Exogenous surfactant enhances mucociliary clearance in the anaesthetized dog

Therapy with exogenous surfactants is currently used for the treatment of respiratory distress syndrome of the newborn (RDS) and is under investigation for treatments related to adult RDS. However, the possible use of exogenous surfactant as a means of enhancing mucus clearance in other respiratory diseases has not been addressed. We therefore studied the effects of an artificial surfactant (Curosurf) on in vivo tracheal mucus velocity in intubated pentobarbital-anaesthetized dogs. Five dogs were randomly administered, on separate occasions, either vehicle (saline) or 10 mg Curosurf by means of local instillation via a catheter into the right lung. Tracheal mucus was collected by inserting a soft-bristled cytology brush to the level of the carina, and analysed for viscoelasticity by microrheometry. Mucociliary clearability in vivo, tracheal mucus velocity (TMV) in mm.min-1, was determined by bronchoscopic observation of charcoal marker particle transit times. The initial placement of charcoal was at the same level of the lower trachea that mucus was collected from. The effect of ciliary beat frequency was assessed on the frog palate assay by a videoscopic technique. In the dog, TMV was significantly increased after administration of surfactant. The values of TMV in the vehicle- and surfactant-treated dogs were 6.3 +/- 4.0 vs 25.6 +/- 6.5 mm.min-1 (SD), respectively. There were no discernible differences between prevehicle and postvehicle TMV values, and no significant differences in any mucus viscoelastic parameter, as determined by magnetic rheometry.(ABSTRACT TRUNCATED AT 250 WORDS)