Novel engineering solutions for easy and accurate manual blood pressure measurement

Clinical need High blood pressure is one of the leading cardiovascular risk factors for coronary artery disease, congestive heart failure, renal disease and stroke. It is a contributory factor in 30% of all deaths in the UK, with 4 million NHS bed days annually. A major review in the Journal of the American Medical Association (JAMA) estimated that a 5 mmHg error would result in 21 million Americans being denied treatment or 27 million being exposed to unnecessary treatment, depending on the direction of the error. The importance of blood pressure measurement is without doubt, but it is still one of the most poorly performed diagnostic measurements in clinical practice.Blood pressure measurement Manual auscultatory blood pressure measurement has changed little over the past 100 years. It contains three main elements: a cuff, pressure display and stethoscope. The cuff encircles the upper arm to occlude the brachial artery, and is deflated with a control, allowing the blood to flow again as the pressure is released. In spite of, or perhaps because of, its simplicity, it is still the most accurate measurement technique. The current International Standards shows that automated blood pressure devices can have an inaccuracy in comparison with manual measurement of +/- 16 mmHg (95% confidence interval), which is not adequate for clinical diagnostic decisions. Guidelines from the three main clinical European Societies addressed the need to re-establish manual measurement. This was further reinforced by the UK Department of Health when they issued a Medical Device Alert, requiring all clinical users to have access to a manual device so that accurate measurements are taken when required.The research problem Manual measurement relies highly on the skills of the trained users to identify the Korotkoff sounds associated with systolic and diastolic blood pressure (SBP and DBP) using the stethoscope. The proposed research will develop novel engineering solutions to achieve easy and accurate manual blood pressure measurement. SME collaboration The applicant is Chair of the British Standards Institute committee on sphygmomanometers and represents the UK on the International Standards Committee (joint International Organization for Standardization, and International Electrotechnical Commission) and has been active in this field for over 25 years. Our Newcastle research group has worked with the only UK manufacturer of sphygmomanometers, the family firm AC Cossor & Son (Surgical) Ltd, cooperating closely and successfully to produce the novel electronic patented Accoson greenlight 300 with a very clear display to make the reading of the measurement much easier, and to display the cuff deflation rate(also patented). These features have produced dramatic improvements, and have been led by UK industry. The only feature still to be improved is the use of the stethoscope. This is complex and requires much basic research before any new prototype device could be proposed. Our proposal to this Healthcare Partnerships will tackle this problem.Our goal In this proposal we will research techniques to aid and improve the identification of systole and diastole in manual blood pressure measurement. This research will study our existing unique database of recorded Korotkoff sounds, develop algorithms to help accentuate key differences in Korotkoff features at systole and diastole, set up a laboratory system to allow investigation of other sensors, investigate more discriminatory ways of presenting the sensor output, and prospectively evaluate the techniques proposed. There is enormous scope for improving this 100 year old acoustic technique.

This proposed research project to develop novel engineering solutions for easy and accurate blood pressure measurement is not only designed to have an immediate impact within academia, but will have wide influence on patients, clinicians, medical devices industry, international standard bodies, charitable bodies, as well as the NHS and UK Government and the UK general public. In detail: Patients - Patients will benefit most as their blood pressure will be measured more accurately than is presently the case. This will lead to earlier clinical diagnosis and better treatment and management of hypertension. Clinicians - GPs and hospital clinicians and nursing staff will benefit from easier measurement, encouraging them to use the manual measurement. Industry - The blood pressure device industry will benefit from the improvement of the technique. The technique being researched could be implemented in any manual device, and so could be licensed across the industry. International Standards Bodies - Research will lead to improved measurement techniques and provide a more accurate reference technique for updating the current International Standards of validation and evaluation method for automated blood pressure devices. Charitable bodies - Various national and international charities such as the British Hypertension Society (BHS), British Heart Foundation (BHF), and European Society of Hypertension (ESH) can use our research outcome as evidence to further deliver and promote their aims. NHS and UK Government - This technique would help reduce the tremendous health burden of hypertension. It will help place the UK in a world leading position in this technique and contribute significantly to enhancing UK economic growth. UK public in general - The research findings will significantly improve medical care to the public in general. It will further raise awareness of the importance of blood pressure measurement.