Scientific title:
Optimisation and application of methods to assess cerebrovascular reactivity in clinical practice, cohorts and interventional trials
University of Oxford
Principal investigator:
Dr Osian Llwyd
Grant value:
Research ID:
SA PDF 21\100029
Research area:
Start date:
Monday 20 September 2021
End date:
Saturday 19 September 2026
5 years
Year awarded:

Why is this research needed?

Stroke strikes every 5 minutes in the UK. It changes lives in an instant, and research is needed to improve how we prevent stroke.  

Impaired control of this blood flow is associated with chronic injury to small blood vessels in the brain. This problem contributes to 30% of strokes and 40% of dementia. No treatments are available due to difficulties in performing assessments of blood flow to the brain. This stands in the way of patient care as well as the research needed to find treatments. 

The researcher, Osian, who you can read about below, is developing a new way to detect abnormalities in blood flow to the brain. This could improve identification and treatment of the problem and lead to improvements in stroke prevention and treatment. 

What is this research aiming to do?

This study aims to test different methods of measuring how blood flow is controlled by the brain and to develop an optimal technique for future studies and use with patients.

An ultrasound scan can be used to detect what is happening inside the body. They are frequently used in healthcare, for example, to monitor pregnancy. This research aims to find out how blood flow to the brain can be accurately measured using ultrasound of an artery that runs from the heart to the brain. During the ultrasound assessment, patients are asked to do a range of different breathing manoeuvers. 

This research builds on Osian’s previous work that was funded by the Society for Vascular Technology that suggests this assessment could be used widely in hospitals.  This research will help develop and improve this type of assessment to increase the likelihood of it being used in hospitals.  

By using this assessment in patients who have had a stroke and combining it with information in ongoing studies, Osian aims to understand how abnormalities in the control of blood flow to the brain could lead to stroke.

How will the research do this?

Firstly, Osian will use the assessment with 60 stroke survivors. He will compare measurements of blood flow in the neck to measurements of blood flow within the brain. This can find out if ultrasound assessment in the neck accurately indicates blood flow in the brain. 

He will then use ultrasound assessment in 50 people with small vessel disease, a condition that can cause stroke and chronic injury to the brain. He will improve the assessment for use in hospitals by testing different techniques and breathing manoeuvres. 

Osian has done calculations to find out the number of participants needed in the studies depending on the study aims, and the type of information and analysis required to achieve the aims.  

Finally, Osian will use information about how blood flow is controlled to the brain in numerous patients in ongoing studies. Using a large amount of information will help understand the importance of blood flow abnormalities in indicating that patients have damage to blood vessels in the brain, and are at risk of stroke.

What benefits could this have?

This research can have many benefits. It can have benefits for: 
  • People affected by stroke, health care professionals and healthcare services 
This type of assessment could make it easier to detect people that are at risk of stroke, so they can get better treatment and support to reduce their risk and avoid potentially devastating impacts of stroke.  
It can help healthcare professionals and healthcare services to improve treatment by making it easier to detect people at risk of stroke. 
  • Research 
By using this assessment, researchers could more easily understand the role of abnormalities in blood flow to the brain as a cause of stroke, and how to treat this to find new ways to prevent damage to the brain.  
Osian said: “I am hopeful that by developing further this type of assessment that is practical for use in busy hospitals and clinics, as well as collecting evidence from trials with patients, the results of my research could help provide a new solution to identify patients at risk of stroke that can be used in health services relatively soon.” 

About the researcher

Osian has worked at universities across the UK, including completing his PhD at Cardiff University. He is also trained as a clinical vascular scientist in the use of ultrasound to diagnose vascular disease. 

At the University of Oxford, Osian works with leading researchers in the field that have been recruiting patients with vascular disease since 2002 and who are translating research findings into beneficial changes in treatment and care for patients.

Osian said: “During this fellowship, I’m looking forward to improving stroke research in my unique position working across teams from the hospital bedside to the laboratory. There is a huge need for new and better techniques to the ones developed thirty years ago that can detect problems with blood vessels in the brain. Better detection of these problems can reduce the devastation to lives caused by stroke and dementia."

Research terms and definitions

These terms are often used in research like Osian’s to describe aspects of stroke prevention and care.  

Cerebrovascular reactivity. This is a method that tests the response of blood vessels to an activity, such as a breathing manoeuvre. Ultrasound assessment can measure this response.

Small vessel disease. This is a disease that affects small blood vessels in the brain that can lead to stroke and dementia.