Qualitative Simulation in Medical Physiology: A Progress Report

Abstract

This progress report describes the current status of the application of the QSIM qualitative simulation representation and algorithm to mechanisms drawn from medical physiology. QSIM takes a qualitative description of the structure of a mechanism and produces and qualitative description of its behavior. Here we apply it to a set of different, medically realistic examples, to represent the following kinds of knowledge: 1) Physiology: qualitative simulation handles the response of normally-functioning mechanisms for salt and water balance to a variety of different environmental perturbations. 2) Pathophysiology: local changes to the structure describing a normal mechanism produces a structure that accurately describes the pathophysiology of a set of diseases. 3) Abstraction: the knowledge of the complexity of human physiology can only be handled by organizing it hierarchically. A hierarchy according to the temporal scale of equilibrium processes appears to be promising. 4) Cardiology: a complex structure describing maintenance of heart rate and blood pressure was adequately constructed during a short meeting with a set of computationally sophisticated physicians. 5) Future Directions: we can outline some of the representation barriers in the way of capturing a broader range of medical knowledge.