Many of the initial studies were performed in premature, surfactant-deficient animal models of respiratory insufficiency. Studies in early preterm animals clearly demonstrated improvement in compliance, gas exchange, and survival during liquid ventilation when compared to gas ventilation. Subsequent research has revealed marked improvements in parameters of gas exchange and pulmonary function during total and partial liquid ventilation, when compared to gas ventilation, in fullterm newborn, pediatric, and adult animal models of respiratory failure. In preterm newborns, gas exchange may be enhanced during liquid ventilation because of a reduction in the alveolar surface tension which is associated with ventilation of the liquid-filled lung. The mechanical lavage associated with total liquid ventilation may have a salutary effect in the setting of ARDS, pneumonia, or meconium aspiration since exudate may be evacuated from the lungs.
Perfluorocarbons also enhance alveolar recruitment in the setting of atelectasis.
Specifically, the atelectatic, consolidated, dependent regions of the lungs, which contribute greatly to the associated physiologic shunt observed during gas ventilation in the setting of ARDS, are re-inflated during liquid ventilation. It appears that perfluorocarbons enhance recruitment of alveoli in the setting of atelectasis and, because they are relatively dense, have a predilection for the dependent zones of the lungs. This results in re-inflation of dependent, atelectatic segments and more homogenous ventilation of the lungs. A second effect of the relatively dense perfluorocarbons may be to redistribute blood flow from the dependent to the non-dependent regions of the lung. In 1990, the first clinical evaluation of liquid ventilation was reported in three premature, moribund newborns who underwent pulmonary lavage with perfluorocarbons.