Current evidence for peri-operative and critical care management of the brain

What better way to see in any new year than with a brand-new Anaesthesia Special Supplement! This year, it is all about the peri-operative and critical care management of the brain, which has been guest edited by Dr Jugdeep Dhesi and Professor Alana Flexman. Flexman and Tung begin by appraising outcomes used in neuroanaesthesia and neurocritical care. They call for a shift towards PROMS as well as perspectives from LMICs, and the tools are available now – we just have to use them. Dhesi and Moppett discuss the implications of the older brain in peri-operative care and ask – what should we do? As we most things, there is no one right answer and no ‘magic bullet’, but one of the key themes appearing throughout the issue is of multidisciplinary thinking and working. The first review seems to have caught the imagination of our followers already, which looks at the implications of nocebo. This is a key paper that could potentially change practice, but not everyone will agree, as many of the nocebos in use are enshrined in practice already (Fig. 1). Time now for phrases such as ‘bee sting’ and ‘sharp scratch’ to be thought of as clumsy verbal relics of the past? We think so!

**Figure 1** Overview of the neurobiology of the nocebo effect. PONV, postoperative nausea and vomiting; ACTH, adrenocorticotrophic hormone; CCK, cholecystokinin; PFC, prefrontal cortex; ACC, anterior cingulate cortex; HPA, hypothalamic–pituitary–adrenal axis; PAG, peri-aqueductal gray.

Stubbs et al. use a stereotyped peri-operative journey to highlight the decision-making points where the expertise of professionals from across the peri-operative medicine team may play an important role for patients with chronic subdural haematoma. The key point is that most patients are managed outside neuroscience centres, and more research is needed to improve the associated care pathways. Peri-operative neurocognitive disorders are the most common complication experienced by older individuals undergoing anaesthesia and surgery. Evered et al. discuss the clinical and practical implications of peri-operative neurocognitive disorder on patients, and possible pathways for identifying at-risk individuals and assessment of modifiable factors.Possible mechanisms include: neurodegenerative disease; inflammation; neuronal damage; and frailty. No longer should we refer to patients as ‘pleasantly confused’ as arguably, there is nothing pleasant about delirium.

There is much emerging evidence of COVID-19-associated delirium, and White and Jackson have brought it all together for us. They describe how it differs from ‘classical’ delirium, as well as potential mechanisms and practical approaches to management (Fig. 2). It turns out that it is more prevalent, longer lasting and associated with worse outcomes. The management remains the same, except for distressing end of life agitation where the need for higher-than-normal doses of sedatives may be required. One area of persistent controversy in neuroanaesthesia relates to the mode of anaesthesia and its relation with outcomes for mechanical thrombectomy. Dinsmore and Tan review the evidence, and suggest more important targets such as blood pressure management, diagnosis and timely management.

**Figure 2** Lived experience of delirium for patients, staff and families.

Is anyone using POCUS for acute brain injury? Dinsmore and Venkatraghavan describe the techniques and applications for and provide evidence of its utility in guiding clinical management both in the peri-operative period and on ICU. They list the commonly used acoustic windows and the structures that are visible. They argue it is an effective, non-invasive, safe and readily available technique for the rapid assessment of cerebral anatomy and cerebral haemodynamics. Will it become an alternative routine imaging technique? The results seem comparable. Most doctors will encounter status epilepticus in their carrer. Migdady et al. discuss the definitions of status epilepticus, evidence behind treatment regimens at various stages, treatment goals, outcomes and the role for newer drugs. Implementing early, evidence-based treatment modalities is important to prevent mortality and complications from prolonged status epilepticus, and this paper is arguably of important relevance for all!

**Figure 3** Treatment timeline of convulsive status epilepticus. *intramuscular (IM) or buccal (depending on availability) preferred in patients without i.v. access. Diazepam can be used if lorazepam and midazolam are not available. ABC, airway, breathing and circulation; IV, intravenous; AED, anti-epileptic drug; CBC, complete blood count; CMP, complete metabolic panel; CT, computed tomography; EEG, electroencephalogram; MRI, magnetic resonance imaging; KD, ketogenic diet; rTMS, repetitive transcranial magnetic stimulation; and VNS, vagal nerve stimulator.

Have you been busy with COVID-19 over the last few years and missed the most recent CPD relevant to the management of traumatic brain injury? Fear not, Matt Wiles has reviewed the recent evidence and brought it all together. In summary, there are few clear therapeutic interventions that are associated with meaningful improvements in mortality, or more importantly, neurological outcome. The early administration of TXA appears to offer a clinically important early mortality benefit and early tracheostomy appears to be of value. Kayambankadzanja et al. review pragmatic sedation strategies to prevent secondary brain injury in low-resource settings, which is common. They emphasise the importance of analgesia, the choice of drugs, the associated risks and the monitoring required for these patients in these settings. Elsewhere we have reviews of: strategies to reduce the incidence of postoperative delirium; peri-operative neurological monitoring with electroencephalography and cerebral oximetry; and the peri-operative management of patients with Parkinson’s disease.

**Figure 4** Summary of recent evidence-based recommendations for the management of traumatic brain injury.

We hope you enjoyed the live broadcast to accompany the issue which was seen by over 2.5k viewers! This has now been converted into a podcast which available in all the usual places. Enjoy!