High-frequency oscillatory ventilation of the perfluorocarbon-filled lung: Dose-response relationships in an animal model of acute lung injury

Objective: To examine dose-response relationships regarding the efficiency of gas exchange and hemodynamic function during high-frequency oscillation and partial liquid ventilation (HFO-PLV) of the perfluorocarbon (PFC)-treated lung in a model of acute lung injury. Setting: An animal research laboratory in a university medical center. Design: A prospective, randomized study comparing animals receiving varying doses (0, 5, 15, and 20 mL/kg) of perflubron during high-frequency oscillatory ventilation (HFOV) with mean airway pressure (Paw) optimized to achieve a minimal percutaneous oxygen saturation (SpO₂). Subjects: Nineteen healthy swine (mean weight 28.9 kg) with saline lavage-induced acute lung injury. Methods: Animals were treated with repetitive saline lavage to achieve a uniform degree of acute lung injury (SpO₂ ≤90% on an FIO₂ of 1.0). After lung injury, subjects were converted to HFOV, and lung volume was optimized. HFO-PLV was initiated by instillation of perflubron at a rate of 0.5 mL·kg^-1·min^-1 to achieve total doses of 5, 15, and 20 mL/kg. After PFC dosing, the only experimental manipulation consisted of adjustment of Paw to achieve an SpO₂ of 90% ± 2% with FIO₂ of 0.6. Gas exchange, hemodynamic variables, and pulmonary mechanics data were collected over a 1-hr period. Five control animals were not dosed with perflubron and remained on HFOV for the 1-hr period of data collection. Measurements and Main Results: After lung volume recruitment with HFOV, the initiation of HFO-PLV was best tolerated with the two lower doses in our protocol. There were essentially no changes in PaCO₂ or pH between groups over the dosing interval. After dosing, analysis of variance demonstrated a PFC dose-dependent effect for oxygenation index (p = .01) only; the lowest oxygenation index was found in the 15 mL/kg group (p = .01). In the 15 mL/kg group, the Paw decreased steadily from 20.6 ± 3.4 cm H₂O at the end of dosing to 18.0 ± 4.9 cm H₂O at 60 mins. The PaO₂ increased from 113 ± 51 torr (15.06 ± 6.79 kPa) to 134 ± 49 torr (17.86 ± 6.53 kPa) during this period and was associated with a decreasing oxygenation index (from 11.4 ± 2.0 to 9.3 ± 1.5). The cardiac index and pulmonary vascular resistance did not change significantly during the dosing period and were relatively stable after the completion of dosing. Conclusions: The combination of HFOV and perflubron administration was well tolerated hemodynamically and was not associated with deterioration of gas exchange during dosing. Our data suggest that the optimal dose of perflubron to achieve the lowest oxygenation index during HFO-PLV is between 5 and 15 mL/kg. The combination of HFOV and perflubron administration is a novel strategy in the treatment of acute lung injury that shows some promise and merits additional investigation, We hope in future studies to address the histopathologic effects of varying perflubron doses during HFOV in a long-term study of the lung-protective effects of HFO-PLV.