Extensions to the Rule-Based Formalism for a Monitoring Task

The Ventilator Manager (VM) program is an experiment in expert system development that builds on our experience with rules in the MYCIN system. VM is designed to interpret on-line quantitative data in the intensive care unit (ICU) of a hospital. After a major cardiovascular operation, patient often needs mechanical assistance with breathing and is put in the ICU so that many parameters can be monitored. Many of those data are relevant to helping physicians decide whether the patient is having difficulty with the breathing apparatus (the ventilator) or is breathing adequately enough to remove the mechanical assistance. The VM program interprets these data to aid in managing postoperative patients receiving mechanical ventilatory assistance. VM was strongly influenced by the MYCIN architecture, but the program was redesigned to allow for the description of events that change over time. VM is an extension of a physiologic monitoring system1 and is designed to perform five specialized tasks in the ICU: