Non-invasive blood pressure monitoring with heartbeat accuracy

January 11, 2013 // By Julien Happich
After having endured hospitalization, cardio patients usually go through a drawn out rehabilitation phase in the form of outpatient treatment. As part of the rehabilitation measures, patients are often prescribed physical activity under the supervision of a physician.

In sports groups of up to 60 participants, patients perform exercises appropriate for their medical conditions. During physical activity it is necessary to monitor the vital functions of all the patients. This data is then used to determine the correct intensity of the exercises, but also to prevent overexertion. The constant measurement of the parameters is especially important here. Along with heart rate, blood pressure is of particular interest in evaluating the cardiovascular system.

Up until now there has been no suitable way of determining blood pressure constantly that was both non-invasive and with heart beat accuracy. In order to solve this problem, the Fraunhofer Institute for Photonic Microsystems IPMS has developed a wireless based system that can simultaneously measure the blood pressure of all participants during their exercise sessions. With the software supported display of all measurements, the exercise instructor maintains a constant overview and is able to quickly recognize anomalies in the cardiovascular parameters of the individual patients should they occur.

The system developed by Fraunhofer IPMS consists of a central physician PC and two sensor units per patient. Each participant wears a chest strap to record the ECG and a headband for pulsewave measurement. The solution lies in the ability to determine blood pressure non-invasively with pulse transit time (PTT). This is determined from the incoming measurements from the headband and the chest strap. All of the measurements are transmitted wirelessly to the central physician PC. The PC runs software that processes and evaluates the data from all of the sensors. The participants' heart rate, systolic and diastolic blood pressure and their fluctuations are later displayed on a monitor for a selected time frame. When predetermined limits are exceeded, an alarm is triggered. All of the electronic components are integrated into a textile structure which can be adjusted to fit various body sizes and forms so that the patient’s movement will at no time be limited or