26 - Liquid Ventilation.pdfVIP

CHAPTER 26 Liquid Ventilation Jürgen P. Meinhardt and Michael Quintel Attempts to improve the outcome of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remain major challenges in contemporary critical care medicine. Both ALI and ARDS represent the final common pathway of widely independent, simultaneously operating cellular and humoral mediator systems and cascades.1 Apparently, numerous and heterogeneous dis- eases as well as extrinsic factors are related to the devel- opment and progression of ALI and ARDS. Primary (pulmonary) and secondary (extrapulmonary) types of ARDS, including their reaction to different therapeutic interventions, may represent epiphenomena of different respiratory mechanics rather than expressing a real relationship with the underlying disease process. Certainly, the most important finding of the last decade was our increasing knowledge about the iatrogenic consequences of ventilatory treatment, including volu- trauma, atelect-trauma, and biotrauma.2 The concept of minimizing the iatrogenic consequences of conventional mechanical ventilation represents the background for the development and investigation of alternative treatment strategies such as high-frequency oscillation ventilation (HFOV), extracorporeal lung support, pulmonary appli- cation of surfactant, and liquid ventilation. This chapter focuses on the intrapulmonary application of liquids to establish liquid ventilation in its different forms. HISTORICAL BACKGROUND The physiologic implications of liquid filling in mammalian lungs, such as in the fetal stage, have occupied researchers for thousands of years. Early knowledge of pulmonary physiology was gained indirectly through the pathophysiology of drowning and pulmonary edema. In ancient times, the role of the lungs as “gas exchange units” was not understood. Galen believed that the lungs of drowning mammals took up water until the overfill of stomach and intestines caused the death of the organism.3 In 1