Control of the fraction of inspiratory oxygen of a decentralized breathing gas source

Abstract

Abstract: This contribution proposes a method of controlling the fraction of inspiratory oxygen (FiO2) by actuating the outflow of a commercial concentrator through the attachment of a stepper motor. The idea is to include available devices as such that breathing gas with an increased fraction of inspiratory oxygen (FiO2) can be provided in case a vast amount of patients need to be ventilated without sufficient infrastructure regarding high pressure supply lines or the distribution of oxygen bottles. The designed system was identified regarding its static and dynamic behaviour which was then used to tune a PI controller. The dosage was tested with the concentrator’s outflow only and on the other hand in combination with a simple ventilation mode (VCV) in which a parallel blower supplied surrounding air into the dosage chamber as well. The results showed that the working principle fulfills its purpose, however further optimization is needed, especially for the systems response speed and precision.