Response by an automated inspired oxygen control system to hypoxemic episodes: assessment of damping

Anotace: Manual titration of inspired oxygen necessary to adequately respond to respiratory fluctuations of the neonate is a challenging task. Furthermore exposure to high and low levels of oxygen saturations are associated with significant morbidity and mortality. Ventilators that automatically control inspired oxygen based on pulse oximeter signals are becoming available, and seem to be safe and effective when compared to manual control. However the potential to overshoot in response to a hypoxemic episode, thus causing excess hyperoxemia, has not been carefully studied. We evaluated the response of one automated FiO2-SpO2control system to 9,486 desaturations in 21 infants over 113 days. We found that the sustained response to desaturations resulted primarily in achievement of normoxemia with balance between high and low saturations. We concluded that this closed loop control system was adequately damped. We suggest that this kind of analysis might be helpful is refining control algorithms.