Mechanical ventilation is a lifesaving intervention for critically ill patients, but can also be harmful due to increased lung stress and strain. High frequency oscillatory ventilation (HFOV) is theoretically an ideal lung protective ventilation strategy. However, superiority of HFOV over conventional mechanical ventilation has not been demonstrated in clinical studies. In this thesis of Pauline de Jager we proposed that one of the explanations for this is how currently HFOV is used in daily practice.
We implemented an individualized, physiology based approach to HFOV in children. The strategy is based on the principles of optimized lung volume and the delivery of small pressure amplitudes to reduce lung stress and strain. For this purpose, we implemented a staircase pressure titration to optimize lung volume and use of low oscillatory frequencies to achieve these smallest pressure amplitudes.
This physiology based approach was shown to be feasible, safe and efficacious in terms of oxygenation and ventilation in children with and without an underlying cardiac anomaly presenting with severe acute lung diseases including pediatric acute respiratory distress syndrome. Importantly, we found strong heterogeneity in lung behavior during the staircase pressure titration, underscoring the need for an individualized approach.
This thesis supports the physiology-driven open lung HFOV approach when targets for oxygenation and ventilation while maintaining non-injurious ventilator settings. We advocate a slow individualized, staircase recruitment of the lung after switching to HFOV. The effects of HFOV should not only be evaluated directly after the lung recruitment but also at least one hour afterwards. Enhanced monitoring tools for HFOV titration are necessitated.
