Medical Fuzzy Control Systems with Fuzzy Arden Syntax.

Arden Syntax is a formal language for representing and processing medical knowledge that is employed by knowledge-based medical systems. In HL7 International's Arden Syntax version 2.9 (Fuzzy Arden Syntax), the syntax was extended by formal constructs based on fuzzy set theory and fuzzy logic, including fuzzy control. These concepts are used to model linguistic and propositional uncertainty - which is inherent to medical knowledge - in a variety of clinical situations. Using these fuzzy methods, we can create medical fuzzy control systems (MFCSs), in which linguistic control rules are used and evaluated in parallel. Their results are aggregated so that gradual transitions between otherwise discrete control states are enabled. In this paper, we discuss the implementation of MFCSs in Fuzzy Arden Syntax. Through code examples from FuzzyArdenKBWean, an MFCS for weaning support in mechanically ventilated patients after cardiac surgery, we illustrate the implementation of fuzzy control.