LIQUID-ASSISTED VENTILATION - PHYSIOLOGY AND CLINICAL-APPLICATION

Liquid-assisted ventilation, as an alternative ventilation strategy fo r respiratory distress, is progressing from theory and basic science r esearch to clinical application. Biochemically inert perfluorochemical liquids have low surface tension and high solubility for respiratory gases. From early immersion experiments, two primary techniques for li quid-assisted ventilation have emerged: total liquid ventilation and p artial liquid ventilation. While computer-controlled, time-cycled, pre ssure/volume-limited total liquid ventilators can take maximum advanta ge of these liquids by completely eliminating the gas phase in the dis tressed lung, partial liquid ventilation takes advantage of having the se liquids in the lung while maintaining gas ventilation. The benefits of both partial and total techniques have been demonstrated in animal models of neonatal and adult respiratory distress syndrome, aspiratio n syndromes and congenital diaphragmatic hernia and also in combinatio n with other therapeutic modalities including extracorporeal membrane oxygenation, high-frequency ventilation and nitric oxide. Additionally , nonrespiratory applications have expanding potential including pulmo nary drug delivery and radiographic imaging. Since its use in neonates in 1989, liquid-assisted ventilation in humans has progressed to a va riety of clinical experiences with different aetiologies of respirator y distress. The future holds the opportunity to clarify and optimize t he potential of multiple clinical applications for liquid-assisted ven tilation.