Robust Closed-Loop Control of the Inspired Fraction of Oxygen for the Online Assessment of Recruitment Maneuvers

Recruitment maneuvers are commonly used in patients suffering from acute respiratory failure. A continuous measurement of PaO₂ would help to assess the proper execution of such maneuvers. Unfortunately, there are only static offline measurement devices available. However, if the oxygen saturation would be held close to a fixed set-point of 90-92% by automatically adjusting the FIO₂ parameter of the mechanical ventilator, the latter would be inversely related to PaO₂. In this work, a new robust PID control system is presented, which accounts for model uncertainty in a modified Smith predictor approach. The controller was tested using a computer model of respiratory failure. The model parameters were identified in an animal experiment with pigs.