Remote sensing of patients' vital parameters is an emerging research topic in advanced Countries, due to the increasing percentage of elderly population.
VI-SENS project aims at developing a compact e-Health solution for remote wireless monitoring of key vital parameters, including respiratory activity, heart rate, oxygen saturation, and blood pressure. This will be obtained by combining a small-scale wireless network with a broadband cellular communication system, in order to provide a higher quality health service, both at home and at the hospital.
Wearable sensors will be integrated, using low-cost and low-consumption microcontrollers with a wireless interface, in a network capable of transmitting monitored parameters to a processing unit. This unit provides a graphical user interface to give 1) an immediate overview of the set of the monitored parameters and 2) the ability to automatically forward alarms to doctors and/or healthcare personnel. An innovative feature of the VI-SENS solution is that the patient is free to move during the monitoring and this greatly improves the patient's quality of life.
To validate the system from a practical point of view, the results of the monitoring obtained with the proposed solution will be compared with gold-standard measurements obtained by using conventional instruments (e.g., ECG, spirometer).
A key outcome of this research project is the reduction of the overall costs for the National health care system due to the possibility of avoiding or reducing the patient recovery period at hospital.
The new challenges in WBAN development consist of i) the identification of the most suitable sensors for the detection and measurement of key clinical parameters and ii) the actions needed to create a wireless network, which allows the dynamic integration of multiple sensors based on different technologies.
VI-SENS project will provide substantial improvement of the state-of-the-art by implementing an innovative and complete system for health care, validated through comparison with conventional system. Foreseen improvements are listed below.
1) a wearable version of the ECG (e.g., three-way ECG) based on an instrument amplifier integrating surface-mounted component on a printed circuit board will be developed.
2) blood oxygen saturation is usually detected by pulse oximetry sensors based on the photoelectric reading of the nail-bed at the fingers. In this project, a low cost realization with photodiodes and superficial mounting components directly connected with the WBAN sensor network will be considered.
3) Blood pressure sensors commonly used need at least one band around the patient's wrist and an inflating device: in this research project, a less invasive and directly wearable device will be investigated. The accuracy and effectiveness of a solution based on the correlation of blood pressure with the transit time of the pressure pulse from the heart to a peripheral region of the body will be evaluated.
4) Body temperature can be measured very easily by means of different sensors using different technologies: the class of sensors that combine the greatest efficiency with the lowest cost will be identified.
5) Breath activity monitoring is generally conducted with an inductive or piezoelectric belt system located at the center of the chest, or through an air-jacket in close contact with the skin. In this context, the possibility of achieving a continuous monitoring that does not overly obstruct patient mobility is a very important aspect. In terms of wearable sensors, solutions based on integrated accelerometers and transthoracic impedance can be adopted [13, 14]. The accelerometer solution would also easily detect any falls of the monitored subject and could be used in order to remove motion artifacts [15]. Moreover, a radar system can be implemented by exploiting EM radiation in the microwave range, to monitor physiological activity that involves movement of parts of the body without contact with the subject under observation [16]. The latter may in particular relate to respiratory activity as well as, with a higher level of complexity, to the heart condition [17], that is particularly useful in a hospital environment.
6) The realized sensors will be metrologically characterized, by comparing obtained results with those achieved with conventional system in order to validate the system from a practical point of view so as to provide a reliable system.
7) The sensors network will be implemented through wireless micro-controllers, which will be suitably programmed, taking into account both cost and energy consumption. The data-sink unit will manage data from various sensors, processing data, presenting results on a graphical interface (with the capability to activate an alarm based on thresholds for the various monitored parameters) and, storing and transmitting main parameters. The sensors are integrated, for example using a Texas Instruments (MSP430) micro-controller with wireless interface (CC2500) [18], on a network that can transmit monitored parameters to a base station. The data is processed and stored using a virtual instrument developed in the LabVIEW environment.
The realization of the VI-SENS system is the first step towards the implementation of the data-sink unit and storing data on a smartphone using the computational power of modern processors installed on mobile phones for preliminary processing of detected signals and displaying the most important data on the device screen.
[13] E. Pittella et al, "Combined Impedance Plethysmography and Spectroscopy for the Diagnosis of Peripheral Vascular System", IEEE Int. Symposium on Medical Measurements and Applications, 2017.
[14] E. Piuzzi et al., "Comparison Among Low-Cost Portable Systems for Thoracic Impedance Plethysmography", I2MTC 2017.
[15] E. Piuzzi, et al. "Impedance plethysmography system with inertial measurement units for motion artefact reduction: Application to continuous breath activity monitoring", in IEEE Int. Symp. Med. Mea. App., pp. 386-390, 2015.
[16] E. Pittella et al, "Breath activity monitoring with wearable UWB radars: measurement and analysis of the pulses reflected by the human body," in IEEE Trans. Bio. Eng., 2016 63(7):1447-54.
[17] E. Pittella et al. "Cardiorespiratory Frequency Monitoring Using the Principal Component Analysis Technique on UWB Radar Signal", Int. J. Ant. Prop., 2017.
[18] Texas Instruments, eZ430-RF2500 Development - Tool User's Guide.