Part 4 of 4 of the Guide to delirium care by Alasdair MacLullich, Professor of Geriatric Medicine, University of Edinburgh.
Overview of delirium prevention
Most delirium is present on admission, but around 30% of delirium arises after hospital admission. Of this studies suggest that 30-40% can be prevented. Importantly preventive strategies not only reduce the risk of delirium, but may also reduce its duration and severity. Therefore guidelines recommend that preventive strategies for delirium should be implemented for higher risk patients (typically defined as older patients in hospital, and/or patients with frailty and multiple comorbidities).
Factors targeted in systems of care aimed at reducing the risk of delirium reflect the multiple possible causes of delirium. Such factors include orientation and engagement, medication review, provision of spectacles and hearing aids, promotion of healthy sleep, early mobilization, pain control, prevention, early identification and treatment of postoperative complications, adequate hydration and nutrition, avoidance of constipation, supplementary oxygen (if required), avoidance of unnecessary ward moves, and for high-risk patients, assistance from their relatives and carers to deliver care.
Pharmacological prevention strategies are ineffective, with no evidence to support prophylactic medication. Use of bispectral index devices to guide the depth of anaesthesia may reduce the postoperative delirium.
Study findings suggest that some post-admission delirium arises as a result of preventable factors arising during hospitalisation. Therefore the degree of delirium prevention depends partly on the extent of suboptimal care that can then be modified. For example, if it is normal practice to administer drugs for sleep (which increase the risk of delirium) then a process that reduces this practice will reduce delirium. Yet some hospitals may already limit the use of such drugs, especially as new prescriptions. Similarly, processes of nursing care that limit dehydration, malnourishment, and prolonged immobility limit the influence of these common causes of hospital-acquired delirium identified in earlier studies.
Achieving systematic coverage of all these factors is challenging. Studies have used a variety of models to achieve this, usually with dedicated staff and in some models using volunteers. The financial and administrative costs of each system vary but the evidence suggests that delirium prevention is cost-effective given the additional costs of delirium.
Delirium prevention at the practitioner level
Patients at high risk of delirium can be assessed systematically for the above risk factors and appropriate actions taken. These can include simple processes such as ensuring that the patient is provided with their hearing aids and spectacles, treating constipation early, monitoring fluid intake, treating pain carefully, and ordering a medication review by an appropriately qualified professional.
Delirium prevention at the systems level
Some delirium can likely be prevented through routine processes such as targets for early mobilisation, avoiding ward moves, family involvement, and a delirium-friendly environment including the provision of orientation and clear information, and measures to improve sleep quality such as keeping the ward quiet at night. Ideally institutions should have a formal system of care which implements and audits known means of reducing delirium risk.