthesia, we present a compilation of articles written by experts from around the world that summarises the current state of the art and provides glimpses into the future that lies ahead. These cover a broad range of topics related to regional anaesthesia, including its role in prevention of chronic postoperative pain and cancer recurrence; technological innovations that promise to improve technical performance and education; novel block techniques; important non-technical issues such as risk disclosure and patient consent; and determination of the value added by incorporating regional anaesthesia into routine care. The practice of regional anaesthesia has come a long way since William S. Halsted, a surgeon, performed the first nerve block by direct application of cocaine in 1884. This was followed by August Bier's description of spinal anaesthesia in 1898, again using cocaine. The next several decades were a period of growth for regional anaesthesia, marked by development of techniques for epidural anaesthesia and peripheral nerve blockade, as well as the synthesis of novel local anaesthetic drugs still in use today (Fig. 1). This progress occurred in parallel with advances in the practice of general anaesthesia, including the development of synthetic opioids, such as fentanyl, that conferred haemodynamic stability and cemented their role as an essential component of a ‘balanced anaesthetic’. The 1970s through 1990s also saw the introduction of safer and more efficient volatile anaesthetic agents (isoflurane, desflurane and sevoflurane). These improvements lessened the appeal of regional anaesthesia, and peripheral nerve blockade in particular acquired a reputation as an arcane and difficult art practiced only by a small group of enthusiasts. Since the beginning of the new millennium, however, several factors have contributed to a renaissance in regional anaesthesia. The first was the increasing appetite for the efficiencies in healthcare delivery offered by outpatient surgery [1]. The advantages of regional anaesthesia, in terms of early postoperative pain control and its superior recovery and adverse-effect profile, generally translate into shorter recovery and discharge times, making it well-suited to this context. Regional anaesthesia also addressed many of the challenges presented by an aging patient population increasingly saddled with a significant burden of cardiorespiratory and metabolic diseases [2]. Perhaps the most important tipping point was the ‘ultrasound revolution’, which had its beginnings in the early 1980s. The use of ultrasound in regional anaesthesia quickly progressed from simple assessment of injectate spread to needle-to-nerve guidance in conjunction with peripheral nerve stimulation, and it has now been established as the standard of practice in performing most peripheral nerve blocks [3]. Note that neurostimulation has not been entirely abandoned but rather repurposed for important secondary roles preventing intraneural injection and confirming the identity of nerve targets [4]. Another major step forward was the discovery that intravenous lipid emulsion is an effective antidote in local anaesthetic systemic toxicity (LAST), which remains one of the primary life-threatening complications of regional anaesthesia. Ultrasound guidance has significantly reduced the risk of LAST as it pertains to peripheral nerve blockade [5]; however, as Macfarlane et al. [6] discuss, continued vigilance is warranted given the current vogue for high-dose local anaesthetic wound infiltration techniques, fascial plane blocks and intravenous lignocaine infusions. More recently, both an epidemic and a pandemic have separately served to thrust regional anaesthesia into the broader spotlight. The opioid epidemic has led to a re-evaluation of the role of opioids in peri-operative management, and to legislative and regulatory changes that limit opioid prescribing for patients who undergo surgical procedures [7]. Regional anaesthesia is a key element of a multimodal approach to opioid-sparing analgesia [8] and is increasingly incorporated into surgical enhanced recovery protocols to promote early functional rehabilitation [9]. Continuous peripheral nerve blocks allow practitioners to titrate regional analgesia and extend its duration to better match the pain trajectories for specific procedures [10]. As an alternative to continuous techniques, local anaesthetic adjuncts, such as intravenous or perineural dexamethasone, may be used to prolong the analgesic duration and benefits of single-injection blocks [11]. The current coronavirus disease-2019 (COVID-19) pandemic has raised concerns about the risk to healthcare workers posed by the aerosolisation associated with tracheal intubation and extubation in general anaesthesia [12], leading to recommendations that surgical regional anaesthesia be considered whenever possible [13]. At the same time, appropriate personal protective equipment and other precautions are essential when administering regional anaesthesia in a COVID-19 patient [12]. Continuous regional anaesthesia techniques may have additional advantages in COVID-19 patients requiring repeated painful procedures such as wound debridement or dressing changes – these can be done at the bed-side in an isolation room, thus minimising the infection risk associated with the multiple transfers to the operating theatre that would otherwise be required [14]. Where do we go