Improvement of gas exchange, pulmonary function, and lung injury with partial liquid ventilation. A study model in a setting of severe respiratory failure.

STUDY OBJECTIVE: To evaluate gas exchange, pulmonary function, and lung histology during gas ventilation of the perfluorocarbon-filled lung compared with gas ventilation of the gas-filled lung in severe respiratory failure. STUDY DESIGN: Application of gas (GV) or partial liquid (PLV) ventilation in lung-injured sheep. SETTING: A research laboratory at a university medical center. SUBJECTS: Eleven sheep 17.1 +/- 1.8 kg in weight. INTERVENTIONS: Lung injury was induced by intravenous administration of 0.07 mL/kg oleic acid followed by saline pulmonary lavage. When alveolar-arterial oxygen pressure difference (P[A-a]O2) was 600 mm Hg or more and PaO2 was 50 mm Hg or less with fraction of inspired oxygen of 1.0, bijugular venovenous extracorporeal life support (ECLS) was instituted. For the first 30 min on ECLS, all animals were ventilated with gas. Over the ensuing 2.5 h, ventilation with 15 mL/kg gas was continued without intervention in the control group (GV, n = 6) or with the addition of 35 mL/kg of perflubron (PLV, n = 5). MEASUREMENTS AND RESULTS: At 3 h after initiation of ECLS, Qps/Qt was significantly reduced in the PLV animals when compared with the GV animals (PLV = 41 +/- 13%; GV = 93 +/- 4%; p < 0.005). At the same time point, pulmonary compliance was increased in the PLV when compared with the GV group (PLV = 0.61 +/- 0.14 mL/cm H2O/kg; GV = 0.41 +/- 0.02 mL/cm H2O/kg; p < 0.005). The ECLS flow rate required to maintain the PaO2 in the 50 to 80 mm Hg range was substantially and significantly lower in the PLV group when compared with that of the GV group (PLV = 25 +/- 20 mL/kg/min; GV = 87 +/- 15 mL/kg/min; p < 0.001). Light microscopy performed on lung biopsy specimens demonstrated a marked reduction in lung injury in the liquid ventilated (LV) when compared with the GV animals. CONCLUSION: In a model of severe respiratory failure, PLV improves pulmonary gas exchange and pulmonary function and is associated with a reduction in pulmonary pathology.

Oxygen dynamics during partial liquid ventilation in a sheep model of severe respiratory failure.

BACKGROUND: We evaluated the relationship of dose of perflubron and gas tidal volume to oxygen dynamics during partial liquid ventilation in the setting of respiratory failure. METHODS: Lung injury was induced in 16 sheep by using right atrial injection of 0.15 ml/kg oleic acid. Animals were ventilated with 15 ml/kg gas tidal volume and stabilized. Animals were then divided into three groups: (1) gas ventilation with a tidal volume of 15 ml/kg (control, GV, n = 5); (2) partial liquid ventilation at a gas tidal volume of 15 ml/kg with 10 ml/kg incremental pulmonary dosage of perflubron from 10 to 50 ml/kg (best fill, BF, n = 6); (3) administration of 35 ml/kg perflubron pulmonary dose with 5 ml/kg incremental increase in gas tidal volume from 10 to 30 ml/kg (best tidal volume, BTV, n = 5). RESULTS: Arterial oxygen saturation increased with increasing dose of perflubron and gas tidal volume (BF, p = 0.01; BTV, p = 0.001). A simultaneous trend toward a reduction in cardiac index was observed with increasing dose of perflubron (BF, p = 0.01). Maximal increase in mixed venous oxygen saturation was observed in the BF and BTV groups at a cumulative perflubron dose of 40 ml/kg and a gas tidal volume of 20 ml/kg, respectively. CONCLUSIONS: In this sheep lung injury model oxygenation improves with incremental increases in perflubron dose or gas tidal volume, and the mixed venous oxygen saturation appears to be optimal at a cumulative perflubron dose of 40 ml/kg and a gas tidal volume of 20 ml/kg.