Surfactant lung lavage is a promising approach in the treatment of meconium aspiration syndrome (MAS). We hypothesise that the enrichment of modified natural surfactant with dextran will enhance meconium clearance from the airspaces during lung lavage and improve lung function in experimental MAS. Human meconium (30 mg/ml; 4 ml/kg) was instilled into the tracheal cannula of anaesthetised and paralysed adult rabbits to induce respiratory failure. The animals were then lavaged with saline (Sal), surfactant without (Surf) and with dextran (Surf+dex). Lung lavage (10 ml/kg in three portions) was performed with diluted surfactant (Curosurf, 10 mg/ml, 100 mg/kg) without or with dextran (3 mg/mg of surfactant phospholipids) or saline and the animals were conventionally ventilated with 100% O(2) for an additional hour. Lung functions were measured prior to and after meconium instillation, and 10, 30 and 60 min after lavage. The recovery of meconium in bronchoalveolar lavage (BAL) fluid was quantified. More meconium solids was recovered in the surfactant-lavaged than in the saline-lavaged groups (Surf: 12.4 +/- 3.9% and Surf+dex: 17.5 +/- 3.5% vs. Sal: 4.8 +/- 1.0%; both P < 0.01). Moreover, more meconium solids was obtained by Curosurf/dextran than by Curosurf-only lavage (P < 0.05). In the Surf group, the values for PaO(2)/FiO(2) were significantly higher than in the controls (at 60 min: 24.5 +/- 4.2 kPa vs.9.1 +/- 2.2 kPa, P < 0.01). An additional increase in oxygenation was seen in the Surf+dex group (at 60 min: 34.2 +/- 8.1 kPa, P vs. Surf group <0.01). The lung-thorax compliance was higher in the Surf+dex group in comparison with the Sal and Surf groups (at 60 min: 9.6 +/- 0.9 vs.7.6 +/- 1.2, P < 0.01 and 8.0 +/- 0.7 ml/kPa/kg, P < 0.05). The enrichment of Curosurf with dextran improves meconium clearance and lung functions in surfactant-lavaged rabbits with meconium aspiration.