Partial liquid ventilation versus conventional mechanical ventilation with high PEEP and moderate tidal volume in acute respiratory failure in piglets

This prospective randomized pilot study aimed to test the hypotheses that partial liquid ventilation combined with a high positive end-expiratory pressure (PEEP) and a moderate tidal volume results in improved gas exchange and lung mechanics without negative hemodynamic influences compared with conventional mechanical ventilation in acute lung injury in piglets. Acute lung injury was induced in 12 piglets weighing 9.0 +/- 2.4 kg by repeated i.v. injections of oleic acid and repeated lung lavages. Thereafter, the animals were randomly assigned either to partial liquid ventilation (n = 6) or conventional mechanical ventilation (n = 6) at a fractional concentration of inspired O-2 of 1.0, a PEEP of 1.2 kPa, a tidal volume < 10 mL/kg body weight (bw), a respiratory rate of 24 breaths/min, and an inspiratory/expiratory ratio of 1:2. Perfluorocarbon liquid 30 mL/kg bw was instilled into the endotracheal tube over 10 min followed by 5 mL/kg bw/h. Continuous monitoring included ECG, mean right atrial, pulmonary artery, pulmonary capillary, and arterial pressures, arterial blood gas, and partial pressure of end-tidal CO2 measurements. When compared with control animals, partial liquid ventilation resulted in significantly better oxygenation with improved cardiac output and oxygen delivery. Dead space ventilation appeared to be lower during partial liquid ventilation compared with conventional mechanical ventilation. No significant differences were observed in airway pressures, pulmonary compliance, and airway resistance between both groups. The results of this pilot study suggest that partial liquid ventilation combined with high PEEP and moderate tidal volume improves oxygenation, dead space ventilation, cardiac output, and oxygen delivery compared with conventional mechanical ventilation in acute lung injury in piglets but has no significant influence on lung mechanics.