High-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in surfactant-treated rabbits with lung injury

The aim of this study was to compare high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) with and without sur factant in the treatment of surfactant-deficient rabbits. A previously desc ribed saline Lung lavage model of lung injury in adult rabbits was used. Th e efficacy of each therapy was: assessed by evaluating gas exchange, Lung d eflation stability and lung histopathology. Arterial oxygenation did not improve in the CMV group without surfactant bu t increased rapidly to prelavage values in the other three study groups. Du ring deflation stability, arterial oxygenation decreased to postlavage valu es In the group that received HFOV alone, but not in both surfactant-treate d groups (HFOV and CMV). The HFOV group without surfactant showed more cell ular infiltration and epithelial damage compared with both surfactant-treat ed groups. There was no difference in HFOV gas exchange, lung deflation sta bility 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 mechani cal ventilation in improving gas exchange, lung deflation stability and in the prevention of lung injury, if lungs are kept expanded. This indicates t hat achieving and maintaining alveolar expansion (i.e. open lung) is of mor e importance than the type of ventilator.