http://repub.eur.nl/res/aut/13461/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/9095/ 1999-01-01T00:00:00Z We have compared three treatment strategies, that aim to prevent repetitive alveolar collapse, for their effect on gas exchange, lung mechanics, lung injury, protein transfer into the alveoli and surfactant system, in a model of acute lung injury. In adult rats, the lungs were ventilated mechanically with 100% oxygen and a PEEP of 6 cm H2O, and acute lung injury was induced by repeated lung lavage to obtain a PaO2 value < 13 kPa. Animals were then allocated randomly (n = 12 in each group) to receive exogenous surfactant therapy, ventilation with high PEEP (18 cm H2O), partial liquid ventilation or ventilation with low PEEP (8 cm H2O) (ventilated controls). Blood-gas values were measured hourly. At the end of the 4-h study, in six animals per group, pressure-volume curves were constructed and bronchoalveolar lavage (BAL) was performed, whereas in the remaining animals lung injury was assessed. In the ventilated control group, arterial oxygenation did not improve and protein concentration of BAL and conversion of active to non-active surfactant components increased significantly. In the three treatment groups, PaO2 increased rapidly to > 50 kPa and remained stable over the next 4 h. The protein concentration of BAL fluid increased significantly only in the partial liquid ventilation group. Conversion of active to non-active surfactant components increased significantly in the partial liquid ventilation group and in the group ventilated with high PEEP. In the surfactant group and partial liquid ventilation groups, less lung injury was found compared with the ventilated control group and the group ventilated with high PEEP. We conclude that although all three strategies improved PaO2 to > 50 kPa, the impact on protein transfer into the alveoli, surfactant system and lung injury differed markedly. http://repub.eur.nl/res/pub/9198/ 1999-01-01T00:00:00Z The aim of this study was to compare high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) with and without surfactant in the treatment of surfactant-deficient rabbits. A previously described saline lung lavage model of lung injury in adult rabbits was used. The efficacy of each therapy was assessed by evaluating gas exchange, lung deflation stability and lung histopathology. Arterial oxygenation did not improve in the CMV group without surfactant but increased rapidly to prelavage values in the other three study groups. During deflation stability, arterial oxygenation decreased to postlavage values in the group that received HFOV alone, but not in both surfactant-treated groups (HFOV and CMV). The HFOV group without surfactant showed more cellular infiltration and epithelial damage compared with both surfactant-treated groups. There was no difference in gas exchange, lung deflation stability and lung injury between HFOV and CMV after surfactant therapy. It is concluded that the use of surfactant therapy in combination with high-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in improving gas exchange, lung deflation stability and in the prevention of lung injury, if lungs are kept expanded. This indicates that achieving and maintaining alveolar expansion (i.e. open lung) is of more importance than the type of ventilator.