Modern medical environments have seen an increase in technological complexity and
pressures of handling more patients with fewer resources, resulting in higher demands
on medical practitioners. Medical informatics designers will have to focus on the
problem of organizing medical information more effectively to enable practitioners
to cope with these challenges. This article addresses this research problem for the
particular area of medical problem solving in patient care. First, we describe a traditional
modeling approach for medical reasoning used as a basis for developing some decision
support systems. We argue these models may be faithful to what is known about biomedical
knowledge, but they have limitations for human problem solving, especially in unanticipated
situations. Second, we present an ontological framework, known as the abstraction
hierarchy (Rasmussen, IEEE Trans. Man. Cybernetics 15 (1985) 234-243), for integrating
patient representations that are faithful to existing biomedical knowledge and that
are consistent with what is known about human problem solving. Through an example
of a critical event in the operating room, we reveal how this framework can support
medical problem solving in unanticipated situations. Third, we show how to use these
representations as a frame of reference for mapping medical roles, responsibilities,
sensors, and controls in an operating room context. Finally, we provide some insight
for medical informatics designers in using this framework to design novel training
programs and human-computer displays.