The effect of the tonicity of saline nasal douching solutions on mucociliary clearance was studied in order to ascertain whether hypertonicity conferred any advantage. Thirty-eight normal subjects were included in a randomised double-blind crossover trial. Saline douching solutions of 0.9%, 3% and 5% tonicity were used and mucociliary clearance was measured by the saccharin clearance time (SCT). The resultant SCT after administration of 5% saline was significantly reduced compared to both 0.9% (P = 0.005) and 3% saline (P = 0.04). There was no difference between 0.9% and 3% saline administration. Thus hypertonic saline solutions improve mucociliary clearance, although this was only observed with solutions of 5% tonicity. The effect is probably brought about by changes in mucus rheology.

Exogenous surfactant therapy is not standard in the acute respiratory distress syndrome (ARDS) because of a lack of proven benefit. Nonuniform surfactant distribution after either bolus or aerosol administration may be an important factor limiting response. In a previous study of acute lung injury, we demonstrated that lavage administration of Exosurf (13.5 mg phospholipid/ml) was both effective and distributed uniformly in the lungs. Since the endogenous surfactant pool is much smaller than the typical dose of exogenous surfactant administered, we hypothesized that dilute surfactant preparations (4-4.5 mg phospholipid/ml) administered by lung lavage would be equally effective in reversing pulmonary dysfunction in a piglet model of acute lung injury. We compared three dilute surfactants: Infasurf (n = 5), KL4-Surfactant (n = 6), and Exosurf (n = 5) with controls (n = 6) and undiluted Exosurf (13. 5 mg phospholipid/ml; n = 6). All dilute surfactant preparations were effective in improving oxygenation and other parameters of pulmonary function. Surfactant administered by lavage resulted in uniform lung distribution. We conclude that dilute surfactants administered by lung lavage are effective in reversing pulmonary dysfunction after acute lung injury. We speculate that doses in the range of 20-40 mg phospholipid/kg may be adequate to improve lung function in ARDS when exogenously administered surfactant is uniformly distributed in the lung.