Late Breaking Abstract - Generating realistic flow limitation patterns using a closed-loop model controlling a mechanical valve

<bold>Background:</bold> Starling resistors are used to simulate upper airway collapse in bench test scenarios assessing ventilatory devices. Setting resistors up to create a desired pattern is complex and can include adjusting length, elasticity, and wall strain of the elastic segment. This poses significant challenges to accurately reproduce various patterns, especially due to aging of the elastic material. <bold>Objective:</bold> To develop a setup that flexibly reproduces different realistic flow-limitation waveforms using a closed-loop mathematical model and a mechanical valve. The setup is parametrized at runtime without the need to disassemble the test bench. <bold>Methods:</bold> Inspired by a starling resistor, a model was developed, which takes airway pressure and flow as input signals. The model was implemented on a microcontroller operating a valve. This setup was connected to an artificial lung (ASL 5000) in lung-model mode. Parameters for the model, (e.g. critical pressure) were determined to obtain different flow-limitation waveforms. Additionally, in-silico simulations were conducted to investigate the influence of upper airway dynamics on the generated flow patterns beyond hardware limitations. <bold>Results:</bold> During physical and in-silico simulations, various types of flow-limitation waveforms (e.g. flattening) were generated. Depending on parameter setting, realistic behavior, such as negative effort dependence, was reproduced. <bold>Conclusions:</bold> This work has shown that it is possible to reproduce physiologically plausible flow-limitation waveforms in a closed-loop simulation setup. The proposed model enables a flexible simulation of different flow-limitation scenarios through live parametrization of a bench test.