Geert Guy Georges Morren

Performance evaluation of a tri-axial accelerometry-based respiration monitoring for ambient assisted living

Ambient Assisted Living (AAL) technology is often proposed as a way to tackle the increasing cost of healthcare caused by population aging. However, the sensing technology for continuous respiratory monitoring at home is lacking. Known approaches of respiratory monitoring are based on measuring either respiratory effect, e.g. tracheal sound recording by a bio-acoustic sensor, or respiratory effort, e.g. abdomen movement measurement by a tri-axial accelerometer. This paper proposes a home respiration monitoring system using a tri-axial accelerometer. Three different methods to extract a single respiratory signal from the tri-axial data are proposed and analyzed. The performance of the methods is evaluated for various possible respiration conditions, defined by the sensor orientation and respiration-induced abdomen movement. The method based on Principal Component Analysis (PCA) performs better than selecting the best axis. The analytical approach called Full Angle shows worse results than the best axis when the gravity vector is close to one of the sensor’s axes (<15 degrees). Hybrid-PCA, which is a combination of both methods, performs comparable to PCA. The system is evaluated using simulated data from the most common postures, such as lying and sitting, as well as real data collected from five subjects. The results show that the system can successfully reconstruct the respiration-induced movement, which is necessary to determine the respiratory rate accurately.

Continuous cuff-less blood pressure monitoring based on the pulse arrival time approach: The impact of posture

There is an unmet need for cuff-less blood pressure (BP) monitoring especially, in personal healthcare applications. The pulse arrival time (PAT) approach might offer a suitable solution to enable comfortable BP monitoring even at beat-level. However, the methodology is based on hemodynamic surrogate measures, which are sensitive to patient activities such as posture changes, not necessarily related to blood pressure variations. In this paper, we analyze the impact of posture on the PAT measure and related hemodynamic parameters such as the pre-ejection period in well-defined procedures. Additionally, the PAT of a monitored subject is investigated in an unsupervised scenario illustrating the complexity of such a measurement. Our results show the failure of blood pressure inference based on simple calibration strategies using the PAT measure only. We discuss opportunities to compensate for the observed effects towards the realization of wearable cuff-less blood pressure monitoring. These findings emphasize the importance of accessing context information in personal healthcare applications, where vital sign monitoring is typically unsupervised.

A handheld device for simultaneous detection of electrical and mechanical cardio-vascular activities with synchronized ECG and CW-Doppler Radar

This paper presents a handheld miniaturized sensor embodiment that allows simultaneous measurement of the electrical and related mechanical cardio-vascular activity. Mechanical motion is detected with a continuous wave Doppler radar sensor and interpreted with a synchronously detected ECG. The patients posture and activity is measured using accelerometers. Challenges of the current technical approach are the positioning of the sensors, the influence of posture and the correct interpretation of the signals. The Doppler signals are compared with phonocardiography measurements, with a focus on the challenges of this technique. There is still research in an improved modeling of the sensor setup and signal interpretation required.

Predicting neurally mediated syncope based on pulse arrival time: algorithm development and preliminary results.

Prediction of Neurally Mediated Syncope. Background: Neurally mediated syncope (NMS) is a common disorder that is triggered by orthostatic stress. The circulatory adjustments to orthostatic stress occur just prior to a sudden loss of consciousness. NMS prediction would protect patients from falls or accidents.

Comparison of Respiration Rate Monitoring with a Low-cost Doppler-Radar Sensor and Inductive Thorax-Plethysmography

Reliable remote measurement of respiration rate is an unmet need in clinical and home settings. Nowadays, state-of-the-art measurement of respiration rate (RR) outside the intensive care unit (ICU) is still based on manual counting of the moving thorax by the visiting nurse. New approaches are required in order to get more reliable RR measurements. In this paper, we show that respiration rate monitoring is feasible with low cost continuous wave Doppler-Radar sensors. In conclusion, even spot check measurements with a breath to-breath rate detection are feasible. However, in-depth clinical research in real-life use case scenarios is needed in order to explore the full potential in terms of clinical accuracy and acceptance.