Anaesthesia and the older brain: what should we do?

The ageing of the surgical population is well described in high-income countries 1. However, there is evidence of inequitable access to surgery for older people across the globe and this is particularly observed as an unmet need in middle- and lower-income countries 2. The demand for surgery in older people is driven by demographic change resulting in a higher prevalence of age-related conditions requiring surgery, and by improvements in safety and efficacy of surgical interventions facilitated by innovative anaesthetic techniques. There are changes in societal and professional attitudes, with age no longer viewed as an impediment to surgery. Appropriate surgery under anaesthesia in older people improves longevity with quality of life and/or provides symptom relief or palliation when surgical ‘cure’ is not the aim. But there are challenges, particularly when it comes to looking after the older person’s brain in the peri-operative setting. Some of these challenges relate to co-existing neurological conditions unrelated to the surgical pathology, for example stroke 3 or Parkinson’s disease 4, whereas other challenges relate to neurological disorders that are a consequence of surgery under anaesthesia, for example postoperative delirium 5 and other neurocognitive disorders 6. The articles collated in this issue provide comprehensive reviews of the literature pertaining to such neurological comorbidities and peri-operative complications. Within the speciality of anaesthesia, it is clear that arguments about whether general, regional or sedation-based techniques provide better neurological outcomes will continue to rage, despite observational data and large randomised controlled trials suggesting a lack of meaningful difference 5, 7. New debates are also emerging and include the role of processed EEG 8 or choice of intravenous vs. inhalational anaesthesia. However, the articles published in this issue demonstrate that improvements in postoperative neurological outcomes are less likely to result from an anaesthetic ‘magic bullet’ or new technique. Of course, good postoperative outcomes are dependent on highly trained and skilled anaesthetists delivering quality care, but the opportunity for an individual anaesthetist to further improve outcomes is small compared with the potential impact of implementing multicomponent evidence-based interventions, quality systems and processes, and team working in the peri-operative setting. A number of common themes emerge in this issue, despite each article considering different pathologies and/or techniques. First, that systematic, thorough but targeted pre-operative assessment is key. This is to ensure early screening of risk-factors for adverse outcome, diagnosis of previously unrecognised conditions and acknowledgement of the potential impact of known comorbidity on postoperative neurological status. For example, with delirium being the most common postoperative neurocognitive complication (associated with high morbidity and mortality), the need for identification of patients at risk of delirium is clear. However, screening is hampered by the lack of a universally accepted, clinically feasible but suitably discriminatory, tool. While artificial intelligence methodology may facilitate the development of a tool with good clinimetric properties, the traditional art of history taking and documentation remains the most useful screening tool 7. Missed diagnoses are common in older people due to: labelling of symptoms as being part of normal ageing; sensory or cognitive impairments; and reduced health-seeking behaviours in older people. Such missed conditions often include syncope or cerebrovascular disease such as transient ischaemic attacks. A diligent approach to history taking ensures not only diagnosis but also allows appropriate adaptation of peri-operative management to reduce complications. Similarly, accurate pre-operative recording of the presence, severity and drug regimes used in comorbidities such as Parkinson’s disease or myasthenia gravis, is essential to inform peri-operative management and reduce the risk of related complications 6. These examples illustrate the need for targeted but open history taking for older surgical patients. Of course, this requires thought and flexibility in our increasingly protocol and pro forma-driven pre-operative assessment clinics and in the context of a growing reliance on virtual consultations as prompted by the COVID-19 pandemic 8. As such, there is a clear imperative to reconsider how we best structure pre-operative assessment and optimisation services for our older population, who are the largest cohort accessing healthcare. The second theme that emerges from this series is that the identification of risk factors for adverse outcome is only useful if action is undertaken to reduce the incidence and severity of predictable complications. As demonstrated in many of the articles, single component interventions are unlikely to change peri-operative outcomes. For example, there is no single drug or intra-operative intervention conclusively shown to reduce the incidence, severity or duration of postoperative delirium, though dexamethasone 9, 10 and processed EEG 8 show promise. On the other hand, it is the act of ensuring patients receive their routine drugs for conditions such as Parkinson’s disease during the peri-operative period that reduces the risk of an adverse