By using wearable sensors developed by H@H, patients’ physio‐pathological cardiovascular and respiratory parameters are acquired and transferred to a remote server. The gathered data are continuously monitored by an automatic processing system and accessible by the medical staff, who can take action in case of necessity.
The involvement of end users’ since the first stages of the project was fundamental for the definition of user requirements. The rationale was to device a flexible and efficient system, taking into consideration both medical and patients’ needs and expectations: for the physicians the telemonitornig system can not be an excessive workload with respect to their regular activities, on the other side, the impact on the patient must be minimal. For these reasons it was developed a system directly integrated with the Hospital Information System (HIS) based on Operating Protocol (OP). The OP consists of a set of actions that the patient must follow during the monitoring. The OP can be customized depending on the patient’s needs and possible disease evolution when necessary. The actions are simple tasks like taking measurements or replying to simple questions.
The system has the typical client/server architecture (see Figure 1). The client side is located at patient’s home and consists of a home gateway and a set of biomedical sensors. The server side, installed at the health service facilities, accepts and processes data from gateways making them available in the Hospital
The Bluetooth technology was chosen for the communication between the sensors and the gateway, due to the wide diffusion of available devices on the market. On the other side, ADSL is the primary transmission channel for data communication between the gateway and the server, while the mobile broadband (GSM/GPRS/UMTS) is used as secondary data channel. Redundant access technologies ensure flexibility and fault tolerance. Furthermore alert messages are sentas SMSs directly to the physician, the patient’s relatives and the caregivers.
The sensing module consists of a set of wireless and wearable sensors to measure the main vital signs.Most significant vital parameters that a CHF patient has to measure are 3 leads ECG, SpO2, weight, blood pressure, chest impedance, respiration and posture. Table 1 shows the features of the sensor devices.
In order to achieve an asset for the implementation and to reduce project risks, the sensing module was divided into two possible configurations: basic and advanced. Basic partitioning is intended as the minimum set of requirements to achieve a complete and useful telemonitoring system. In the advanced configuration additional features were considered in order to enlarge the kind of CHF patients to be enrolled into the telemonitoring program.
The home gateway includes all needed computation and communication resources. The home gateway is responsible of the acquisition, management and forwarding of data on vital signs captured by the biomedical pool of sensors. The acquisition consists of handling all the sensor‐dependent communication protocols in order to receive specific data sets and extract their information content. Data management includes a first level of analysis, consisting of comparisons with thresholds in order to detect anomalies, and the permanent storage of data waiting to be transferred, so that power supply failures do not result in data loss. Collected data are made available also for local consultations. The transmission process allows flooding data into the patient’s Hospital Information System (HIS) record. The following list summarizes all the gateway functionalities:
- Acquisition of data from wireless sensors;
- Data forwarding to a remote collection server using a safe and reliable connection;
- Reminder function, in order to help patient to follow the medical therapy and perform the planned measurements;
- Detection and management of emergency events, both coming from threshold comparison on incoming data or manually submitted by the patient through a selectable list of symptoms;
- Execution of an operating protocol customized basing on patient’s needs;
- System failure detection and management during data acquisition or data transmission to the server;
The gateway device is based on a netbook integrating all the computation and communication resources. In order to simplify the use of the gateway, the original keyboard of the netbook was replaced by a simpler keypad, realized as a membrane keybo.
The server side, installed at the health service facilities, accepts and processes data from the gateways making them available in the Hospital Information System. The H@H server is a web‐based application that receives data from all controlled gateways, providing a detailed process of analysis based on expert systems and finally updating the patient record in the HIS. It exports graphical interfaces that allow the clinicians to request and display: the data of a patient to detect early changes in vital signs, the historical data of a patient, monitoring the progress of the disease and to update the operating protocol. The server platform main functions are related to the patient management since their enrolment when the physician inserts the patient data and configures the OP on the basis of the patient needs. During the monitoring period the server collects patient measurements coming from the gateway. The physician can always access patient clinical data, comparing the patient heath status in different periods by means of measurement trends. The platform also highlights the alarms shown during the monitoring with respect to the OP established for that patient or simply to report symptoms manually indicated by the patient. If necessary, the physician can modify the OP at any time by producing an automatic and transparent update of the gateway.
As data exchanged between the gateway and the server involves the public Internet, the HTTPS protocol uses HTTP messages over an SSL channel established after certificate validation, fitting completely the requirements of confidentiality, authenticity and integrity for the data traffic and the web service interaction.