Partial liquid ventilation (PLV)

Abstract

Partial liquid ventilation using PFCs is a relatively new therapeutic approach for the treatment of acute lung injury (ALI) and ARDS. Partial liquid ventilation combines the intrapulmonary application of an oxygen carrying liquid with conventional gas ventilation and was firstly introduced by Fuhrman in 1991 as perfluorocarbon associated gas exchange (PAGE). Today mostly the term partial liquid ventilation (PLV) is used. To our current knowledge the PFCs instilled into the lungs during the procedure are not metabolized in the human body due to their mostly unbranched carbon chains and their extremely stable fluorine-carbon bonds. PFCs are nearly totally eliminated via exhalation; only a very small amount of about 1% is eliminated via transpiration and unchanged biliary excretion. The unique physialchemical properties of PFCs allow the transport of reasonable amounts of oxygen and carbon dioxide. Additionally, these properties are responsible for the preferential distribution of the liquid to otherwise atelectatic, non aerated and ventilated areas, thus inducing lung recruitment. Gas transport to these regions and/or a redistribution of pulmonary blood flow result in an improvement of gas exchange by improved V/Q matching. Additionally PFCs can reduce the inflammatory reaction of the alveolar environment. The mechanisms responsible for these anti-inflammatory properties are currently unknown. Numerous animal studies have demonstrated the efficacy of PLV in various species and in different models of lung injury. In the US and Canada, clinical studies with patients of all ages have been performed using the PFC perflubron (LiquiVent®, Alliance Pharmaceutical, San Diego, CA). First results of a randomized controlled multicenter phase I–II study in 90 adult patients have been presented in 1997; this study was published definitively in 1998. PLV can be combined with other therapeutic interventions for the treatment of severe pulmonary failure. Studies combining PLV with different ventilator patterns including high frequency oscillation ventilation (HFOV) have been performed. Additionally, the combined application with surfactant or the use in combination with inhaled nitric oxide and inhaled or instilled prostaglandin (PGE1) has been investigated. In 1998, a new randomized controlled multicenter study was started in the US and Canada which was been extended to Europe in 1999 and is currently underway.