Mechanical Blender Control for Closed-Loop Oxygenation Feedback Control Systems

Premature newborns often suffer from airway disease and require mechanical invasive or non-invasive ventilatory support. This article briefly discusses oxygen therapy options for neonates, including automated FiO2 closed-loop systems. The aim of this study is to construct a computer-controlled system to control a mechanical oxygen-air blender. Such a device will serve as a tool for designing and testing feedback control algorithms for oxygenation with short and clearly described delays of oxygen distribution in the ventilation circuit. The system was implemented using a stepper motor attached to the blender shaft with the design printed on a 3D printer. The motor was controlled through the Arduino platform and the whole system was controlled by software developed in the Matlab Simulink environment. The result of this work is a working system for controlling the oxygen fraction in the inspired mixture on a Sechrist Low Flow mechanical oxygen-air blender. The system was verified under laboratory conditions. The system delay was measured for two different fraction changes and four different flow rates. The results of the laboratory experiment show that the fraction change set on the mechanical blender leads to a shorter delay than on the ventilator used in clinical practice, which uses an electronic blender.