Comparing the effects of four different perfluorocarbons on gas exchange and lung mechanics in an animal model of acute lung injury

Partial liquid ventilation (PLV), a hybrid technique that superimposes gas ventilation on lungs that are filled with perfluorocarbons (PFCs), has been shown to improve oxygenation in animal models of acute lung injury (ALI). Several physico-chemical properties of perfluorocarbons are considered impo rtant in their capability to improve pulmonary function. This study was per formed to allow a direct comparison of four perfluorocarbons with different physico-chemical properties during PLV with respect to gas exchange, lung mechanics, alveolar protein influx and surfactant system. Thirty-six adult male Sprague-Dawley rats were anesthetized, tracheotomized and submitted to pressure controlled mechanical ventilation at an FiO(2) of 1.0, 30 breaths /min, I/E of 1:2, a positive inspiratory pressure (PIP) of 26 cmH(2)O, and a PEEP of 6 cmH(2)O. Acute lung injury was induced by repeated lung lavages to obtain a PaO2 < 100 mmHg. After steady state, animals were randomly div ided teach group n=6) to receive either APF-140, APF-215, APF-175A or FC 32 80 intratracheally, in a dose of 15 ml/kg body weight. One group received n o PFCs, but was ventilated with a PIP of 28 cmH(2)O and a PEEP of 8 cmH(2)O (ventilated control group). Gas exchange was determined hourly during a 4 h observation period. In the groups that received PFCs, evaporational losse s were compensated for. Instillation of APF 175A resulted in a significant and sustained improvement in gas exchange, an increase in total lung capaci ty, and prevented an increase in alveolar protein influx. Instillation of A PF 140 transiently increased oxygenation and prevented an increase in alveo lar protein influx, but did not increase total lung capacity. In the other two perfluorocarbon treated groups, gas exchange did not improve and no dif ferences were found compared with the ventilated controls. We conclude that the efficacy of perfluorocarbons to improve pulmonary function cannot be p redicted based on their physico-chemical properties.