postoperative outcome 6. Such work demonstrates the need to ‘get the basics right’ in order to reduce postoperative neurocognitive complications. This is illustrated in the Hospital Elder Life Program (HELP), a set of standardised processes delivered as bundles of care, that are designed to reduce the incidence and severity of delirium 11. Such models of care have been shown to be feasible and deliverable in surgical settings with results and cost effectiveness similar to those reported in medical settings 12. In parallel, there is evidence that we need to ‘get the processes right’. For example, prompt receipt of primary intervention is associated with improved neurological outcomes, whether for mechanical thrombectomy 5 or hip fracture 13. While getting the basics and processes right requires input and expertise from individual specialities and disciplines, it hinges on effective team and system working. This is apparent particularly in the older surgical population, who present with surgical pathology but with co-existing physiological decline, multimorbidity and geriatric syndromes such as frailty and social care needs. Whether in the elective setting, where there may be time to screen, assess and optimise, or in the emergency setting where intervention may be time limited, the need for holistic, specialist care is clear. Furthermore, in this complex and vulnerable group, shared decision-making about the proposed benefits, risks and alternatives of surgery under anaesthesia is acutely apparent and must take into account the risks of peri-operative neurocognitive disorders. Despite the association between delirium and long-term morbidity, and its impact on the trajectories of underlying cognitive impairment and mortality, consent processes do not routinely document the risk of peri-operative delirium 14. Inadequately informed consent may be one factor contributing to the observation that one in seven patients undergoing major surgery regret undergoing the procedure 15 and simultaneously why we see that patients at centres with well-established shared decision-making services not infrequently choose not to go ahead with the initial proposed surgery. The reasons for decisional regret are complex but relate in part to a mismatch between expectation of the quality of postoperative recovery (beyond survival) and reality. Many units are utilising comprehensive geriatric assessment and optimisation methodology to support older patients undergoing elective and/or emergency surgery. The use of this multicomponent intervention is associated with cost-effective reductions in peri-operative neurocognitive complications, alongside improved process outcomes 16-18. The utility of such methodology lies in its multidimensional approach to holistic care for older patients taking medical, functional, psychological and social domains into account and inherently providing trimodal prehabilitation strategies. With the increasing recognition of the inter-relationship between physical and cognitive frailty, multiprofessional guidelines published by the UK Centre for Perioperative Care and British Geriatrics Society 19 should be used to develop and embed services for older adults who are at risk of peri-operative neurocognitive disorders. Establishing such services requires a systematic approach to processes: use of information systems to triage patients to the appropriate pre-operative services early in the pathway; sharing of documentation between community and secondary care sectors; establishment of teams with the right skill mix for the patient cohort; development of cross specialty bundles of care supported by guidelines; and follow through of the patient from the contemplation of surgery through to recovery. Finally, to improve clinician- and patient-reported outcomes for older adults presenting for surgery, we need to openly acknowledge the barriers: the gaps in evidence particularly for multicomponent interventions in ‘real-world’ patients; the silo approach to education and training; the continuing culture of specialty-based healthcare rather than truly patient-centred care (e.g. the label of a ‘surgical’ or ‘medical’ patient whereas the issues are often surgical, medical as well as social); unwarranted variation in funding for cross-boundary services (e.g. geriatricians working in peri-operative care, psychologists working with surgeons and support workers/navigators in primary care to support patients with long-term conditions such as Parkinson’s disease 6); and of course, the gaps in our workforce. Although there are questions as to whether older patients should be managed pro-actively by specialist physicians rather than surgeons after the immediate postoperative period, such changes need careful exploration of potential risks and benefits. Cross-boundary organisations such as the Centre for Perioperative Care are working with patients, researchers, education authorities and managers and commissioners to address some of these key issues. However, this will require cultural and behavioural buy-in from all health and social care professionals involved in the care of older surgical patients if we are to truly improve not only neurocognitive but also overall outcomes for older people. JD is a deputy director of the Centre for Perioperative Care, Vice President at the British Geriatrics Society and Deputy Editor of Age and Ageing. IM is an Editor of Anaesthesia. No other competing interests declared.