South West Anaesthesia Research Matrix


COMPASS: Cognitive Monitoring in Planned Arthroplasty Surgery - Pilot Study


Post-operative cognitive dysfunction (POCD) is an accepted phenomenon. A perioperative gradient in cognitive trajectory occurs whether patients have a general anaesthetic (GA) or spinal anaesthetic. There is great uncertainty over what causes the trajectory change (e.g. operation itself, exposure to anaesthesia agents, emotional stress, or a combination of factors) or indeed whether the gradient would be there in similar patients without surgery.

About 3000 hip and knee replacements a year are done in the South West Peninsula region of England. These present a planned inflammatory insult with a potentially long lead in period (i.e. patients are on waiting lists for many months). This gives the opportunity to perform cognitive testing at distinct points in the pre-operative period to define the pre-operative trajectory described above and then follow the patients up with further testing in the short- and long-term post-operative period. Furthermore, because the relatively standard nature of these operations, patients will be subjected to a similar inflammatory insult from a surgical point of view.

Cognitive testing can take on many different forms. In-depth neuropsychological testing is time consuming and requires specialist training to deliver. By using a validated online-based cognitive testing tool that takes a short time to deliver and has minimal learning effect, we will be able to test a large number of patients within the time constraints of the patient’s perioperative journey.

SWARM have teamed up with primary care researchers and will be able to perform cognitive testing in a parallel group of patients who are not subjected to surgery.  In essence we aim to collect cognitive data on a large number of patients over a long period of time. Some of these patients will be subjected to surgery. By doing this we will be able to map the cognitive trajectories of these patients, taking into account any other variables during the study period.



- What is the perioperative cognitive trajectory of elderly patients undergoing planned arthroplasty surgery?


- What is the cognitive trajectory of similar patients, over a similar time frame, who are not subjected to surgery?

- What factors influence this cognitive trajectory? – identify and collect candidate covariates (e.g. levels of pain, gender, age band, drugs, comorbidities, presence of chronic pain inflammatory arthritis vs. osteoarthritis)

- Can we predict those at greater risk of significant cognitive decline?

- Is it feasible to track cognitive function before and after surgery in this population?

- Does our chosen tool for monitoring cognition during this perioperative period work (i.e. is it sensitive enough to pick up deflection at time of surgery?)

- Is it feasible to track cognitive function before and after surgery remotely (e.g. with an app) in this population?