from here? As highlighted by the articles in this issue, regional anaesthesia remains an area ripe for scientific inquiry and progress. One of the main frontiers to be explored relates to increasing patient access. Despite its current popularity, regional anaesthesia's potential impact on patient care has yet to be fully realised. In the USA, for example, national administrative databases indicate that only one in five patients undergoing knee replacement surgery receive nerve blocks [15, 16]. It has been estimated that out of the millions of patients undergoing day-case surgery, 25% are eligible for regional anaesthesia but only 3% actually receive a nerve block [17]. In the paediatric population, there are unique risks of general anaesthesia in neonates and younger children related to postoperative apnoea and possible neurocognitive side-effects, yet regional anaesthesia remains relatively under-utilised. Heydinger et al. [18] usefully summarise the latest research that addresses many of the challenges related to the effective and safe performance of regional anaesthesia in smaller humans; in particular, the results from large databases support the safety of blocks performed under general anaesthesia or deep sedation [19]. It goes without saying that equipping all anaesthetists with the requisite skills is essential if universal access to regional anaesthesia is to be achieved. There is little doubt that ultrasound-guided regional anaesthesia has led to a significant increase in the number of practitioners who are comfortable performing blocks. However, the motor and cognitive skills it demands are quite different from landmark or neurostimulation-guided techniques, forcing us to re-think our educational strategies. In 2009, the American Society of Regional Anesthesia and Pain Medicine (ASRA) and the European Society of Regional Anaesthesia and Pain Therapy (ESRA) published the first joint recommendations on education and training in ultrasound-guided regional anaesthesia [20]. Since then, our understanding of specific elements required for competence has continued to progress and shape future approaches to learning [21]. For example, recognition of the importance of visual processing of the information presented on the ultrasound screen has raised the possibility of using eye-tracking as a tool for evaluating competence and providing feedback [22], and of the application of artificial intelligence in facilitating image interpretation [23]. One of the paradoxes of ultrasound, however, is that it may have accidentally complicated regional anaesthesia for the general anaesthetist by introducing ‘choice overload’. The number of publications describing new techniques, particularly with ‘plane block’ in the title, increases every year (Fig. 2). A ‘back to basics’ approach to teaching and implementing regional anaesthesia has been advocated, with an emphasis on identifying a core set of high-yield ‘Plan A’ blocks for the most common surgical procedures, that can then be integrated into basic training programs for all anaesthetists [24]. These techniques should be chosen not only for their ease of learning and use, but also for their clinical impact on patient care [25]. However, effective training in regional anaesthesia is only one aspect of translating evidence into changes in clinical practice [26]. It is critical to raise awareness among surgical colleagues and healthcare administrators of the value that regional anaesthesia offers. To do this, we need sustained investment into high-quality studies that demonstrate the impact it has on outcomes beyond just acute pain. Both Hamilton et al. and Johnston et al. provide a succinct overview of appropriate metrics worthy of evaluation, as well as frameworks such as the Institute for Healthcare Improvement's triple aim [27] for thinking about how regional anaesthesia may improve healthcare in general [28, 29]. Investigation into important long-term patient outcomes such as chronic postoperative pain and cancer recurrence must also continue as there is a sound mechanistic rationale for peri-operative management incorporating regional anaesthesia, even if the clinical evidence is as yet somewhat equivocal [30, 31]. One of the principal aims of this special supplement of Anaesthesia is to strengthen the sense of community and shared purpose between peri-operative physicians who already possess training and skills in regional anaesthesia and those who have yet to attain them. To this end, it summarises our current understanding of many of the fundamental issues in regional anaesthesia facing us today and maps out possible directions for the future that will help optimise peri-operative care for as many patients as possible. We invite readers to join us as we step forward on the path blazed by the pioneers and innovators in our specialty, towards the next landmark in our journey towards regional anaesthesia excellence and access for all. This work was supported with resources and the use of facilities at the Veterans Affairs Palo Alto Health Care System (Palo Alto, CA, USA). The contents do not represent the views of the Department of Veterans Affairs or the United States Government. KE has received funding, research or educational support from Ambu, GE Healthcare and Fisher and Paykel Healthcare. KE and EM are Editors of Anaesthesia. No other competing interests declared.

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