Abstract
Current advances in sensing devices and wireless technologies are providing a high opportunity for improving care quality and reducing the medical costs. This chapter presents the architecture of a mobile healthcare system and provides an overview of mobile health applications. Furthermore, it proposes a framework for patient monitoring that performs real-time stream analysis of data collected by means of non-invasive body sensors. It evaluates a patient’s health conditions by analyzing different physiological signals to identify anomalies and activate alarms in risk situations. A risk function for identifying the instantaneous risk of each physiological parameter has been defined. The performance of the proposed system has been evaluated on public physiological data and promising experimental results are presented. By understanding the challenges and the current solutions of informatics appliances described in this chapter, new research areas can be further investigated to improve mobile healthcare services and design innovative medical applications.
TopMobile Health System Architecture
The overall architecture of a mobile health system (see, e.g., [Jones, 2006], [Apiletti, 2006]) is shown in Figure 1. It may be composed by some or all of the following subsystems:
Figure 1. General architecture of a mobile health system
Each individual (patient) wears a set of sensors that monitor physiological signals. These sensors, which are integrated into non-invasive objects, are connected to the user’s device (also called personal server, e.g., a smart phone or a PDA) through a short range communication link (e.g., Bluetooth), in charge of transmitting recorded signals. The device may locally elaborate the incoming signals to immediately detect life-threatening situations. The set of wearable sensors and the mobile device form the body sensor network.
The second subsystem allows the communication between the user’s mobile device and the elaboration centre, possibly by means of an infrastructure node (e.g., an access point). Communication with the elaboration centre may occur when recorded data is transferred to the system for off-line analysis or to backup/gather historical data. Finally, through the GSM network an alert message may be sent to the closest medical centre to request prompt medical intervention when a risk situation is detected.
A more detailed description of each subsystem is presented in the following.
Key Terms in this Chapter
Bluetooth: Radio standard and communications protocol (i.e., IEEE 802.15.1 standard) for wireless personal area networks characterized by short transmission ranges (1-100 m). It has been designed for low power consumption and it is based on low-cost transceiver microchips in each device.
Saturation of Peripheral Oxygen (SpO2): It measures the percentage of haemoglobin binding sites in the bloodstream occupied by oxygen. It is usually evaluated by a non-invasive pulse oximeter which relies on the light absorption characteristics of saturated haemoglobin to give an indication of oxygen saturation
Global System for Mobile Communications Gsm (Originally from Groupe Spécial Mobile): It is the most popular standard for mobile phones in the world. GSM is a cellular network which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM networks operate in four different frequency ranges and use a variety of voice codecs
Personal Digital Assistant (PDA): It is a handheld computer, also known as pocket or palmtop computer. A typical PDA has a touch screen for data entry, a memory card slot for data storage, IrDA and USB ports for connectivity. Wi-Fi and Bluetooth are often integrated in newer PDAs.
Smartphone: It is a full-featured mobile phone with personal computer like functionalities. Applications for enhanced data processing and connectivity can be installed on the device, and may be developed by the user. Smart functionalities may include miniature keyboard, touch screen, operating system, and modem capabilities.
Heart Rate: (HR): The heart rate describes the frequency of the cardiac cycle. It is a vital sign and usually it is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as “beats per minute” (bpm). When resting, the adult human heart beats at about 70 bpm (males) and 75 bpm (females), but this rate varies among people.
ABPdias: Diastolic Arterial Blood Pressure. Diastole is the period of time when the heart relaxes after contraction. The diastolic pressure is the lowest pressure in the cardiac cycle (i.e., in the relaxing). A typical value for a healthy adult human is approximately 80 mmHg.
ZigBee: Name of a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks. The ZigBee 1.0 specification was ratified on December 14, 2004 and is available to members of the ZigBee Alliance.
ABPsys: Systolic Arterial Blood Pressure. Systole is the contraction of the chambers of the heart, driving blood out of the chambers. The systolic arterial blood pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle (i.e., in the contraction). A typical value for a healthy adult human is approximately 120 mmHg.
Wireless Local Area Network: (WLAN): It is a network which uses a modulation technology based on radio waves to enable communication among devices in a limited area, without using wires. Among benefits of WLAN there are: convenience, cost efficiency, mobility, expandability, and ease of integration with other networks and network components.