Usage of fuzzy systems in critical care environments

In critical care, patients are surrounded by a multitude of devices for monitoring, diagnostics, and therapy. These devices include patient monitors to measure and monitor vital signs, therapeutic devices to support or replace impaired or failing organs and also to administer medications and fluids for the patients. The concept of fuzzy set theory, which was developed by Zadeh (1965), makes it possible to define inexact medical entities as fuzzy sets. It provides an excellent approach for approximating medical text. Furthermore, fuzzy logic provides reasoning methods for approximate inference. Fuzzy relations and fuzzy control were two initiated research areas from the origin fuzzy set theory in the 1970s. Therefore, this approach may be suitable for intensive care medicine, where experience and intuition play an important role in decision-making. This paper surveys the utilisation of the fuzzy set theory of two research areas, i.e. fuzzy relations and fuzzy control in medical sciences in general, as well as on the basis of three concrete medical fuzzy applications.