PARTIAL LIQUID VENTILATION

Partial liquid ventilation (PLV) is a relatively new therapeutic appro ach to acute lung injury (ALI) and the acute respiratory distress synd rome (ARDS). The idea of combining the intrapulmonary application of a n oxygen-carrying substance and positive pressure ventilation was intr oduced by Fuhrman in 1991 and originally called perfluorocarbon-associ ated gas exchange (PAGE). Nowadays, the technique is mostly known as p artial liquid ventilation (PLV). The efficacy of PVL treatment has bee n demonstrated in numerous animal studies in different models of lung injury.The results of those studies led to multicenter phase I-II stud ies in patients of all age groups in the United States and Canada. Rec ently the first randomized, controlled study in 90 adult patients suff ering from ALI and ARDS was completed and first results have been publ ished. Comparison of overall mortality and number of ventilator-free d ays (VFD's) in a 28-day period showed no differences between PLV and c onventionally treated patients. A post-hoc stratification by age (<55 years) demonstrated a tendency to lower mortality (PLV 25.6%; CMV 36.8 %) and a significant increase of VFD (PLV 8.95 days; CMV 4.11 days; p= 0,03) in PLV when compared to conventionally treated patients. Perfluo rocarbons (PFCs) are chemically stable and inert.They are mostly elimi nated via exhalation (>99%).The unique physicochemical properties of P FCs permit access to atelectatic, non-ventilated lung areas,enhance ga s exchange and decrease inflammation.The dense PFCs prevent the endexp iratory collapse of alveoli and reestablish functional residual capaci ty (FRC).Comparable to positive endexpiratory pressure (PEEP), these e ffects have been described as ''liquid or fluid PEEP''. These properti es offer a new approach to the underlying pathophysiology of ALI and A RDS. In addition, the combination with other therapeutic approaches to ALI and ARDS like high-frequency oscillations (HFO), inhaled nitric o xide (NO) therapy, and surfactant replacement can be considered and is already the subject of recent publications. However, combination ther apy is still experimental and further investigation is necessary to ev aluate efficacy and potential risks. Many questions still exist which need to be answered by experimental as well as human pilot studies, Ea sed on these studies, the results of ongoing human trials can be asses sed properly and new multicenter trials can be planned effectively.