HUMAN PHYSIOLOGY AND PERFORMANCE LABORATORY
Primed Risk
A five-year cross-sectional observational study of older patients presenting for major surgery. The goal of this study is to assess the predictors of poor postoperative cognitive outcomes in older patients. In addition to epidemiological information derived from being embedded within a larger cognitive outcomes epidemiology study (DELPHIC), preoperative CSF and blood samples are collected to assess for biomarkers of neuroinflammation and blood-CSF gradients of such. Intraoperative predictors of poor neurological outcome such as hypotension, excessive anaesthesia, reduced EEG activity are also being assessed for impact on long term outcomes.
What is postoperative Delirium?
Delirium, a syndrome that can cause disturbances in consciousness and thinking, is a common response to major surgery. There is evidence that the amount of stress caused by surgery needed to trigger delirium is lower in people who are at increased risk. This means people who are frail or have more medical problems are at greater risk. Delirium is consistently associated with a range of adverse outcomes: increased length of stay, admission to critical care, institutionalisation and subsequent cognitive impairment and dementia risk.
A need to understand the Mechanisms
The mechanisms that underpin perioperative delirium and its consequence need to be studied. Certain pathways may account for the development of delirium itself, while others may drive longer-term cognitive outcomes such as progression of dementia. The degree to which these interact is largely unknown. One approach to investigate the basis of delirium has been to use cerebrospinal fluid (CSF) samples obtained through regional anaesthesia.
Modifiable risk factors
Potential modifiable risk factors for delirium around surgery include depth of anaesthesia, intraoperative hypotension and cerebral oxygenation. These measures have been investigated separately and together in various surgical contexts but have not been extensively correlated with CSF biomarkers and longer-term outcomes.
Our aim
We aim to understand mechanisms underlying perioperative delirium by assessing CSF and blood-based biomarkers of acute and chronic brain injury. Through pre- and post-operative follow-up, the cross-sectional and longitudinal significance of delirium and its biomarkers can be assessed. We will include intra-operative fronto-temporal processed EEG and functional near-infrared spectroscopy with perioperative delirium and subsequent cognitive decline. Together, we envisage these findings will lead to better ways of predicting delirium and long-term cognitive outcomes.