Surfactant and partial liquid ventilation via conventional and high-frequency techniques in an animal model of respiratory distress syndrome

Objective:To compare the physiologic and pathologic effects of conventional ventilation (CV) and high-frequency ventilation (HFV) during partial liquid ventilation (PLV) with perflubron after surfactant treatment with the results of HFV plus surfactant in an animal lung-injury model created by saline lavage. We also studied the dose effects of perflubron during HFV. Design:Randomized experimental study. Setting:Research animal laboratory. Subjects:A total of 32 newborn piglets. Interventions:After lung injury was induced, the animals were randomized to one of four groups: a) CV+ surfactant+ perflubron to functional residual capacity (FRC); b) HFV+ surfactant+ perflubron to FRC; c) HFV+ surfactant+ 10 mL/kg perflubron; and d) HFV+ surfactant. All then received intratracheal surfactant. After 30 mins, perflubron was administered to the PLV groups. The animals underwent ventilation for 20 hrs. Measurements and Main Results:Arterial blood gases and hemodynamic variables were continuously monitored. Pulmonary histologic and morphometric analyses were performed after death or euthanasia at 20 hrs. All animals had sustained improvements in arterial/alveolar oxygen ratios, and no differences were observed among groups. All HFV groups required higher mean airway pressures to maintain oxygenation (p <. 05). Hemodynamics did not differ among groups. Pathologic analysis demonstrated decreased lung injury in both cranial-dorsal (nondependent) and caudal-ventral (dependent) lobes of all animals treated with PLV when compared with those treated with HFV+ surfactant (p <. 05). Conclusions:After surfactant treatment, physiologic support over 20 hrs was similar during HFV with or without perflubron and CV with perflubron. All PLV modalities improved lung pathologic factors uniformly to a greater degree than did HFV+ surfactant. A lower treatment volume of perflubron during HFV produced physiologic and pathologic results similar to those produced by perflubron with respect to FRC during either CV or HFV.