An image of a heart-lung machine that temporarily takes over the function of the heart and lungs during open-heart surgery by maintaining the circulation of blood and oxygen throughout the body
Press release issued: 26 September 2024
A new intervention which keeps lungs regularly expanding when using a heart-lung machine during heart valve surgery might protect lung function and exercise capacity in adult patients after the operation, a University of Bristol-led clinical trial has found.
The research, published in the Journal of American Heart Association [JAHA] today [26 September], could benefit thousands of similar patients globally undergoing cardiac surgery if adopted by the NHS in the future.
The aim of this National Institute of Health and Care Research (NIHR)-funded randomised controlled trial was to find out if keeping the lungs regularly expanding, known as low frequency ventilation (LFV), during heart-lung machine in patients undergoing heart valve surgery could be linked to better postoperative lung function and exercise ability.
The study also wanted to find out the feasibility and safety of keeping lungs expanding during heart-lung machine, whether it affected surgery and if any specific change in biomarkers of lung injury could be identified and therefore targeted in future studies to develop a lung protection drug.
Current practice involves the lungs being left collapsed when using heart-lung machine during heart surgery, which is already known to trigger lung damage and reduced function after an the operation. These complications are associated with a longer hospital stay and a greater risk of mortality in high-risk cases.
Sixty-three patients with severe mitral or aortic valve disease were randomised to either LFV or usual care with collapsed lungs. The average age of the patients was 66.8 year, 30 per cent were women, and participants were followed up for six to eight weeks after discharge.
The trial found it was feasible and safe to use LFV when using heart-lung machine in patients undergoing heart valve surgery. In addition, it showed preserved lung function and patients walked significantly longer during the six minutes walking test before discharge compared to those treated with usual care. Also, LFV triggered a change to a specific biomarker/mediator (sRAGE) of lung function, which could be targeted in future studies.
Raimondo Ascione, Professor of Cardiac Surgery and Translational Research and Director of TBRC at Bristol Medical School: Translational Health Sciences (THS), NHS Consultant Cardiac Surgeon, Chief Investigator and senior author on the paper, said: “Our randomised clinical phase II trial has found using low frequency ventilation (LFV) during heart-lung machine in the targeted heart valve surgery patients is viable, safe and effective”.
“Our next step will be to undertake a larger national phase III trial in a large number of patients with severe heart valve disease. If the future larger trial confirms the results of this study then this treatment could be adopted in the NHS as routine practice and could lead to significant cost savings.
“Also, future mechanistic studies on sRAGE might lead to the development of a new lung protection drug that could be given to all patients undergoing cardiac surgery using a heart-lung machine.”
The trial was conducted at the Bristol Heart Institute, sponsored by the University Hospital Bristol and Weston NHS Foundation Trust (UHBW), and supported by the National Institute of Health Research (NIHR) Bristol Biomedical Research Unit (BRC). The trial, data collection and data analysis were managed independently by the Bristol Trials Centre, a UKCRC registered clinical trials unit.
Paper
‘Low Frequency Ventilation during cardiopulmonary bypass to protect postoperative lung function in cardiac valvular surgery: the PROTECTION phase II randomised trial’ by Raimondo Ascione et al. in Journal of American Heart Association [JAHA] [open access]
Further information
About cardiopulmonary bypass (CPB)
Cardiopulmonary bypass (CPB) or heart-lung machine also called the pump or CPB pump is a machine that temporarily takes over the function of the heart and lungs during open-heart surgery by maintaining the circulation of blood and oxygen throughout the body.
About the National Institute for Health and Care Research
The mission of the National Institute for Health and Care Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:
- Funding high quality, timely research that benefits the NHS, public health and social care;
- Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
- Partnering with patients, service users, carers and communities, improving the relevance, quality and impact of our research;
- Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
- Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
- Funding applied global health research and training to meet the needs of the poorest people in low and middle income countries.
NIHR is funded by the Department of Health and Social Care. Its work in low and middle income countries is principally funded through UK Aid from the UK government.
About the Bristol Heart Institute
The Bristol Heart Institute is a Specialist Research Institute at the University of Bristol. We are a world-leading centre for translational cardiovascular research and the leading academic cardiac surgery centre in the UK.
We specialise in preventing, predicting, detecting, reducing and treating cardiovascular disease, bringing together scientists and clinicians from across the University and the NHS in Bristol, and training the next generation of cardiovascular scientists and clinical academics.
We harness the expertise of Bristol's translational science community and benefit from close proximity to outstanding medical facilities, such as the Bristol Heart Institute Clinical Facility at University Hospitals Bristol & Weston NHS Foundation Trust (UHBW).
In this way, we make the journey from bench to bedside, from scientist to patient, in our fight against heart disease, still the UK’s number one killer.
About the National Institute for Health and Care Research Bristol Biomedical Research Centre (NIHR Bristol BRC)
The National Institute for Health and Care Research Bristol Biomedical Research Centre’s (NIHR Bristol BRC) innovative biomedical research takes science from the laboratory bench or computer and develops it into new drugs, treatments or health advice. Its world-leading scientists work on many aspects of health, from the role played by individual genes and proteins to analysing large collections of data on hundreds of thousands of people. Bristol BRC is unique among the NIHR’s 20 BRCs across England, thanks to its expertise in ground-breaking population health research.
About Bristol Trials Centre
Bristol Trials Centre (BTC) is a UKCRC-registered Clinical Trial Unit. We offer a wide range of expertise in trials methodology, study design, study management, statistical analyses and data management, including bespoke database design.
BTC is hosted in the University of Bristol’s Faculty of Health Sciences, an internationally recognised centre of excellence for population health research and teaching.
Follow on Twitter: @BrsTrialsCentre
