Partial liquid ventilation compared with conventional mechanical ventilation in an experimental model of acute lung...

To compare the effects of partial liquid ventilation with conventional mechanical ventilation on oxygenation and pulmonary mechanics in saline lavaged rabbits.

Following acute lung injury (saline-lavage), rabbits were assigned to continue conventional mechanical ventilation (n = 6) or commence partial liquid ventilation (n = 6). In both groups the inspired oxygen concentration was 100% throughout the study. The target PaCO2 of 40-60 mmHg was accomplished by keeping the tidal volume between 7 and 10 mL/kg. During the study the peak inspiratory pressure was adjusted to maintain the target PaCO2. Arterial blood gases were taken pre-lavage, immediately post-lavage (time = 0) and then hourly for 5 hours. Pulmonary mechanics were estimated by measuring compliance and resistance. Pulmonary function was measured pre-lavage, immediately post-lavage and at 1 and 5 hours. At 5 hours the rabbits were killed and the lungs were removed for histological examination.

Baseline PaO2, compliance and resistance were not significantly different between groups. The partial liquid ventilation group had a higher PaO2 and a significantly better oxygenation index one hour after commencing partial liquid ventilation and a significantly higher PaO2 averaged over the three hours post-treatment. There were no significant differences in compliance, resistance or lung damage scores.

In this experimental model of acute lung injury, partial liquid ventilation resulted in immediate and sustained increase in PaO2 over 3 hours without significant change in lung mechanics or histological lung damage.