Transforming the way we measure blood pressure

CASPro, a new blood pressure monitor, could transform how this crucial bodily parameter is measured. The developers say it gives a more accurate reading than current methods by using central aortic systolic pressure (CASP).

CASP is blood pressure at the base of the aorta (the largest artery in the body) and measures the blood as it emerges from the heart. Currently blood pressure is normally measured using the brachial artery in the upper arm, known as the brachial pressure.

Although this is a convenient place for measurements to be taken, it is not the most accurate as it may not reflect the pressure of the larger blood vessels closer to the heart. Normal brachial blood pressure ranges from 120/80 to 140/90 millimetres of mercury (mmHg), a standard measure of pressure. In most people, however, the CASP is usually lower than the brachial pressure, sometimes dropping by as much as 30mmHg.

CASPro uses a sensor on the wrist, called BPro by its inventors, to record a pulse wave which shows the increase in pressure through the arteries with each contraction of the heart. Mathematical modelling software called A-Pulse is then used to calculate the CASP. Patients have found the sensor easy to use as it is worn like a watch.

A version named CASPal allows patients to monitor their blood pressure easily at home. Previous methods of measuring the CASP are invasive and involve inserting a catheter tube into the base of the aorta via an artery in the thigh or the chest. Therefore this new technology is a more comfortable way to monitor hypertension, high blood pressure.

CASPal and CASPro have been approved for use in the USA by the Food and Drug Administration and by the European Medicines Agency for use in the EU including the UK.

The project is a collaboration between the University of Leicester and Singapore medical devices company HealthSTATS International, which specialises in new approaches to monitoring and managing hypertension.

Professor Williams of the University of Leicester’s Department of Cardiovascular Sciences said: “Critical to the success of this project has been the synergies of combining clinical academic work here with HealthSTATS and their outstanding medical technology platform in Singapore. This has been the game-changer and I really do think this is going to change clinical practice.”

This new product could be aid management of hypertension and reduce the risk of complications associated with it such as heart attacks and stroke. The ability to measure blood pressure of the aorta is important as it is closer to the heart and brain. These are areas where hypertension can cause the most problems.

The new technology will identify those who have a higher CASP, thereby targeting treatment to high risk heart disease patients. This is especially important in younger people, as their brachial pressure is usually very different from their CASP.

Image from Harmid

Williams, B., Lacy, P., Yan, P., Hwee, C., Liang, C., & Ting, C. (2011). Development and Validation of a Novel Method to Derive Central Aortic Systolic Pressure From the Radial Pressure Waveform Using an N-Point Moving Average Method Journal of the American College of Cardiology, 57 (8), 951-961 DOI: 10.1016/j.jacc.2010.09.054