The Young Teaching Recognition Award 2018: Postoperative delirium and cognitive dysfunction in the elderly

The Young Teaching Recognition Award 2018: Postoperative delirium and cognitive dysfunction in the elderly

  • Issue 76

Editor’s note:This is the first, of three, presentations that received the Young Teaching Recognition Award. We are glad to publish the summaries of these lectures, evaluated and highly appreciated during the last Euroanaesthesia, Copenhagen, June 2018.

Ahmed A Gilani FRCA DPMSA MBChB
University Hospital Birmingham, Birmingham, United Kingdom
ahmedgilani@doctors.org.uk

Europe’s population is continuing to age; these elderly patients often have multiple co-morbidities which can impact their care in the perioperative period.1It is reasonable to assume that our workload to anaesthetise such patients will increase. One major related risk in the perioperative period is cognitive impairment; this is usually delineated as post-operative delirium (POD), post-operative cognitive dysfunction (POCD), and dementia.

Despite this apparent sudden interest in the management of such patients, the risk of POD was mentioned as early as 1887 by Sir George Savage.2He describes the condition as ‘acute delirious mania’, and also suggests that it may lead to ‘chronic weak-mindedness’– a term we may now describe as POCD. Since then, our understanding and management of POD has marginally improved (although, historically, our anaesthetic practice has changed such as the avoidance of hypoxic gas mixtures).

POD is a patho-physiologically obscure, underdiagnosed, common, and serious neurological complication of surgery.3It is usually assumed to be an acute, fluctuating, transient, and reversible condition caused by physical illness. It increases hospital length of stay (21 vs 11 days), increases time on mechanical ventilation (9 vs 4 days), and leads to a three-fold increase in mortality.3 Our ability to define the condition has helped delineate and research the phenomenon more thoroughly; the definition used by the Diagnostic and Statistical Manual(DSM) is currently widely held.4It can present as a spectrum defined as hyperactive (<25% patients), mixed, and hypoactive (~75% patients). While sometimes subtle to detect (especially in hypoactive delirium), the 4AT can be used as a rapid clinically relevant tool to detect POD. It is designed to be used in busy clinical areas, and is internationally validated.5

We understand POD to be caused by multiple factors divided into environmental (e.g., immobility, unfamiliar environment, sleep disruption), acute illness (e.g., acute pain, inflammation, and the up/down regulation of neurotransmitters), and host factors (e.g., age, multiple co-morbidities, and pre-existing dementia). Various guidelines exist to suggest preventative and treatment strategies, all based on these multifactorial causes. The European Society of Anaesthesiology published their guidance (2017) recommending a multidisciplinary and multi-treatment approach.6These include pharmacological methods such as avoiding benzodiazepines, good analgesia, low-dose atypical neuroleptics, and non-pharmacological methods including fast-track surgery, orientation (e.g., visual/hearing aids), early mobilization, and the importance of maintaining a day/night rhythm. These are also reflected in the Royal College of Anaesthetists’ Guidelines for the Provision of Anaesthesia Services(GPAS), which also highlights the importance of consenting patients to the risk of POD.

POCD is comparatively subtler and less frequently encountered during the perioperative period. While interest in the condition picked up in the mid-2000s, Bedford in 1955 started to define the condition and its management (including the avoidance of morphine, atropine, barbiturates, and hypotensive anaesthesia); his term ‘he’s just not the same person since (the operation)’ seems pathognomonic of the condition.7Unlike POD, POCD has no internationally agreed definition such as that in the DSM (recent attempts have been made to create a standardised definition). This lack of definition has hindered the attempts of researching the syndrome (with variant terminology used) yet is acknowledged to occur after anaesthesia and surgery, usually weeks afterwards, and requires progressive and repetitive neuropsychological testing of the patient at intervals.

There appear to be multiple risk factors, similar to POD, including increasing age, usage of sedative medication, and a BIS <40; other risks include years of education, post-operative respiratory complications, and conflicting evidence to suggest POD may itself lead to POCD (as first suggested in 1887).

Unlike POD and POCD, dementia is more recognisable as the patient already has a diagnosis (although the risk of an increasing aging population may lead us as anaesthetists to encounter more patients who have not yet been formally diagnosed). The Association of Anaesthetists of Great Britain and Ireland (AAGBI) is formulating guidance on such patients in the perioperative period. It recognises such patients to be at risk of longer inpatient stays, institutionalization and rehospitalisation, with personal and financial consequences. It is important to discuss the risk of surgery in a multidisciplinary approach, including whether surgery may be warranted in the first instance, and the review of advance directives and ceilings of care.

Polypharmacy is common in such patients; specifically, the use of anticholinesterase inhibitors has interactions with neuromuscular blocking agents. Consideration of stopping drugs such as donepezil and rivastigmine pre-operatively (a decision requiring communication with elderly care physicians) may be required – in some cases warranted if no longer beneficial. The ideal scenario of managing such patients involves avoiding ‘deliriants’ and ‘normalising/personalising’ perioperative care.

It is reasonable to assume our current workload towards anaesthetising elderly patients will increase, and as such we will encounter cognitive impairment more frequently. As anaesthetists we have much to offer towards the perioperative care of such patients. Such patients will require a tailored and multidisciplinary approach. It is hoped that the drive in perioperative training will encourage more research to show how such services and treatment modalities would best work.

 

References

  1. Eurostat: Statistics Explained; http://ec.europa.eu/eurostat/statistics-explained/index.php/Population_structure_and_ageing
  2. Savage, GH. Br Med J1887;2:1405.
  3. Inouye SK, Westendorp RGJ, Saczynski JS. Lancet2014;383:911-22.
  4. American Psychiatric Association. Diagnostic and statistical manual of mental disorders; 5th ed. Arlington, VA: American Psychiatric Association, 2013.
  5. Bellelli G, Morandi A, Davis DH, et al. Age Ageing2014;43:496-502.
  6. Aldecoa C, Betteli G, Bilotta F, et al. Eur J Anaesthesiol2017;34;192-214.
  7. Bedford, PD. Lancet;1955;269(6884):259-63.