The Global Architecture of Interrelated Devices

In this attempt to learn more about the standards and the standardization process, let’s take a closer look at the architecture of what is referred to as “ecosystem” of devices so as to better understand the capabilities and requirements a standard should satisfy.

This architecture puts forward five different devices classes (PAN, LAN, Application Hosting, WAN and Health Record Device) and four interfaces. Maybe it’s not quite obvious, but these interfaces actually make up the concept of interoperability between devices; based on how devices are able to connect across these interfaces, the certification is issued or not.

The PAN (Peripheral Area Network) interface makes the connection between PAN devices (sensors or actuators) and AHD (Application Hosting Devices) like mobile phones, PDAs or personal computers. This interface has a lower layers level, also known as the transport level (encompassing the classic open-systems interconnection layers 1–4) and an upper layer level – the data level encompassing the classic OSI layers 5–7. For transportation, both wired and wireless methods are accounted for in the form of Bluetooth and USB. The PAN interface upper layers are implemented using the ISO/IEEE 11073-20601 Optimized Exchange Protocol, which leverages work from the ISO/IEEE 11073 Medical Device Communications working group.

The LAN (Local Area Network) interface connects a LAN device with an AHD. The LAN device can has a proxy function implemented which allows it to access the information of a PAN device through a network. A LAN device can also implement sensor and actuator functionality directly. Therefore, the same data model can be implemented in both the PAN and the LAN interface (the ISO/IEEE 11073-20601 data model), which is a milestone in the interoperability quest.

The WAN (Wide Area Network) interface links an AHD to a WAN device – a device which gathers information from one or more AHD and can perform other forms of processing as well, like a heart monitoring program hosted on a network server. The data format on the WAN interface upper layer is also compatible with the data format on the LAN upper layer, giving once again way to interoperability.

The xHRN (Electronic/Personal Health Records Network) interface deals with the connection between user services (WAN Devices carrying out services like weight loss and disease management), and electronic/personal health records (Health Record Devices). In order to ensure the connection between WAN devices and xHR systems, Integrating the Healthcare Enterprise (IHE) Cross-Enterprise Document Reliable Interchange (XDR) profile was chosen. On top of this profile the Health Level 7 (HL7) Personal Health Monitoring (PHM) Report document format was chosen to ensure consistent data encoding.

Now, here comes the dilemma: since electronic health records originate from hospitals health data archives, the patient has no access or control rights. Patients can be given the right to access their own personal data in electronic format, but that means a huge amount of work for most hospitals still keep their files on paper. Commendable initiatives from Microsoft HealthVault or Google Health allow patients to collect and store their own health information and have full control over it. However, these systems, also called personal health records (PHR), should also ensure the security of this kind of information, since a personal computer as storage medium is highly prone to virus attacks or digital theft. In addition, let’s think twice about the reasons companies like Google and Microsoft who already have monopolistic control in their market would like to do apparently a totally altruistic deed for that matter. I would say they are just trying to grow roots in other areas and make our lives even more dependent on their products, chaining us irreparably to their reign.