An integrated system to compensate for temperature drift and ageing in non-invasive blood pressure measurement

Abstract

Accurate blood pressure (BP) measurement is critical in the diagnosis and management of hypertension, as an error of 5 mmHg can be responsible for doubling or halving the number of patients diagnosed with this condition. Sensor drift, due to changing environmental factors, such as ambient temperature, can contribute to the inaccuracy. Studies also show that long term sensor drift, or ageing, can lead to a change of almost 9 mmHg in blood pressure measurement during the first three months of usage. In this work, a new stage is added to current cuff-based BP devices. This stage is responsible for adjusting the pressure reading before displaying it to end users, by monitoring changes in the ambient temperature and sensor ageing and adaptively compensating for these inaccuracies. These sources of inaccuracy are suppressed using algorithms based on Empirical Mode Decomposition (EMD), which has the feature of removing unwanted noise components without affecting the phase or the frequency distribution of the measured signal.