Polyethylene glycol (PEG) attenuates exogenous surfactant in lung-injured adult rabbits

Exogenous surfactant administration in patients with the acute respiratory distress syndrome is currently being evaluated, although resource limitations and the potential expense are existing concerns. Previous in vitro and in vivo studies have shown that substances such as polyethylene glycol (PEG) added to exogenous surfactant improved the function of the surfactant. Based on these data, we hypothesized that PEG would augment surfactant function in an adult rabbit model of lung injury induced by lung lavage and mechanical ventilation, and that this would be accomplished by altering surfactant metabolism. Contrary to our hypothesis, however, mean Pa-O2, Pa-CO2, and peak inspiratory pressures values 3 h after treatment were significantly worse in the surfactant + PEG treatment groups compared with the surfactant alone groups. These effects were observed for two different doses of surfactant tested. Lavage analyses after sacrifice showed that animals given PEG with their surfactant had significantly lower total and large aggregate surfactant pool sizes compared with animals given surfactant alone. We conclude that in this lung injury model, PEG attenuated surfactant responses, suggesting that further preclinical studies are required before testing this approach in humans.