Fuzzy and conventional control of high-frequency ventilation

Abstract

A high-frequency ventilator was developed, consisting of a single-phase induction motor, an unbalanced mass and a mechanical vibration system. Intermittent positive pressure respiration was combined with high-frequency ventilation to measure end-tidal pCO2. Hysteresis was observed between the rotational frequency of the high-frequency ventilator and end-tidal pCO2. A fuzzy proportional plus integral control system, designed on the basis of the static characteristics of the controlled system and a knowledge of respiratory physiology, successfully regulated end-tidal pCO2. The characteristics of gas exchange under high-frequency ventilation was approximated by a first-order linear model. A conventional PI control system, designed on the basis of the approximated model, regulated end-tidal pCO2 with a performance similar to that of the fuzzy PI control system. The design of the fuzzy control system required less knowledge about the controlled system than that of the conventional control system.

An intelligent ventilation and oxygenation management system in neonatal intensive care using fuzzy trend template fitting

“…Previous studies were aimed to design systems to guide the ventilation therapy by monitoring the patient's vital signs and suggesting direction of therapy (Wolf et al 1996, Sittig et al 1992. Others modelled parts of the ventilation management process, such as FiO 2 -SaO 2 (fraction of inspired oxygen-oxygen saturation) controllers (Sun et al 1994), controlled pressure support (Nemoto et al 1999) and maintained pCO 2 (end-tidal carbon dioxide pressure) (Noshiro et al 1994).…”