plate in the broadest sense is simply a constraint on a more generic model that permits, among other things, the definition of a complex object, such as a blood chemistry measurement or a heart murmur (Hammond, 2002). For example, an HL7 message format for laboratory observations may specify that the data elements for a complete blood count test must include measurements for hemoglobin, hematocrit, and platelets. The design of constraints will be left to the discretion of health care organizations and providers, as HL7 provides the mechanisms and technical specifications for their use. Clinical templates will be important in the development of electronic structure for the collection and analysis of clinical and patient safety data, particularly those related to the 20 priority areas identified by the Institute of Medicine (2003).
The medical device industry is well versed in developing user interfaces that make devices safer, more effective, and easier to use by employing a voluntary standard for human factors design established by the Association for the Advancement of Medical Instrumentation (AAMI) and approved by the American National Standards Institute (ANSI) (Association for the Advancement of Medical Instrumentation, 2001). This standard—the ANSI/ AAMI HE74 Human Factors Design Process for Medical Devices—establishes tools and techniques to support the analysis, design, testing, and evaluation of both simple and complex systems; these tools and techniques have been applied for many years in the engineering of consumer products, military applications, aviation equipment, and nuclear power systems. Consideration of the HE74 standard may provide insight into the processes employed for designing and developing user-friendly clinical information systems, including electronic patient safety reporting systems.
An overview of the human factors engineering process that governs HE74 is provided in Figure 4-2. The specific activities at each step in the cycle vary with the particular development effort (Association for the Advancement of Medical Instrumentation, 2001). The cycle in Figure 4-2 emphasizes the iterative nature of the development process, whereby the outcomes (i.e., outputs) of one step provide input to the next step, but also, as needed, the output of some steps feeds back to previous steps. Although entry into the cycle can begin at any step, involving users at the early stages of development is critical. Once user needs and the consequent concept for the device (system) have been well defined, it becomes possible to address the design criteria/requirements that define the operating conditions, user