Addition of ionic and nonionic water-soluble
polymers to
pulmonary surfactants in the presence of inactivating substances prevents
surfactant inactivation in vitro and improves lung function in several models of
lung injury. However, a recent report found opposite effects when
surfactant plus
polyethylene glycol (PEG) was used to treat
lung injury caused by saline lung lavage. Therefore, we examined the reasons why the
polymer effect is less evident in the saline lung lavage
lung injury model. We treated rats with lavage
lung injury with a commercial lung
surfactant extract derived from bovine lung (
Survanta) with or without addition of PEG. Groups treated with
Survanta + PEG had significantly higher static post mortem lung volumes than groups treated with
Survanta. However, groups treated with
Survanta + PEG had more tracheal fluid and no significant benefit in arterial oxygenation compared with the group treated with
Survanta, despite our use of measures to reduce
pulmonary edema. Measurements after intravascular
injections of (125)I-labeled
albumin confirmed that addition of PEG increased extravascular lung water and that this effect is mitigated by
furosemide. We conclude that
surfactant + PEG mixtures are less effective in lavage injury than in other forms of
lung injury because of increased extravascular lung water.